Journal articles: 'Two-stroke engines'

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Shokrollahihassanbarough, Farzad, Ali Alqahtani, and Mirosław Wyszynski. "Thermodynamic simulation comparison of opposed two-stroke and conventional four-stroke engines." Combustion Engines 162, no. 3 (August 1, 2015): 78–84. http://dx.doi.org/10.19206/ce-116867.

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Today’s technology leveraging allows OP2S (Opposed Piston 2-Stroke) engine to be considered as an alternative for the conventional four-stroke (4S) engines as mechanical drive in various applications, mainly in transportation. In general, OP2S engines are suited to compete with conventional 4-stroke engines where power-to-weight ratio, power-to-bulk volume ratio and fuel efficiency are requirements. This paper does present a brief advent, as well as the renaissance of OP2S engines and the novel technologies which have been used in the new approach. Also precise thermodynamic benefits have been considered, to demonstrate the fundamental efficiency advantage of OP2S engines. Hence, simulations of two different engine configurations have been taken into consideration: a one-cylinder opposed piston engine and two-cylinder conventional piston four-stroke engine. In pursuance of fulfilling this goal, the engines have been simulated in AVL Boost™ platform which is one of the most accurate Virtual Engine Tools, to predict engine performance such as combustion optimization, emission and fuel consumption. To minimize the potential differences of friction losses, the bore and stroke per cylinder are taken as constant. The closed-cycle performance of the engine configurations is compared using a custom analysis tool that allows the sources of thermal efficiency differences to be identified and quantified. As a result, brake thermal efficiency, power and torque of OP2S engine have been improved compared to conventional engines while emission concern has been alleviated.

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MITIANIEC, Władyslaw, and Konrad BUCZEK. "Modification of four-stroke engine for operation in two-stroke cycle for automotive application." Combustion Engines 162, no. 3 (August 1, 2015): 3–12. http://dx.doi.org/10.19206/ce-116860.

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The main disadvantages of two-stroke engines such a big fuel consumption and big emission of hydrocarbons or carbon monoxide can be reduced by new proposal of design of two stroke engine based on four stroke engines. The paper describes the operation of high supercharged spark ignition overhead poppet valve two-stroke engine, which enables to achieve higher total efficiency and exhaust gas emission comparable to four-stroke engines. The work of such engines is possible by proper choice of valve timings, geometrical parameters of inlet and outlet ducts and charge pressure. The engine has to be equipped with direct fuel injection system enabling lower emission of pollutants. The work is based on theoretical considerations and engine parameters are determined on the simulation process by use GT-Power program and CFD program for different engine configurations. The initial results included in the paper show influence of valve timing on engine work parameters and predicted exhaust gas emission. The simulation results show that the nitrogen oxides are considerably reduced in comparison to four-stroke engines because of higher internal exhaust gas recirculation. The innovation of this proposal is applying of variable valve timing with turbocharging system in the two-stroke engine and obtaining a significant downsizing effect. The conclusions shows the possibilities of applying two-stroke poppet valve engine as a power unit for transportation means with higher total efficiency than traditional engines with possible change of engine operation in two modes: two- and four stroke cycles. The main disadvantages of two-stroke engines such a big fuel consumption and big emission of hydrocarbons or carbon monoxide can be reduced by new proposal of design of two stroke engine based on four stroke engines. The paper describes the operation of high supercharged spark ignition overhead poppet valve two-stroke engine, which enables to achieve higher total efficiency and exhaust gas emission comparable to four-stroke engines. The work of such engines is possible by proper choice of valve timings, geometrical parameters of inlet and outlet ducts and charge pressure. The engine has to be equipped with direct fuel injection system enabling lower emission of pollutants. The work is based on theoretical considerations and engine parameters are determined on the simulation process by use GT-Power program and CFD program for different engine configurations. The initial results included in the paper show influence of valve timing on engine work parameters and predicted exhaust gas emission. The simulation results show that the nitrogen oxides are considerably reduced in comparison to four-stroke engines because of higher internal exhaust gas recirculation. The innovation of this proposal is applying of variable valve timing with turbocharging system in the two-stroke engine and obtaining a significant downsizing effect. The conclusions shows the possibilities of applying two-stroke poppet valve engine as a power unit for transportation means with higher total efficiency than traditional engines with possible change of engine operation in two modes: two- and four stroke cycles.

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Ivanov, A. B., D. A. Man’shev, and S. A. Kriushin. "Two-stroke gasoline engine lubricants." World of petroleum products 1 (2022): 48–58. http://dx.doi.org/10.32758/2782-3040-2022-0-1-48-58.

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The article considers the design and lubrication of small 2-stroke engines installed on snowmobiles, quad bikes, motorcycles and drones. The compositions of the 2-stroke engine oils, base oils and additives, actual specification JASO, NMMA, API, TISI and ISO are analysed. Concern the short characteristics of JASO engine test methods.

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Kenny, R. G. "Developments in Two-Stroke Cycle Engine Exhaust Emissions." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 206, no. 2 (April 1992): 93–106. http://dx.doi.org/10.1243/pime_proc_1992_206_165_02.

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This paper is concerned with the exhaust emissions from two-stroke cycle spark ignition engines and the means being investigated to reduce them. The simple two-stroke engine has inherently low levels of NOx emissions and high levels of hydrocarbon emissions. The reasons for these emissions characteristics are explained by reference to the open literature. The two-stroke engine is used in a wide range of applications including low-cost, low-output mopeds and high-performance motorcycles. More recently there has been a resurgence of interest in the two-stroke as an alternative to the four-stroke engine for automotive use. A number of the recently reported approaches to emissions control are reviewed, including the use of exhaust oxidation catalysts in simple low-cost engines and direct fuel injection on more costly, multi-cylinder engines.

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Ramakrishnan, V., R. Thamilarasan, and K. Purushothaman. "Performance Evaluation of EGR in Two Stroke I.C. Engine." Applied Mechanics and Materials 812 (November 2015): 60–63. http://dx.doi.org/10.4028/www.scientific.net/amm.812.60.

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Petrol engines are known for their simplicity, low cost and maintenance. However nowadays use of two stroke petrol engines are fading away from the market. An attempt has been made here to revive the use of these old engines by using Exhaust Gas Recirculation (EGR) to improve performances.Short circuiting of fresh charge is an important contributing factor for reduction in performance in two stroke engines. Our project is aimed to reduce short circuiting of fresh charge by admitting cooled exhaust gas to pass through reed valves fitted at the upper end of the transfer passage, in a crank case scavenged two stroke engine. Reed valves were provided at the upper end of the transfer passage using a flange arrangement. Exhaust gas temperature at around 4000 was cooled using a heat exchanger to avoid pre-ignition inside the engine cylinder. The performance of the engine is tested using eddy current dynamometer. The study indicates an appreciable decrease in specific fuel consumption and in HC/CO emissions in a crank case scavenged two stroke engine.

