Search

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main purpose of this study is to improve the level of marine safety management. The safety checklist and reverse management model are used to check and measure marine safety. The results indicate that the test results are M1 = 88.705 and M2 = 95.164 respectively (M2 > M1), suggesting that the reverse management safety model has played a positive role in the actual operation. It has been concluded the reverse management model can improve the safety level of marine engineering management, but not all factors are significantly improved. This paper summarizes the working principle of reverse management, which is feasible in practical application. [ABSTRACT FROM AUTHOR]

This study measured the particle number (PN) emissions from spark ignition (SI) engines according to the use of gasoline fuel and liquefied petroleum gas (LPG) fuel for particles greater than 23 nm or 5 nm. A 0.8-L two-cylinder gasoline engine, which has variable valve timing system and electronic control unit, was used in the experiment. The engine was operated at 1500 rpm, 3000 rpm, low load, and high load, and the fuel injection timing, intake valve opening timing, exhaust valve closing timing, and valve overlap period were used as variables in the experiment. According to the experimental results, the gasoline engine emitted particulate matter (PM) is in the range of 1 × 109 to 3 × 1013 #/kWh, whereas that of the LPG engine is in the range of 1 × 109 to 1 × 1011 #/kWh. For the LPG engine, the operating conditions and experimental variables had minimal influence on the PN, whereas for the gasoline engine, the experimental conditions and experimental variables had a significant influence on the PN. For this test engine, the ratio of PM smaller than 23 nm increased as the emissions of PM larger than 23 nm decreased, which were observed for values between 1 × 1010 #/kWh and 1 × 1011 #/kWh. [ABSTRACT FROM AUTHOR]

The article describes the methodology of engine tests on new types of low-sulphur marine fuels in laboratory conditions in order to conduct a comprehensive assessment of their suitability for powering full-size marine engines. The innovativeness of the proposed solution consists of adapting the laboratory Diesel Engine Test Bed to carry out experimental tests using residual and alternative fuels so that it is possible to imitate the real operating conditions of the ship engine. The main aim of the research program was to assess the energy efficiency of six different low-sulphur marine fuels and their impact on the chemical emissivity of engine exhaust gases and air pollution with toxic and harmful chemical compounds. In order to achieve the research purpose formulated in this way, it was necessary to: (1) equip the constructed laboratory stand with highly specialised measuring equipment and (2) develop a technology for determining diagnostic parameters representing the basis for developing a ranking of the energy and emission quality of the tested marine fuels according to the proposed physical model. The model distinguishes 10 diagnostic parameters that, after normalisation, form two subsets of evaluation parameters - stimulant and destimulant. Determining their values made it possible to estimate a synthetic variable, according to which all the tested fuels were adjusted in the order from the "best" to the "worst", in accordance with the adopted qualitative criteria of such an assessment. The results of the laboratory tests show that among the considered fuels, i.e., MDO, MGO, RMD 80/L, RMD 80/S, RME 180, and RMG 380 type, the best solution is to use MDO distillate fuel to power full-size marine engines. However, taking into account its high purchase price, a rational alternative decision is to choose RMG 380 type residual fuel, which ranks second in the ranking of the functional quality of the tested marine fuels. [ABSTRACT FROM AUTHOR]

The current exploration of alternative fuels to conventional engines is tested on two fronts: the thermophysical property assessment and the other, real‐time evaluation using engine testing using the fuel. The engine testing fueled with modified oils/esterified blends does give real‐time analysis but at the cost of harmful emissions dumped into the polluted environment. The current work describes the use of possible simulations and the validity of simulation confirmed from real‐time experimentation at varying engine compression ratios (CRs). Engine parameters were kept the same for simulations that were performed on the Diesel RK module and experimental analysis. Neem oil blends were prepared and tested for the composition of FFA and later the required properties were supplemented to software for possible thermal performance and emission detections. The thermal efficiency deviation observed between RK model and experimental values for CR 18 for Diesel, B20, B40, and B100 was 5.8%, 1.9%, 3.4%, and 2.1%, respectively, and for NOx, the deviation observed for Diesel, B20, B40, and B100 was 8.9% and 13.7%, 12.2% and 14.1%, and 9.4% and 11.1%, respectively. The peak HRR and cylinder pressures observed for software simulations and real‐time experimental approaches did not vary much, but the peak values do differ by 6.7% and 4.7%, respectively. [ABSTRACT FROM AUTHOR]

Remaining useful life prediction is of huge significance in preventing equipment malfunctions and reducing maintenance costs. Currently, machine learning algorithms have become hotspots in remaining useful life prediction due to their high flexibility and convenience. However, machine learnings require large amounts of data, and their prediction performance depends heavily on the selection of hyper-parameters. To overcome these shortcomings, a novel remaining useful life prediction method for small sample cases is proposed based on multi-support vector regression fusion. In the offline training phase, the fusion model is established, consisting of multiple support vector regression sub-models To obtain the optimal sub-model parameters, the Bayesian optimization algorithm is applied and an improved optimization target is formulated with various metrics describing regression and prediction performance. In the online prediction phase, an adaptive weight updating algorithm based on dynamic time warping is developed to measure the fitness of each sub-model and determine the corresponding weight value. The C-MAPSS engine dataset is used to test the performance of the proposed method, along with some existing machine learning methods as comparison. The proposed method only requires 30% of the training data sample to achieve high accuracy, with a root mean square error of 14.98, which is superior to other state-of-the-art methods. The results demonstrate the superiority of the proposed method. • A multi-support vector regression fusion model is proposed for remaining useful life prediction. • The Bayesian optimization algorithm with improved optimization target is applied for parameter selection. • An adaptive weight updated algorithm is proposed to measure model fitness. • The proposed method can achieve high accuracy with fewer data sample. • The effectiveness is validated by aero-engine dataset. [ABSTRACT FROM AUTHOR]

