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Distillation-based waste water pretreatment and recovered water posttreatment methods are proposed for the NASA Space Station. Laboratory investigation results are reported for two nonoxidizing urine pretreatment formulas (hexadecyl trimethyl ammonium bromide and Cu/Cr) which minimize the generation of volatile organics, thereby significantly reducing posttreatment requirements. Three posttreatment methods (multifiltration, reverse osmosis, and UV-assisted ozone oxidation) have been identified which appear promising for the removal of organic contaminants from recovered water.

International audience; Recent internal combustion (IC) engine developments focus on gasoline fuel. This requires a better understanding of fuel reactivity at different thermodynamic conditions. Gasoline fuel reactivity control by additives is an efficient method to get better IC engine performances. 2-Ethylhexyl nitrate (EHN) promoting effect (0.1-1% mol.) on combustion has been investigated experimentally and numerically. Rapid compression machine (RCM) experiments were carried out at equivalence ratio 0.5 at 10 bar, from 675 to 995 K. The targeted surrogate fuel is a mixture of toluene and n-heptane in order to capture the additive effect on both cool flame and main ignition. A kinetic model was developed from literature data assembly and validated upon a large set of variations including species profiles and ignition delays of pure compounds as well as mixtures. At the experimental conditions, it was found that the EHN reduces the ignition delay time (IDT) of the surrogate fuel in the whole temperature range. EHN effectiveness tends to be minimum around 705 K and increases with temperature. The results also indicate that EHN effect increases nonlinearly with EHN doping levels. Numerical analyses revealed that the EHN effect is linked to NO2-NO loops, which enhances fuel reactivity. The methodology proposed here enable to simulate the EHN effect with simple compounds rather than the full EHN chemistry set. This strategy could simplify the consideration of additive effect when computational fluid dynamics (CFD) simulations are performed on engine. Finally, the study also highlights the EHN effectiveness on several thermodynamic conditions as well as equivalence ratios. The objective is to assess its performance upon large operating conditions which appears to be of interest with novel combustion systems targeting low temperature as well as lean combustion.

In this work the performance and noxious emissions of a prototype Spark Ignition (SI) engine, working in ultra-lean conditions, are investigated. It is a four-cylinder engine, having a very high compression ratio, and an active pre-chamber. The required amount of air is provided by a low-pressure variable geometry turbocharger, coupled to a high-pressure E-compressor. The engine is equipped with a variable valve timing device on the intake camshaft. The goal of this activity is to support the development and the calibration of the described engine, and to exploit the full potential of the ultra-lean concept. To this aim, a combustion model for a pre-chamber engine, set up and validated in a previous paper for a similar single-cylinder unit, is utilized. It is coupled to additional in-house developed sub-models, employed for the prediction of the in-cylinder turbulence, heat transfer, knock and pollutant emissions. Such a complex architecture, schematized in a commercial 1D modeling framework, presents several control parameters which have to be properly selected to maximize the engine efficiency and minimize the noxious emissions over its whole operating domain. A Rule-Based (RB) calibration strategy is hence implemented in the 1D model to identify the optimal values of each control variable. The reliability of the RB calibration is also demonstrated through the comparison with the outcomes of a general-purpose optimizer, over a load sweep at a constant speed. The 1D model and the RB methodology are then applied for the performance prediction over the whole engine operating domain. The predicted performances show the possibility to achieve a wide zone of very high efficiency, with limited penalizations only at very low loads. Main advantages of the lean-combustion concept are highlighted, concerning a higher specific heat ratio, reduced heat losses, improved knock mitigation, and abatement of pollutant emissions, especially regarding CO and NOx. The presented methodology demonstrates to be a valuable tool to support the development and calibration of the considered high-efficiency engine architecture.

This paper evaluates a thermodynamic ice crystal icing model that has been previously presented to describe the possible mechanisms of icing within the core of a turbofan jet engine. The model functions between two distinct ice accretions based on a surface energy balance: freeze-dominated icing and melt-dominated icing. Freeze-dominated icing occurs when liquid water (from melted ice crystals) freezes and accretes on a surface along with the existing ice of the impinging water and ice mass. This freeze-dominated icing is characterized as having strong adhesion to the surface. The amount of ice accretion is partially dictated by a freeze fraction, which is the fraction of impinging liquid water that freezes. Melt-dominated icing occurs as unmelted ice on a surface accumulates. This melt-dominated icing is characterized by weakly bonded surface adhesion. The amount of ice accumulation is partially dictated by a melt fraction, which is the fraction of impinging ice crystals that melts. Experimentally observed ice growth rates suggest that only a small fraction of the impinging ice remains on the surface, implying a mass loss mechanism such as splash, runback, bounce, or erosion. The fraction of mass loss must be determined in conjunction with the fraction of freezing liquid water or fraction of melting ice on an icing surface for a given ice growth rate. This mass loss parameter, however, along with the freeze fraction and melt fraction, are the only experimental parameters that are currently not measured directly. Using icing growth rates from ice crystal icing experiments, a methodology that has been previously proposed is used to determine these unknown parameters. This work takes ice accretion data from tests conducted by the National Aeronautics and Space Administration (NASA) at the Glenn Research Center in 2018 that examined the fundamental physics of ice crystal icing. This paper continues evaluation of the thermodynamic model from a previous effort, with additions to the model that account for sub-freezing temperatures that have been observed at the leading edge of the airfoil during icing. The predicted temperatures were generally in good agreement with measured temperatures. Other key findings include the total wet-bulb temperature being a good first order indicator of whether icing is freeze-dominated (sub-freezing values) or melt-dominated (above freezing). Maximum sticking efficiency values, the fraction of impinging mass that adheres to a surface, was calculated to be about 0.2, and retained this maximum value for a range of melt ratios (0.3 to 0.65 and possibly higher), which is defined as the ratio of liquid water content to total water content. Higher air velocities reduced the maximum sticking efficiency and shifted the icing regime to higher melt ratio values. Finally, the leading edge ice accretion angle was found to be related to ice growth (lower growth rates for smaller angles) and melt ratio (smaller melt ratios resulted in smaller angles, likely due to erosion effects).

This paper describes an ice-crystal icing experiment conducted at the NASA Propulsion System Laboratory during June 2018. This test produced ice shape data on an airfoil for different test conditions similar to those inside the compressor region of a turbo-fan jet engine. Mixed-phase icing conditions were generated by partially freezing out a water spray using the relative humidity of flow as the primary parameter to control freeze-out. The paper presents the ice shape data and associated conditions which include pressure, velocity, temperature, humidity, total water content, melt ratio, and particle size distribution. The test featured a new instrument traversing system which allowed surveys of the flow and cloud. The purpose of this work was to provide experimental ice shape data and associated conditions to help develop and validate ice-crystal icing accretion models. The results support previous experimental observations of a minimum melt-ratio threshold for accretion to occur as well as the existence of a plateau region where the icing severity is high for a range of melt ratios. However, a maximum limit for melt ratio, which is suggested in the ice crystal icing literature, was not observed perhaps complicated by the potential for some supercooling of the water at these conditions.