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Markov, V. A., F. B. Barchenko, E. A. Savastenko, A. A. Savastenko, Sh R. Lotfullin, and V. A. Neverov. "Forcing a Four-Stroke Engine by Switching it to a Two-Stroke Cycle at Low-Speed Modes." Proceedings of Higher Educational Institutions. Маchine Building, no. 2 (743) (February 2022): 38–52. http://dx.doi.org/10.18698/0536-1044-2022-2-38-52.

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Improving the dynamic qualities of internal combustion engines and the throttle response of vehicles equipped with them is an urgent problem in engine building. To solve it, we suggest switching a four-stroke engine to a two-stroke cycle at low-speed modes. Within the study, we found that the worst indicators of fuel efficiency of two-stroke engines are partially compensated by the best indicators of their power density. We took a close look at the switching of the 2 / 4SIGHT gasoline engine of the British company Ricardo from a four-stroke cycle to a two-stroke cycle. To implement the switching, we used a two-stage intercooled supercharging and a gas distribution valve switching system. The method proved to be applicable to diesel engines as well. Hence, we studied a diesel engine D-245 (4 CHN 11.0 / 12.5) mounted on a tracked vehicle. At a speed of 1600… 2400 min – 1, such a diesel engine operates in a four-stroke cycle, at lower speeds it operates in a two-stroke cycle. Finally, we did computational studies of the working process of this diesel engine. The study showed the expediency of switching the engine to a two-stroke cycle at low-speed modes.

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Li, Yaozong, Han Wu, Yanli Liu, Lu Zhang, Yongping Qiang, Wei Liu, Jinlong Liu, Honglin Bai, Caifeng Hao, and Yang Li. "Study on Engine Performance and Combustion System Optimization of a Poppet-Valve Two-Stroke Diesel Engine." Energies 15, no. 10 (May 18, 2022): 3685. http://dx.doi.org/10.3390/en15103685.

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Two-stroke engines have higher power density than traditional four-stroke engines, and therefore are suitable for engine downsizing. In this work, a four-stroke single-cylinder diesel engine is modified for two-stroke operation, and the combustion system is designed and optimized using a 3D simulation. Three different combustion chamber profiles and injection spray angles are compared to determine an optimized combustion system. The engine test results show that the two-stroke engine equipped with the newly designed combustion system is able to achieve the same effective power output at a much lower speed than the original four-stroke engine, as well as obtain a better indicated thermal efficiency. This indicates that the poppet-valve two-stroke engine could be an effective technical approach for engine downsizing.

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Giernalczyk, Mariusz. "Analysis of the Possibility of Using Low Speed Two-Stroke Dual-Fuel Engines for Propulsion of Sea-Going Vessels." Journal of KONES 26, no. 2 (June 1, 2019): 45–52. http://dx.doi.org/10.2478/kones-2019-0031.

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Abstract The use of gas/LNG to supply marine engines in addition to tangible economic benefits is also a method of limiting emissions of harmful substances into the atmosphere and meeting strict environmental protection regulations, especially in special areas. The technology of supplying liquid and gas fuels (Dual Fuel) is most easily used in four-stroke engines but the highest thermal efficiency is ensured by combustion two-stroke piston engines. However, in the first two-stroke dual-fuel engines, the gas supply installation was more complicated than in the four-stroke engine. It resulted, among others from the necessity of compressing the gas to high pressures (15÷30 MPa), for which extremely energy-consuming multi-stage compression systems were needed. The complicated technical system is inherently prone to failures, which is why the dual-fuel low-speed two-stroke diesel engines remained for a long period in the design and experimental phase. In recent years, there has been a significant breakthrough thanks to the introduction of new solutions with the possibility of supplying two-stroke engines with low-pressure gas (less than 1.6 MPa). In recent years, many ships powered by two-stroke, dual-fuel internal combustion engines were commissioned. Some ship-owners owning a fleet of LNG carriers with two-stroke diesel engines that so far have been powered only by liquid fuels have decided to adapt them to gas combustion. This required the adaptation of the engine for gas combustion and the expansion of the supply gas fuel system. This paper is an attempt to analyse the legitimacy of introducing two-stroke, dual-fuel internal combustion engines into the propulsion system and adaptation of engines that are already used to burn gas in them. It presents the changes introduced on one of the LNG gas carriers consisting in adapting the engine to gas combustion through modification of the cylinder head and fuel supply installation. Parameter results of the modified engines obtained during sea trials have been presented. Both advantages and disadvantages resulting from gas combustion have been pointed out. Finally, the possibility of this solution application to other LNG carriers was assessed.

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Haddad, S. D. "Piston Motion and Thermal Loading Analyses of Two-Stroke and Four-Stroke Cycle Engines for Locomotives." Journal of Engineering for Gas Turbines and Power 111, no. 3 (July 1, 1989): 536–42. http://dx.doi.org/10.1115/1.3240288.

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Two-stroke cycle and four-stroke cycle diesel engines are in use in rail traction, with the four-stroke cycle design dominating the field. Cycle simulations using computer programs have shown that the conventional two-stroke cycle is somewhat inferior to its four-stroke cycle counterpart in combustion efficiency and thermal loading. Research at Sulzer concluded that the conventional two-stroke cycle engine is not very suitable for locomotive application. A survey by Ricardos, based on an investigation of engines in current production for traction application, suggested that there are potentials in two-stroke cycle design. This paper presents a summary of the results of a research project concerned with comparison of two well-proven typical locomotive diesel engines, one with a two-stroke cycle and the other with a four-stroke cycle. Performance, mechanical loading, thermal loading, and vibration were chosen as parameters to be investigated to provide information on the status of the two cycles in relation to power range, fuel consumption, reliability, and durability, with a view to assisting the users of locomotive engines to make the correct choice.

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Sapate, Kumar D., and A. N. Tikekar. "Mechanical Modifications to Convert Small Two Strokes Carbureted Engine to Electronic Fuel Injection System Engine to Reduce Emission and Fuel Consumption." Advanced Materials Research 768 (September 2013): 213–17. http://dx.doi.org/10.4028/www.scientific.net/amr.768.213.