The measurement of NOx emissions in vehicles has so far been exclusively carried out during the type-approval process. For this purpose, high-precision gas measurement laboratory equipment and Portable Emission Measurement Systems (PEMS) are used. Both types of equipment are costly in terms of price, maintenance, complexity, and time of use (calibration and maintenance requirements). Currently, NOx emissions measurements in Periodic Technical Inspections (PTIs) are being considered, but PEMS or laboratory equipment is unsuitable for this function, and PTI-grade equipment has to be used. Although CO and O2 are currently being reliably measured with this equipment, there is not enough information about its accuracy for NOx measurements. Accordingly, in this paper, simultaneous measures have been performed over the same engine in a test cell, with a laboratory and a PTI gas analyser to assess the accuracy of the latter. When performing the test with the most similar conditions found in PTI, our results show that the PTI gas analyser shows an average deviation of 2.6 ppm and 9% rel. with respect to high-precision laboratory equipment for concentrations below 700 ppm NOx, which can be considered acceptable for periodic technical inspections. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, ten different blends were prepared with binary and ternary combinations of diesel, palm oil biodiesel (0 vol%, 15 vol%, 20 vol% and 30 vol%), and diethyl ether (0 vol%, 5 vol% and 10 vol%) and were tested in a diesel engine. The experiments were performed on various engine loads (500 W, 750 W, 1000 W and 1250 W) and various injection timings (25° CA bTDC, 30° CA bTDC and 35° CA bTDC) at a fixed crankshaft speed of 3000 rpm. The prepared blends were compared in terms of exergy and exergoeconomics. It may be said that exergy efficiency and specific exergy cost of work for blends improved with increasing injection timings at high engine loads. However, at low engine loads, these parameters worsened with increasing injection timings. As a result, at 500 W, relative exergy efficiency of D70PO20DE10 was 0.57 for 25° CA bTDC and 0.54 for 35° CA bTDC. However, at 1250 W, this value was 0.59 for 25° CA bTDC and 1.16 for 35° CA bTDC. Similarly, at 500 W, relative specific exergy cost of work for D70PO20DE10 was 5.29 for 25° CA bTDC and 5.94 for 35° CA bTDC. However, at 1250 W, this value was 5.31 for 25° CA bTDC and 2.66 for 35° CA bTDC. Finally, it can be concluded that neat diesel had the best results compared to all blends considered in this study in terms of exergy and exergoeconomics. [ABSTRACT FROM AUTHOR]

This article discusses the issues of ensuring the accuracy and reliability of the measurement results of controlled engine parameters during acceptance tests. GOST 18509-88 "Tractor and combine diesel engines. Bench test method" establishes the permissible errors of the main controlled parameters of engines during acceptance tests; however, no requirements hold for the permissible error in engine power measurements. On the basis of probability theory, an equation was derived for calculating power measurement errors, and the permissible measurement errors (according to GOST 18509-88) in the power measurements of overhauled engines of various brands were calculated. A comparative analysis of these calculated results and the actual error in measuring power during running-in on the stands KI-5274, KI-5540M, KI-5541M, KI-542M, and KI-2118A of the Russian Scientific Research Technological Institute for the Repair and Operation of the Machine and Tractor Park of the Russian Agricultural Academy was performed. This comparison established that the power measurement errors exceed the maximum allowable values. Recommendations were developed for calculating acceptance windows with a shift relative to the nominal power value to improve the veracity of power control results. The limiting errors in measuring the power of engines of various brands and acceptance limits were calculated depending on the required reliability. This methodology increases the veracity of control results at the acceptance test stage of an overhauled engine. [ABSTRACT FROM AUTHOR]

Regarding the problem of the valve gap health status being difficult to assess due to the complex composition of the condition monitoring signal during the operation of the diesel engine, this paper proposes an adaptive noise reduction and multi-channel information fusion method for the health status assessment of diesel engine valve clearance. For the problem of missing fault information of single-channel sensors in condition monitoring, we built a diesel engine valve clearance preset simulation test bench and constructed a multi-sensor acquisition system to realize the acquisition of diesel engine multi-dimensional cylinder head signals. At the same time, for the problem of poor adaptability of most signal analysis methods, the improved butterfly optimization algorithm by the bacterial foraging algorithm was adopted to adaptively optimize the key parameter for variational mode decomposition, with discrete entropy as the fitness value. Then, to reduce the uncertainty of artificially selecting fault characteristics, the characteristic parameters with a higher recognition degree of diesel engine signal were selected through characteristic sensitivity analysis. To achieve an effective dimensionality reduction integration of multi-channel features, a stacked sparse autoencoder was used to achieve deep fusion of the multi-dimensional feature values. Finally, the feature samples were entered into the constructed one-dimensional convolutional neural network with a four-layer parameter space for training to realize the health status assessment of the diesel engine. In addition, we verified the effectiveness of the method by carrying out valve degradation simulation experiments on the diesel engine test bench. Experimental results show that, compared with other common evaluation methods, the method used in this paper has a better health state evaluation effect. [ABSTRACT FROM AUTHOR]

