汽化潜热和黏度对含氧燃料喷雾特性影响研究

以复合进气转子发动机为研究对象, 构建并验证了适用于转子发动机工作过程的CFD模型, 探究了周边气道形状对转子发动机性能的影响. 通过数值模拟的方法, 对不同周边气道形状下氢气/汽油双燃料转子发动机的缸内流场和燃烧过程进行了研究. 研究结果表明: 进气后期缸内混合气受挤压作用出现回流现象, 且此时的周边进气口面积越大, 混合气的回流现象越明显; 在上止点附近缸内会形成与转子运动方向一致的单向流; 周边气道形状对点火时刻缸内混合气流速的影响不大, 与气道形状为圆形时相比, 当气道形状为三角形时, 点火时刻缸内湍动能增加26.91%, 峰值缸压提升了5.87%, 同时, 较高的缸内温度导致NO_x生成量增多.

Numerical investigation of the effects of hydrogen enrichment on combustion and emissions formation processes in a gasoline rotary engine

To analyze the effect of peripheral-ported shape on the performance in a hydrogen/gasoline bi-fuel rotary engine, a CFD model was implemented and validated by the experimental data. The flow field, combustion process and major emissions formation in rotary engines with different peripheral-ported shapes were numerically studied. Results show that the mixture in the cylinder was squeezed and the backflow phenomenon occurred during the end of the intake stroke. The larger the corresponding peripheral-ported area was, the more evident the backflow phenomenon of the mixture would be. At the end stage of compression stroke, a mainstream flow field whose direction was identical to the rotor rotating direction was formed. The shape of peripheral-ported had little effect on the velocity of the mixture in the cylinder at ignition timing. Compared with the round shape, as the peripheral-ported shape was triangle, the average turbulence kinetic energy and peak pressure increased by 26.91% and 5.87%, respectively, and nitric oxides emissions increased due to higher in-cylinder temperature.