The major contribution of this paper is to propose a low-cost accurate distance estimation approach. It can potentially be used in driver modelling, accident avoidance and autonomous driving. Based on MATLAB and Python, sensory data from a Continental radar and a monocular dashcam were fused using a Kalman filter. Both sensors were mounted on a Volkswagen Sharan, performing repeated driving on a same route. The established system consists of three components, radar data processing, camera data processing and data fusion using Kalman filter. For radar data processing, raw radar measurements were directly collected from a data logger and analyzed using a Python program. Valid data were extracted and time stamped for further use. Meanwhile, a Nextbase monocular dashcam was used to record corresponding traffic scenarios. In order to measure headway distance from these videos, object depicting the leading vehicle was first located in each frame. Afterwards, the corresponding vanishing point was also detected and used to automatically compute the camera posture, which is to minimize the interference caused by camera vibration. The headway distance can hence be obtained by assuming the leading and host vehicles were in the same ground plane. After both sensory data were obtained, they were synthesized and fused using Kalman filter, to generate a better estimation of headway distance. The performances of both sensors were assessed individually and the correlation between their measurements was evaluated by replotting radar measurements on the video stream. The results of individual sensors and Kalman filter were compared to investigate the optimization performance of the data fusion approach.This is a general guidance of headway distance estimation with a low cost radar and a monocular camera. With described general procedures, this paper can allow researchers to easily fuse radar and camera measurements to obtain optimized headway distance estimation. This paper can facilitate the development of a more realistic robotic driver that can mimic human driver behaviors.

A computational fluid dynamics study of the scavenging process in a large two-stroke marine engine is presented in this work. Scavenging which is one of the key processes in the two-stroke marine engines, has a direct effect on fuel economy and emissions. This process is responsible for fresh air delivery, removing the combustion products from the cylinder, cooling the combustion chamber surfaces and providing a swirling flow for better air-fuel mixing. Therefore, having a better understanding of this process and the associated flow pattern is crucial. This is not achievable solely by experimental tests for large engines during engine operation due to the difficulties of measuring the flow field inside the cylinder. In this study, the axial and tangential velocities are compared and validated with the experimental results obtained from Particle Image Velocimetry (PIV) tests [1]. The simulations are conducted using both Unsteady Reynolds Averaged Navier Stokes (URANS) and Large Eddy Simulation (LES) turbulence models. We observe in general, there is a good agreement between the numerical and experimental results. The flow inside the cylinder is studied in different locations related to the bottom of the scavenging ports during the period with open exhaust valve. Moreover, the replacement of combustion products with fresh scavenge air is analysed. The effective flow angle is calculated for the air flow through the scavenging ports. It is found that the effective flow angle is different from the geometrical angle of the ports (20o). Results illustrate better performance of LES, especially in the prediction of the tangential velocity which is crucial for the simulation of an accurate swirl and air-fuel mixing inside the marine engines. LES predicts a uniform profile for the tangential velocity at the top of cylinder which is consistent with the experimental results while URANS predicts a solid body rotation.

This paper is based upon work supported by Saudi Aramco Research and Development Center FUELCOM3 program under Master Research Agreement Number 6600024505/01.FUELCOM (Fuel Combustion for Advanced Engines), is a collaborative research undertaking between Saudi Aramco and KAUST intended to address the fundamental aspects of hydrocarbon fuel combustion in engines, and develop fuel/engine design tools suitable for advance combustion modes.

CO 2 regulations on heavy-duty transport are introduced in essentially all markets within the next decade, in most cases in several phases of increasing stringency. To cope with these mandates, developers of engines and related equipment are aiming to break new ground in the fields of combustion, fuel and hardware technologies. In this work, a novel diesel fuel injector, Delphi's DFI7, is utilized to experimentally investigate and compare the performance of ramped injection rates versus traditional square fueling profiles. The aim is specifically to shift the efficiency and NO x tradeoff to a more favorable position. The design of experiments methodology is used in the tests, along with statistical techniques to analyze the data. Results show that ramped and square rates- A fter optimization of fueling parameters-produce comparable gross indicated efficiencies. Tests were carried out at 1200 and 1425 rpm; for the latter engine speed peak efficiency was attained at considerably lower NO x levels by applying a ramped injection rate. Particulate matter emissions, on the other hand, are generally lower with the use of square profiles. Heat release analysis further reveals that ignition delays in ramped rate operation are quite long, hinting at vastly different spray behavior. The relatively low loads applied in this work only sustain the delays further. Altogether, this causes the potential of the rate shaping capabilities to be underexploited, as direct control over the burn rate is limited with the combustion system used in this work. The results emphasize the need to carefully select ramp slopes for a particular engine geometry, load and speed point, and additional operating parameter settings.

The paper is based upon work supported by Saudi Aramco Research and Development Center FUELCOM3 program under Master Research Agreement Number 6600024505/01. FUELCOM (Fuel Combustion for Advanced Engines) is a collaborative research undertaking between Saudi Aramco and KAUST intended to address the fundamental aspects of hydrocarbon fuel combustion in engines, and develop fuel/engine design tools suitable for advanced combustion modes. The author would like to thank King Abdullah University of Science and Technology (KAUST) and the Clean Combustion Research Center (CCRC) for lab facilities and research support. Last but not least, the authors would like to convey gratitude towards the IC Engine Lab Safety Supervisor Adrian I. Ichim and the lab technician Riyad H. Jambi for their kind input and assistance in performing the experiments.

Since, ice accretion can significantly degrade the performance and the stability of an airborne vehicle, it is imperative to be able to model it accurately. While ice accretion studies have been performed on airplane wings and helicopter blades in abundance, there are few that attempt to model the process on more complex geometries such as fuselages. This paper proposes a methodology that extends an existing in-house Extended Messinger solver to complex geometries by introducing the capability to work with unstructured grids and carry out spatial surface streamwise marching. For the work presented here commercial solvers such as STAR-CCM+ and ANSYS Fluent are used for the flow field and droplet dispersed phase computations. The ice accretion is carried out using an in-house icing solver called GT-ICE. The predictions by GT-ICE are compared to available experimental data, or to predictions by other solvers such as LEWICE and STAR-CCM+. Three different cases with varying levels of complexity are presented. The first case considered is a commercial transport airfoil, followed by a three-dimensional MS(1)-317 swept wing. Finally, ice accretion calculations performed on a Robin fuselage have been discussed. Good agreement with experimental data, where applicable, is observed. Differences between the ice accretion predictions by different solvers have been discussed.

In this paper the effects of a rough underbody on the rear wake structure of a simplified squareback model (the Windsor model) is investigated using balance measurements, base pressure measurements and two and three component planar PIV. The work forms part of a larger study to develop understanding of the mechanisms that influence overall base pressure and hence the resulting aerodynamic drag. In the work reported in this paper the impact of a rough underbody on the base pressure and wake flow structures is quantified at three different ground clearances. The underbody roughness has been created through the addition of five roughness strips to the underbody of the model and the effects on the wake at ground clearances of 10.3%, 17.3% and 24.2% of the model height are assessed. All work has been carried out in the Loughborough University Large Wind Tunnel with a scale model giving a blockage ratio of 4.4% for a smooth under-body or 4.5% with the maximum thickness roughness strips. The tests are conducted with a fixed ground plane. Results are presented for the base pressure distribution and these are compared against the stream-wise PIV results. This work demonstrates the need for rough underbody structures to be considered during base pressure investigations before any model scale work is conducted due to their influence on the wake structures. Copyright © 2013 SAE International.

This joint mobility KC lecture included information from two papers, "A Method for and Issues Associated with the Determination of Space Suit Joint Requirements" and "Results and Analysis from Space Suit Joint Torque Testing," as presented for the International Conference on Environmental Systems in 2009 and 2010, respectively. The first paper discusses historical joint torque testing methodologies and approaches that were tested in 2008 and 2009. The second paper discusses the testing that was completed in 2009 and 2010.