The article presents the results of numerical simulations using the FEM (Finite Element Method) of the engine mount strength for mounting an aircraft diesel engine with opposite pistons called PZL-100. Four versions of the mount prepared by aircraft engine producer WSK “PZL-Kalisz” company were analyzed. Tests were performed in Catia v5 software in the Generative Structure Analysis module. The boundary conditions were engine gravity force, propeller thrust force, and propeller torque. S235JR steel was defined as the material. A design grid with tetrahedral elements with a single element size of 2 mm was used. As part of the simulation study, four structural solutions for the test engine mounts were calculated in terms of strength. The results of stress maps and the magnitude of deformation of the mount elements were compared. Based on the obtained results, one of the mount versions was recommended for actual fabrication. [ABSTRACT FROM AUTHOR]

Urban digital twins have become an essential factor for cities and communities to visualize, simulate and analyze data. The conventional geospatial standards work great with online platforms such as CesiumJS or ArcGIS API for JavaScript. However, their usage in different platforms such as game engines has not been well established yet. Game engines provide an interesting application case because they offer a different approach to visualizing large city models and provide a high graphical fidelity.This paper aims to answer how the existing standards, such as the API standards GeoVolumes and SensorThings, as well as the 3D model standards 3D Tiles and Esri Indexed 3D Scene Layer (I3S), can interact with game engines. For this purpose, three use-cases were selected and have been used to build applications. These focus on using sensor data in AR and different city development scenarios in a digital environment.This study shows that different geospatial standard formats such as 3D Tiles, I3S, and GL Transmission Format (glTF) can be used in game engines, either directly or over a GeoVolumes Server. Their implementation makes it possible to use the advantages of game engines with real-world datasets. [ABSTRACT FROM AUTHOR]

This research work focuses on durability tests on diesel engines powered by 30 vol% distilled tyre oil with diesel (DTPO30). The duration of the study was for 1500 running hours and includes an analysis of engine performance, emission formation, viscosity, wear, and additives in lubrication oil with a ferrographic examination. The respective wear and additives in the oil were measured every 450 hours. In the engine running on DTPO30, brake thermal efficiency (BTE) declined by up to 0.5% and brake specific fuel consumption (BSFC) also diminished by up to 1.5% after 1500 hours when compared with the initial stage operation. In addition, all the harmful emission parameters such as NOx, CO, and HC grew by between 0.7 % and 1.1%. The viscosity of lube oil was observed to fall by up to 13% with diesel and 36% with DTPO30 compared with the initial condition. The amount of additives was also lower in the lubrication oil in DTPO30 compared with in pure diesel. A higher carbon deposition was also found in many places, such as in the piston top, around the injector nozzle, and in the valve seat with DTPO30. The wear of each part was identified by estimating the metal contamination in the lube oil by means of a ferrography tester. Further, the metal contaminations in the lube oil were found to amount to as high as 79% in DTPO30. In addition, the size of the particles was identified to be larger than in the case of diesel. [ABSTRACT FROM AUTHOR]

Engine knocking is often identified by an operator based on the combustion sound emanating from the cylinder block during engine calibration in a test cell. Such human-hearing-based acoustic knock determination is considered the most reliable real-time knock-monitoring method, and it is necessary for selecting an accurate spark timing. In this study, the characteristics of this combustion sound were investigated. To this end, a normal engine calibration experiment was conducted. The engine sound was recorded under various operating conditions by using a copper tube attached to the cylinder block and the microphone of a smartphone. The measured signals were subjected to acoustic analyses, including Fast Fourier transform, smoothing, spectral analysis, and autocorrelation, to compare the sounds recorded at the knock borderline with those recorded in the cases with significantly advanced spark timing. The results of these analyses revealed several features that distinguished the knock sound from the normal combustion sound. The knock sound exhibited distinctions in a high-frequency band between 6,000 and 8,000 Hz. These features can be used to develop effective knock classification models. [ABSTRACT FROM AUTHOR]

The oxidation resistance of 4140 steel was evaluated for use in the next generation of high-output diesel engines at temperatures up to 900 °C using isothermal furnace testing, a novel highly transient combustion-based laboratory test, and direct high temperature engine exposure. Isothermal tests were used both to evaluate the temperature capability of the alloy and to derive oxidation kinetics. An anisothermal model was then applied to predict oxide growth during impulse cyclic heating tests (ICHT), where the steel is directly exposed to combustion. Isothermal oxidation kinetics are shown to accurately predict scale growth in this scenario despite the presence of the flame, large thermal transients, and thermal gradients present in the alloy. This is found to not translate well to oxidation observed on the 4140 piston after engine testing, where the observed oxidation is significantly thicker than expected. Several potential error sources are discussed including the role of in-cylinder pressure, combustion interactions, and engine build-to-build variability. [ABSTRACT FROM AUTHOR]

