点火提前角对天然气转子发动机燃烧过程的影响

以火花点燃式转子发动机为研究对象，建立了相应的湍流和燃烧模型，实现了发动机工作过程的动态模拟。在此基础上，计算得到了转子发动机缸内流场、温度场的演变及火焰传播过程，并计算分析出了不同点火提前角对缸内燃烧过程的影响。计算结果表明：燃烧室内部涡流对火焰传播起着积极的加速作用，点火时火花塞位于涡流区到单向流的过渡区域最好。随着转子运动，涡流会因燃烧室容积减小而受到挤压并消失，在涡流消失时刻一定的情况下，为了充分利用涡流的作用时间，应该适当地增大点火提前角。在计算工况下，当点火提前角为47°时，发动机的燃烧效率和气缸内压力峰值均最高，并且NO_x的排放较少。此研究为其他不同工况下，转子发动机的最佳点火提前角的确定提供了理论参考依据。

Effect of Ignition Advance Angles on Combustion Process in Natural Gas-fueled Rotary Engine

The calculation models of combustion and turbulent flow are established for a spark-ignition rotary engine in order to realize dynamic simulation of operating process of natural gas-fueled rotary engine. The evolution processes of flow and temperature fields and the propagation process of flame in cylinder are obtained by numerical simulation, and the effects of different ignition advance angles on the flame propagation are analyzed under the same ignition. The results show that the eddy in cylinder can largely accelerate the flame propagation speed. When the spark plug begins to ignite, it is best to be located at the transition region between eddy zone and unidirectional flow. With the motion of rotor, the eddy is extruded and disappears because the volume of combustion chamber decreases. The ignition advance angle should be appropriately increased for making full use of the eddy action time under the constant eddy disappearance moment condition. Under the computational conditions, when the ignition advance angle is 47°, the combustion efficiency and the peak pressure in the cylinder are the highest, and the lower NO_x exhaust is also taken into consideration. This study provides some theoretical guidance for the determination of best ignition advance angles under different working conditions.