In partially premixed combustion engines high octane number fuels are injected into the cylinder during the late part of the compression cycle, giving the fuel and oxidizer enough time to mix into a desirable stratified mixture. If ignited by auto-ignition such a gas composition can react in a combustion mode dominated by ignition wave propagation. 3D-CFD modeling of such a combustion mode is challenging as the rate of fuel consumption can be dependent on both mixing history and turbulence acting on the reaction wave. This paper presents a large eddy simulation (LES) study of the effects of stratification in scalar concentration (enthalpy and reactant mass fraction) due to large scale turbulence on the propagation of reaction waves in PPC combustion engines. The studied case is a closed cycle simulation of a single cylinder of a Scania D13 engine running PRF81 (81% iso-octane and 19% n-heptane). Two injection timings are investigated; start of injection at -17 CAD aTDC and -30 CAD aTDC. One-equation transported turbulence sub-grid closure is used for the unresolved momentum and scalar fluxes and the fuel spray is modelled using a Lagrangian particle tracking (LPT) approach. Initial flow conditions (prior to intake valve closing) are generated using a scale forcing method with a prescribed large-scale swirl mean flow motion. Fuel reactivity is modeled using finite rate chemistry based on a skeletal chemical kinetic mechanism (44 species, 140 reactions). The results are compared with optical engine experimental data and satisfactory agreement with the experiments is obtained in terms of the liquid spray length, cylinder pressure trace and ignition location. A majority of the fuel consumption is found to be in ignition fronts where small variations in temperature at low fuel concentrations are observed to cause large stratification in ignition delay time. (Less)

High altitude ice crystals can pose a threat to aircraft engine compression and combustion systems. Cases of engine damage, surge and rollback have been recorded in recent years, believed due to ice crystals partially melting and accreting on static surfaces (stators, endwalls and ducting). The increased awareness and understanding of this phenomenon has resulted in the extension of icing certification requirements to include glaciated and mixed phase conditions. Developing semi-empirical models is a cost effective way of enabling certification, and providing simple design rules for next generation engines. A comprehensive ice crystal icing model is presented in this paper, the Ice Crystal Icing ComputationaL Environment (ICICLE). It is modular in design, comprising a baseline code consisting of an axisymmetric or 2D planar flowfield solution, Lagrangian particle tracking, air-particle heat transfer and phase change, and surface interactions (bouncing, fragmentation, sticking). In addition, an efficient particle tracking method has been developed into the code, which employs the representative particle size distribution at each injection location and a deterministic particle sticking method by using an in-situ particle based scaling factor without aborting the particle trajectories. Various time integration algorithms, including implicit and explicit Euler and Runge-Kutta methods, are discussed and the effect on an acceptable timestep investigated. The model then improves on those available in the literature in three ways: firstly, an adaptation of the Extended Messinger Model (EMM) to mixed phase conditions is incorporated, improving the fidelity of the ice accretion prediction compared with the classical Messinger model. Secondly, an experimentally-derived model for sticking efficiency improves the accuracy of the continuity equation in the EMM; thirdly a simple model for integrating two-way coupling of mass and energy is proposed.

NASA and the FAA (Federal Aviation Administration) conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding and develop onboard weather radar processing to detect regions of high ice water content ahead of an aircraft and enable tactical avoidance of the potentially hazardous conditions. Both High Ice Water Content (HIWC) RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory which was equipped with a Honeywell RDR-4000 weather radar and icing instruments to characterize the ice crystal clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results.

As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a 2018 Toyota Camry A25A-FKS 4-cylinder, 2.5-liter, naturally aspirated, Atkinson Cycle engine with cooled exhaust gas recirculation (cEGR) was benchmarked. The engine was tested on an engine dynamometer with and without its 8-speed automatic transmission, and with the engine wiring harness tethered to a complete vehicle parked outside of the test cell. Engine and transmission torque, fuel flow, key engine temperatures and pressures, onboard diagnostics (OBD) data, and Controller Area Network (CAN) bus data were recorded. This paper documents the test results under idle, low, medium, and high load engine operation. Motoring torque, wide open throttle (WOT) torque and fuel consumption are measured during transient operation using both EPA Tier 2 and Tier 3 test fuels. The design and performance of this 2018 2.5-liter engine is described and compared to Toyota’s published data and to EPA’s previous projections of the efficiency of an Atkinson Cycle engine with cEGR. The Brake Thermal Efficiency (BTE) map for the Toyota A25A-FKS engine shows a peak efficiency near 40 percent, which is the highest value of any publicly available map for a non-hybrid production gasoline internal combustion (IC) engine designed to run on 91 RON fuel. Further improvement is possible by application of fixed discrete or full continuous cylinder deactivation, both of which are currently in production on other engines.

Approximately 25 % of a passenger vehicle’s aerodynamic drag comes directly or indirectly from its wheels, indicating that the rim geometry is highly relevant for increasing the vehicle’s overall energy efficiency. An extensive experimental study is presented where a parametric model of the rim design was developed, and statistical methods were employed to isolate the aerodynamic effects of certain geometric rim parameters. In addition to wind tunnel force measurements, this study employed the flowfield measurement techniques of wake surveys, wheelhouse pressure measurements, and base pressure measurements to investigate and explain the most important parameters’ effects on the flowfield. In addition, a numerical model of the vehicle with various rim geometries was developed and used to further elucidate the effects of certain geometric parameters on the flow field. The results showed that the most important parameter was the coverage area, and it was found to have a linear effect on the aerodynamic drag. Interestingly, parameters associated with the outer radial region of wheel (rim cover) were also found to be significant, along with the wheel depth of center (flatness). The flowfield measurements showed, again, that the coverage area had the most significant effect, with it directly affecting how much flow passes through the front rim and subsequently affecting features like the near-ground jetting vortex and vortices out of the wheelhouse. In addition, the coverage area also affected the pressure recovery at the base of the vehicle and the wheelhouse pressure. The effects of other parameters are also detailed in the paper. The effects of different coverage area at the front and rear rims on the drag coefficient were investigated, where having a high coverage at the rear reduced drag the most.

This paper presents an experimental methodology which can be adopted to measure the friction torque of the bearings in the wheel hubs of passenger vehicles. The first section of the paper highlights the reasons why an experimental device is necessary to have an objective evaluation of the performance of the bearing in terms of friction. In particular, the high level of approximation of the current formulas for the estimation of the friction inside a single bearing is discussed and demonstrated. An analytical methodology for the evaluation of the distribution of the axial load between the two bearings of the wheel hub is presented. However, its practical application for the precise calculation of the distribution of the load has to be checked through experimental tests. The following part of the paper is focused on the possible solutions which can be adopted to conceive a test rig to measure friction inside the bearings of wheel hubs by considering the effect of the real loads acting on the hubs of the vehicle (due to the forces between the tires and the road surface). The most efficient solution of test rig is developed and implemented for the evaluation of the friction of the bearings of a 3-wheel low consumption vehicle. This solution, which can be properly sized according to the considered application, can be extended also to the evaluation of the performance, in terms of friction, of the hubs of series production passenger cars

Observation problems have been garnering increasing at- tention in recent years. They can be seen as the esti- mation of a periodic output dynamics driven by periodic inputs. At various level of modelling, automotive engine dynamics can be considered as a linear periodic sys- tem mechanically coordinated through the revolution of the crankshaft. In this paper, two practical examples are addressed. The first example is the inversion of sensor dynamics. A classical way of modelling such a sensor is a first order dynamics with periodic excitations which can be, depending on the application, the intake pressure, the intake temperature, the exhaust pressure, the Air Fuel Ra- tio, or the Mass Air Flow. The second example is the es- timation of the engine speed next to the cylinder using as only sensor the easily available instantaneous crankshaft angle speed at the end of the connecting rod. The contribution of this paper is the design of a real-time observer of the periodic excitation of a linear periodic sys- tems by the estimation of the Fourier decomposition of the signal. The estimation of the coefficients of the Fourier basis decomposition of the input periodic excitation is a handy tool for engineering purposes. Indeed, the energy levels of the signal allow another interpretation of the sig- nal and can lead to detect the balance of the engine. This high frequency (6 o crankshaft estimation) information can be used for imbalance diagnosis and torque balance con- trol. Real application observation problems are exposed in their practical context and illustrated by experimental results on a 4 cylinder HCCI engine.