In the current research, the engine performance, combustion, and emission parameters of biodiesel mixture 20% Tamarind oil methyl ester and 80% Diesel (B20) with the inclusion of titanium dioxide (TiO2) in different concentrations (25.50 and 75 ppm) and 10% v/v dimethyl carbonate (DMC) as fuel additive investigated using a single-cylinder, 4-stroke, direct injection (DI), compression ignition (CI) engine. The nano fuel blends were prepared through the ultrasonication process. The ratio of 1:4 TiO2: QPAN80 was produced higher stability and consistency out of five trials. TiO2 were characterized using FESEM, HRTEM, and Fourier Transform Infrared (FTIR). Fuel properties were determined as per the ASTMstandards. Engine tests were carried out to determine the engine performance under varied loads such as 25, 50, 75, and 100% while keeping a uniform speed of 1500 rpm. The maximum reduction in BSFC, CO, HC, and NOx were found to be 17.64%, 9.49%, 7.81%, and 6.53%, and the increased BTE was observed to be 6.13% for B20T50DMC10 compared to B20 blend at full load. Thus, the combined effect of TiO2 and DMC served excellent engine performance, combustion, and emission characteristics in CI engine operation. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study of the emission levels of selected greenhouse gases (CO2, CH4, NOx) arising from the combustion of different forms of biomass, i.e., solid biomass in the form of pellets and liquid biomass in the example of engine biofuel (biodiesel). Both types of biomass under study are rape-based biofuels. The pellets are made from rape straw, which, as a waste product, can be used for energy purposes. Additionally, biodiesel contains rape oil methyl esters (FAME) designed to power diesel engines. The boiler 25 kW was used to burn the pellets. Engine measurements were performed on a dynamometer bench on an S-4003 tractor engine. An analyzer Testo 350 was used to analyze the exhaust gas. CO2 emission studies do not indicate the environmental benefits of using any alternative fuels tested compared to their conventional counterparts. In both the engine and boiler tests for NOx emissions, no environmental benefits were demonstrated from the use of alternative fuels. The measured average NOx emission levels for biodiesel compared to diesel were about 20% higher, and for rapeseed straw pellets, they were more than 60% higher compared to wood pellets. Only in the case of engine tests was significantly lower CH4 (approx. 30%) emission found when feeding the engine with rape oil methyl esters. [ABSTRACT FROM AUTHOR]

This article reviews the state of the knowledge and technology in the field of friction-loss measurements in internal combustion piston engines. The dependencies that describe the loss of energy in combustion engines and injection apparatus are presented. Currently, very little can be found in the literature on the study of frictional forces in injection apparatus, but mainly in the piston–cylinder group, so this work significantly fills that gap. The aim of this article is to construct a device and to develop a method for assessing the technical state of injector nozzles to minimize friction losses in internal combustion engines at the stages of evaluation, design, production and operation. This article presents a stand for determining the maximum friction forces due to gravity loading by water-jet control. This article also presents test results on the maximum friction force between a needle and a body of injector nozzles in piston combustion engines on a designed and purpose-built stand outside of the combustion engine. Various designs and injector nozzles are made from various types of alloy steel for marine and automotive piston internal combustion engines fueled with distillation or residual fuels, and are tested. The research concerned conventional elements for the injection apparatus as well as electronically controlled subsystems. Precision pairs of injection equipment are selected for the tests: new ones are employed after the storage period and operated in natural conditions. The elements dismantled from the internal combustion engines are tested in the presence of fuel or calibration oil of similar properties. The maximum static frictional forces under the hydrostatic loading are measured, alongside the parameters for the dynamic movement of the nozzle needles from bodies of the injector nozzle as time, speed, acceleration and dynamic force. The influence of the angular position of the needle in relation to the bodies of the precision pairs conventional internal combustion engines, the diametral clearance between the nozzle body and needle, and the surface conditions on the values of the maximum friction force are also presented. Errors in shape and position result in the uniqueness of the friction force at the mutual angular position of the needle in relation to the nozzle body, and the decrease in diametral clearance and deterioration of the surface state increase the friction losses. A model was elaborated of the influence of various factors on the value of the maximum friction force. [ABSTRACT FROM AUTHOR]

Unlike the conventional engine, the valve train of a certain type of engine uses a circular shim instead of a tappet to wear against the cam. To verify the reliability of the shim, an engine bench test was used to test its wear performance. The total duration of the bench test was 1000 h, which was divided into three stages. In each stage, the test equipment was stopped, and the shims were disassembled to observe the surface morphology during the worn process. Precious long-term data were obtained. With the extension of the bench test time, weight loss increased. The maximum weight loss occurs 1000 h after worn, which is about twice that of 350 h. During the wear process, a plastic flow of material was found on the subsurface, and fatigue wear marks occurred on the surface. With an increase in test time, the wear marks increased, leading to material spalling and the formation of pits. The wear mechanism was the mixed wear of fatigue wear and adhesive wear. [ABSTRACT FROM AUTHOR]