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The evolution of four stroke engines and improved environmental pollution control norms has pushed the two-stroke engines towards obsolescence due to their inherent design problems. This has made the existing manufacturers & users of two-stroke engines a setback. In this paper attempt has been made to high light the performance parameters in respect of fuel efficiency and emission control. In this research work an effort is made to retrofit the commonly used two stroke engine for optimal performance by using EFI engine. It mainly includes injector locations with reference to spark plug which decides the combustion efficiency of engine. It also includes the location of different sensors and subsequent modification of silencer. As the automobile engine has to operate at higher speeds, proper and firm mounting of different electronic part is essential which affects the performance of engine. After mechanical modification of engine with EFI system it is tested by connecting it to dynamometer. The results are compared with that of carbureted engine.

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Kyrtatos, N. P., and I. Koumbarelis. "A Three-Zone Scavenging Model for Two-Stroke Uniflow Engines." Journal of Engineering for Gas Turbines and Power 110, no. 3 (July 1, 1988): 531–37. http://dx.doi.org/10.1115/1.3240167.

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A three-zone scavenging model for two-stroke uniflow engines was developed and used in conjunction with a control-volume-type engine simulation code for performance prediction of long stroke uniflow-type marine engines. In this model it is attempted to simulate the three different regions perceived to exist inside the cylinder during scavenging, namely the air, mixing, and combustion products regions, by modeling each region as a separate control volume. Two time-varying coefficients are used to specify the rates of entrainment of the air and the burned gases into the mixing region. Results of the use of the model for predicting the performance of a large marine two-stroke engine are presented.

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Moskwa, John J., Wenbo Wang, and Duane J. Bucheger. "A New Methodology for Use in Engine Diagnostics and Control, Utilizing “Synthetic” Engine Variables: Theoretical and Experimental Results." Journal of Dynamic Systems, Measurement, and Control 123, no. 3 (September 1, 2001): 528–34. http://dx.doi.org/10.1115/1.1387019.

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This paper describes new methodologies and algorithms for use in engine diagnostics that simplify and improve combustion quality monitoring and closed-loop engine control in order to meet stringent emission standards. The “synthetic” variables these algorithms produce can be used to indicate the work produced by each cylinder combustion event at all engine speeds, and can be effectively used for on-board combustion quality measurements, engine diagnostics, and closed-loop control. The algorithms are very simple in form, run in real time, and the methodologies can be applied to compression ignition or spark ignition, 2-stroke or 4-stroke gasoline or diesel engines. Both simulation and experimental results are given for a two-stroke, two-cylinder in-line engine. The rotational dynamics and firing sequence of this configuration of engine is very similar to a four-stroke, four cylinder in-line engine, and nearly identical results will be seen with these two designs. Even more dramatic improvements can be seen with engines of fewer cylinders because of greater variations in their inertial forces. The algorithms can be successfully applied to many other engine configurations as well. Therefore, benefits can be derived from the application of these algorithms and their “synthetic” variables to control strategies for almost all modern small and medium size automotive and marine engines, as well as utility engines used for lawn care, snow removal, and other similar applications.

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Hooper, P. R., T. Al-Shemmeri, and M. J. Goodwin. "Advanced modern low-emission two-stroke cycle engines." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 225, no. 11 (August 4, 2011): 1531–43. http://dx.doi.org/10.1177/0954407011408649.

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This paper reviews recent engines and associated technology offering potential low-emission two-stroke cycle operation for a range of applications. The study considers and discusses successfully applied modern production engines together with concepts exploring advanced possibilities for future application. The published results from research and development projects and the data from available technology are compared in terms of the specific performance. The paper does not compare combustion strategies or fluid dynamic aspects of two-stroke cycle engines but does consider and compare the data from engines using the crankcase, external, and stepped piston scavenging intended for automotive, marine, and defence applications.

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Marques, Crístofer, Jean-D. Caprace, Carlos Belchior, and Alberto Martini. "An Approach for Predicting the Specific Fuel Consumption of Dual-Fuel Two-Stroke Marine Engines." Journal of Marine Science and Engineering 7, no. 2 (January 22, 2019): 20. http://dx.doi.org/10.3390/jmse7020020.

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Increasing environmental demands, alongside the planned penetration of natural gas as marine fuel, have rendered dual-fuel engines as an attractive prime mover alternative. In this context, knowing the specific fuel consumption is essential to selecting the most efficient engine. The specific fuel consumption can be approached by simulation models with varying levels of complexity that are either implemented by basic programming languages or simulated by dedicated packages. This study aims to develop a simplified model to predict the specific fuel consumption of dual-fuel two-stroke marine engines driving fixed or controllable pitch propellers. The model relies on clear trends approachable by polynomials that were revealed by normalizing specific fuel consumption. This model requires only the value of specific fuel consumption at a nominal maximum continuous rating to predict the engine consumption at any specified rating, including at partial engine load. The outcome of the study shows that the maximum deviations regarding the two simulated engines did not exceed −3.6%. In summary, the proposed model is a fast and effective tool for optimizing the selection of dual-fuel, two-stroke Diesel engines regarding fuel consumption.

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Amin, Mahmoudzadeh Andwari, and Abdul Aziz Azhar. "Homogenous Charge Compression Ignition (HCCI) Technique: A Review for Application in Two-Stroke Gasoline Engines." Applied Mechanics and Materials 165 (April 2012): 53–57. http://dx.doi.org/10.4028/www.scientific.net/amm.165.53.

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Since Homogeneous Charge Compression Ignition (HCCI) has significantly low temperature combustion, NOx will be dramatically reduced while the mixture will be largely homogenous, thus soot formation will naturally be reduced too. The system can be operated under an ultra lean fuel condition thus able to achieve high efficiency and low emission. In addition to, two-stroke engines advantages i.e. light, simple construction, less components and cheap to manufacture, two-stroke engines have the potential to pack almost twice the power density than that of four-stroke engine with similar capacity. The problem of poor combustion efficiency and high white smoke emission, which is caused by burnt engine oil, can be addressed by the incorporation some features that will ultimately convert a typical two-stroke engine into an efficient HCCI engine demonstrating bulk combustion. This paper briefly described an attempt to modify two-stroke engine design to prove the claim. Such an engine with its conversion will be suitable for use as a prime mover for series Hybrid Electrical Vehicle (HEV) giving high power-to-weight ratio and improved efficiency of the overall vehicle powertrain system.

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MITIANIEC, Wladyslaw. "Study of Atkinson cycle in two-stroke diesel engine with opposed pistons." Combustion Engines 178, no. 3 (July 1, 2019): 121–28. http://dx.doi.org/10.19206/ce-2019-321.

