异步点火相位对四冲程发动机性能影响

为研究双火花塞点火相位差对安装有预燃室的四冲程点燃式航空重油活塞发动机的整机性能的影响规律,利用AVL-Fire软件建立了发动机燃烧室的CFD模型,并验证了模型的有效性;研究异步点火相位增加对整机缸内燃烧、火焰传播和缸内爆震的影响等。结果表明:在转速为5 000 r/min,30%节气门开度、喷油量为20 mg的条件下,主燃室中火花塞点火固定在上止点前20°曲轴转角,另一个火花塞相对其分别提前4°、 8°、 12°点火。随着异步点火相位的增大,缸内平均压力、放热率及累计放热量呈现逐渐增加趋势,但爆震发生的角度逐渐向上止点移动,强度有所增加。

Effect of asynchronous ignition phase on performance of four-stroke engine

In order to understand the impact of asynchronous ignition phase on the performance of four-stroke aircraft piston engine fueled with aviation kerosene, one CFD model about combustion chamber was established and confirmed. The simulation results showed that: at 5 000 r/min, 30% throttle opening position and 20 mg fuel quantity condition, the spark ignition timing for the spark plug inside the main chamber was fixed at 20° crank angle (CA) before top dead center (BTDC), another ignition timing for the spark plug inside the pre-chamber was set ahead of 4°, 8°and 12° relatively; with the increase of the phase difference for the two spark plugs, the in-cylinder pressure and heat release rate increased, the occurrence of the knocking combustion moved to the top dead center and the concentration of the knock intensity increased gradually as well.