The combustion phenomena are always complex in nature due to the involvement of complex series and parallel reactions. There are various methods that are involved in analyzing combustion phenomena. Viscosity is the first and foremost factor that acts as the DNA of fuel. By evaluating the viscosity, it is possible initially to understand the combustion phenomena. Thermophysical and transport properties are helpful during the intensification of the combustion process. Combustion experiments are economically infeasible and time-consuming processes. Combustion simulations demand excellent computational facilities with detailed knowledge of chemical kinetics. So far, the majority of researchers have focused on analyzing coal combustion phenomena, whereas less work has been carried out on liquid fuels, especially biodiesel combustion analysis. Traditional engine testing provides only performance parameters, and it fails to have oversight of the thermodynamic aspects. The application of thermal analysis methods in combustion research is useful in the design, modeling, and operation of the systems. Such investigations are carried out extensively in the combustor, engine, and process industries. The use of differential scanning calorimetry (DSC) and thermogravimetry (TG) to assess the properties of biofuels has been attracting researchers in recent years. The main objective of this paper is to discuss the application of TGA and DSC to analyze heat flow, enthalpy, thermal stability, and combustion indexes. Moreover, this paper reviews some of the other aspects of the kinetics of combustion, transport properties' evaluation, and combustion simulations for biodiesels and their blends. TG curves indicate two phases of decomposition for diesel and three phases for biofuel. The B-20 blend's (20% biodiesel and 80% diesel) performance was found to be similar to that of diesel with the combustion index and intensity of combustion nearly comparable with diesel. It is thermally more stable with a high offset temperature, confirming a longer combustion duration. A case study reported in this work showed diesel and B20 JOME degradation start from 40 °C, whereas jatropha oil methyl ester (JOME) degradation starts from 140 °C. JOME presents more decomposition steps with high decomposition temperatures, indicative of more stable compound formation due to the oxidation process. The peak temperature of combustion for diesel, JOME, and B20 JOME are 250.4 °C, 292.1 °C, and 266.5 °C, respectively. The ignition index for the B-20 blend is 73.73% more than that of diesel. The combustion index for the B20 blend is 37.81% higher than diesel. The B20 blend exhibits high enthalpy, better thermal stability, and a reduced peak temperature of combustion with an improved combustion index and intensity of combustion nearly comparable to diesel. [ABSTRACT FROM AUTHOR]

The fuel characteristics of hydrous ethanol (HE) and gasoline blends (HE10, HE15 and HE20) were investigated as an alternative fuel for spark-ignition (SI) engines and test their performance. The densities of the blends (754.4-769.1 kg m-3) were higher than that of gasoline (739.7 kg m-3); however, their API gravity (55.88-52.3) was lower than that of gasoline (59.53). The kinematic viscosity of the blends (0.588 to 0.670 mm2 s-1) indicated that the blends were more viscous than gasoline (0.4872 mm2 s-1). Flashpoint values of the blends varied from 28.4 to 29.2°C, which were higher than that of gasoline flashpoint value (25.0°C); however, the calorific value of the blends (ranging between 45.21 and 45.08 MJ kg-1) was lower compared to that of gasoline (45.27 MJ kg-1). The Octane number of the blends varied from 92.9 to 95.8, which was higher compared to that of gasoline (90.5). At low engine speed (1500 rpm) and high load (2.5 kg), the engine torque obtained with gasoline was 10.7% higher than that obtained with the blends. However, at high engine speed (2500 rpm) and high load (3.2 kg), the torque with gasoline was only 2.7% higher than with the blends. Overall, HE15 blend showed the best results among the examined blends. [ABSTRACT FROM AUTHOR]

This article presents the influence of various ship's operational conditions occurring during manoeuvres related to entering and leaving the ports and mooring operations. Frequent starts and stops of the ship's propulsion unit are then required, which affect the variability of the energetic loads of the ship's power plant, causing accelerated, non-design wear of the ship's main propulsion engine. The effects of cold start-ups of the main ship engine are the subject of this study. Conditions of the engine inlet valve damage process are discussed. The physics of the degradation process leading to air inlet valve damage was considered. Laboratory tests of structure continuity and their results are discussed, and the valve material defects were excluded as the cause of the damage. The causes of repeated damage to the inlet air valves were identified. The effectiveness of the performed corrective measures was confirmed by a documented control test of the engine start-up. The article is a utilitarian premise for the requirements of the Classification Society. [ABSTRACT FROM AUTHOR]

The paper presents the process of designing an unmanned Micro class aircraft, from the analysis of the dynamically developing market and the condition of the Polish Armed Forces to construction of objects and flight test. The possibilities and limitations of using miniature UAVs on the modern battlefield were determined. For the designed UAV the propulsion was selected based on tests carried out on the engine test bench. The avionics equipment was selected based on components readily available on the market. The object was then made and inspected in flight. During the flight tests, the aircraft performance was verified and compared with the assumptions. It has been shown that the developed object is able to fulfill the reconnaissance tasks entrusted to it, while maintaining the assumed simplicity of construction and low cost of execution and service. [ABSTRACT FROM AUTHOR]

