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[EN] The generalization of exhaust aftertreatment systems along with the growing awareness about climate change is leading to an increasing importance of the efficiency over other criteria during the design of reciprocating engines. Using experimental and theoretical tools to perform detailed global energy balance (GEB) of the engine is a key issue for assessing the potential of different strategies to reduce consumption. With the objective of improving the analysis of GEB, this paper describes a tool that allows calculating the detailed internal repartition of the fuel energy in DI Diesel engines. Starting from the instantaneous in-cylinder pressure, the tool is able to describe the different energy paths thanks to different submodels for all the relevant subsystems. Hence, the heat transfer from gases to engine walls is obtained with specific convective and radiative models in the chamber and ports; the repartition of the heat flux throughout the engine metal elements towards the oil and coolant is estimated with a lumped capacitance model; finally, the ancillary systems and friction losses are obtained through specific semiempirical submodels. The validation of the tool is performed in a 4- cylinder DI Diesel engine instrumented to perform detailed experimental GEB. Finally, a simple analysis of combined internal and external analysis in the complete engine map shows the effect of operating conditions on each energy term. Thus it is demonstrated the utility of the proposed tool, that complements the experimental heat flow measurements in Diesel engine researches oriented to the reduction of energy consumption.

The assessment of the service durability of aerospace components and assemblies has become an important segment of design. In order to meet strict safety requirements, a number of complex and long experiments are carried out. The use of finite element method (FEM) and extended finite element method (XFEM) for the estimation of fatigue life and fatigue crack growth predictions has been proved as a good alternative to the expensive experimental methods. In this paper, both experimental and numerical analyses of 2024-T3 aluminum spar of a light aircraft under variable amplitude loading are presented. FEM has been used for estimation of the spar life to crack initiation, whereas XFEM has been used for fatigue crack growth predictions and fatigue life estimation of damaged spar. The values of stress intensity factors were extracted from the XFEM solution in MorfeoCrack for Abaqus software. Numerical results (i.e. number of cycles to failure) have corresponded well with the experimental values obtained for the spar made of 2024-T3 aluminum alloy. The investigations have shown that it's possible, using XFEM, to obtain not only the good estimation of fatigue life of the assembly such as the spar of the light aircraft, but also a good prediction of a number of load cycles which will propagate a crack to a certain length. On the basis of these results, it is possible to determine the proper inspections intervals which could prevent the catastrophic failure of the aircraft structure under variable amplitude loading.

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.

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.

[EN] Nowadays turbocharging the internal combustion engine has become a key point in the reduction on pollutant emissions and the improvement on engine performance. The matching between the turbocharger and the engine is vital due to the highly unsteady flow the turbocharger works with. In the present paper the importance of the heat transfer phenomena inside small automotive turbochargers will be analyzed. This phenomenon will be studied from the point of view of both the turbine and the compressor in one-dimensional modelling. The goodness of the model will be demonstrated predicting turbine and compressor outlet temperatures. An accurate prediction of these parameters will be key designing the intercooler and the after treatment devices. A series of tests in a gas stand with steady and pulsating hot flow in the turbine side will be modeled to show the good agreement in turbocharger enthalpies prediction.

Problems in the turbocharger lubrication system can cause serious deterioration in their overall performance and even their complete destruction. The paper describes several tests with different critical lubrication conditions, in order to determine the thresholds at which the operation may be appropriate. In an IC engine, these problems can be produced mainly by several factors: the decreasing in the supply pressure of the oil, a delay in the lubrication oil pressure and an intermittent lubrication interruption. A turbocharger test bench and an IC engine test bench has been used to test the turbocharger, in order to reproduce the conditions and cycles similar to the operation of the turbocharger in an IC engine (pressures, temperatures, mass flows, accelerations, etc..). Thermodynamic variables and mechanic variables measured in the tests help to identify some of the operating limits of lubrication in critical conditions. In addition, optical techniques have been combined with accelerometer measurements, in order to detect modifications in the movement of the turbocharger shaft. The main conclusions obtained from these tests are that accelerations from low rotational speed to 100krpm, without lubrication oil in the bearing system, don’t cause significant problems in the turbocharger, for 20 sec. However, the accelerations to 150krpm can cause critical problems depending on the lubrication delay and the bearing configuration. Finally, higher acceleration rates to 200krpm, without lubrication, cause the turbocharger destruction in a few seconds. By other hand, a low oil inlet pressure given by an oil column, of about 1m in height, allows to the turbo survive during accelerations from low rotational speed to 150 krpm.

