Numerical Analysis of a Downsized 2-Stroke Uniflow Engine

Ma, Ji; Zhao, Hua; Freeland, Paul; Hawley, Martyn; Xia, Jun

doi:10.4271/2014-01-9051

Cited by 13 publications

(10 citation statements)

References 8 publications

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“…ASI was also applied to control the connectivity between exhaust domains and cylinder domain with the movement of exhaust valves. One dimensional (1D) simulations were performed to obtain more realistic fired in-cylinder conditions using WAVE [23]. In the cases with fired conditions, the initial mixture components in the cylinder are pure burned gas, i.e.…”

Section: Simulation Conditionsmentioning

confidence: 99%

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Evaluations of Scavenge Port Designs for a Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) Engine by 3D CFD Simulations

Wang

Zhao

2016

SAE Technical Paper Series

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The 2-stroke engine has great potential for aggressive engine downsizing due to its double firing frequency which allows lower indicated mean effective pressure (IMEP) and peak in-cylinder pressure with the same output toque compared to the 4-stroke engine. With the aid of new engine technologies, e.g. direct injection, boost and variable valve trains, the drawbacks of traditional 2-stroke engine, e.g. low durability and high emissions, can be resolved in a Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) engine. Compared to the loop-flow or cross-flow engines, the BUSDIG engine, where intake ports are integrated to the cylinder liner and controlled by the movement of piston top while exhaust valves are placed in the cylinder head, can achieve excellent scavenging performance and be operated with high boost. In order to fulfil the potential of the BUSDIG engine, various scavenge ports were designed with different scavenge port number (SPN), Axis Inclination Angle (AIA) and Swirl Orientation Angle (SOA), and their effects were evaluated by three dimensional (3D) computational fluid dynamics (CFD) under different intake pressures and engine speeds. The scavenging process was analyzed by its delivery ratio (DR), trapping efficiency (TE), scavenging efficiency (SE) and charging efficiency (CE). In addition, the in-cylinder flow motions, which play important roles in controlling the charge mixing and combustion process, were studied for different scavenge port designs. Finally, the vertical position of scavenge ports, which determines the scavenge port opening (SPO) timing, the scavenge port height (SPH), and the exhaust valve opening (EVO) timings were varied to investigate their impacts on the scavenging performance and in-cylinder flow motions.

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Section: Simulation Conditionsmentioning

confidence: 99%

“…delivery ratio (DR), trapping efficiency (TE), scavenging efficiency (SE) and charging efficiency (CE), are used to characterise the scavenging performance of the BUSDIG engine. They are defined as following [23]:…”

Section: Mesh Sensitivity Studymentioning

confidence: 99%

Evaluations of Scavenge Port Designs for a Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) Engine by 3D CFD Simulations

Wang

Zhao

2016

SAE Technical Paper Series

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“…Yan Zhang et al investigated the effect of valve timing on the gas-exchange process and the subsequent combustion processes were investigated on a single-cylinder poppet-valve gasoline direct injection (GDI) engine running in two-stroke engine operation [10]. By individually varying intake and exhaust valve opening and closing the timing at a low load boundary, middle load boundary, and high load boundary of engine operation, Jun Ma et al optimized the intake charge organization to optimize the two-stroke uniflow engine performance on vehicle application through building a 3D CFD model [11]. The scavenging process was investigated, and the intake port design details were improved.…”

Section: Introductionmentioning

confidence: 99%

Simulation Modeling and Optimization of Uniflow Scavenging System Parameters on Opposed-Piston Two-Stroke Engines

Zhang

Tie-xiong

2018

Energies

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Based on the introduction of opposed-piston two-stroke (OP2S) gasoline direct injection (GDI) engines, the OP2S-GDI engine working principle and scavenging process were analyzed. GT-Power software was employed to model the working process based on the structural style and principle of OP2S-GDI engine. The tracer gas method and OP2S-GDI engine experiment were employed for model validation at full load of 6000 rpm. The OP2S-GDI engine scavenging system parameters were optimized, including intake port height stroke ratio, intake port circumference ratio, exhaust port height stroke ratio, exhaust port circumference ratio, and opposed-piston motion phase difference. At the same time, the effect of the port height stroke ratio and opposed-piston motion phase difference on effective compression ratio and expansion ratio were considered, and the indicated work was employed as the optimization objective. A three-level orthogonal experiment was applied in the calculation process to reduce the calculation work. The influence and correlation coefficient on the scavenging efficiency and delivery ratio were investigated by the orthogonal experiment analysis of intake and exhaust port height stroke ratio and circular utilization. The effect of the scavenging system parameters on delivery ratio, scavenging efficiency and indicated work were calculated to obtain the best parameters. The results show that intake port height stroke ratio is the main factor for the delivery ratio, while exhaust port height stroke ratio is the main factor to engine delivery ratio and scavenging efficiency.

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“…A 3D CFD model has been built for the optimization of intake charge organization in order to optimize the 2-stroke uniflow engine performance for vehicle applications. The scavenging process was investigated and the intake port design details were improved [23]. Achates Power has perfected the OP engine architecture, demonstrating substantial breakthroughs in combustion and thermal efficiency after more than 3300 h of dynamometer testing, which is also a good fit for other applications due to its high thermal efficiency, high specific power and low heat rejection [24].…”

Section: Introductionmentioning

confidence: 99%

Parameter Optimization on the Uniflow Scavenging System of an OP2S-GDI Engine Based on Indicated Mean Effective Pressure (IMEP)

Wang

Feng

et al. 2017

Energies

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Abstract:In this paper, an opposed-piston two-stroke (OP2S) gasoline direct injection (GDI) engine is introduced and its working principles and scavenging process were analyzed. An optimization function was established to optimize the scavenging system parameters, include intake port height, exhaust port height, intake port circumference ratio, the exhaust port circumference ratio and opposed-piston motion phase difference. The effect of the port height on the effective compression ratio and effective expansion ratio were considered, and indicated mean effective pressure (IMEP) was employed as the optimization objective instead of scavenging efficiency. Orthogonal experiments were employed to reduce the calculation work. The effect of the scavenging parameters on delivery ratio, trapping ratio, scavenging efficiency and indicated thermal efficiency were calculated, and the best parameters were also obtained by the optimization function. The results show that IMEP can be used as the optimization objective in the uniflow scavenging system; intake port height is the main factor to the delivery ratio, while exhaust port height is the main to engine trapping ratio, scavenging efficiency and indicated thermal efficiency; exhaust port height is the most important factor to effect the gas exchange process of OP2S-GDI engine.

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Numerical Analysis of a Downsized 2-Stroke Uniflow Engine

Cited by 13 publications

References 8 publications

Evaluations of Scavenge Port Designs for a Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) Engine by 3D CFD Simulations

Evaluations of Scavenge Port Designs for a Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) Engine by 3D CFD Simulations

Simulation Modeling and Optimization of Uniflow Scavenging System Parameters on Opposed-Piston Two-Stroke Engines

Parameter Optimization on the Uniflow Scavenging System of an OP2S-GDI Engine Based on Indicated Mean Effective Pressure (IMEP)

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