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The paper presents possibilities of change working parameters of two-stroke diesel engine with opposed pistons. Obtaining of higher engine efficiency is realized by applying of Atkinson cycle. Modification of scavenging process by changing pistons position connecting with two crankshafts enables asymmetrical scavenge timing. Decreasing of shorter time of closing exhaust ports before compression process and longer expansion process give higher engine work and with high charging ratio increases engine power. These types of engines are recently recommended for power plant stations. The paper includes full analysis of engine work with scavenge and combus-tion processes for different timing phases based on geometry of the CI Leyland L60 engine by using of CFD modelling and own 0D model. Simulation tests indicate a high scavenge efficiency, good penetration of injected fuel and fast combustion process. The work contains figures of pressure, temperature traces and emission of main chemical species in exhaust gases with comparison of engine works for different timing phases. Atkinson cycle in two-cycle work of engine and full combustion process enables to achieve high total efficiency. The study is an input for realization of such processes in a future of power plant engines with different fuelling systems.

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French, C. C. J. "Alternative Engines—Curiosities or Competitors?" Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power Engineering 203, no. 2 (May 1989): 79–96. http://dx.doi.org/10.1243/pime_proc_1989_203_012_02.

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This paper describes different types of engine used for transportation purposes. Some of the more interesting developments in spark ignition and diesel engines are outlined, but the paper is mainly a review of some of the alternative power plants that have been studied over the past 40 years. These include vapour cycle engines, free-piston engines, compound engines, Stirling engines, gas turbines, stratified charge engines, the catalytic engine, rotary engines and two-stroke spark ignition engines. The paper concludes by discussing possible future developments for some of these alternative engines.

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KOPCZYŃSKI, Marian, Jacek MAŃCZAK, and Władysław PRZEWOŹNY. "Evolution of two-stroke marine diesel engines design in H. Cegielski-Poznan S.A. production." Combustion Engines 126, no. 3 (July 1, 2006): 3–37. http://dx.doi.org/10.19206/ce-117341.

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The article presents only few chosen issues on the design of two-stroke marine diesel engines produced at HCP, which have a considerable influence on the development of these engines types and provide fully operational basis for a wide future development of these means ofpropulsion. Each of the described representatives of subsequent engine types was, is, or will be produced at HCP-W2.

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Trapnell, Nicholas M. "SCAVENGING IN TWO-STROKE-CYCLE DIESEL ENGINES." Journal of the American Society for Naval Engineers 31, no. 3 (March 18, 2009): 708–13. http://dx.doi.org/10.1111/j.1559-3584.1919.tb00832.x.

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Spahni, Marc, and Andreas Kyrtatos. "New Generation Low Speed Two-stroke Engines." MTZ industrial 4, no. 2 (August 23, 2014): 12–19. http://dx.doi.org/10.1007/s40353-014-0134-9.

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Alturki, Eng Waleed. "Four-Stroke and Two-Stroke Marine Engines Comparison and Application." International Journal of Engineering Research and Applications 07, no. 04 (April 2017): 49–56. http://dx.doi.org/10.9790/9622-0704034956.

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Liang, Jinhui, Dongdong Zhang, and Shuwen Wang. "Vibration characteristic analysis of single-cylinder two-stroke engine and mounting system optimization design." Science Progress 103, no. 3 (July 2020): 003685042093063. http://dx.doi.org/10.1177/0036850420930631.

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Compared with four-stroke engines, single-cylinder two-stroke engines have the characteristics of small inertia, high rotational speed, and wide excitation frequency range. However, the structural vibration and noise generated by the two-stroke engine are very violent. Hence, it is necessary to reduce the vibration and noise of the single-cylinder two-stroke engine. Based on the design theory of the engine mounting system, the excitation frequency, direction, and magnitude of a single-cylinder two-stroke engine are analyzed. The rubber isolator is selected as the new mount element, and the dynamic model of the engine powertrain mounting system is established based on ADAMS software. Based on the sensitivity analysis of the design variables of the mounting system, the natural frequency of the mounting system is used as an objective, and the three-directional stiffness of the mounting system is taken as design variables for the optimization problem. The optimization model is solved by the sequential quadratic programming method. The results show that the maximum frequency of the mounting system after optimization is less than 1/[Formula: see text] of the excitation frequency, and the isolation effect is achieved. The dynamic model and the optimization method presented in this article would provide a useful tool for the design and optimization of mounting system for the single-cylinder two-stroke engine to reduce vibration from the engine to the engine support.

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Chapuy, J. F. "Long-Stroke Pielstick Engine Design Philosophy and Service Result Confirmation." Journal of Engineering for Gas Turbines and Power 111, no. 3 (July 1, 1989): 553–59. http://dx.doi.org/10.1115/1.3240290.

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Shipowners and diesel engine users are faced with changing fuel costs. The high price of fuel in recent years has pushed SEMT Pielstick to introduce recently a new version of its long-stroke PC engines. SEMT Pielstick worked on basic parameters of engines to reduce fuel consumption. Research was done on supercharging by adapting a new exhaust manifold, by pass arrangement and new turbo-blowers. The combustion chamber parameters have been thoroughly examined regarding firing pressure, stroke-to-bore ratio, and rotational speed. Reliability was checked by designing components of engines according to the state of art and the experience of SEMT Pielstick. The levels of stresses or temperatures were kept the same as for previous engines or even improved in order to give better reliability. This reliability has been confirmed by the results of the first long-stroke Pielstick engines put into service: the PC 20 L installed on the “Sovereign of the Sea” (RCCL) and the PC 40 L, installed on “New Hamanasu,” “New Shirayuri,” and “Muroto.” The oldest of these has operated trouble-free for more than two years. The availability of engines is very good, and service results, such as wear of components, are even better than with the previous standard stroke engine.

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Wang, Yang, Wuqiang Long, Jingchen Cui, Hua Tian, Xiangyu Meng, Xin Wang, and Duo Xu. "Development of a variable mode valve actuation system for a heavy-duty engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 10-11 (February 12, 2020): 2618–33. http://dx.doi.org/10.1177/0954407020901659.

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A new variable mode valve actuation system for a heavy-duty engine was proposed and designed in this paper. The variable mode valve actuation system can significantly enhance braking safety and improve fuel economy and emission of heavy-duty engines through flexible switching among four-stroke driving mode, two-stroke compression-release braking mode, and cylinder deactivation mode on a conventional four-stroke engine. The switching was controlled by four-stroke driving modules and two-stroke braking modules, both of which have two operation states: effective state and failure state. For the control of the multi-cylinder engine, all cylinders can be divided into several groups, and all the four-stroke driving modules in the same group were controlled by one solenoid valve, as well as all the two-stroke braking modules were controlled by another solenoid valve. A hydraulic-mechanical multi-body dynamics model was established to investigate the switching response of the variable mode valve actuation system. The results indicated that when the engine operated at 2000 r/min, the switching of the four-stroke driving module and the two-stroke braking module required 30 °CA and 101 °CA at most, respectively. In addition, to avoid the conflict between the four-stroke driving valve lift and the two-stroke braking valve lift, the switching between the four-stroke driving mode and the two-stroke compression-release braking mode must have a reasonable sequence. The variable mode valve actuation system has an excellent switching response and it is convenient for the control of the multi-cylinder engine. Therefore, the variable mode valve actuation system has a good application prospect for heavy-duty engines.