The goal of this research is to produce bio-alcohol and biodiesel from S. quadricauda and C. pyrenoidosa microalgae in a sustainable manner using phototrophic and heterotrophic pathways. Experimental and statistical approaches are used to assess the viability of the bioenergy produced as a prospective alternative to diesel fuel. On analysis, it was observed that the %age weight of the dry cell of C. pyrenoidosa cultures on scaling-up resulted lipid content of 44.1%, 46.7%, and 41%, respectively. On scaling up, the cultures' biomass concentrations reached 5.15 g L −1, 4.24 g L −1, and 4.36 g L −1. Similarly, upscaling S. quadricauda cultures resulted in yield rates of 4.2 g L −1 and 2.96 g L −1 d −1 and a lipid productivity of 2.96 g L −1 d −1, respectively. On engine testing, AA20D80 and AA30D70 blend combinations shows an improvement of 4.84% and 6.9% in BTE with a reduction of 88.6% and 72.41% in fuel consumption. Similarly, as compared to amyl alcohol blends and diesel fuel at full load, CP20D80 and CP30D70 efficiently lower HC, NOx, and smoke emissions. The statistical analysis revealed that the similarity index of the 20% and 30% proportions were ideal in achieving optimal engine output characteristics. [Display omitted] • Phototrophic and heterotrophic upscaling of third generation microalgae feedstock. • Biosynthesis of long-chain bio-alcohol and low-density biodiesel from microalgae. • Higher yield and conversion rates for heterotrophic upscaling of C. pyrenoidosa. • S. quadricauda based bio-alcohol shows superior engine output characteristics. • Statistical COA identified the optimal mixtures as CP20D80 and AA20D80. [ABSTRACT FROM AUTHOR]

After approximately 50 years, NASA is restarting efforts to develop nuclear thermal propulsion (NTP) for interplanetary missions. Building upon nuclear engine tests performed from the late 1950s to the early 1970s, the present research and testing focuses on advanced materials and fabrication methods. A number of transient tests have been performed to evaluate materials performance under high-temperature, high-flux conditions, with several more experiments in the pipeline for future testing. The measured data obtained from those tests are being used to validate the Griffin reactor multiphysics code for this particular type of application. Griffin was developed at Idaho National Laboratory (INL) using the MOOSE framework. This article describes the simulation results of the SIRIUS-CAL calibration experiment in the Transient Reactor Test Facility (TREAT). SIRIUS-CAL was the first transient test conducted on NASA fuels, and although the test was performed with a relatively low core peak power, the test specimen survived a temperature exceeding 900 K. Griffin simulations of the experiment successfully matched the reactor's power transient after calibrating the initial control rod position to match the initial reactor period. The thermal-hydraulics model largely matches the time-dependent response of a thermocouple located within the experiment specimen to within the uncertainty estimate. However, the uncertainty range is significant and must be reduced in the future. [ABSTRACT FROM AUTHOR]

A multi-objective optimization study and sensitivity analysis of a SI engine piston-rings pack using dynamics analysis software (AVLExcite Piston&Rings) and optimizer software (modeFRONTIER) are presented. The effects of changing the piston rings' tangential force and face profile on the oil and gas flow behavior inside the piston-rings pack are investigated by calculating the lubrication oil consumption, blow-by, and power losses. The feasibility of the simulation model was determined by comparing it to empirical data obtained from experimental testing of the engine to estimate the amount of oil consumption and blow-by gas flow. Using the statistical modeling algorithm SS-ANOVA, multi-objective optimization investigates the individual and interaction effects of the three rings' tangential forces. This method significantly reduces the time and cost required to find the optimal design, an approach not reported in previous studies. The results showed a strong correlation between simulation and experimental test results, indicating an acceptable match during model validation. Furthermore, the predictions show that tangential forces affect sealing performance; thus, modifying the tangential force resulted in a 30% reduction in oil consumption and less than a 0.8 percent increase in friction. Furthermore, the LKZ oil control ring model efficiently reduces oil consumption by 25% while slightly increasing friction (about 10 percent without face coating). [ABSTRACT FROM AUTHOR]

Ab Anbars were used in most areas of Iran, especially in hot and dry climates, to keep water cool. The dome of Ab Anbars had varying heights and forms used to cover the reservoir. The present study conducted an experimental and numerical review of five sample Ab Anbar domes of different structures from a hot dry climate in Yazd. To conduct the research, Tg and Ta parameters inside and outside the domes were simultaneously taken from morning to evening with two data loggers on the hottest days of the year, while during the day, the surface temperature was exposed to radiation and dome shadow were captured using a thermometer. For validation, samples of the fixed span were modeled in Rhinoceros5 software and tested with Radiance Engine of solar radiation analysis algorithm on the hottest day of the year in three intervals of 2,4, 6 p.m. in order to identify the most suitable dome in terms of heat reception for hot and dry climates. The findings indicated that there was a good relationship between experimental and simulation data. The amount of sunlight reception on the dome surfaces varied in each time interval. The discrepancy level of Tg and Ta parameters inside and outside high-rise domes was found to be lower than that of low-rise domes, as low-rise domes absorbed more heat and stored it inside. Therefore, high-rise domes were among the most suitable covering areas for Ab Anbars in the hot and dry climate of Yazd. [ABSTRACT FROM AUTHOR]