This paper illustrates the applicability of a sequential fluid mechanics, multi-zone chemical kinetics model to analyze HCCI experimental data for two combustion chamber geometries with different levels of turbulence: a low turbulence disc geometry (flat top piston), and a high turbulence square geometry (piston with a square bowl). The model uses a fluid mechanics code to determine temperature histories in the engine as a function of crank angle. These temperature histories are then fed into a chemical kinetic solver, which determines combustion characteristics for a relatively small number of zones (40). The model makes the assumption that there is no direct linking between turbulence and combustion. The results show that the multi-zone model yields good results for both the disc and the square geometries. The model makes good predictions of pressure traces and heat release rates. The experimental results indicate that the high turbulence square geometry has longer burn duration than the low turbulence disc geometry. This difference can be explained by the sequential multi-zone model, which indicates that the cylinder with the square bowl has a thicker boundary layer that results in a broader temperature distribution. This broader temperature distribution tends to lengthen the combustion, as cold mass withinmore » the cylinder takes longer to reach ignition temperature when compressed by the expansion of the first burned gases. The multi-zone model, which makes the basic assumption that HCCI combustion is controlled by chemical kinetics, is therefore capable of explaining the experimental results obtained for different levels of turbulence, without considering a direct interaction between turbulence and combustion. A direct connection between turbulence and HCCI combustion may still exists, but it seems to play a relatively minor role in determining burn duration at the conditions analyzed in this paper.« less

lnteraction of the human arm and deploying airbag has been studied in the laboratory using post mortem human subjects (PMHS). These studies have shown how arm position on the steering wheel and proximity to the airbag prior to deployment can influence the risk of forearm bone fractures. Most of these studies used older driver airbag modules that have been supplanted by advanced airbag technology. ln addition, new numerical human body models have been developed to complement, and possibly replace, the human testing needed to evaluate new airbag technology. The objective of this study is to use a finite element-based numerical (MADYMO) model, representing the human arm, to evaluate the effects of advanced driver airbag parameters on the injury potential to the bones of the forearm. The paper shows how the model is correlated to Average Distal Forearm Speed (ADFS) and arm kinematics from two PMHS tests. The PMHS testing employed different offsets (0 and 25mm) between the airbag and forearm in a driving position, using the two arms of the same human subject. The model is then exercised to determine predictive ability for forearm fracture seen with the Omm offset test, but not seen with the 25mm offset. The model accurately predicts fracture in the 0mm offset test, and no fracture in the 25mm offset test using a ADFS criterion of 10.5 m/s. Model elements in the ulna that rapidly exceed an arbitrary 1%o effective strain criteria correspond to fracture locations on the ulna of the Omm offset PMHS test. The model is then exercised to predict fracture using the ADFS criterion for multiple inflator outputs. The paper also discusses issues and recommendations for human model parameters to further increase the robustness of the model.

In Europe, over recent years, there has been a marked shift in the regulatory approach to ensuring system safety. Whereas compliance with prescriptive safety codes and standards was previously the norm, the responsibility has now shifted back onto the developers and operators to construct and present well reasoned arguments that their systems achieve acceptable levels of safety. These arguments (together with supporting evidence) are typically referred to as a safety case. This paper describes the role and purpose of a safety case (as defined by current safety and regulatory standards). Safety arguments within safety cases are often poorly communicated. This paper presents a technique called GSN (Goal Structuring Notation) that is increasingly being used in safety-critical industries to improve the structure, rigor, and clarity of safety arguments. Based upon the GSN approach, the paper also describes how an evolutionary and systematic approach to safety case construction, in step with system development, can be facilitated.

This paper shows a numerical evaluation of fuels and additives for HCCl combustion. First, a long list of candidate HCCl fuels is selected. For all the fuels in the list, operating conditions (compression ratio, equivalence ratio and intake temperature) are determined that result in optimum performance under typical operation for a heavy-duty engine. Fuels are also characterized by presenting Log(p)-Log(T) maps for multiple fuels under HCCl conditions. Log(p)-Log(T) maps illustrate important processes during HCCl engine operation, including compression, low temperature heat release and ignition. Log(p)-Log(T) diagrams can be used for visualizing these processes and can be used as a tool for detailed analysis of HCCl combustion. The paper also includes a ranking of many potential additives. Experiments and analyses have indicated that small amounts (a few parts per million) of secondary fuels (additives) may considerably affect HCCl combustion and may play a significant role in controlling HCCl combustion. Additives are ranked according to their capability to advance HCCl ignition. The best additives are listed and an explanation of their effect on HCCl combustion is included.

Copyright © 2002 SAE International. This paper is posted on this site with permission from SAE International. Further use of this paper is not permitted without permission from SAE Controlled Auto-Ignition (CAI) combustion was realised in a production type 4-stroke 4-cylinder gasoline engine without intake charge heating or increasing compression ratio. The CAI engine operation was achieved using substantially standard components modified only in camshafts to restrict the gas exchange process The engine could be operated with CAI combustion within a range of load (0.5 to 4 bar BMEP) and speed (1000 to 3500 rpm). Significant reductions in both specific fuel consumption and CO emissions were found. The reduction in NOx emission was more than 93% across the whole CAI range. Though unburned hydrocarbons were higher under the CAI engine operation. In order to evaluate the potential of the CAI combustion technology, the European NEDC driving cycle vehicle simulation was carried out for two identical vehicles powered by a SI engine and a CAI/SI hybrid engine, respectively. The simulation results showed only moderate improvement in fuel economy and exhaust emissions because of low utilisation of CAI during the drive cycle. In order to take full advantage of the CAI combustion technology, detailed analyses were carried out on the engine’s performance, heat release and combustion characteristics, emissions and the effect of gas exchange processes. These analyses showed that the engine’s performance and emissions were mainly affected by the trapped residual fractions and residual temperature. In addition, the backflow was found to affect the combustion and emission as well.