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Lalić, Branko, Nikola Račić, and Gojmir Radica. "Two-Stroke Low Speed Diesel Engine Simulation Model for NOx Analysis." Transactions on Maritime Science 6, no. 1 (April 20, 2017): 14–23. http://dx.doi.org/10.7225/toms.v06.n01.002.

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All commercial marine engines have to comply with IMO regulations on emissions, especially of nitrogen oxides. This paper describes the gases produced in the combustion process in the diesel engine, and the manner of pollutant creation. Several models of slow-speed diesel engines have been developed and analysed. The characteristics of the simulation model are compared with the characteristics obtained on the testbed, and their differences considered. Using the term for the formation of NOx, as well as independently developed programs in MATLAB, the rate of nitrogen oxide formation was obtained as a function of excess air, pressure and temperature. The reduction of excess air increases adiabatic flame temperature and has an effect on NOx emissions. The obtained results are compared with the actual values measured on the testbed.

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Taranin, A. G. "USAGE FEATURES OF THE ELECTRONIC INDICATORS FOR SHIP’S AND SHORE POWER SUPPLY TWO– STROKE INTERNAL COMBUSTION ENGINES (DIESEL ENGINES)." EurasianUnionScientists 5, no. 4(73) (May 12, 2020): 42–49. http://dx.doi.org/10.31618/esu.2413-9335.2020.5.73.682.

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The present publication illuminate the tasks as follows: Electronic indicator proper usage at four–stroke internal combustion engines (diesel engines) indication; Indication results & diagram proper transfer to PC; indicator diagram top dead center TDC correction and engine performance data output values such as PMI–mean indicated pressure, PME–mean effective pressure, NIND–indicated power and NEFF–effective power proper calculations for each cylinder and engine total.

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Taranin, A. G. "USAGE FEATURES OF THE ELECTRONIC INDICATORS FOR SHIP’S AND SHORE POWER SUPPLY TWO– STROKE INTERNAL COMBUSTION ENGINES (DIESEL ENGINES)." National Association of Scientists 1, no. 27(54) (May 14, 2020): 39–47. http://dx.doi.org/10.31618/nas.2413-5291.2020.1.54.187.

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The present publication illuminate the tasks as follows: Electronic indicator proper usage at four–stroke internal combustion engines (diesel engines) indication; Indication results & diagram proper transfer to PC; indicator diagram top dead center TDC correction and engine performance data output values such as PMI–mean indicated pressure, PME–mean effective pressure, NIND–indicated power and NEFF–effective power proper calculations for each cylinder and engine total

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Fathallah, Aguk Zuhdi Muhammad, Ian Bimatara, and Rosli Abu Bakar. "Prediction Performance of Two Stroke Semi Free Piston Diesel Engine with Dual Piston System." IOP Conference Series: Earth and Environmental Science 972, no. 1 (January 1, 2022): 012083. http://dx.doi.org/10.1088/1755-1315/972/1/012083.

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Abstract The design of the semi-free piston two-stroke diesel engines has been successfully implemented. Before the engine is built, it is necessary to predict its performance. Prediction is done by using the simulation method. This method is considered the most effective because it does not fabricate the machine first. Modelling and simulation are done using application software. Simulation modelling covers all parts of the engine, namely the intake system, block, injection system, and then exhaust system. Engine performance predictions are based on speed variations as well as load variations. Validation is done with a conventional machine. The difference between the two engines lies in friction losses, where the free piston concept is to reduce friction losses. The simulation results are engine performance such as torque, power, bsfc, bmep, and combustion processes such as heat release, pressure, and ignition delay. The difference in the performance of the semi-free piston compared to a conventional engine with the same combustion chamber size. Prediction results state that the difference in performance is very significant.

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Lalić, Branko, Ivan Komar, and Danilo Nikolić. "Optimization of Ship Propulsion Diesel Engine to Fulfill the New Requirements for Exhaust Emissions." Transactions on Maritime Science 3, no. 1 (April 20, 2014): 20–31. http://dx.doi.org/10.7225/toms.v03.n01.003.

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Impacts of exhaust gas emissions on the environment and air pollution from ships have received considerable attention in the past few decades. Due to the characteristics of the combustion process, typical for large marine two-stroke low-speed engines, and the use of residual fossil fuels, the world’s fleet emits into the atmosphere significant amount of pollutants such as nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), hydrocarbons (HC), sulphur oxides (SOx) and carbon particles (PM). Impact assessment of the process of their formation, emitted amounts and the influence of emission are important factors for decision making in regulation development and also for engine designers who aim to improve low-speed two-stroke marine engines, for further tightening of regulations regarding limiting emissions. This paper consists of three parts: the first section describes the injection and combustion process in lowspeed two-stroke marine engines, the second part describes the formation of the exhaust as emissions as a product of the combustion process and the third part, in which the known techniques to reduce harmful emissions that are currently used in low-speed two-stroke marine engines are described.

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Maehara, Mitsuhiro, Kuniaki Nakajima, Takenori Fukushima, Kozo Uchiyama, Seiichi Shiga, Mikiya Araki, Hisao Nakamura, and Tomio Obokata. "Operation of a Two-Stroke S. I. Engine with Scavenging-Port Injection of CNG(CNG and Alternative Fuels, CNG Engines)." Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2004.6 (2004): 409–15. http://dx.doi.org/10.1299/jmsesdm.2004.6.409.

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KOWALAK, Przemysław, Stefan ŻMUDZKI, and Tadeusz BORKOWSKI. "Marine diesel engine – a novel approach of indicated power determination and related uncertainty level." Combustion Engines 168, no. 1 (February 1, 2017): 15–20. http://dx.doi.org/10.19206/ce-2017-102.

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A proposal of a new method for marine engine indicated power determination, based on direct piston position, instead of crankshaft angular position measurement, was presented. With the aid of bond graph theory, it was proved, that the new method is equivalent to conventional method. To verify hypothesis, that the new method has potential of determined indicated power uncertainty reduction, simulated calculations were carried out. Results of calculations for two marine diesel engines: medium-speed, four stroke and slowspeed two stroke type, at assumption of engine crankshaft constant speed, were compared with results obtained by a conventional method. Data, collected by means of a typical portable, industrial, digital indicator on engines in service, were used for simulation. The uncertainties of engines indicated power determined by means of two methods were analysed. The indicated power uncertainty, achieved for conventional method, was nearly twice higher than for new proposed method. Finally, uncertainty structure was analysed and evaluated for both: new and conventional method of engine indicated power determination.