[Display omitted] • CI engine tests include study of preheating and distinct – WSB, IAA, IT, and EGR. • Novel (Diesel-WSB-IAA) blends test results are analysed by TOPSIS and ANFIS methods. • TOPSIS optimum factors are load-12 kg, WSB-5 %, IAA-15 %, IT-25° bTDC, and EGR-21 %. • Optimum to diesel: CO (14.29 %↓), CO 2 (32.89 %↓), NO x (58.12 %↓), and smoke (38.13 %↓). • WSB5IAA15 blend is the best, according to the analysis of ternary blend graphs. This study investigates the significance of isoamyl alcohol (IAA) in a CI engine by blending with watermelon seed biodiesel (WSB) at preheating and varying load, injection timing (IT), and exhaust gas recirculation (EGR). Adaptive-Network Based Fuzzy Inference Systems (ANFIS), and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods were employed to analyze the test results. From statistical indices data, the ANFIS models predicted more accurately. TOPSIS technique confirmed the preheated optimum ternary blend (POTB) as load-12 kg, WSB-5 %, IAA-15 %, IT-25° bTDC, and EGR-21 %. The closeness coefficient values model R2 = 0.9736. In comparison to diesel, the POTB blend (WSB5IAA15) offers lower viscosity, density, CN, and heating value, with higher oxygen and latent heat of vaporization (Lv), most of which contribute to improved atomized spray and better combustion. Hence, at load-80 %, POTB to diesel results decrease BTE by 0.11 %, CO by 25 %, CO 2 by 16.39 %, NO x by 37.08 %, and smoke by 16.16 %, while increasing BSEC by 0.40 %, and HC by 39.83 %. Further, at load-100 %, the results of POTB to diesel diminish BTE by 2.12 %, CO by 14.29 %, CO 2 by 32.89 %, NO x by 58.12 %, and smoke by 38.13 %, while elevating BSEC by 7.57 %, and HC by 31.30 %. IAA exhibits elevated levels of oxygen, energy density, Lv, and OH active radicals, accompanied by reduced heating value and CN. IAA is crucial in lowering NO x and smoke levels, which are difficult for WSB to control on its own. Lastly, plots are illustrated for each response parameter to dominant (EGR and WSB) concerning ternary blends and diesel data for specific conditions. Ultimately, the POTB demonstrated that it can serve as an effective diesel fuel substitute. [ABSTRACT FROM AUTHOR]

A synergistic combination of oils from Ceiba pentandra, Mahua longifolia, and Azadirachta indica can be harnessed to produce biodiesel, effectively mitigating the seasonal constraints associated with relying on a single feedstock. A novel bifunctional liquid catalyst sulfonate ester was prepared and characterized by various spectroscopic techniques to confirm its capability in efficient biodiesel conversion. Using a 4 % bifunctional catalyst, a 98 % biodiesel yield was achieved, with optimization of methanol/oil ratio, temperature, and stirring speed through RSM, and validation against ANN and ANFIS predictions. The biodiesel properties met EN and ASTM standards, ensuring compatibility. Engine tests under full load conditions examined various blends (B0-B100) and compression ratios (16–20). At a compression ratio of 19, the B20 biodiesel blend outperformed others by achieving the highest brake thermal efficiency of 30.42 % and the lowest brake-specific fuel consumption, measuring just 0.219 kg/kWh. In addition to these efficiency gains, the use of higher biodiesel blends led to a substantial decrease in exhaust emissions relative to pure diesel. The findings from this research advocate for the adoption of biodiesel from mixed non-edible oils as a green and sustainable replacement for conventional diesel fuel. [Display omitted] • Blending various 2G oils at variable ratios creates a sustainable feedstock. • Novel bifunctional liquid sulfonate ester efficiently converted the biodiesel. • Process parameters were optimized by RSM and compared with predicted ANN and ANFIS. • Engine compatibility was confirmed by various Bs and CRs through its performance. [ABSTRACT FROM AUTHOR]

To address the limitations of existing stall/surge warning methods—including variations in research subjects, sensor configurations, computational complexity, and the universality of thresholds—this study proposes a novel incipient instability warning approach utilizing adaptive wavelet synchrosqueezed transform. Each detection cycle begins with the acquisition of a low-pass filtered and downsampled total pressure signal from the compressor outlet, captured via a sliding window to represent the pressure sample. Then, the adaptive wavelet synchrosqueezed transform (AWSST), employing dynamic discretization with scales and synchrosqueezing technology, analyzes the real-time pressure sample to extract precise instantaneous frequency changes at low computational costs. Features of instability severity are derived from the amplitude, phase, and pressure drop within the time-frequency spectrum, leading to the formulation of a warning logic. The proposed method's effectiveness and universality are validated through hardware-in-loop (HIL) tests using multiple surge test data. Results show that the proposed method outperforms traditional real-time warning methods, which rely on the pressure change rate, by enhancing accuracy and advancing warning times by 15 ms–50 ms. Notably, the threshold is universal for compressors or engines of the same model. By increasing the acceptable performance decline criteria, compressors, turbofan engines, and turboshaft engines can employ a common set of thresholds. • Novel AWSST method enhances real-time detection of gas turbine engine instabilities. • AWSST offers superior accuracy and earlier warnings compared to traditional methods. • Validated through hardware-in-loop tests on various engines and surge inducements. • Effective implementation on embedded platforms with low computational costs. • Universal threshold settings applicable across different engine types and speeds. [ABSTRACT FROM AUTHOR]