We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. This methodology combines a detailed fluid mechanics code with a detailed chemical kinetics code. Instead of directly linking the two codes, which would require an extremely long computational time, the methodology consists of first running the fluid mechanics code to obtain temperature profiles as a function of time. These temperature profiles are then used as input to a multi-zone chemical kinetics code. The advantage of this procedure is that a small number of zones (10) is enough to obtain accurate results. This procedure achieves the benefits of linking the fluid mechanics and the chemical kinetics codes with a great reduction in the computational effort, to a level that can be handled with current computers. The success of this procedure is in large part a consequence of the fact that for much of the compression stroke the chemistry is inactive and thus has little influence on fluid mechanics and heat transfer. Then, when chemistry is active, combustion is rather sudden, leaving little time for interaction between chemistry and fluid mixing and heat transfer. This sequential methodology has been capable of explaining the mainmore » characteristics of HCCI combustion that have been observed in experiments. In this paper, we use our model to explore an HCCI engine running on propane. The paper compares experimental and numerical pressure traces, heat release rates, and hydrocarbon and carbon monoxide emissions. The results show an excellent agreement, even in parameters that are difficult to predict, such as chemical heat release rates. Carbon monoxide emissions are reasonably well predicted, even though it is intrinsically difficult to make good predictions of CO emissions in HCCI engines. The paper includes a sensitivity study on the effect of the heat transfer correlation on the results of the analysis. Importantly, the paper also shows a numerical study on how parameters such as swirl rate, crevices and ceramic walls could help in reducing HC and CO emissions from HCCI engines.« less

The ability for crewmembers to explore the surface of the Moon or Mars effectively on foot remains a significant test of any exploration design. The availability of a pressurized rover would substantially increase the range of exploration by space suited crewmembers. The design of the airlock systems or functions will facilitate crewmembers in accomplishing these efforts. The pressurized rover for planetary exploration incorporates three types of airlocks or pressure ports: the EVA airlock, the sample airlock and the habitat docking port. This paper conducts a survey of selected precedents in pressurized rover design and then analyzes the key issues for airlock design. INTRODUCTION: THREE ENVIRONMENTS -THREE AIRLOCKS The airlock is the physical interface between the three working environments for crewmembers on the lunar or Mars surface. These environments are: the pressurized habitat in which the crew will live and work; the lunar/planetary surface and its atmosphere that require astronauts to wear space suits and carry their own life support; and the pressurized rover that gives them mobility over the surface. All three of these environments intersect in the pressurized rover. Thus, the pressurized rover for planetary exploration incorporates, at a minimum, three types of airlocks or pressure port functions: EVA egress and ingress, scientific sample ingress and removal, and docking or berthing to the pressurized habitat at the planetary base. Each of these three airlocks provides its own unique function that probably cannot be combined into a smaller number of devices. The EVA airlock enables spacesuited astronauts to egress and reenter the rover. The sample airlock provides the connection through which EVA crewmembers pass samples they have collected for analysis in the Astrobiology glove box, inside the rover. The habitat docking port is the connection through which the rover “docks” to the pressurized modules at the planetary base, and through which shirtsleeve crewmembers enter and exit the rover. REVIEW OF ROVER CONCEPTS & REQUIREMENTS In conducting this literature survey, the author began with the Apollo era studies such as the Lockheed MIMOSA study (1966-67) and the Boeing LESA study (1964-66). However, there was a remarkable 20 year hiatus between those studies in the mid-60s and the new flood of concepts that followed the landmark1984 conference on Lunar Bases and Space Activities of the 21st Century at the National Academy of Science in Washington DC (Mendell, 1985). This Conference set the philosophical agenda for human space exploration for at least the next 15 years, envisioning the return to the Moon and going on to Mars as one programmatic continuum. Beginning this review in the 1980s makes it possible to assume a common set of mission objectives and technologies, or at least an awareness of them on the part of the designers. The different approaches to these designs and technologies are significant for understanding why particular rover designs have certain attributes and lack others. Despite this sweep of time, the literature survey reveals surprisingly few serious studies of rover airlocks. Most airlock studies look at airlocks in general, in connection to Space Station or some other orbital vehicle. Thus, in selecting concepts from the literature for this review, it was a goal to find studies that address of airlocks, while including as many science-driven concepts as possible. From a design methodology perspective, this survey groups the pressurized rover concepts into three types of design approaches or sources: science-driven, mission architecture-driven, and system analysis-driven. TABLE 1 provides a comparative overview of the salient characteristics of each of the selected pressurized rover concepts that this paper discusses. These sets of requirements appear here much as they occur in the literature, with no effort to fill in

A contemporary approach for improving and developing the understanding of heavy-duty Diesel engine combustion processes is to use a concerted effort between experiments at well-characterized boundary conditions and detailed, high-fidelity models. In this paper, combustion processes of n-dodecane fuel sprays under heavy-duty Diesel engine conditions are investigated using this approach. Reacting fuel sprays are studied in a constant-volume pre-burn vessel at an ambient temperature of 900 K with three reference cases having specific combinations of injection pressure, ambient density and ambient oxygen concentration (80, 150 & 160 MPa - 22.8 & 40 kg/m3-15 & 20.5% O2). In addition to a free jet, two different walls were placed inside the combustion vessel to study flame-wall interaction. Experimentally, low- and high-temperature reaction product distributions are imaged simultaneously using single-shot planar laser-induced fluorescence (PLIF) of formaldehyde and high-speed line-of-sight imaging of the chemically-excited hydroxyl radical (OH). Interference of soot incandescence in experimental OH∗ recordings is assessed to improve interpretation of the results. Interference by poly-cyclic aromatic hydrocarbon (PAH) LIF and soot radiation is mostly evaded by evaluating flame structures shortly after ignition for one of the studied cases, but presumably included in others. Simulations were performed using a recently developed computational fluid dynamics (CFD) methodology with detailed chemistry and turbulence-chemistry interaction. Apart from the capability to model flame structures and combustion indicators based on optical diagnostics, heat-release rate trends are predicted accurately at varying boundary conditions. Significant variation in the distribution of low-temperature combustion products under heavy-duty operating conditions are explained using both CFD simulations and a one-dimensional jet model.

Particulate emissions from Gasoline Direct Injection (GDI) engines have been an important topic of recent research interest due to their known environmental effects. This review paper will characterise the influence of different gasoline direct injection fuel systems on particle number (PN) emissions. The findings will be reviewed for engine and vehicle measurements with appropriate driving cycles (especially real driving cycles) to evaluate effects of the fuel injection systems on PN emissions. Recent technological developments alongside the trends of the influence of system pressure and nozzle design on injector tip wetting and deposits will be considered. Besides the engine and fuel system it is known that fuel composition will have an important effect on GDI engine PN emissions. The evaporation qualities of fuels have a substantial influence on mixture preparation, as does the composition of the fuel itself. Recently a number of studies have attempted to link fuel composition with PN emissions, developing a variety of indices including the PM index (Aikawa et al.) and the PN index (Leach et al.). An extensive literature search has been carried out and the PN index evaluated against these data. In addition the PM index and PN index are compared. The results of the review show that the Aikawa index should be applied when the fuel quality is known by lab reports, whereas the Leach index is relevant when only minimal information about a fuel is known, even the latter giving a relatively good prediction of PN emission trends from fuels in GDI engines.

Lightly damped non-linear systems such as vehicular drivelines undergo a plethora of Noise, Vibration and Harshness (NVH) problems. The clonk phenomenon is one concern which occurs as the result of impulsive torque input in the form of sudden clutch actuation or throttle tip-in and back-out. The resulting impact of meshing gear pairs propagate structural waves down the driveline. With lightly damped thin-walled tubes having high modal density, elasto-acoustic coupling occurs. High frequency noise emission is of metallic nature and quite disconcerting to vehicle occupants as well as passers-by. It is perceived as structural failure and/or poor-quality build. Therefore, the occurrence of the phenomenon is a concern to vehicle manufacturers and progressively constitutes a warranty concern. This paper investigates the clonk phenomenon through use of a long-wheel base rear drive light truck test rig. The investigation uses psychoacoustic metrics to establish the severity of clonk noise in different maneuvers. This is an attempt to quantify the effect of transient clonk event which is usually ascertained through subjective evaluation ratings in a customer/jury clinic in industry. Alternatively, detailed numerical analysis is carried out with parametric studies to quantify different clonk events, a very time consuming approach which is not usually correlated with occupants’ perception of the event. Therefore, the experimental NVH monitoring-psycho-acoustic approach is new for the case of clonk and not hitherto reported in literature. The study corroborates the results and conclusions of previous work, pointing to the loudness and sharpness of high frequency short-lived “metallic” response, which is attuned to human aural perception. The psychoacoustic analysis has shown this to be as the result of short duration hard impact (accelerative period). This hard impact duration accounts for the bulk loudness and sharpness of the overall event. Therefore, effective palliation should focus on the attenuation of particular frequency bands, which carry the main contribution to loudness and sharpness.