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Al-Kaf, Saqaff A., Ahmad Suhaimi, and Hakim A. Abbas. "Radical Combustion: New Concept For Two Stroke Engines." ASEAN Journal on Science and Technology for Development 17, no. 2 (November 1, 2000): 91. http://dx.doi.org/10.29037/ajstd.117.

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NAKASHIMA, Masaru, Shunta MIYAZAKI, Kohei KAWATE, Kota TOSHIMA, Hiroyuki ASOU, Changjun LIN, and Korai TAKAO. "Development of an Opposed-Piston Two-Stroke Engine Device using Model Engines." Proceedings of Conference of Kyushu Branch 2021.74 (2021): B31. http://dx.doi.org/10.1299/jsmekyushu.2021.74.b31.

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Kravchenko, Serhii, Oleg Linkov, Maxim Shelestov, Alexander Bekaryuk, and Eduard Bozhko. "Mathematical Modeling of the Working Process of a Two-Stroke Engine with Countermoving Pistons." NTU "KhPI" Bulletin: Power and heat engineering processes and equipment, no. 4 (December 30, 2021): 22–28. http://dx.doi.org/10.20998/2078-774x.2021.04.03.

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Simulation of the working process of an internal combustion engine is the basis for all further calculations and studies of the engine. Of particular relevance is the availability of an adequate mathematical model of the engine process due to the fact that due to the trend of continuous improvement of engine performance, it is necessary to take into account many influencing factors to obtain a satisfactory result. The most complex and dependent on many physicochemical parameters is the process of combustion of fuel in the engine. Models of combustion in diesel engines can be divided into three groups: detailed models; empirical and semipemirical models. The analysis of world experience in research and mathematical modeling of combustion process in internal combustion engines is performed in the work. The advantages and disadvantages of different mathematical models are indicated. It is proposed to use a semi-empirical mathematical model of combustion which describes the differential characteristic of the combustion rate by two curves corresponding to the periods of the first flash and diffusion combustion. Use of such model simplifies performance of calculations and at the same time allows to receive qualitative results considering many factors of influence.

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Rønnedal, Per. "Propeller Phasing for Large Two-stroke Diesel Engines." Journal of The Japan Institute of Marine Engineering 40, no. 5 (2005): 642–47. http://dx.doi.org/10.5988/jime.40.5_642.

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Aabo, Kjeld. "Operation on Low-Sulphur Fuels: Two-Stroke Engines." Journal of The Japan Institute of Marine Engineering 41, no. 1 (2006): 4–11. http://dx.doi.org/10.5988/jime.41.4.

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37

Frigge, Patrick, Samuel Affolter, Daniel Bachmann, and Ronald de Jong. "New Two-Stroke Marine Diesel Engines from Wärtsilä." MTZ worldwide 72, no. 11 (November 2011): 10–17. http://dx.doi.org/10.1365/s38313-011-0105-2.

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38

Tsui, Yeng-Yung, and Hong-Ping Cheng. "Tumbling Flow in Loop-Scavenged Two-Stroke Engines." Journal of Fluids Engineering 117, no. 4 (December 1, 1995): 628–32. http://dx.doi.org/10.1115/1.2817314.

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A multidimensional calculation procedure is used to investigate the flow in loop-scavenged two-stroke engine with curved cylinder heads. Five different cylinder heads are considered. The curvature of cylinder head increases from case I to case IV. In case V the head curvature is further increased, but it is shaped in the radially outer region. Calculations reveal that a tumbling vortex forms after the exhaust port is closed and the vortex constantly dominates the flow structure in the cylinder throughout the compression period. With high head curvatures the vortex is well organized and occupies the entire cylinder volume in the late compression stage. Due to compression of the better organized tumbling vortex by the moving piston more energy cascades from mean flow to turbulence in the high curvature cases III and IV. As for case V, the larger clearance in the bowl center region leads to lower shear stresses and, thus, the turbulence augmentation phenomenon is less prominent than that for cases III and IV.

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Volckens, John, David A. Olson, and Michael D. Hays. "Carbonaceous species emitted from handheld two-stroke engines." Atmospheric Environment 42, no. 6 (February 2008): 1239–48. http://dx.doi.org/10.1016/j.atmosenv.2007.10.032.

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40

Biryuk, V. V., A. A. Gorshkalev, M. O. Zakharov, and V. L. Larin. "Development of a methodology for calculating the working process of a small-size two-stroke internal combustion engine." VESTNIK of Samara University. Aerospace and Mechanical Engineering 20, no. 3 (December 1, 2021): 97–109. http://dx.doi.org/10.18287/2541-7533-2021-20-3-97-109.

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On the basis of the available theoretical calculations, methods for calculating the working process and power characteristics of internal combustion engines and the experimental studies carried out, a method for calculating the working process for small-sized two-stroke internal combustion engines was developed and tested. In the course of this work, the following results were obtained: the parameters of the working process and power characteristics of a small two-stroke internal combustion engine; the parameters obtained by calculation during the study of the Evolution 20GX2 engine were compared with the results of an experimental study. According to the results of the comparison, deviations in the values of the parameters of the engine under study from the results of the experimental study at the maximum power and maximum speed modes were identified.

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Llamas, Xavier, and Lars Eriksson. "Control-oriented modeling of two-stroke diesel engines with exhaust gas recirculation for marine applications." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 233, no. 2 (May 11, 2018): 551–74. http://dx.doi.org/10.1177/1475090218768992.

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Large marine two-stroke diesel engines are widely used as propulsion systems for shipping worldwide and are facing stricter NO x emission limits. Exhaust gas recirculation is introduced to these engines to reduce the produced combustion NO x to the allowed levels. Since the current number of engines built with exhaust gas recirculation is low and engine testing is very expensive, a powerful alternative for developing exhaust gas recirculation controllers for such engines is to use control-oriented simulation models. Unfortunately, the same reasons that motivate the use of simulation models also hinder the capacity to obtain sufficient measurement data at different operating points for developing the models. A mean value engine model of a large two-stroke diesel with exhaust gas recirculation that can be simulated faster than real time is presented and validated. An analytic model for the cylinder pressure that captures the effects of changes in the fuel control inputs is also developed and validated with cylinder pressure measurements. A parameterization procedure that deals with the low number of measurement data available is proposed. After the parameterization, the model is shown to capture the stationary operation of the real engine well. The transient prediction capability of the model is also considered satisfactory which is important if the model is to be used for exhaust gas recirculation controller development during transients. Furthermore, the experience gathered while developing the model about essential signals to be measured is summarized, which can be very helpful for future applications of the model. Finally, models for the ship propeller and resistance are also investigated, showing good agreement with the measured ship sailing signals during maneuvers. These models give a complete vessel model and make it possible to simulate various maneuvering scenarios, giving different loading profiles that can be used to investigate the performance of exhaust gas recirculation and other controllers during transients.