In-flame soot sampling based on the thermophoresis of particles and subsequent transmission electron microscope (TEM) imaging has been conducted in a diesel engine to study size, shape and structure of soot particles within the reacting diesel jet. A direct TEM sampling is pursued, as opposed to exhaust sampling, to gain fundamental insight about the structure of soot during key formation and oxidation stages. The size and shape of soot particles aggregate structure with stretched chains of spherical-like primary particles is currently an unknown for engine soot modelling approaches. However, the in-flame sampling of soot particles in the engine poses significant challenges in order to extract meaningful data. In this paper, the engine modification to address the challenges of high-pressure sealing and avoiding interference with moving valves and piston are discussed in detail. Of particular interest is the uncertainty caused by a selection of the on-grid locations for transmission electron microscope imaging and cycle-to-cycle fluctuations of the engine combustion. Marked variations are observed in the number and projected area of soot particles depending on these variations; however, their impacts on the size of aggregates and primary particles is found to be minor. Also, the morphology of soot particles appears not to be sensitive to the exposure duration of the grid to the sooting flame; however, the duration is ultimately limited by soot over-loading. Two different injection pressures are selected to test the usefulness of the in-flame soot sampling in a diesel engine and the results show that a decrease in the size of soot aggregates and primary particles with increasing injection pressure exceeds the uncertainty.

Problems in the turbocharger lubrication system can cause serious deterioration in their overall performance and even their complete destruction. The paper describes several tests with different critical lubrication conditions, in order to determine the thresholds at which the operation may be appropriate. In an IC engine, these problems can be produced mainly by several factors: the decreasing in the supply pressure of the oil, a delay in the lubrication oil pressure and an intermittent lubrication interruption. A turbocharger test bench and an IC engine test bench has been used to test the turbocharger, in order to reproduce the conditions and cycles similar to the operation of the turbocharger in an IC engine (pressures, temperatures, mass flows, accelerations, etc..). Thermodynamic variables and mechanic variables measured in the tests help to identify some of the operating limits of lubrication in critical conditions. In addition, optical techniques have been combined with accelerometer measurements, in order to detect modifications in the movement of the turbocharger shaft. The main conclusions obtained from these tests are that accelerations from low rotational speed to 100krpm, without lubrication oil in the bearing system, don’t cause significant problems in the turbocharger, for 20 sec. However, the accelerations to 150krpm can cause critical problems depending on the lubrication delay and the bearing configuration. Finally, higher acceleration rates to 200krpm, without lubrication, cause the turbocharger destruction in a few seconds. By other hand, a low oil inlet pressure given by an oil column, of about 1m in height, allows to the turbo survive during accelerations from low rotational speed to 150 krpm.

[EN] Nowadays turbocharging the internal combustion engine has become a key point in the reduction on pollutant emissions and the improvement on engine performance. The matching between the turbocharger and the engine is vital due to the highly unsteady flow the turbocharger works with. In the present paper the importance of the heat transfer phenomena inside small automotive turbochargers will be analyzed. This phenomenon will be studied from the point of view of both the turbine and the compressor in one-dimensional modelling. The goodness of the model will be demonstrated predicting turbine and compressor outlet temperatures. An accurate prediction of these parameters will be key designing the intercooler and the after treatment devices. A series of tests in a gas stand with steady and pulsating hot flow in the turbine side will be modeled to show the good agreement in turbocharger enthalpies prediction.