With the increasing stringent emissions legislation on internal combustion engines, alongside requirements for enhanced fuel efficiency as key driving factors for many OEMs, there are many research activities supported by the automotive industry that focus on the development of hybrid and pure Electric Vehicles. This change in direction from engine downsizing to the use of electric motors presents many new challenges concerning NVH performance, durability and component life. This paper provides an experimental investigation into the measurement of NVH characteristics in these new powertrains, thus characterising the structure borne noise transmissibility through the shaft and the bearing to the housing. A feasibility study and design of a new system level test rig have been conducted to allow for sinusoidal radial loading of the shaft, which is synchronised with the shaft’s rotary frequency under high-speed transient conditions in order to evaluate the phenomena in the system. In the present work, simulations of the rig were conducted using the commercial multi-body dynamics software, AVL EXCITE Power Unit, providing insight to the systems response to different types of bearings such as deep groove ball bearings, tapered roller bearings and the cylindrical roller bearings. Moreover, influence factors such as bearing clearance and the amount of axial bearing preload are investigated. The test rig has multiple novel elements compared to those previously developed. In particular, the rotational speed of the shaft, which significantly exceeds that of previously reported rigs, and the excitation frequency ramp up at the same rate as the frequency of the shaft enabling the phenomena found in Hybrid and Electric Vehicles. The sinusoidal radial load is supplied using a loading device featuring a single load point to minimize undesired excitation effects. With respect to structure borne noise the system response is captured through the vibrational displacement of the shaft and bearing housing.

In this paper, computation fluid dynamics (CFD) simulations are employed to describe the effect of flow parameters on the formation of soot and NOx in a heavy duty engine under low load and high load. The complexity of diesel combustion, specially when soot, NOx and other emissions are of interest, requires using a detailed chemical mechanism to have a correct estimation of temperature and species distribution. In this work, Multiple Representative Interactive Flamelets (MRIF) method is employed to describe the chemical reactions, ignition, flame propagation and emissions in the engine. A phenomenological model for soot formation, including soot nucleation, coagulation and oxidation with O2 and OH is incorporated into the flamelet combustion model. Different strategies for modelling NOx are chosen to take into account the longer time scale for NOx formation. The numerical results are compared with experimental data to show the validity of the model for the cases under study. A good agreement is achieved between the model results and the pressure and heat release rate from the experiment. For soot and NOx, the model is able to correctly predict the trends between different cases. The effect of number of RIFs on the behaviour of the model is discussed.

This paper is a direct continuation of a previous study that addressed the performance and design of a variable compression engine, the Alvar-Cycle Engine [1]. The earlier study was presented at the SAE International Conference and Exposition in Detroit during February 23- 26, 1998 as SAE paper 981027. In the present paper test results from a single cylinder prototype are reviewed and compared with a similar conventional engine. Efficiency and emissions are shown as function of speed, load, and compression ratio. The influence of residual gas on knock characteristics is shown. The potential for high power density through heavy supercharging is analyzed. (Less)

Partially premixed combustion (PPC) can be applied to decrease emissions and increase fuel efficiency in direct injection, compression ignition (DICI) combustion engines. PPC is strongly influenced by the mixing of fuel and oxidizer, which for a given fuel is controlled mainly by (a) the fuel injection, (b) the in-cylinder flow, and (c) the geometry and dynamics of the engine. As the injection timings can vary over a wide range in PPC combustion, detailed knowledge of the in-cylinder flow over the whole intake and compression strokes can improve our understanding of PPC combustion. In computational fluid dynamics (CFD) the in-cylinder flow is sometimes simplified and modeled as a solid-body rotation profile at some time prior to injection to produce a realistic flow field at the moment of injection. In real engines, the in-cylinder flow motion is governed by the intake manifold, the valve motion, and the engine geometry. The deviation of the real in-cylinder flow from a solid body rotation flow field varies with different piston positions. This paper reports on an CFD study of the formation and development of a real engine in-cylinder flow field in an optical light duty PPC engine from the opening of the intake valve at -360 CAD ATDC up to 20 CAD ATDC in a motored case (without fuel injection). The focus is put on the analysis of the temporal and spatial development of the swirl flow motion. The resulting flow field of the simulation is compared with the results from CFD simulation of an initial axially symmetric (sector-mesh) flow in the cylinder. The adequateness of sector type mesh including solid-body rotation assumption as an initial flow is analyzed. (Less)

Second generation biomass is an attractive renewable feedstock for transport fuels. Its sulfur content is generally negligible and the carbon cycle is reduced from millions to tens of years. One hitherto non-valorized feedstock are so-called humins, a residual product formed in the conversion of sugars to platform chemicals, such as hydroxymethylfurfural and methoxymethylfurfural, intermediates in the production of FDCA, a building block used to produce the polyethylene furanoate (PEF) bottle by Avantium. The focus of this study is to investigate the spray combustion behavior of humins as a renewable alternative for heavy fuel oil (HFO) under large two-stroke engine-like conditions in an optically accessible constant volume chamber. To reduce the viscosity to HFO levels of the otherwise crystalline humins, methyl levulinate (ML), another side-stream from the same sugar dehydration process, is blended to the former compound at 25 wt.-%; a ratio comparable to that actually produced in many dehydration processes. Various fuel properties of interest, including elemental composition, heating value, density, ignition quality, acid number, flash point, pour point, carbon residue, sediment, water and ash content are measured for the resulting humins-ML blend. The blend is injected into an optically accessible constant volume chamber, the dimensions, injector characteristics and prevailing ambient conditions of which are representative of those found in large two-stroke marine engines. Commercial HFO is used as a benchmark. The combustion process is evaluated by means of shadow imaging and OH∗-chemiluminescence. The former and latter optical techniques are used to determine the phasing and overall magnitude of the heat release event, and ignition delay/location and flame lift off length, respectively. From the results becomes clear that the average ignition delay is comparable to that of HFO, albeit at a higher cycle-to-cycle variation. Notwithstanding a longer lift off length and more downstream ignition kernels, the overall results suggest that the proposed bio-blend is a feasible renewable alternative for HFO in terms of technical feasibility.