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Boretti, Albert. "Design of Direct Injection Jet Ignition High Performance Naturally Aspirated Motorcycle Engines." Designs 3, no. 1 (February 5, 2019): 11. http://dx.doi.org/10.3390/designs3010011.

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Thanks to the adoption of high pressure, direct injection and jet ignition, plus electrically assisted turbo-compounding, the fuel conversion efficiency of Fédération Internationale de l'Automobile (FIA) F1 engines has been spectacularly improved up to values above 46% peak power, and 50% peak efficiency, by running lean of stoichiometry stratified in a high boost, high compression ratio environment. Opposite, Federation Internationale de Motocyclisme (FIM) Moto-GP engines are still naturally aspirated, port injected, spark ignited, working with homogeneous mixtures. This old fashioned but highly optimized design is responsible for relatively low fuel conversion efficiencies, and yet delivers an outstanding specific power density of 200 kW/liter. The potential to improve the fuel conversion efficiency of Moto-GP engines through the adoption of direct injection and jet ignition, prevented by the current rules, is herein discussed based on simulations. As two-stroke engines may benefit from direct injection and jet ignition more than four-stroke engines, the opportunity of a return of two-stroke engines is also argued, similarly based on simulations. About the same power, but at a better fuel efficiency, of today’s 1000 cm3 four stroke engines, may be obtained with lean stratified direct injection jet ignition engines, four-stroke of 1450 cm3, or two-stroke of 1050 cm3. About the same power and fuel efficiency may also be delivered with stoichiometric engines direct injection jet ignition two-stroke of 750 cm3.

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Wang, Yang, Wuqiang Long, Jingchen Cui, Xin Wang, Hua Tian, and Xiangyu Meng. "Research on two-stroke compression release braking performance of a variable mode valve actuation system." International Journal of Engine Research 21, no. 9 (December 24, 2019): 1696–708. http://dx.doi.org/10.1177/1468087419894449.

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In order to enhance the braking safety and improve the fuel economy and emission of heavy-duty engines, a variable mode valve actuation system which can switch operation modes flexibly among four-stroke driving, two-stroke compression release braking, and cylinder deactivation modes on a four-stroke engine was developed in this article. The switching was controlled by the four-stroke driving module and the two-stroke braking module, both of which have two states: effective state and failure state. Besides, a full-cycle numerical model of a six-cylinder turbocharged engine was established for the performance analysis of two-stroke compression release braking mode. The orthogonal design method was introduced in the present study to obtain the optimum valve parameters which can result in high braking power and maintain the maximum cylinder pressure at a lower level at the same time. Then, the two-stroke compression release brake braking power with the optimum valve parameters was compared with four-stroke compression release braking power. Meanwhile, the two-stroke braking cam profile of the variable mode valve actuation system was designed according to the optimum valve parameters, and the two-stroke braking performance with the dynamic valve lift of the variable mode valve actuation system was validated by the numerical model including the hydraulic system. The results indicated that a higher engine speed leads to higher braking power at the same valve lift. Besides, two-stroke compression release brake braking power of the variable mode valve actuation system achieved 525.3 kW at 2600 r/min and 358.1 kW at 1900 r/min, 52.9% and 71.3% higher than four-stroke compression release braking power, respectively. Although the two-stroke compression release brake braking power with dynamic valve lift is slightly less than that with the optimum valve parameters, it is still much higher than that of the four-stroke compression release braking power. Therefore, it has a good application prospect for heavy-duty engines.

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44

Herrmann, Samara, Macklini Dalla Nora, and Thompson Diordinis Metzka Lanzanova. "Development of a Two-Stroke Cycle Engine for Use in the Agricultural Aviation Sector." Journal of Aerospace Technology and Management, no. 12 (November 21, 2020): 52–61. http://dx.doi.org/10.5028/jatm.cab.1155.

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Reciprocating internal combustion engines have wide application in agricultural, recreational and experimental aircraft, resulting from their low cost and less complex maintenance compared to other engines. Thus, this work analyzed the performance of a conventional four-stroke engine operating in the two-stroke cycle by means of direct fuel injection and mechanical air supercharging. The use of a supercharger was essential in this design to provide adequate gas exchange inside the cylinder during the long valve overlap required, while direct fuel injection made it possible to reduce the short circuit of air-fuel mixture to the exhaust. Due to the double ignition frequency compared to a four-stroke engine, it was possible to obtain a large power density (40 kW/L) at a speed of 2400 rpm, also a specific fuel consumption of 270 g/kWh with gasoline and 400 g/kWh with ethanol. The use of ethanol in replacement of gasoline made it possible to operate at full load (160 Nm/L) at 800 rpm without the occurrence of knocking combustion.

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Heywood, John B. "Fluid Motion Within the Cylinder of Internal Combustion Engines—The 1986 Freeman Scholar Lecture." Journal of Fluids Engineering 109, no. 1 (March 1, 1987): 3–35. http://dx.doi.org/10.1115/1.3242612.

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The flow field within the cylinder of internal combustion engines is the most important factor controlling the combustion process. Thus it has a major impact on engine operation. This paper reviews those aspects of gas motion into, within, and out of the engine cylinder that govern the combustion characteristics and breathing capabilities of spark-ignition engines and compression-ignition or diesel engines. Necessary background information on reciprocating engine operating cycles, the primary effect of piston motion and the spark-ignition and diesel engine combustion processes is first summarized. Then the characteristics of flow through inlet and exhaust valves in four-stroke cycle engines, and through ports in the cylinder liner in two-stroke cycle engines are reviewed. These flows govern the airflow through the engine, and set up the in-cylinder flow that controls the subsequent combustion process. The essential features of common in-cylinder flows—the large scale rotating flows set up by the conical intake jet, the creation and development of swirl about the cylinder axis, the flows produced during compression due to combustion chamber shape called squish, flow during the combustion process, and two-stroke scavenging flows—are then described. The turbulence characteristics of these flows are then defined and discussed. Finally, flow phenomena which occur near the walls, which are important to heat transfer and hydrocarbon emissions phenomena, are reviewed. The primary emphasis is on developing insight regarding these important flow phemomena which occur within the cylinder. To this end, results from many different research techniques—experimental and computational, established and new—have been used as resources. It is the rapidly increasing convergence of engine flow information from these many sources that make this an exciting topic with promise of significant practical contributions.

