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1
Kowalski, Jerzy. "An Experimental Study of Emission and Combustion Characteristics of Marine Diesel Engine in Case of Cylinder Valves Leakage". Polish Maritime Research 22, nr 3 (1.09.2015): 90–98. http://dx.doi.org/10.1515/pomr-2015-0061.
Pełny tekst źródłaStreszczenie:
Abstract Presented paper shows the results of the laboratory tests on the relationship between throttling of both air intake duct and exhaust gas duct and a gaseous emission from the marine engine. The object of research is a laboratory, four-stroke, DI diesel engine, operated at loads from 50 kW to 250 kW at a constant speed equal to 750 rpm. During the laboratory tests over 50 parameters of the engine were measured with its technical condition recognized as a „working properly” and with simulated leakage of both air intake valve and exhaust gas valve on the second cylinder. The results of this laboratory research confirm that the leakage of cylinder valves causes no significant changes of the thermodynamic parameters of the engine. Simulated leakages through the inlet and exhaust valve caused a significant increase in fuel consumption of the engine. Valve leakages cause an increase of the exhaust gas temperature behind the cylinder with leakage and behind other cylinders. The exhaust gas temperature increase is relatively small and clearly visible only at low loads of the engine. The increase of the temperature and pressure of the charging air behind the intercooler were observed too. Charging air temperature is significantly higher during the engine operation with inlet valve leakage. The study results show significant increases of the CO, NOx and CO2 emission for all the mentioned malfunctions. The conclusion is that the results of measurements of the composition of the exhaust gas may contain valuable diagnostic information about the technical condition of the air intake duct and the exhaust gas duct of the marine engine.
2
Choi, Gyeung Ho, Seong Keun Shin, Seok Choun Bae, Yong Jong Chung i Sung Bin Han. "Effects of injector leakage on liquid propane injection engine performance". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, nr 4 (1.04.2005): 559–64. http://dx.doi.org/10.1243/095440705x11149.
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This study aims to provide basic technical information for research regarding starting performance improvement by using a 2.656 cm3 V6 liquid propane injection engine to study the effects of varying the liquefied petroleum gas (LPG) leakage on starting performance and to analyse the effects of such leakage on emission characteristics. To determine the LPG injection amount that corresponds to the desired LPG leakage, 1–30 l was injected to find the critical point and, since the injected fuel was detected at the intake starting from 5.5 l, starting performance comparisons of engine speed and exhaust gases were made at 0 l, 1 l, 2 l, 3 l, 4 l, 5 l, and 6 l by measuring the desired value five times and taking the average. Also, to study the effects of a small leak, the starting performance was tested while injecting 0 l, 0.2 l, 0.4 l, 0.6 l, 0.8 l, and 1 l. The major conclusions of this work are as follows: The results of determining the critical point of starting delay for LPG leakages of 1–30 l show that the critical point is 21 l and 14 cycles. For LPG leakages of 1–6 l, the starting time and unburned hydrocarbon (HC) increases with increasing LPG leakage. At LPG leakage of 0.2 l, the starting time is much faster at 1 cycle, but unburned HC increases with increasing LPG leakage.
3
Miao, Shujing, Haiyang Liu, Haitang Cen, Jiang Liu, Huaqiang Li i Gang Xu. "Study on Leakage Effect Factors of Two-Stroke Micro Free Piston Swing Engine". Micromachines 13, nr 8 (14.08.2022): 1314. http://dx.doi.org/10.3390/mi13081314.
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The two-stroke micro free piston swing engine (MFPSE) is a portable power device. Its seal performance plays an important role in the dynamic properties and efficiency of microengines. The present work established the leakage model of the two-stroke micro free piston swing engine by utilizing the compressible flow Reynolds Navier–Stokes equation. The obtained nondimensional mass leakage was related to the seal gap height, seal inlet pressure, size factor and compression ratio. Simulation investigated how the different seal gap heights and size factors affected the pressure, temperature and mass leakage of micro engines. The results showed that when the seal gap height of the combustion chamber increased, the maximum pressure and cycle power declined, obviously. However, the maximum temperature was scarcely affected. The mass leakage was not greatly impacted when the compression ratio was less than 5. However, the mass leakage dramatically increased when the seal gap was more than 10 μm or the size factor was less than 0.4. The investigation revealed these mass leakage effect factors and provided a guide for the seal and structure design of the two-stroke micro free piston swing engine.
4
DZIUBAK, Tadeusz, i Mirosław KARCZEWSKI. "Operational malfunctions of turbochargers – reasons and consequences". Combustion Engines 164, nr 1 (1.02.2016): 13–21. http://dx.doi.org/10.19206/ce-116484.
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The paper discusses the most frequently occurring types of damage in turbochargers fitted in modern combustion engines and their influence on the engine basic operational indexes. The following causes of turbocharger malfunctions have been discussed: no lubrication, low lubricant pressure, reduced lubricant quality, foreign objects in the charged air and in the exhaust gas. Example malfunctions resulting from the said causes have been shown. The experimental part discusses the influence of a reduction of the charging pressure resulting from a leakage in the intake system on the effective parameters of a diesel engine fitted in light-duty and heavy-duty vehicles. The leakage in the intake system has been simulated by boring holes of the diameter of 3 and 12 mm in the intake manifold downstream of the turbocharger. The influence has been determined of the leakage of the turbocharging system on the value of the charging pressure, maximum effective power, engine torque, unit and hourly fuel consumption and the concentration of the exhaust components. A significant impact has been observed of the leakage of the turbocharging system on the effective parameters of the tested diesel engine and exhaust gas composition.
5
Kołodziej, Szymon. "The effect of the leakage of the engine arrest engine and emissions of harmful substances". AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 19, nr 6 (30.06.2018): 502–5. http://dx.doi.org/10.24136/atest.2018.121.
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In this article, the issues related to vehicular traffic in big cities and heightened harmful substance emissions stemming from it were described. In the research part, the effect of air leakage in the SI engine intake manifold on substance emissions was investigated. The manifold was customized to simulate air leakage in each of its air ducts. Same ratio of leakage was assumed for each duct, and substance emissions were measured in full range of engine rotational speeds. A difference in exhaust gas composition was shown for each researched variant, being the result of varying cylinder filling ratio due to simulated air leakage.
6
Jukl, Michal, Adam Polcar i Jiří Čupera. "Possibilities of Monitoring the Technical Condition of the Combustion Engine with Starter Load Current". Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 62, nr 5 (2014): 961–69. http://dx.doi.org/10.11118/actaun201462050961.
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This article deals with the verification of relations between the electric current of engine starter and tightness of the combustion chamber and the possibility of its use for the evaluation of the state in terms of engine wear. Engine wear is closely related to the quality of fuel combustion and also with the amount of produced harmful emissions. On this basis, it would be possible to extend the technical requirements of the protocol OBD to include the indirect control of engine wear. To meet the objectives set out above measurement was carried out by a petrol engine, which was located in the vehicle Škoda Felicia Combi GLX 1.3 The whole measurement was divided into several parts. The first measurement was carried out on the abovementioned motor without simulating leakage. The second measurement was performed when the leakage of one cylinder was simulated. Simulated leakage was conducted at removing the spark plugs. Other measurements simulated “mild” leak of the whole engine – all cylinders. Leakage was implemented by loosing all the spark plugs about 8 turns against full tightening with the appropriate torque. The last, fourth measurement simulates a “large” leaks of engine cylinders. This leakage was induced by removing all the spark plugs from all cylinders. As the measurement results showed leakage of one cylinder, and also the whole engine is reflected not only in the individual amplitude of the starter current, but also the shape of the entire curve.