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.

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.

To respond growingly strict environmental regulations the acousticians are challenging to develop novel types of silencing elements. There are different types of flow duct elements designed for silencing the pulsating gas flows into and out of fluid machines. The silencing effect is typically achieved by introducing acoustic reflection and absorption. In order to achieve a good absorption in a wide frequency band, various fibrous materials e.g. wools are typically implemented. However, the physical properties of such materials do not often remain constant during the lifetime of a silencer. As the fibers tend to relocate and can partly be blown out to surroundings, acoustical performance may deteriorate. Therefore, it is in great interest to avoid fibrous materials in the design of the flow duct silencing elements. The present work is focused on the modern type of absorptive acoustic element - a micro-perforated element. The absorption in micro perforated element is dominantly originating from the viscous effect inside the openings, non-linear acoustic vortex shedding and grazing flow iteration. To exert the advantages of this type of perforation, the opening dimensions have to be smaller than the thickness of the acoustic boundary layer i.e. in the sub millimeter range. Although different micro-perforated panels have been studied by several authors mainly for room acoustic applications, only a relatively few publications concerning the flow duct elements are currently available. In this paper a number of different perforated elements including micro-perforates have been studied by varying the perforation shape and porosity. The studies have resulted in the development of micro perforated tubes with high absorptive properties. The micro-perforated tubes have successfully been implemented in the design of a Formula SAE racing silencer. The scattering matrix elements, as well as the transmission loss are presented and analyzed for a variety of perforated tubes and the, QC 20220126

Engine simulation based on one-dimensional gas dynamics is well suited for integration of all aspects arising in engine and powertrain developments. Commonly used turbocharger performance maps in engine simulation are measured in non-pulsating flow and without taking into account the heat transfer. Since on-engine turbochargers are exposed to pulsating flow and varying heat transfer situations, the maps in the engine simulation, i.e. GT-POWER, have to be shifted and corrected which are usually done by mass and efficiency multipliers for both turbine and compressor. The multipliers change the maps and are often different for every load point. Particularly, the efficiency multiplier is different for every heat transfer situation on the turbocharger. The aim of this paper is to include the heat transfer of the turbocharger in the engine simulation and consequently to reduce the use of efficiency multiplier for both the turbine and compressor. A set of experiment has been designed and performed on a water-oil-cooled turbocharger, which was installed on a 2 liter GDI engine with variable valve timing, for different load points of the engine and different conditions of heat transfer in the turbocharger. The experiments were the base to simulate heat transfer on the turbocharger, by adding a heat sink before the turbine and a heat source after the compressor. The efficiency multiplier of the turbine cannot compensate for all heat transfer in the turbine, so it is needed to put out heat from the turbine in addition to the using of efficiency multiplier. Results of this study show that including heat transfer of turbocharger in engine simulation enables to decrease the use of turbine efficiency multiplier and eliminate the use of compressor efficiency multiplier to correctly calculate the measured gas temperatures after turbine and compressor., QC 20191014

Micro-pitting is a fatigue effect that occurs in geared transmission systems due to high contact stress, and monitoring its progression is vital to prevent the eventual failure of the tooth flank. Parameter signature analysis has been successfully used to monitor bending fatigue failure and advanced phases of gear surface fatigue failure such as macro-pitting and scuffing. However, due to modern improvements in steel production the main cause of gear contact fatigue failure can be attributed to surface micro-pitting rather than sub-surface phenomena. Responding to the consequent demand to detect and monitor the progression of micro-pitting, this study experimentally evaluated the development of micro-pitting in spur gears using vibration and oil debris analysis. The paper presents the development of an online health monitoring system for use with back-to-back gear test rigs. The results validate the system capabilities in detecting early gear defects and reliably identifying the type of failure so that it can be used in predictive health monitoring (PHM) systems.

