转速对复合进气掺氢双燃料转子机性能影响的数值模拟

Effect of Engine Speed on the Performance of a Hydrogen-enriched Bi-fuel Rotary Engine with Compound Intake

以复合进气转子机为研究对象,构建了适合转子机工作过程的CFD模型,并结合试验结果验证了所构建模型的准确性。通过数值模拟的方法,分别研究了转速对纯汽油转子机和氢气/汽油双燃料转子机性能的影响研究结果表明,在相同转速下,掺氢可以增加燃烧室内内OH、O和H的质量,进而加快火焰的传播速度,提升燃料的燃烧效率。随着转速的升高,缸内混合气流速和湍动能显著增加,但火焰传播相对转子运动的速度降低。与转速为3000 r/min相比,当转速提升至4500 r/min,6000 r/min和9000 r/min时,峰值缸压分别降低4.22%,11.17%和22.21%,所对应的曲轴转角延迟5.2℃A、7.5℃CA和12.8℃CA。当转速为3000 r/min时,尽管燃烧室内NO_x的生成量有所上升,但CO生成量最低。

The present study established a CFD model for compound-ported rotary engine and validated by experimental results.The numerical model was employed to investigate the influence of engine speed on the performance of pure gasoline and hydrogen/gasoline bi-fuel rotary engines,respectively.Results showed that,the mass of OH、O and H radicals increased after hydrogen addition,which could accelerate the velocity of flame propagation and accordingly improve combustion efficiency.In-cylinder velocity and turbulent kinetic energy increased significantly with the increment of the engine speed,whereas the flame speed decreased in contrast to rotor movements.Compared with the engine speed of 3000 r/min,the peak pressure reduced by 4.22%,11.17% and22.21% for engine speed of 4500 r/min,6000 r/min and 9000 r/min,and its corresponding crank angle retarded by 5.2℃A,7.5℃A and 12.8℃A,respectively.When the engine speed was 3000 r/min,the carbon monoxide production was the lowest in the combustion chamber,though the nitric oxide mass increased slightly.