7
Zhang, Saifei, Chunhua Zhang, Yong Liu, Wei Wu, Han Wu i Shihua Yuan. "Parametric Simulations on Leakage and Performance of a Miniature Free-Piston Generator (MFPG)". Applied Sciences 11, nr 16 (23.08.2021): 7742. http://dx.doi.org/10.3390/app11167742.
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The miniaturization of electrical equipment and popularization of portable devices is an appealing motivation for the development of small-scale heat engines. However, the in-cylinder charge leaks severely as the engine dimension shrinks. The free-piston engine on a small scale provides better sealing than other miniature heat engines. Therefore, a miniature free-piston generator (MFPG) with a single-piston internal combustion engine (ICE) and a voice coil motor (VCM) was proposed in this work. A dynamic model with special attention on the heat transfer and leakage was established accordingly, upon which parametric studies of leakage and its effects on the performance of the MFPG system were performed. Four key parameters, including scavenging pressure, ignition position, combustion duration and piston mass, were considered in the model. The results showed that the mass leakage during the compression decreases with the rise of the motoring current. The indicated thermal efficiency can be improved by boosting scavenging pressure and increase motoring current. The critical ignition position is 2 mm before the top dead center. When ignition occurs later than that, the MFPG system is incapable of outputting power. The chemical to electric energy conversion efficiency is about 5.13%, with an output power of 10~13 W and power density around 4.7~5.7 W/cc.
8
Qi, Congzheng, Zemin Ding, Lingen Chen, Yanlin Ge i Huijun Feng. "Modeling and Performance Optimization of an Irreversible Two-Stage Combined Thermal Brownian Heat Engine". Entropy 23, nr 4 (31.03.2021): 419. http://dx.doi.org/10.3390/e23040419.
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Based on finite time thermodynamics, an irreversible combined thermal Brownian heat engine model is established in this paper. The model consists of two thermal Brownian heat engines which are operating in tandem with thermal contact with three heat reservoirs. The rates of heat transfer are finite between the heat engine and the reservoir. Considering the heat leakage and the losses caused by kinetic energy change of particles, the formulas of steady current, power output and efficiency are derived. The power output and efficiency of combined heat engine are smaller than that of single heat engine operating between reservoirs with same temperatures. When the potential filed is free from external load, the effects of asymmetry of the potential, barrier height and heat leakage on the performance of the combined heat engine are analyzed. When the potential field is free from external load, the effects of basic design parameters on the performance of the combined heat engine are analyzed. The optimal power and efficiency are obtained by optimizing the barrier heights of two heat engines. The optimal working regions are obtained. There is optimal temperature ratio which maximize the overall power output or efficiency. When the potential filed is subjected to external load, effect of external load is analyzed. The steady current decreases versus external load; the power output and efficiency are monotonically increasing versus external load.
9
Kurhekar, Swapnil D., i Abhijeet B. Tamse. "Quality Improvement of Oil and Fuel Leakage in Diesel Engine by using Semi Automatic Setup". International Journal for Research in Applied Science and Engineering Technology 11, nr 3 (31.03.2023): 310–18. http://dx.doi.org/10.22214/ijraset.2023.49405.
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Abstract: As we know when engine goes to testing department before that we test it through semi-automatic setup which is installed on assembly line converyor to test the oil and fuel leakage of diesel engine.Now different trial were taken on engine by using methodology which includes ATEQ D520 unit and air pressure regulator for detecting the leakage quantity.Actually ATEQ D520 UNIT is a flowmeter which measure a drop in pressure with a differential sensor.Here we supplied pressurized air into the engine through breather plug and overflow pipe.If leakage not found engine will dispatched to testing department and if leakage is found the problem may solve by spraying soap water in leakage area so that in that area bubbles comes out .This work which emphasis on the analysis of problem due to which engine reject from testing department and also time and cost saving analysis for one month.Due to this setup improvement in PQCDSM,PPM and reduction in cost poor quality supplied to customers from 28% to 18% of cost per benefit,better customer satisfaction
10
Hu, Ming Jiang. "Optimizing Crankcase Ventilation System of Gasoline Engine". Applied Mechanics and Materials 58-60 (czerwiec 2011): 171–76. http://dx.doi.org/10.4028/www.scientific.net/amm.58-60.171.
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Based on the design goals of the gasoline engine crankcase ventilation system, the features and the layout were described on the gasoline engine crankcase ventilation system, the working model was established on the gasoline engine crankcase ventilation system; using the fluid properties and the mathematical calculation method, the optimizing strategy was proposed on the piston gas leakage, the influencing factors were analyzed on the gasoline engine crankcase vacuum, the design strategy of the flow characteristics was developed on the PCV valve. Using analog control test platform of the gasoline engine, the tests were made on the piston gas leakage, the crankcase vacuum and PCV valve flow characteristics of the gasoline engine crankcase ventilation system. The test result showed that the optimized maximum piston leakage flow was 14L/min; the increasing rates of the optimized intake pipe and crankcase vacuum average were according 5.6% and 8.0%. This could indicate that the working model on the gasoline engine crankcase ventilation system was correct; the proposed strategies on the piston gas leakage, the crankcase vacuum and PCV valve flow characteristics were feasible in the gasoline engine crankcase ventilation system.
11
Xia, Chen, Zhiguang Zhang, Guoping Huang, Tong Zhou i Jianhua Xu. "A Micro Swing Rotor Engine and the Preliminary Study of Its Thermodynamic Characteristics". Energies 11, nr 10 (9.10.2018): 2684. http://dx.doi.org/10.3390/en11102684.
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The rapid progress in microelectromechanical system technology has facilitated great developments in micro heat engines, however, defects in these engines still need to be overcome. Thus, a novel four-stroke micro swing rotor engine (MSRE) that features the advantages of Wankel engine and the micro swing engine is proposed in this study. Kinematic and thermodynamic analyses of the MSRE were performed, and a preliminary experimental research was conducted. In the MSRE, the driver assembly was used to dominate the movements of the two rotors. By the design guideline adaptable to the engine operation principle, the volume of each chamber will vary in a sine-like waveform, which was validated by kinematic analyses. Then, a prototype in mesoscale was designed and fabricated. In consideration of the leakage effect, the thermodynamic characteristics of this engine were numerically investigated. Results indicate that the engine thermodynamic processes were seriously affected by leakage flow, especially when working at low frequencies. Gap height and operation frequency were the two dominant factors that affected engine performance. Under a certain gap height, the MSRE had to work at a specific frequency range and the corresponding optical values exist for engine efficiency and power. With a 20 μm height, the MSRE reached the maximum efficiency of 23.62% at 55 Hz and the maximum power of 3442 W at 95 Hz. Feasibility of the engine was further verified by an experimental test on the operation characteristics, including the cold state test with pressured air blow and the combustion test for engine operation at thermal state. This research lays a good foundation for future development of MSRE, which is of great practical significance for the progress in micro power systems.