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Kutlar, Osman Akin, and Fatih Malkaz. "Two-Stroke Wankel Type Rotary Engine: A New Approach for Higher Power Density." Energies 12, no. 21 (October 26, 2019): 4096. http://dx.doi.org/10.3390/en12214096.

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The Wankel engine is a rotary type of four-stroke cycle internal combustion engine. The higher specific power output is one of its strong advantages. In Wankel rotary engine, every eccentric shaft revolution corresponds to one four-stroke cycle, whereas conventional reciprocating engine fulfills four-stroke cycle in two crankshaft revolutions. This means the power stroke frequency is twice that of conventional engines. Theoretically, application of two-stroke cycle on Wankel geometry will duplicate the power stroke frequency. In this research, a single-zone thermodynamic model is developed for studying the performance characteristic of a two-stroke Wankel engine. Two different port timings were adapted from the literature. The results revealed that late opening and early closing port geometry (small opening area) with high supercharging pressure has higher performance at low speed range. However, as the rotor speed increases, the open period of the port area becomes insufficient for the gas exchange, which reduces power performance. Early opening and late closing port geometry (large opening area) with supercharging is more suitable in higher speed range. Port timing and area, charging pressure, and speed are the main factors that characterize output performance. These preliminary results show a potential for increasing power density by applying two-stroke cycle of the Wankel engine.

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Masi, Massimo, Matteo Pregrasso, and Paolo Gobbato. "A Practical Design Approach to Improve the Charging Efficiency of a Small Two-Stroke High Speed Engine Based on Basic CFD." E3S Web of Conferences 197 (2020): 06005. http://dx.doi.org/10.1051/e3sconf/202019706005.

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The paper deals with the optimisation of the charging efficiency in a small two-stroke high-speed engine according to well-established design guidelines. The aim is to present the method successfully used in the preliminary screening of the performance improvement attainable in a crank-case-compression engine by design modifications to the transfer ports and manifolds. The method applies a basic CFD model of the steady-state flow across the cylinder block validated against experimental tests at the discharge flow bench. This model is used to approximate the actual scavenging process through a transient simulation of the cold flow across the cylinder inside which the piston is fixed at the bottom centre. A fast assessment of the charging efficiency is permitted by a transported passive scalar implemented in the model to easily estimate all the parameters needed for monitoring the effectiveness of the scavenging process at each crankangle. This practical design approach has been applied to the geometry of a Schnürle-type loop-scavenged 125cc single-cylinder engine compliant with the 2018 FIA homologation form for the KF2 karting competition category. The maximum increase of indicated mean effective pressure expected according to the comparison between the CFD simulations of the original and the modified design of the transfer ports is approximately equal to 4%. This result demonstrates that the CFD analyses are sensitive to the limited modifications commonly needed to tune two-stroke racing-engines and confirms that the suggested design approach can be profitably employed by engineers and technicians involved in the design of small two-stroke highspeed engines.

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Giernalczyk, Mariusz, Filip Łoński, and Wojciech Kaniak. "Ways of Adjusting the Two-Stroke Diesel Engine to be Run on Liquefied Natural Gas." New Trends in Production Engineering 1, no. 1 (October 1, 2018): 317–24. http://dx.doi.org/10.2478/ntpe-2018-0039.

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Abstract This article attempts at assessing the feasibility and validity of adjusting the two-stroke diesel engine to be fuelled by liquefied natural gas (LNG). It discusses a set of modifications introduced onto one of the ships carrying liquefied natural gas. These changes consisted in adjusting the engines of the main drive so that they can be fuelled by gas. This has been achieved by the modification of the cylinder head and fuel supply installation. Parameter results of the modified engines obtained during sea trials have been presented. Both advantages and disadvantages resulting from gas combustion have been pointed out. Ultimately, the authors of this article assess the applicability of this solution to other LNG carriers.

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Sheng, Jing, Yuping Zeng, Guoman Liu, and Rui Liu. "Determination of Weak Knock Characteristics for Two-Stroke Spark Ignition UAV Engines Based on Mallat Decomposition Algorithm." Mathematical Problems in Engineering 2021 (February 19, 2021): 1–11. http://dx.doi.org/10.1155/2021/1250327.

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Two-stroke spark ignition (SI) unmanned aerial vehicle (UAV) engines do not allow heavy knock and require a certain knock safety margin. However, weak knock can help the engine increase power output and reduce fuel consumption. To accurately extract the knock characteristics of engine vibration signals under the condition of weak knock, a signal feature extraction method based on the Mallat decomposition algorithm was proposed. Mallat decomposition algorithm can decompose the signal into two parts: a low-frequency signal and a high-frequency noise signal. The decomposed high-frequency noise is eliminated, and the low-frequency signal is retained as the characteristic domain signal. Simulation results show the effectiveness of the proposed algorithm. The engine vibration signal of a two-stroke SI UAV engine was decomposed into the low-frequency signal and the high-frequency signal by the Mallat decomposition algorithm. The low-frequency signal is taken as the knock characteristic domain signal component, and the wavelet packet energy method is used to verify the correctness of the obtained signal component. The relative energy parameter is calculated by using the knock characteristic domain signal component, which can be used as the determination index of knock intensity. This method provides a reference for the weak knock control of two-stroke SI UAV engines.

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Voelund, Anders, Peder Klit, and Sebastian Persson. "Testing of bearing materials for large two-stroke marine diesel engines." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, no. 4 (August 5, 2016): 503–8. http://dx.doi.org/10.1177/1350650115597462.

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In large two-stroke marine diesel engines, bearings are designed to last the lifetime of the engine. The design has shown very good service experiences. The design parameters of the main bearings are, among others, based on the average maximum specific load which the bearing should operate under. In general, the frictional loss is less than 1% of the nominal power of the engine but is still a target for optimization. Fatigue mechanisms of bearing lining material are not fully understood and the design limits with regards to minimum oil film thickness, max oil film pressure and oil film pressure gradient are not established. Large two-stroke journal bearings are not suitable for fatigue test due to the size, the low rotational speed and the complexity of such a test-rig. The disc fatigue test rig was designed with the purpose to test white metal coatings under realistic bearing conditions, in a confined time-frame. The test-rig simulates a scale model of a thrust bearing, in contrary to standard design, the bearing lining material is applied to the rotating collar. Parameters, such as bearing load, rotational speed, oil temperature, oil contamination is controlled/monitored in order to achieve repeatability and a systematic approach to the experiments. Test performed on the test-rig shows good correlation on the fatigue cracks with those experienced on large two-stroke journal bearings.

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Journal articles on the topic 'Two-stroke engines'

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