The reliance on fossil fuels as well as engine emissions can be curbed by adopting low-carbon alternative fuels, which, when blended with diesel, may require minimal engine modifications. Fuels derived from plant and biological sources such as ethanol and jatropha oil are considered some of the low-carbon fuels. The blended fuel droplets may undergo smooth burning, puffing, and micro-explosions based on their composition and the surrounding environment. The current study focuses on the effect of composition and temperature on blended fuel droplet combustion and correlates the observations with the microstructure of the blend. Droplet combustion behaviour at three different temperatures, viz. 500, 600, and 700 °C, that are relevant to combustion engines were tested. The ethanol concentration in the blends varied between 10 and 50 % by volume, while the jatropha oil concentration changed between 10 and 40 %. As the temperature increased from 500 to 700 °C, the burning characteristics of the droplets changed from puffing to micro-explosions due to the rapid evaporation of ethanol. Puffing and explosions gave rise to secondary and tertiary droplets, which were similar in size (∼50–100 μm) to diesel spray droplets and exhibited cascaded puffing and explosions. The blends with ethanol to jatropha oil (E/J > 1) greater than 1 produced a larger dispersed phase and larger agglomerates and hence promoted micro-explosions. The findings of this study highlight the importance of blend composition and temperature for achieving micro-explosions in diesel–jatropha oil–ethanol ternary blends, which are potential alternative fuels for compression ignition (CI) engines and spray flames. [Display omitted] • Puffing and microexplosions were observed in diesel-ethanol-jatropha oil droplets above 500 °C. • Increasing the temperature from 500 to 700 °C promoted puffing and microexplosions. • The dispersion of ethanol in the blend affected the combustion behaviour of the droplet. • High ethanol concentrations promoted larger dispersed phases and microexplosions. [ABSTRACT FROM AUTHOR]

Ammonia is a promising future energy carrier because of its carbon-free nature and high volumetric energy density compared to hydrogen. However, implementing ammonia as a fuel appears challenging due to its low reactivity. This can be improved, inter alia, by cofiring with a highly reactive fuel like hydrogen. A fuel mixture of ammonia, hydrogen, and nitrogen with favorable thermochemical properties can be produced by partially cracking ammonia. To assess the combustion behavior of ammonia and partially cracked ammonia at engine conditions, this study performs experiments on an optical engine test rig. Ammonia cracking ratios of 0, 7.5, and 10%, fuel-air equivalence ratios of 0.7 to 1.2, and different turbulence conditions at variable engine speeds are investigated at a compression pressure of 7 MPa. A turbulent flame speed approach is determined from high-speed schlieren imaging in the combustion chamber. The corresponding laminar flame properties and effective Lewis number are calculated numerically and the combustion regimes are assessed. The results show that ammonia/air flames propagate significantly faster under turbulent, engine-like conditions than expected from results at laminar, ambient conditions. Additionally, the partial cracking of ammonia further improves the turbulent combustion behavior. With lean fuel/air mixtures, a cracking ratio of 10% is sufficient to achieve flame speeds close to that of methane under highly turbulent flow conditions. The observed stronger influence of turbulence on the flame speed of ammonia and partially cracked ammonia compared to methane is due to the lower effective Lewis numbers and higher Karlovitz numbers of these fuels. • NH 3 , partially cracked NH 3 , and CH 4 are investigated on an optical engine test rig. • The combustion regimes of the investigated fuel/air mixtures are determined. • Equivalence ratio variations are compared for turbulent and laminar conditions. • The effect of turbulence intensity on different fuels is evaluated. • The strong effect of turbulence on NH 3 and partially cracked NH 3 is discussed. [ABSTRACT FROM AUTHOR]

The electric superchargers driven by a high-speed motor instead of exhaust gas to operate the compressor have excellent transient characteristics and can effectively reduce the turbo lag of diesel engines. To develop an optimal control strategy for the electric superchargers, it is necessary to explore the combined effects of the electric supercharger and turbocharger under transient processes. Therefore, this study investigated the influence of different intervention speed and time of the electric supercharger on the transient performances of a turbocharged diesel engine. The combined effects of the electric supercharger and turbocharger were analyzed to optimize control strategy through simulations. Effects of the optimization in control strategies were tested through engine experiments. According to the results, the optimized control strategy (slope control strategy) was able to effectively balance transient responsiveness and stability since the rise time of intake pressure were reduced by 52.5 % compared to the base engine and the fluctuations in intake pressure and engine torque were significantly eliminated. Besides, the slope control strategy achieved the lowest PM and NOx emissions during the transient loading process. • The transient characteristics are greatly improved by the electric supercharger. • The combined effects of the electric supercharger and turbocharger are investigated. • An advanced control strategy of the electric supercharger is developed. • Emissions during the transient process are reduced by the electric supercharger. [ABSTRACT FROM AUTHOR]