端面进气角度对掺氢转子机性能的影响

Influence of side-ported angle on the performance in a rotary engine with hydrogen enrichment

为了探究进气角度对转子机性能的影响,以复合进气转子机为研究对象,构建并验证了适用于转子机工作过程的CFD模型。通过数值模拟的方法,对不同端面进气角度下氢气/汽油双燃料转子机的缸内流场和燃烧过程进行了研究。结果表明,随着进气角度的增加,从端面进气口进入的混合气与气缸后端盖的撞击点不断向燃烧室前方移动,从周边进气口进入的气体在燃烧室后端形成滚流,缸内混合气的平均涡度变大;在上止点附近缸内会形成与转子运动方向一致的单向流;在点火时刻缸内混合气的流速随着进气角度的增加略有降低,导致火焰传播速度变慢,燃料放热速率降低;相比于进气角度为0°时,当进气角度增加为60°时峰值缸压上升了7.44%,但NO x的生成量增加了27.67%。

To analyze the effect of side-ported angle on the performance in a hydrogen/gasoline bi-fuel rotary engine,the CFD model was built and validated by the experimental data.The flow field,combustion process and major emissions formation in rotary engines with different side-ported angles were numerically studied.Results show that,with the increase of the side-ported angle,the impinge location of the mixture moved to the front of the combustion chamber,and formed a swirl in the rear part of the combustion chamber,the average vorticity of the vortex also increased.At the end stage of compression stroke,a mainstream flow field whose direction was identical to the rotor rotating direction was formed.At the ignition time,the velocity of in-cylinder mixture decreased slightly with the increase of the side-ported angle,which led to the slow flame propagation and the decrease of the heat release rate of the fuel.Compared with the side-ported angle of 0°,when the inlet angle increased to 60°,the peak pressure increased by 7.44%.When the combustion chamber connected to the exhaust port,nitric oxides emissions increased by 27.67%due to highter in-cylinder temperature.