Effect of injection pulse width on hydrogen direct-injection oval rotary engine under different oxygen-enriched strategy

Yutao Deng, Changwei Ji, Jinxin Yang, Sergey Zambalov and Dmitry Kasaev

Energy, 2025, vol. 328, issue C

Abstract: The oval rotary engine(ORE) retains the Wankel rotary engine's smooth rotation and high power density, and features variable compression ratio, fixed combustion chambers, and a simple seal structure. The numerical simulation is used to study the performance of hydrogen direct-injected spark-ignited ORE under an oxygen-enriched strategy, and to investigate the effect of injection pulse width(IPW) on it. The results show that with the impact of intake and rotor wall movement on the flow field, the two vorticity peaks occur in the intake stroke and before top dead center. Minimally oxygen-enrichment solves the problem of slow combustion in atmospheric conditions, but brings higher NOx emissions. As the oxygen concentration(OC) rises, much hydrogen is wrapped in oxygen, leading to a significant decrease in combustion efficiency(CE) and indicated thermal efficiency(ITE). Reduced IPW results in a wider distribution of hydrogen during combustion, promoting combustion and improving CE and ITE, but leading to more NOx emissions. The optimal condition is OC = 24 % with IPW = 12°CA, improving CE and ITE to 99 % and 34.6 %, 6.7 % higher and the same with initial atmospheric condition, but has more NOx emission of 0.3 mg per cylinder per cycle.

Keywords: Oval rotary engine; Hydrogen direct-injection; Flow field characteristic; Oxygen-enriched strategy; Variable injection pulse width; NOx emission (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:328:y:2025:i:c:s0360544225022297

DOI: 10.1016/j.energy.2025.136587

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