12
Liu, Xiaojing, Shuiting Ding, Longtao Shao, Shuai Zhao, Tian Qiu, Yu Zhou, Xiaozhe Zhang i Guo Li. "Investigation on the Formation and Evolution Mechanism of Flow-Resistance-Increasing Vortex of Aero-Engine Labyrinth Based on Entropy Generation Analysis". Symmetry 14, nr 5 (25.04.2022): 881. http://dx.doi.org/10.3390/sym14050881.
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Labyrinth seals are widely employed in the air system of aircraft engines since they reduce the leakages occurring between blades and shrouds, which affect the entropy generation significantly. Excessive leakage flow of the labyrinth may be reduced the efficiency and performance of the engine. This paper proposes the concept of flow-resistance-increasing vortex (FRIV) on the top of the labyrinth that is based on the flow entropy generation mechanism of the stepped labyrinth and the main flow characteristics that lead to entropy generation. A three-dimensional simulation model of the labyrinth structure was established, and the model was compared and verified with the experimental data of the reference. The relative dissipation strength and vorticity distribution of the FRIV were theoretically analyzed. It was confirmed that the dissipative intensity distribution was the same as the vorticity distribution, and the correlation coefficient was larger in the labyrinth tip region. Therefore, a parametric study was conducted on design parameters related to the FRIV, including the teeth inclined angle, tooth crest width, step inclined angle, and other parameters. The results are beneficial for the construction of a stronger FRIV to reduce the leakage. This research is of great significance for the improvement of engine efficiency and for the reduction of fuel consumption in the future.
13
Liu, Xiaojing, Shuiting Ding, Longtao Shao, Shuai Zhao, Tian Qiu, Yu Zhou, Xiaozhe Zhang i Guo Li. "Investigation on the Formation and Evolution Mechanism of Flow-Resistance-Increasing Vortex of Aero-Engine Labyrinth Based on Entropy Generation Analysis". Symmetry 14, nr 5 (25.04.2022): 881. http://dx.doi.org/10.3390/sym14050881.
Pełny tekst źródłaStreszczenie:
Labyrinth seals are widely employed in the air system of aircraft engines since they reduce the leakages occurring between blades and shrouds, which affect the entropy generation significantly. Excessive leakage flow of the labyrinth may be reduced the efficiency and performance of the engine. This paper proposes the concept of flow-resistance-increasing vortex (FRIV) on the top of the labyrinth that is based on the flow entropy generation mechanism of the stepped labyrinth and the main flow characteristics that lead to entropy generation. A three-dimensional simulation model of the labyrinth structure was established, and the model was compared and verified with the experimental data of the reference. The relative dissipation strength and vorticity distribution of the FRIV were theoretically analyzed. It was confirmed that the dissipative intensity distribution was the same as the vorticity distribution, and the correlation coefficient was larger in the labyrinth tip region. Therefore, a parametric study was conducted on design parameters related to the FRIV, including the teeth inclined angle, tooth crest width, step inclined angle, and other parameters. The results are beneficial for the construction of a stronger FRIV to reduce the leakage. This research is of great significance for the improvement of engine efficiency and for the reduction of fuel consumption in the future.
14
LEWIŃSKA, Joanna. "The influence of fuel injection pump malfunctions of a marine 4-stroke Diesel engine on composition of exhaust gases". Combustion Engines 167, nr 4 (1.10.2016): 53–57. http://dx.doi.org/10.19206/ce-2016-405.
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The article presents results of a laboratory study on exhaust gas emission level from a marine diesel engine. The object of the laboratory study was a four-stroke marine diesel engine type Al 25/30 Sulzer, operated at a constant speed. The examination on the engine was carried out according to regulations of the Annex VI to MARPOL 73/78 Convention. The laboratory study consisted of 3 observations: the engine assumed to be operating without malfunctions, delay of the fuel injection by 5° of crankshaft angle in the second engine cylinder, and the leakage of the fuel pump on the second engine cylinder. Additionally, parameters of fuel consumption and thermodynamic parameters of the marine engine were measured during the research. Simulated malfunctions caused changes in total weighed NOx, CO, and CO2 emissions for all considered engine loads. All simulated malfunctions caused a small change in measured thermodynamic parameters of the engine. The engine operation with the delayed fuel injection and the fuel leakage in the fuel pump in one cylinder caused a decrease of NOx and CO emission level. Fuel leakage in the fuel pump causes the CO2 emission to decrease only at low engine load. Calculations of the weighed specific fuel consumption present a 1-2% change in the engine efficiency.
15
Chupp, R. E., i G. F. Holle. "Generalizing Circular Brush Seal Leakage Through a Randomly Distributed Bristle Bed". Journal of Turbomachinery 118, nr 1 (1.01.1996): 153–61. http://dx.doi.org/10.1115/1.2836596.
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Brush seals have established a niche in the gas-to-gas sealing against leakage in modern turbine engines. The variable nature of the brush during operation makes leakage prediction difficult. A simple semi-empirical model based on an effective brush thickness parameter has been successfully used to correlate and predict brush seal leakage in engine environments. The model was extended to correlate a range of brush densities using a physically realistic brush thickness. Later, the model was based on mean diametric brush properties for a large range of circular brush seal geometries. However, the best basis for modeling bristle, distribution was unknown. This paper proposes a solution to the distribution problem by assuming a randomly distributed bristle bed. A random distribution leads to a rectangular array model that is supported by the quality of leakage data generalization. Applying the resultant effective thickness parameter to predict brush seal performance in turbine engines is discussed.
16
Liu, Chunrui, Lidong He, Xingyun Jia, Haozhe Zhu, Tao Chen i Wenhao Wang. "Effect of Installation Error on Rotary Seal of Aero Engine". Aerospace 9, nr 12 (14.12.2022): 820. http://dx.doi.org/10.3390/aerospace9120820.
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The rotary seal is a key component of the aero engine. Under actual working conditions, most rotary seals always operate in an eccentric state (caused by installation errors), and when a large eccentricity occurs, it may lead to a large amount of gas leakage, resulting in a decrease in aero engine efficiency, which ultimately affects the reliability and life of the aero engine. Therefore, the effect of installation error on the rotary seal of the aero engine was studied in this research. The flow field numerical models of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal were established, the effects of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal on leakage were numerically analyzed, the sealing mechanisms of three types of seals were revealed, and the effect of radial eccentricity on the leakage of three types of seals was also studied. Additionally, the high-pressure and high-speed rotary seal experiment bench was improved, the effect of eccentricity on the leakage characteristics of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal was studied using the improved experiment bench, and the leakage characteristics of the three types of seals were compared under the same condition. The experimental results are consistent with the numerical simulation results; the honeycomb seal is the least sensitive to eccentricity, and its sealing performance is the best. The research results in this paper reveal the seal mechanisms of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal and demonstrate the effect law of eccentricity regarding the leakage characteristics of these three types of seals. The results of this research can provide theoretical support for aero engine efficiency improvement.
17
Chen, Yan, Chenkun Cai i Gaowen Liu. "Experimental Analysis of Clearance Leakage Characteristics at Blade Edge Plates of a Gas Turbine Engine". Energies 15, nr 7 (22.03.2022): 2303. http://dx.doi.org/10.3390/en15072303.