Micro-pitting is a fatigue effect that occurs in geared transmission systems due to high contact stress, and monitoring its progression is vital to prevent the eventual failure of the tooth flank. Parameter signature analysis has been successfully used to monitor bending fatigue failure and advanced phases of gear surface fatigue failure such as macro-pitting and scuffing. However, due to modern improvements in steel production the main cause of gear contact fatigue failure can be attributed to surface micro-pitting rather than sub-surface phenomena. Responding to the consequent demand to detect and monitor the progression of micro-pitting, this study experimentally evaluated the development of micro-pitting in spur gears using vibration and oil debris analysis. The paper presents the development of an online health monitoring system for use with back-to-back gear test rigs. The results validate the system capabilities in detecting early gear defects and reliably identifying the type of failure so that it can be used in predictive health monitoring (PHM) systems.

Advanced functionalities unthinkable a few decades ago are now being introduced into automotive vehicles through embedded systems for reasons like emission control, vehicle connectivity, safety and cooperative behaviors. As the development often involves stakeholders from different engineering disciplines and organizations, the complexity due to shared requirements, interdependencies of data, functions, and resources, as well as tight constraints in regards to timing, safety, and resource efficiency makes the system integration, quality control and assurance, reuse and change management increasingly more difficult. This calls for a more rigorous approach to the development of automotive embedded systems and components. This paper describes the CESAR reference technology platform (RTP) that supports the formalization of various engineering concerns in the development of safety-relevant embedded systems and thereby a model-based integration of various tools and methods to form seamless environments or toolchains for the development of such systems., QC 20191008. QC 20191108

This paper explores the combined effects of boosting, intake air temperature, trapped residual gas fraction, and dilution on the Maximum Pressure Rise Rate (MPRR) in a boosted single cylinder gasoline HCCI engine with combustion controlled by negative valve overlap. Dilutions by both air and by cooled EGR were used. Because of the sensitivity of MPRR to boost, the MPRR constrained maximum load (as measured by the NIMEP) did not necessarily increase with boosting. At the same intake temperature and trapped residual gas fraction, dilution by recirculated burn gas was effective in reducing the MPRR, but dilution by air increased the value of MPRR. The dependence of MPRR on the operating condition was interpreted successfully by a simple thermodynamic analysis that related the MPRR value to the volumetric heat release rate., United States. Dept. of Energy (University Consortium on Low Temperature Combustion)

Micro-pitting is a fatigue effect that occurs in geared transmission systems due to high contact stress, and monitoring its progression is vital to prevent the eventual failure of the tooth flank. Parameter signature analysis has been successfully used to monitor bending fatigue failure and advanced phases of gear surface fatigue failure such as macro-pitting and scuffing. However, due to modern improvements in steel production the main cause of gear contact fatigue failure can be attributed to surface micro-pitting rather than sub-surface phenomena. Responding to the consequent demand to detect and monitor the progression of micro-pitting, this study experimentally evaluated the development of micro-pitting in spur gears using vibration and oil debris analysis. The paper presents the development of an online health monitoring system for use with back-to-back gear test rigs. The results validate the system capabilities in detecting early gear defects and reliably identifying the type of failure so that it can be used in predictive health monitoring (PHM) systems.

Micro-pitting is a fatigue effect that occurs in geared transmission systems due to high contact stress, and monitoring its progression is vital to prevent the eventual failure of the tooth flank. Parameter signature analysis has been successfully used to monitor bending fatigue failure and advanced phases of gear surface fatigue failure such as macro-pitting and scuffing. However, due to modern improvements in steel production the main cause of gear contact fatigue failure can be attributed to surface micro-pitting rather than sub-surface phenomena. Responding to the consequent demand to detect and monitor the progression of micro-pitting, this study experimentally evaluated the development of micro-pitting in spur gears using vibration and oil debris analysis. The paper presents the development of an online health monitoring system for use with back-to-back gear test rigs. The results validate the system capabilities in detecting early gear defects and reliably identifying the type of failure so that it can be used in predictive health monitoring (PHM) systems.