Traffic related NOx and particle emission remain a significant concern particularly in the urban environment. Electrification offers a medium to long term solution, but there remains a need to significantly reduce internal combustion engine emissions in the short and medium term, and potentially in the long term for long range inter city transportation. Late injection low temperature combustion (LTC) has the potential to achieve ultra-low emissions levels in a compression ignition engine by increasing the lean pre-mixed burn fraction. However, significant quantities of diluent are normally required to achieve the required delay in ignition and pre-mixing to achieve LTC. This results in high boost requirements, increased pumping work and the complexity of the air handling system and potentially adversely impacting fuel economy. In this paper, results from a single cylinder light duty research engine are presented using a novel ramped combustion chamber focused at mid to high engine loads. The ramped combustion chamber improves mixing and enables more retarded injection timings than those possible on conventional bowl designs. This combustion strategy has enabled LTC conditions to be achieved at lower dilution rates, typically 20-30% at loads up to 15bar IMEP. CFD analysis of the air-fuel interaction indicates the ramped bowl effectively deflects fuel away from the squish region enabling very late injection timings. One dimensional analysis of the engine system was used to investigate the potential of late exhaust valve opening in improving work recovery, resulting in improved fuel consumption over the baseline LTC valve timings

A precise estimation of the recirculated exhaust gas rate and oxygen concentration as well as a predictive evaluation of the possible EGR unbalance among cylinders are of paramount importance, especially if non-conventional combustion modes, which require high EGR flow-rates, are implemented. In the present paper, starting from the equation related to convergent nozzles, the EGR mass flow-rate is modeled considering the pressure and the temperature upstream of the EGR control valve, as well as the pressure downstream of it. The restricted flow-area at the valve-seat passage and the discharge coefficient are carefully assessed as functions of the valve lift. Other models were fitted using parameters describing the engine working conditions as inputs, following a semi-physical and a purely statistical approach. The resulting models are then applied to estimate EGR rates to both conventional and non-conventional combustion conditions. In a following step, a correlation was proposed between EGR rate and combustion metrics. This function was then applied to check the possibility of estimating the EGR unbalance, which can negatively affect combustion stability, in particular at high EGR rates. EGR unbalance was also evaluated considering the measurements of the temperature of the charge entering each cylinder. These two methods to evaluate EGR unbalance were then compared to CFD calculations.

This paper explores the potentiality of reducing noise and vibration of a vehicle transmission thanks to powertrain control integration with active braking. Due to external disturbances, coming from the driver, e.g. during tip-in / tip-out maneuvers, or from the road, e.g. crossing a speed bump or driving on a rough road, the torsional backlashes between transmission rotating components (gears, synchronizers, splines, CV joints), may lead to NVH issues known as clonk. This study initially focuses on the positive effect on transmission NVH performance of a concurrent application of a braking torque at the driving wheels and of an engine torque increase during these maneuvers; then a powertrain/brake integrated control strategy is proposed. The braking system is activated in advance with respect to the perturbation and it is deactivated immediately after to minimize losses. The powertrain control compensates for the added resistance and reestablishes the vehicle longitudinal performance according to driver's commands. The torsional preload created in the driveline is effective in preventing/reducing vibrations and associated noise. It is worth underlining that the proposed methodology can be directly applied to existing ABS/ESC units, composed of digital solenoid valves, and does not require additional hardware components. The effectiveness of this method has been experimentally validated by means of a Hardware In the Loop (HIL) test bench which includes a Dual Clutch (DCT) transmission and a hydraulic brake system with a customized ABS/ESC unit.

Clutches are commonly utilised in passenger type and off-road heavy-duty vehicles to disconnect the engine from the driveline and other parasitic loads. In off-road heavy-duty vehicles, along with fuel efficiency start-up functionality at extended ambient conditions, such as low temperature and intake absolute pressure are crucial. Off-road vehicle manufacturers can overcome the parasitic loads in these conditions by oversizing the engine. Caterpillar Inc. as the pioneer in off-road technology has developed a novel clutch design to allow for engine downsizing while vehicle’s performance is not affected. The tribological behaviour of the clutch will be crucial to start engagement promptly and reach the maximum clutch capacity in the shortest possible time and smoothest way in terms of dynamics. A multi-body dynamics model of the clutch system is developed in MSC ADAMS. The flywheel is introducing the same speed and torque as the engine (represents the engine input to the clutch). The hydraulic pressure is applied behind the piston to initiate the engagement. The angular motion of the plates is supported by friction torque between the plates and friction linings. The conjunctions between paper-based linings and steel plates are designed to be dry. Friction (the most significant tribological feature of the linings in torque transmission) is measured in a pin-on-disc tribometer and mapped into the dynamics model in MSC ADAMS. The pin-on-disc tribometer is able to capture the variation of friction coefficient with contact pressure and sliding velocity. The surface topography is obtained experimentally to examine the consistency of surface properties. The normal pressure and tribology of the contacting components determines the engagement time, clutch capacity and dynamic behaviour of the clutch.

Gaps in composite structures are a risky factor in aeronautical assemblies. For mechanically joined composite components, the geometrical conformance of the part can be problematic due to undesired or unknown re-distribution of loads within a composite component, with these unknowns being potentially destructive. To prevent unnecessary preloading of a metallic structure, and the possibility of cracking and delamination in a composite structure, it is important to measure all gaps and then shim any gaps greater than 127 microns. A strategy to overcome the high relative tolerances for assemblies lies in the automated manufacturing of shims for the gaps previously predicted through the evaluation of their volumes via a simulation tool. This paper deals with the development of a special end-effector prototype to enable the shimming of gaps in composites structures using a pre-processed geometry. The aim of this end-effector is to provide movement to a temperature controlled hot-end in order to generate a solid shim of ABS on the target composite surface. This process is defined according to the trajectories and velocities marked by the 3D printing process using standard G-code. The geometry and material volume to be printed are indicated by the simulated gap volume which is based on previous metrological measurements. The final objective will be to attach this end-effector to an anthropomorphic robot to enable autonomous manufacturing. This work is part of the EU FP7 funded LOCOMACHS project, under grant agreement n◦314003. European Union Seventh Framework Programme FP7/2007-2013 under grant agreement n° 314003; Basque program Elkartek Basqtech 2016

Selective catalytic reduction (SCR) has become the mainstream approach for removing heavy-duty (HD) diesel engine NOx emissions. Highly efficient SCR systems are a key enabling technology allowing engines to be calibrated for very high NOx output with a resultant gain in fuel consumption while still maintaining NOx emissions compliance. One key to the successful implementation of high efficiency SCR at elevated engine out NOx levels is the ability to introduce significantly more AdBlue into the exhaust flow while still ensuring complete ammonia production and avoiding the formation of deposits. This paper presents a body of experimental work conducted on an exhaust test bench using optical techniques including high-speed imaging and phase Doppler interferometry (PDI), applied under representative exhaust conditions to a HD diesel engine after-treatment system with optical access inside the mixer tube. Two different sprays were used to dose AdBlue onto the mixing device. A three-hole injector and a single-hole pressure-swirl injector were characterised in ambient and heated exhaust flow conditions. A metallic two-stage mixer and an uncoated cordierite ceramic substrate mixer were compared and demonstrated the ability of the substrate mixer to reduce deposit formation at higher dosing rates inside the mixer tube when used with the correct spray type. High-speed imaging revealed the ability of the substrate to absorb injected AdBlue spray at cooler exhaust temperatures. However, using the incorrect spray can lead to liquid saturation inside the substrate channels, which is detrimental due to the formation of deposits on the rear face of the substrate.

To further improve the efficiency and emissions profiles of internal combustion engines, many new combustion concepts are currently being investigated. Examples include homogeneous charge compression ignition (HCCI), stratified charge compression ignition (SCCI), lean stratified premixed combustion, and the use of high levels of exhaust gas recirculation (EGR) in diesel engines. The typical combustion temperatures in all of these concepts are lower than those in traditional spark ignition or diesel engines. Most of the combustion models that are currently used in computational fluid dynamics (CFD) simulations were developed to describe either premixed or non-premixed combustion under the assumption of fast chemistry. The refinement of existing combustion concepts for highly efficient clean engines and the development of new ones would be greatly facilitated by the introduction of new computational tools and combustion models that are mode- and regime-independent, i.e. capable of modeling both premixed and non-premixed and also fast and non-fast chemistry. Such tools should enable more accurate simulation of combustion under non-standard conditions such as those established during low temperature combustion. This paper presents a new regime-independent combustion modeling strategy for non-premixed combustion in which the linear eddy model (LEM) is used as a representative interactive regime-independent turbulent combustion model and coupled to a 3D CFD solver. Parameters and boundary conditions that determine the evolution of the LEM are supplied by the 3D CFD calculation and updated at each time step. The LEM is then solved for the corresponding time step, providing the 3D CFD code with an updated composition state. This new representative interactive linear eddy model (RILEM) is used to simulate an n-heptane spray, demonstrating some potential to describe spray combustion processes.