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The loss of cold air from the blade edge plates of the turbine has a negative impact on engine performance and safety. Using an experimental method, this paper investigates the effect of geometric and aerodynamic parameters on cold air leakage through pressure and mass flow measurements. Based on the results, it can be concluded that, with a change in sheet spacing, the proportion of bypass leakage and clearance leakage changes. At the same sheet spacing, the edge plate clearance is increased from 1 mm to 1.1 mm, resulting in a 30% increase of total leakage and a 25.7% increase of leakage equivalent mass flow. The edge plate clearance was increased from 1.1 mm to 1.2 mm, the total leakage increased by 19.2%, and the equivalent mass flow of leakage was 19%. The proportion of clearance leakage in the total leakage increased gradually for a given edge plate clearance. When the sheet spacing was 1 mm, bypass leakage accounted for 68% of the total leakage and was the primary source of leakage. The clearance leakage accounted for 83% of the total leakage with a plate spacing of 10 mm. When the sheet spacing is small, bypass leakage dominates; when it is large, clearance leakage dominates. The variation law of leakage with pressure, structural parameters and the ratio of sheet spacing to sealing slot length play an important role in the design of sealing structures.
18
KOSZAŁKA, Grzegorz, Michał GĘCA i Andrzej SUCHECKI. "Simulation research into the influence of the combustion chamber blowby on the efficiency of a diesel engine". Combustion Engines 158, nr 3 (1.07.2014): 73–79. http://dx.doi.org/10.19206/ce-116939.
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Combustion chamber leakage, caused mainly by blowby, results in a reduced engine performance and higher fuel consumption. The blowby rate is, to some extent, determined by the design of the piston-ring-cylinder assembly (PRC) and the blowby rate varies throughout the life of an engine due to wear of the said assembly. The paper presents a quantitative evaluation of the influence of the combustion chamber blowby on the engine performance and fuel consumption on the example of two diesel engines: older generation naturally aspirated indirect injection diesel engine and a modern turbocharged direct injection engine. The assessment was made based on a simulation research using the AVL Boost software and the input data for the calculations were ascertained based on measurements performed on actual objects. The results have shown that a reduction of the blowby by half compared to the values occurring in engines of good technical condition would increase the maximum torque and power by approx. 0.5% for both investigated engines. The results of the simulation have also shown that increases in the blowby occurring in engines after long service lead to increased fuel consumption from 1% to 7% and the lower the engine speed and load the greater theses values.
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Chupp, R. E., i C. A. Dowler. "Performance Characteristics of Brush Seals for Limited-Life Engines". Journal of Engineering for Gas Turbines and Power 115, nr 2 (1.04.1993): 390–96. http://dx.doi.org/10.1115/1.2906721.
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Brush seals are potential replacements for air-to-air labyrinth seals in gas turbine engines. An investigation has been conducted to determine the performance characteristics of brush seals for application in limited-life gas turbine engines. An elevated temperature, rotating test rig was designed and built to test labyrinth and brush seals in simulated subsonic and supersonic engine conditions. Results from initial tests for subsonic applications demonstrated that brush seals exhibit appreciably lower leakage compared to labyrinth seals, and thus offer significant engine performance improvements. Performance results have been obtained showing the effect of various brush seal parameters, including: initial interference, backplate gap, and multiple brush seals in series.
20
Ao, Liang Zhong. "The Faults Analysis of HPTACCV Fuel Leakage on CFM56-5B Engine". Advanced Materials Research 503-504 (kwiecień 2012): 1510–13. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1510.
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The high pressure turbine clearance control valve (HPTACCV) fuel leakage on CFM56-5B engine can cause some flight delays and cancellations. The basic structure of HPTACCV is introduced. The root cause of the fuel leakage is given. In the field, to provide a more reliable engine, Weibull Analysis can be used to determine the soft time. This paper presents how to use Weibull Distribution to calculate the soft time life and forecast the spare parts equipments. This method can be used to evaluate the other failures of the aero engine components.
21
Sareh, Daneshgar, Zahedi Rahim i Asemi Hamidreza. "Experimental investigation of gamma stirling engine coupling to convert thermal to cooling energy in different laboratory conditions". Global Journal of Biotechnology and Biomaterial Science 8, nr 1 (14.06.2022): 009–22. http://dx.doi.org/10.17352/gjbbs.000017.
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The main aim of this research is to experimentally investigate the two coupled identical ST500 gamma-type Stirling engines and convert thermal energy to cooling energy. Using a new structure and two coupled Stirling engines at different temperatures and pressures and the use of biomass fuel within the 4 -8 bar average pressure range of the first engine heat source, the 1-4 bar average pressure range of the second engine heat sink, and Stirling heat engine temperature range of 480-580 ºC, the effective cooling is obtained in the cooling engine. In doing tests, attempts were made to reach lower than 9 percent error results in different parts of the engine, including insulation, fluid leakage, belt loss, and measurement devices. According to the obtained results, 8 bars increase in the average pressure range of the gas in the first engine heat source, a 1 bar reduction in the average pressure range of the gas in the second engine heat sink, the increased temperature of the heat source up to 580ºC, and the use of the light operating fluid such as helium will affect the generation of cooling up to-16ºC.
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Dudzik, Krzysztof, i Adam Charchalis. "Possibility Analysis of Using Acoustic Emission for Monitoring Technical Condition of Compressed Air Installation of 3AL25/30 Engine". Journal of KONBiN 49, nr 3 (1.10.2019): 1–15. http://dx.doi.org/10.2478/jok-2019-0047.
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Abstract This paper presents the methodology and research results of monitoring of compressed air starting system of 3AL25/30 engine placed in Maritime Engineering Faculty of Gdynia Maritime University. Research was carried out using a set of acoustic emission Vallen System. Analysis of recorded parameters revealed leakage in the installation – damage of one of the valves. The test results indicate that the AE method can be useful for monitoring the technical condition of pressure systems of engines and devices in a ship's engine room during normal operation as an on-line system.
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Li, Shen, Li Hua Guo, Dan Hua Wang i Hui Qun Yuan. "Valve Leakage Simulation and Fault Diagnosis of Diesel Engine". Applied Mechanics and Materials 312 (luty 2013): 620–24. http://dx.doi.org/10.4028/www.scientific.net/amm.312.620.
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To valve leakage in working process of diesel engine, the corresponding fault simulation is an important measure for finding a diagnostic method. By the Law of Conversation of Energy, Conversation of Mass and the Classical Equations, mathematical model of working cycle of diesel engine is reasonably built and calculated. Through analyzing valve leakage fault, the single Weber-function is used as a combustion model in fault simulation. Fault diagnosing of valve via the energy parameters of cylinder head vibration signal is proposed. The key to diagnose valve leakage closely lies in analyzing its high frequency components through selecting the cylinder head vibration signal close to the maximum burning and exploding pressure step and proposing spectrum analysis.
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Hennek, Krystian, i Mariusz Graba. "The influence of exhaust system leak on the operating parameters of a turbocharged spark ignition engine". AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 19, nr 6 (30.06.2018): 468–72. http://dx.doi.org/10.24136/atest.2018.114.
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Turbocharging of an internal combustion engine is the most common technique to improve an engines’ performance. In present it is not hard to meet vehicles on the road with turbocharged SI engines, which have a high mileage, and because of this fact there is a high risk of exhaust systems leak. This might have its influence not only on the emissions, but also on the vehicles performance. Thereby this dissertation shows the comparative analysis of the influence of exhaust system leak in the catalyzer input on the exhaust gasses composition in the catalyzer output and the operation parameters of an turbocharged SI engine. During the research some parameters were recorded and compared, e. g.: the engines power and torque, the injec-tors opening time, the oxygen sensors voltage signals in the input and in the output of the catalyzer, the concentration of harmful gasses in the exhaust tailpipe. The research was conducted with the use of a single roller MAHA MSR 500 chassis dynamometer. A series of torque measurements was performed. Under these measurements a simulation of the exhaust system leakage of a turbocharged SI passenger car engine was made. As a result three variations of the wideband oxygen sensor acting were reached. The wideband sensor is mounted between the turbocharger unit and the input of the catalyzer. In the test the influence of the leakage on the injector’s opening time and the composition of harmful exhaust substances were pointed.
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Kluka, J. A., i D. G. Wilson. "Low-Leakage Modular Regenerators for Gas-Turbine Engines". Journal of Engineering for Gas Turbines and Power 120, nr 2 (1.04.1998): 358–62. http://dx.doi.org/10.1115/1.2818130.
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One of the significant problems plaguing regenerator designs is seal leakage resulting in a reduction of thermal efficiency. This paper describes the preliminary design and analysis of a new regenerative heat-exchanger concept, called a modular regenerator, that promises to provide improved seal-leakage performance. The modular regenerator concept consists of a ceramic-honeycomb matrix discretized into rectangular blocks, called modules. Separating the matrix into modules substantially reduces the transverse sealing lengths and substantially increases the longitudinal sealing lengths as compared with typical rotary designs. Potential applications can range from small gas-turbine engines for automotive applications to large stationary gas turbines for industrial power generation. Descriptions of two types of modular regenerators are presented including sealing concepts. Results of seal leakage analysis for typical modular regenerators sized for a small gas-turbine engine (120 kW) predict leakage rates under one percent for most seal-clearance heights.
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Han, Bingjie, Wei Niu i Tanbao Yan. "Fault Modeling and Simulation of Engine Driven Pump in Aircraft Hydraulic System". Journal of Physics: Conference Series 2252, nr 1 (1.04.2022): 012057. http://dx.doi.org/10.1088/1742-6596/2252/1/012057.
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Abstract The structure of engine driven pump in aircraft hydraulic system is complex, its fault forms are diverse, and the fault transmission path is complex and multi factor coupling. In view of the above problems, based on the in-depth analysis of the working principle of the engine driven pump, the engine driven pump model is established, and the leakage fault injection mechanism of the friction pair is added. The relationship between the flow fluctuation characteristics of engine driven pump and the changes of pump spindle speed, swashplate inclination and pump outlet cavity volume are obtained through model simulation analysis. The mechanism of internal leakage fault of plunger pair, port pair and slipper pair are analyzed, the influence of leakage clearance parameters on key performance indexes such as pump pressure and flow are simulated, and the simulation test data of internal leakage fault of pump are obtained. The simulation results show that the inclination angle of swashplate and spindle speed are positively correlated with the output flow of the pump. The increase of pump outlet volume can effectively alleviate the pressure and flow fluctuation behind the pump. In addition, when the radial clearance of the plunger pair of this type of pump exceeds 0.2mm, the pump fault characteristics begin to appear. At the same time, the load change behind the pump will affect the characterization of the fault of internal leakage of the pump.
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Han, Bingjie, Wei Niu i Tanbao Yan. "Fault Modeling and Simulation of Engine Driven Pump in Aircraft Hydraulic System". Journal of Physics: Conference Series 2252, nr 1 (1.04.2022): 012057. http://dx.doi.org/10.1088/1742-6596/2252/1/012057.
Pełny tekst źródłaStreszczenie:
Abstract The structure of engine driven pump in aircraft hydraulic system is complex, its fault forms are diverse, and the fault transmission path is complex and multi factor coupling. In view of the above problems, based on the in-depth analysis of the working principle of the engine driven pump, the engine driven pump model is established, and the leakage fault injection mechanism of the friction pair is added. The relationship between the flow fluctuation characteristics of engine driven pump and the changes of pump spindle speed, swashplate inclination and pump outlet cavity volume are obtained through model simulation analysis. The mechanism of internal leakage fault of plunger pair, port pair and slipper pair are analyzed, the influence of leakage clearance parameters on key performance indexes such as pump pressure and flow are simulated, and the simulation test data of internal leakage fault of pump are obtained. The simulation results show that the inclination angle of swashplate and spindle speed are positively correlated with the output flow of the pump. The increase of pump outlet volume can effectively alleviate the pressure and flow fluctuation behind the pump. In addition, when the radial clearance of the plunger pair of this type of pump exceeds 0.2mm, the pump fault characteristics begin to appear. At the same time, the load change behind the pump will affect the characterization of the fault of internal leakage of the pump.
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Han, Bingjie, Wei Niu i Tanbao Yan. "Fault Modeling and Simulation of Engine Driven Pump in Aircraft Hydraulic System". Journal of Physics: Conference Series 2252, nr 1 (1.04.2022): 012057. http://dx.doi.org/10.1088/1742-6596/2252/1/012057.
Pełny tekst źródłaStreszczenie:
Abstract The structure of engine driven pump in aircraft hydraulic system is complex, its fault forms are diverse, and the fault transmission path is complex and multi factor coupling. In view of the above problems, based on the in-depth analysis of the working principle of the engine driven pump, the engine driven pump model is established, and the leakage fault injection mechanism of the friction pair is added. The relationship between the flow fluctuation characteristics of engine driven pump and the changes of pump spindle speed, swashplate inclination and pump outlet cavity volume are obtained through model simulation analysis. The mechanism of internal leakage fault of plunger pair, port pair and slipper pair are analyzed, the influence of leakage clearance parameters on key performance indexes such as pump pressure and flow are simulated, and the simulation test data of internal leakage fault of pump are obtained. The simulation results show that the inclination angle of swashplate and spindle speed are positively correlated with the output flow of the pump. The increase of pump outlet volume can effectively alleviate the pressure and flow fluctuation behind the pump. In addition, when the radial clearance of the plunger pair of this type of pump exceeds 0.2mm, the pump fault characteristics begin to appear. At the same time, the load change behind the pump will affect the characterization of the fault of internal leakage of the pump.
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Zhang, Zhenzhen, Hui Chen, Chao Qi i Yazhou Liu. "Model-Based Leakage Estimation and Remaining Useful Life Prediction of Control Gas Cylinder". International Journal of Aerospace Engineering 2023 (9.05.2023): 1–10. http://dx.doi.org/10.1155/2023/3606822.