The over-riding objective in modern engine development is fuel efficiency. This has led to a host of pursued measures, including down-sizing (a lower number of cylinders), high output power-to-weight ratio, variable valve activation or cylinder de-activation (CDA) as well as a gradual trend towards mild or micro-hybrid technology. Furthermore, The main aim is to combine a suitable combination of the aforementioned methods with various driving conditions in order to reduce thermal and frictional losses as well as meeting the ever stringent emission directives as outlined in the NEDC. Another imperative is to ensure good NVH refinement which can be adversely affected by application of the above trends, such as light weight constructions and exacerbated power torque variations with CDA. The highlighted issues affect all the load bearing conjunctions in an engine. In particular, increased load fluctuations with CDA can also affect the whirl stability of big-end bearings. Therefore, the current paper concentrates on the issues that affect the big-end bearing thermo-frictional characteristics and dynamic stability in NEDC cycle. The predictive approach, which is critical in a multi-variate problem of this kind, includes determination of regime of lubrication under fluctuating loads and rictional characteristics contributed by both elastohydrodynamics of the bearing overlay as well as boundary friction as the result of asperity interactions. Predictive results include applied dynamics, contact kinematics, frictional power loss, maximum lubricant temperature and minimum film thickness variations during the NEDC. The difference between the CDA mode and the normal mode (all active cylinders). These show that the general benefits accrued through fuel efficiency do not necessarily conform to improved big end bearing frictional efficiency.

In this paper a novel approach to mimic through numerical simulation Cycle-to-Cycle Variations (CCV) of the combustion process of Spark Ignition (SI) engines is described. The proposed methodology allows to reproduce the variability in combustion which is responsible for knock occurrence and thus to replicate the stochastic behavior of this abnormal combustion phenomenon. On the basis of the analysis of a comprehensive database of experimental data collected on a typical European downsized and turbocharged SI engine, the proposed approach was demonstrated to be capable to replicate in the simulation process the same percentage of knocking cycles experimentally measured in light-knock conditions, after a proper calibration of the Kinetics-Fit (KF), a new phenomenological knock model which was recently developed by Gamma Technologies. Finally, the capability of the proposed methodology, coupled with the usage of the KF knock model, to correctly identify the Knock Limited Spark Advance (KLSA) on the basis both of the CCV-replicating model and of a more traditional average-cycle simulation was assessed over a wide range of different operating conditions, thus confirming its reliability and robustness.

Internal combustion engine components have been a main research interest over many decades [1]. While bulk material and surface engineering developments have improved the resistance to fatigue, reduced the amount of wear and friction during operation, small improvements in race applications designs can increase the engine performance and give a competitive edge to racing engines. Piston rings are designed to create a seal which means that they will suffer large levels of material loss due to wear during operation. The compression ring is the top or closest ring to combustion gases and is exposed to the highest operating temperature. In this paper, the authors propose a design modification to the compression ring coated chamfer which can reduce stress concentration and material loss during operation.

This paper develops an exhaust manifold pressure estimation method for a Diesel engine equipped with a variable geometry turbine (VGT) turbocharger. Extrapolated VGT data-maps are used directly for the estimation of the exhaust pressure using a non-iterative Newton-Raphson based method suitable for real-time applications. This approach can give more accurate estimations than traditional methods because it takes into account the turbine speed effect on the turbine mass flow rate. All this without increasing the calculation load significantly. The proposed exhaust manifold estimation can be used to relieve the exhaust manifold pressure physical sensor during engine operating conditions where its reliability is low. The estimator is evaluated in transient with two different engine cycles using a engine model validated in a benchmark as a reference.

The paper presents the development of a novel approach to the solution of detailed chemistry in internal combustion engine simulations, which relies on the analytical computation of the ordinary differential equations (ODE) system Jacobian matrix in sparse form. Arbitrary reaction behaviors in either Arrhenius, third-body or fall-off formulations can be considered, and thermodynamic gasphase mixture properties are evaluated according to the well-established 7-coefficient JANAF polynomial form. The current work presents a full validation of the new chemistry solver when coupled to the KIVA-4 code, through modeling of a single cylinder Caterpillar 3401 heavy-duty engine, running in two-stage combustion mode. The code has been tested on a wide range of simulations, at different injection timings, intake pressures, and EGR mass fractions, and considering two reaction mechanisms: a skeletal one with 29 species and 52 reactions, and a comprehensive, semi-detailed one with 160 species and 1540 reactions. The results show that the developed approach allows computational time savings of more than one order of magnitude in comparison to a reference chemistry solver, even with no reduction of the combustion mechanism size.

The brushless DC motors with permanent magnets are used primarily in law power applications. There are no limits on weight and motor dimensions in considered motors with DC stator excitation. Brushless series connected machine with DC stator excitation do not have rotor coils. Field coil and armature coils are mounted in the stator. Armature windings are connected to DC voltage source trough power transistors commutator. Power transistors are controlled by reflective optical sensors in function of rotor position. In the report, the new principle design of the motor with DC stator excitation is considered. The new principle of design supposes individual excitation for each of the armature phase. Such approach gives an opportunity to design electrical machine with any number of armature phases spaced in phase from each other. In series connected DC machines, the field winding is connected in series with the armature winding. In general, the series connection leads to a torque-speed characteristic that is useful in transport and crane mechanisms where need high start torque. For realization series connected machine with DC stator excitation, the number of armature phase can be two, three, or more. Increasing number of phase leads to more complicated design of machine and gives some advantages in performance. The minimum two or three phase gives the simplest design power electronic controller and the sensors position circuit. Like DC universal motor, the machine with series connected DC stator excitation, in principle, can operate from either from AC or DC voltage sources. The universal mode operation is described in this paper when motor operate from one phase AC voltage source. The prototype of two phase motor with DC stator excitation was realized on the base of a car alternator. Results of tests prototype motor and modeling in steady state condition prove that the property of brushless machine with DC stator excitation similar to those series, shunt connected, and separate exited DC machines. Considered machine can find application in the electric drive cars and hybrid electrical vehicles. Copyright © 2012 SAE International.

The influences of ethanol and iso-butanol blended with gasoline on engine-out and post Three-Way Catalyst (TWC) particle size distribution and number concentration were studied using a GM 2.0L turbocharged Spark Ignition Direct Injection (SIDI) engine. The engine was operated using the production ECU with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. US federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at ten selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm. Idle and low speed / low load conditions emitted higher total particle numbers than other operating conditions. At idle, the engine-out Particulate Matter (PM) emissions were dominated by nucleation mode particles, and the production TWC reduced these nucleation mode particles by more than 50%, while leaving the accumulation mode particle distribution unchanged. At engine load higher than 6 barmore » NMEP, accumulation mode particles dominated the engine-out particle emissions and the TWC had little effect. Compared to the baseline gasoline (E0), E10 does not significantly change PM emissions, while E20 and BU12 both reduce PM emissions under the conditions studied. Iso-butanol was observed to impact PM emissions more than ethanol, with up to 50% reductions at some conditions. In this paper, the issues related to PM measurement using FMPS are also discussed. While some uncertainties are due to engine variation, the FMPS must be operated under careful maintenance procedures in order to achieve repeatable measurement results.« less