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The high-pressure gas cylinder is the pressure source for liquid propellant engine valve control. Leakage is a significant cause of pressure loss in gas cylinders, leading to engine control failure and serious flight accidents. In this paper, a model-based approach to estimate the leakage area and remaining useful life (RUL) of gas cylinders is proposed. To estimate the leakage area, a state space representation of the cylinder system is developed based on the nonlinear model derived from momentum, energy, and continuity equations. Leakage is defined as a system state, and an extended Kalman filter (EKF) as a state observer is implemented to estimate the leakage area. Internal pressure measurements of the gas cylinder are required as output parameters in the estimation process. Then, the estimated states are fed into the nonlinear model to iteratively calculate the RUL of the cylinder. To evaluate the effectiveness of the proposed method, scaling leakage test data, computational fluid dynamics (CFD) simulation results, and liquid rocket engine (LREs) hot test data are used. Calibration results have proved the validity and universality of the method, with the mean absolute error (MAE) for the remaining 80% useful life prediction results being less than 0.02, 0.04, and 1.10. This study can provide technical support for fault tolerance control and orbital replanning in case of control gas cylinder leaks.
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Dzhus, O. A., Yu V. Rodionov, A. E. Lomovskikh, V. V. Novichikhin, D. Yu Vnukov i A. O. Sukhova. "Environmentally Friendly Power Plants Based on Rotary Type Internal Combustion Engine". Voprosy sovremennoj nauki i praktiki. Universitet imeni V.I. Vernadskogo, nr 1(83) (2022): 027–39. http://dx.doi.org/10.17277/voprosy.2022.01.pp.027-039.
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Two well-known designs of rotary piston engines and a directly promising design of a rotary engine with an improved separating blade developed by Professor Yu. V. Vorobyov are considered. It has been found that in the created design of a rotary engine there is no connecting rod and piston group, instead of which a rotor is made that performs a circular motion, and then, using an eccentric mechanism, this motion is converted into a rotational motion of the output shaft. It was found that the proposed technical solution will reduce the leakage of gases from the working chambers of the engine, increase the tightness of isolated chambers or cylinders, which will ultimately lead to an increase in power and an increase in engine efficiency by 10 - 15 % and a decrease in toxic emissions by up to 12 %.
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Dolatabadi, Nader, Ramin Rahmani, Stephanos Theodossiades, Homer Rahnejat, Guy Blundell i Guillaume Bernard. "Tribodynamics of hydraulic actuated clutch system for engine-downsizing in heavy duty off-highway vehicles". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, nr 4 (25.02.2018): 976–93. http://dx.doi.org/10.1177/0954407018756789.
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Engine downsizing is desired for modern heavy-duty vehicles to enhance fuel economy and reduce emissions. However, the smaller engines usually cannot overcome the parasitic loads during engine start-up. A new clutch system is designed to disconnect the downsized engine from the parasitic losses prior to the idling speed. A multi-scale, multi-physics model is developed to study the clutch system. Multi-body dynamics is used to study the combined translational–rotational motions of the clutch components. A micro-scale contact model is incorporated to represent the frictional characteristics of the sliding surfaces. Although the clutch is designed for dry contact operation, leakage of actuating hydraulic fluid can affect the interfacial frictional characteristics. These are integrated into the multi-body dynamic analysis through tribometric studies of partially wetted surfaces using fresh and shear-degraded lubricants. Multi-scale simulations include sensitivity analysis of key operating parameters, such as contact pressure. This multi-physics approach is not hitherto reported in the literature. The study shows the importance of adhesion in dry clutch engagement, enabling full torque capacity. The same is also noted for any leakage of significantly shear-degraded lubricant into the clutch interfaces. However, the ingression of fresh lubricant into the contact is found to reduce the clutch torque capacity.
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Deng, Gao-xiang, Wei Shao, Yu Liu i Zheng Cui. "Continuous three-level quantum heat engine with high performance under medium temperature difference". Journal of Applied Physics 133, nr 12 (28.03.2023): 124903. http://dx.doi.org/10.1063/5.0139998.
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The possibility of utilizing quantum effects to enhance the performance of quantum heat engines has been an active topic of research, but how to enhance the performance by optimizing the engine parameters needs to be further studied. In this study, the temperature difference and dissipation modes affecting the performance of a three-level quantum heat engine were analyzed using an orthogonal test. The results indicated that the dissipation mode dominated the performance of the quantum heat engine. The quantum heat engine performs best when there is only resonance and no detuning; however, when detuning exists, a lower resonance can improve the efficiency by reducing energy losses. Regarding the temperature difference, the best performance was achieved at a medium temperature difference owing to the decreasing heat leakage. Finally, the “quantum friction” caused by the detuning could make the maximal efficiency lower than the Carnot efficiency.
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Chen, P.-C. "A novel diagnostic system for gasoline-engine leakage detection". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 225, nr 5 (maj 2011): 673–85. http://dx.doi.org/10.1177/0954407010395687.
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Fu, Chao, Xiaoxia Liang, Qian Li, Kuan Lu, Fengshou Gu, Andrew D. Ball i Zhaoli Zheng. "Comparative Study on Health Monitoring of a Marine Engine Using Multivariate Physics-Based Models and Unsupervised Data-Driven Models". Machines 11, nr 5 (15.05.2023): 557. http://dx.doi.org/10.3390/machines11050557.
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The marine engine is a complex-structured multidisciplinary system that operates in a harsh environment involving high temperatures and pressures and gas/fluid/solid interactions. Many malfunctions and faults can occur to the marine engine and efficient condition monitoring is critical to ensure the expected performance. In this paper, a marine engine test rig is established and its process data are recorded, including various temperatures and pressures. Two data-driven models, i.e., principal component analysis and the sparse autoencoder, and a physics-based model are applied to the marine engine for two classic faults, i.e., lubrication oil filter blocking and cylinder leakage. Comparative studies and discussions are conducted regarding their performance in terms of anomaly detection and fault isolation. The data points collected for the filter blocking fault are generally two times higher than the fault thresholds set by the data-driven models. In the physics-based model, it is observed that the lubrication oil pressure falls from the predicted 3.2–3.8 bar to around 2.3 bar. For the cylinder leakage fault, the fault test data are nearly four times higher than the thresholds in the data-driven models. The exhaust gas temperature of the leaked cylinder falls from an estimated 150–200 °C to about 100 °C. The transferability and interpretability of these models are finally discussed. The findings of the present study offer insights into the two types of models and can provide guidance for the effective condition monitoring of marine engines.
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Koszalka, Grzegorz, i Paweł Krzaczek. "Energy Losses Related to Ring Pack Wear in Gasoline Car Engine". Energies 15, nr 24 (16.12.2022): 9570. http://dx.doi.org/10.3390/en15249570.
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Decreasing production and rising prices of cars, especially those with electric drive, lead to longer use of cars with internal combustion engines. It can be assumed that in the future, more and more cars powered by such engines with high mileage and therefore high wear will be used. Engine wear leads to reduced efficiency and increased emissions. This paper analyzes the impact of wear of the piston–rings–cylinder system components on energy losses associated with gas leakage from the combustion chamber and friction of the rings against the cylinder liner in a car spark-ignition engine. A ring pack model was used for the analyses. The input data for the simulation were gained in measurements made on the engine test stand and measurements of the wear of the engine components used in the car. The energy losses associated with blow-by in an unworn engine ranged from 1.5% of the indicated work at high load to almost 5% at low load. In the engine after 300,000 km, these losses increased to 2.5% and 7.5%, respectively. Ring friction losses in an unworn engine ranged from 1.5% at high load to 9% at low load. The effect of wear on these losses was smaller. They increased by only 0.1% at high load and 1% at low load.
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Pabón León, J. A., J. P. Rojas Suárez i M. S. Orjuela Abril. "Numerical study of the physical processes of gas leakage in the compression ring in diesel engines". Journal of Physics: Conference Series 2118, nr 1 (1.11.2021): 012016. http://dx.doi.org/10.1088/1742-6596/2118/1/012016.
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Abstract In this research, the construction of a numerical model is proposed for the analysis of the friction processes and the thickness of the lubrication film present in the compression ring of internal combustion engines. The model is built using MATLAB software, and three load conditions are used as reference (2 Nm, 4 Nm, and 6 Nm) with a rotation speed of 3600 rpm, which correspond to a stationary single-cylinder diesel engine. Comparison between model estimates and experimental results show that the development model could predict the actual engine conditions. The deviation between the numerical model and the experimental data was 17%. It was shown that the increase in engine load causes a 16% increase in the friction force of the compression ring, which implies a 50% increase in power loss due to friction processes. In general, the model developed allows the analysis of the friction processes in the compression ring and its effect on the lubrication film, considering the leakage of the combustion gases. In this way, the construction of a more complex mathematical model is achieved, which allows improving the precision in the analyzes related to the interaction between the compression ring and the cylinder liner.
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Lee, Chan Hee, Yu Chan Nam, Se Chul Yi i Hun Kee Lee. "A Study on the Improvement of Oil Pump Assembly for K9 Self-Propelled Howitzer Engine*". Taegu Science University Defense Security Institute 7, nr 3 (30.06.2023): 15–24. http://dx.doi.org/10.37181/jscs.2023.7.3.015.
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This paper is on the improvement of the oil pump assembly for preventing low oil pressure symptoms of the K9 Self-Propelled howitzer engine. Although the TBO(Time Between Overhauls) of K9 self-propelled howitzer engine is 1,500 engine operating hours, 13.37 % of K9 Self-Propelled howitzer engines which were operated for only hundreds of hours suffered low oil pressure symptoms and failed to operate normally. Detailed investigation into the engine was conducted to establish the cause and generation mechanism of the symptoms and it was found that oil leakage due to abrasive wear of pressure relief valve piston housing occurred in the oil pump assembly. To prevent abrasive wear of piston housing, new design concept and design parameters of pressure relief valve have been proposed. Performance, durability and system installation test on the prototype based on the proposed design were followed and results validated the proposed design. Oil pump assembly based on this study is applied to mass production.
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Hendricks, R. C. "Brush Seal Performance and Durability Issues Based on T-700 Engine Test Results". International Journal of Rotating Machinery 1, nr 2 (1995): 117–28. http://dx.doi.org/10.1155/s1023621x95000029.
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The integrity and performance of brush seals have been established. Severe bench and engine tests have shown high initial wear or rub-in rates, material smearing at the interface, and bristle and rub-runner wear, but the brush seals did not fail. Short-duration (46 hr) experimental T-700 engine testing of the compressor discharge seal established over 1-percent engine performance gain (brush versus labyrinth). Long-term gains were established only as leakage comparisons, with the brush at least 20 percent better at controlling leakage. Long-term materials issues, such as wear and ultimately seal life, remain to be resolved. Future laeeds are cited for materials and analysis tools that account for heat generation, thermomechanical behavior, and tribological pairing to enable original equipment manufacturers to design high-temperature, high-surface-speed seals with confidence.
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Affanali A. Sayyad and Roshani R. Chavhan, Prof Gaffar G. Momin, Aakanksha P. Purkar. "A Review on Vehicle Health Monitoring System". International Journal for Modern Trends in Science and Technology 06, nr 09 (29.10.2020): 31–34. http://dx.doi.org/10.46501/ijmtst060906.
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Vehicles need repair after a certain interval of time and if are not repaired at fixed intervals it can lead to accidents. The objective of the project is to continuously notify the owner about the air pressure of tire, quality of exhaust gas, wear of breaks, leakage of oil, the excessive heating of the engine or the blockage in fuel pipe, etc. Tire pressure monitoring sensor is used to get live tire pressure reading, gas sensor gives the readings of amount of carbon dioxide (CO2), Nitrogen Oxides (NOx) etc. as amount and quality of exhaust gives the proper working condition of engine, flow sensor is used that senses the over flow of oil or leakage of oil, temperature sensor is employed in the engine that warns the owner about overheating of engine and a flow sensor is used that senses the proper flow of fuel in the pipe. All these sensor data is displayed on LCD display unit integrated with Arduino microcontroller.
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Zeng, Ji, Bowen Jin, He Zhang, Songyan Mai, Bo Yuan, Hui Jiang, Mengkai Yang i Chaochun Huang. "The Mathematical Model of Marine Engine Room Equipment Based on Machine Learning". Wireless Communications and Mobile Computing 2022 (4.04.2022): 1–8. http://dx.doi.org/10.1155/2022/8366670.
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This study is aimed at reducing the occurrence of oil spill accidents in the engine room of ships and carries out risk prevention for the equipment of the port ships, thereby reducing pollution to the marine ecological environment. Firstly, the concepts and principles of cluster analysis and ship automatic identification system are expounded. Secondly, the data information collected by the ship’s automatic identification system (AIS) is combined with density-based cluster analysis. The accident area and extent at different stages of the ship’s engine room equipment are classified. Finally, cluster analysis is used to evaluate the risk of equipment of the port ship engine room. The results show that there are 43000 ship operation information points in port a, the average operating speed of ships is 9 kilometers, and the fastest operation speed is 16.9 kilometers. In addition, many ship routes in port a need to take risk prevention measures to minimize the impact between ships and reduce the risk of oil leakage in the engine room. The proposed cabin model can easily and quickly analyze the orientation information of the ship and classify all the data into different types according to the surrounding information points. AIS can realize the information transfer between ships and between ship and shore. Information such as the position, speed, and direction of the ship needs to be accurately known to ensure safety at sea. These data need to relate to some terminals and networks to form a maritime monitoring network. The ship AIS based on cluster analysis can cluster the areas where the ship’s speed and direction change significantly in the port area, effectively preventing accidents. Scientific risk prevention measures can effectively reduce the oil leakage risk of ship engine room equipment, improve the working efficiency of marine engines, and provide a strong foundation for the entire marine ecological environment protection.
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Lin, Ze-Bin, Wei Li, Jing Fu, Yun-Yun Yang i Ji-Zhou He. "A Three-Terminal Quantum Well Heat Engine with Heat Leakage". Chinese Physics Letters 36, nr 6 (maj 2019): 060501. http://dx.doi.org/10.1088/0256-307x/36/6/060501.
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JIN, Peng, i Jung-Sik KIM. "Design and Fabrication of a Micro Reciprocating Engine". Combustion Engines 122, nr 3 (1.07.2005): 32–41. http://dx.doi.org/10.19206/ce-117398.
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This paper presents an ongoing project of developing a micro reciprocating internal combustion engine. The engine is designed on the basis of a two stroke piston engine, but heavy modifications have been made to suit the 2D MEMS fabrication. All the engine parts are located in two layers. Piston seals are not used and leakage is prevented by the introduction of microgrooves on the piston, tight tolerance control and an extended contact area between the piston and the cylinder. With the assistance of a film of lubrication oil, these measures prove effective in preventing leakage. A new approach has been developed to fabricate high temperature resistant engine components at low cost. The approach relies on the UltraThick SU-8 Process (UTSP) to make micromoulds; then ceramic and metallic engine components can be produced based on the moulds. The UTSP is a UV lithography process for producing up to 1000 ?m thick SU-8 layers and the quality of the fabrication results can be compared with those made by using X ray exposure process in the same thickness. A complete microengine has been fabricated in SU-8 using the UTSP for test drive. High quality ceramic and metallic components have been produced based on the SU-8 moulds, proving the new approach is feasible for building
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Cai, Yijie, Zhe Xu, Quan Wen, Jinni Shi, Fei Zhong, Xiaojun Yang, Jianguo Yang i Hongdi Zhou. "Fault States Diagnosis of Marine Diesel Engine Valve Based on a Modified VGG16 Transfer Learning Method". Mathematical Problems in Engineering 2023 (8.05.2023): 1–14. http://dx.doi.org/10.1155/2023/1225536.
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The marine diesel engine is an important power machine for ships. Traditional machine learning methods for diesel engine fault diagnosis usually require a large amount of labeled training data, and the diagnosis performance may decline when encounters vibrational and environmental interference. A transfer learning convolutional neural network model based on VGG16 is introduced for diesel engine valve leakage fault diagnosis. The acquired diesel engine cylinder head vibration signal is first converted to time domain, frequency domain, and wavelet decomposition images. Secondly, the VGG16 deep convolutional neural network is pretrained using the ImageNet dataset. Subsequently, fine tuning the network based on the pretrained basic parameters and image enhancement methods. Finally, the well-trained model is adopted to train and test the target dataset. In addition, the cosine annealing learning rate setting method is used to make the learning rate close to the global optimal solution. Experimental results show that the proposed method has higher accuracy and better robustness against noise with a small sample dataset than traditional methods and deep learning models. This study not only demonstrates a novel view for the diagnosis of marine diesel engine valve leakage, but also provides an applicable diagnosis method for other similar issues.
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Wang, Yun, Xi Chen i Xiang Yu Ding. "Finite Element Analysis of Leakage about Metallic Sealing Ring Used in Aircraft Engine". Advanced Materials Research 971-973 (czerwiec 2014): 885–88. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.885.
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based on process equation, momentum equation, state equation and continuity equation, building ax symmetric finite element model of sealing ring used in aero engine, combined with characters of flowing gas in small gap deduce the formula of gas leakage rate, and discuss the impact of working environment for its sealing capability. The result show, as the compression ratio increased, the leakage was correspondingly reduced.
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Fessler, H., T. H. Hyde i L. V. Lewis. "Leakage Through Loaded Flat-Flanged Joints without Gaskets". Proceedings of the Institution of Mechanical Engineers, Part A: Power and Process Engineering 202, nr 1 (luty 1988): 1–13. http://dx.doi.org/10.1243/pime_proc_1988_202_002_02.
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Experimentally determined air leakage data are interpreted using fluid flow theory, finite element deflections and initial gap measurements. It is shown that laminar flow equations do not apply at practical aero-engine pressures and that the leakage flow can be overestimated by assuming choked isentropic flow at the outside diameter of the joint. Design against leakage is thereby reduced to a structural consideration of gap height at the outside diameter. It is shown that the gap height will usually reduce with load. A ‘divergent’ initial gap is shown to cause excessive leakage. However, the machining of a very small cone angle on the contact face is shown to be an effective method of significantly reducing leakage.
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Outirba, A. Bilal, B. Patrick Hendrick i C. Kevin Nicolas. "Experimental characterisation of carbon fibre brush seal leakage performance as a function of bristle pack geometrical parameters under dry conditions". Aeronautical Journal 121, nr 1245 (5.09.2017): 1627–47. http://dx.doi.org/10.1017/aer.2017.92.
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ABSTRACTOver the last decades, it has been progressively acknowledged that reducing the specific fuel consumption and the emission of pollutants, as well as improving the thrust-to-weight ratio involves extensive research on advanced sealing technologies. Amongst these, brush seals are particularly well considered for their excellent leakage performance, their low friction properties, and their ability to cope with inevitable rotor excursions during flights. This paper presents the experimental work that has been carried on in order to characterise carbon fibre brush seals leakage rate in function of the bristle pack geometry, under different pressure loads and rotational speeds. The analysed parameters are the bristle-free length, the density and the inter-plate distance. The work, performed by the ULB (Université Libre de Bruxelles) in collaboration with French engine manufacturer Safran Aircraft Engines, highlights specific behaviour of carbon fibre brush seals under differential pressure, proposes a leakage prediction model developed through empirical equations, and discusses over the most influential parameters that influence the air consumption of a brush seal.
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Ponmurugan, M. "Attainability of Maximum Work and the Reversible Efficiency of Minimally Nonlinear Irreversible Heat Engines". Journal of Non-Equilibrium Thermodynamics 44, nr 2 (26.04.2019): 143–53. http://dx.doi.org/10.1515/jnet-2018-0009.
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Abstract We use the general formulation of irreversible thermodynamics and study the minimally nonlinear irreversible model of heat engines operating between a time-varying hot heat source of finite size and a cold heat reservoir of infinite size. We find the criterion under which the optimized efficiency obtained by this minimally nonlinear irreversible heat engine can reach the reversible efficiency under the tight coupling condition: a condition of no heat leakage between the system and the reservoirs. We assume the rate of heat transfer from the hot to the cold heat reservoir obeys Fourier’s law and discuss physical conditions under which one can obtain the reversible efficiency in a finite time with finite power. We also calculate the efficiency at maximum power for the minimally nonlinear irreversible heat engine under the nontight coupling condition.
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Wang, Qian, Jin Hua Yang, Jin Bai, Jun Jie Chen i Ze Chen. "Research of Micro Free-Piston Engine Generator Performance". Advanced Materials Research 199-200 (luty 2011): 198–202. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.198.
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Based on the operating characteristics of a micro HCCI (Homogeneous Charge Compress Ignition) free-piston engine, a multidimensional model which coupled CFD code, chemical dynamic model and piston dynamic model has been established. Using this model, an ignition and combustion process of the micro engine is simulated, the cylinder pressure and temperature profiles are obtained, and the influence of leakage and heat lost on micro engine combustion process is analyzed. Meanwhile, working characteristics of micro engine generator are evaluated by employing the simulation result. Power, combustion efficiency, etc of the micro engine are obtained. Lastly, the micro engine working characteristics with different load, fuel and piston mass are compared and effects of those varying conditions on engine performance are investigated. Simulation result provides essential requirements for micro free-piston engine control and design.
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Vinogradov, A. S., i T. V. Sergeeva. "LEAKAGE ACCOUNT FOR RADIAL FACE CONTACT SEAL IN AIRCRAFT ENGINE SUPPORT". IOP Conference Series: Materials Science and Engineering 302 (styczeń 2018): 012003. http://dx.doi.org/10.1088/1757-899x/302/1/012003.
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Li, Guoqing, Qian Zhang, Zhijun Lei, Enliang Huang, Hongwei Wu i Gang Xu. "Leakage performance of labyrinth seal for oil sealing of aero-engine". Propulsion and Power Research 8, nr 1 (marzec 2019): 13–22. http://dx.doi.org/10.1016/j.jppr.2018.12.003.
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