丙烷自燃特性及爆震机理的试验研究

Experimental Study of Spontaneous Combustion Characteristics and Knocking Mechanism of Propane

为了深入揭示丙烷自燃和爆震燃烧机理,基于一台新型快速压缩机试验平台,开展了不同初始压力、当量比条件下丙烷-空气混合气自燃和爆震燃烧的试验研究,并通过瞬态压力和高速相机同步测试方法进行了缸内燃烧过程研究.结果表明:爆震压力振荡强度随着初始压力的提升显著增强,压力振荡的产生与着火方式无绝对关系,其振荡强度主要取决于自燃发生前末端混合气的状态.轻微爆震和弱爆震由末端自燃导致,自燃时未燃混合气区域越大,爆震强度也越高.超级爆震的形成是由于超声速自燃火焰的传播导致压力波在火焰面前方的汇聚,并最终导致爆燃向爆轰模式转变所致,从而形成峰值极高的压力振荡.

In order to reveal the mechanism of propane auto-ignition and knocking combustion,an experimental study was carried out on a newly designed rapid compression machine,and the auto-ignition and knocking combustion of propane/air mixture under different intake pressures and equivalence ratios were investigated through synchronous test of transient pressure and high speed camera in measurement of in-cylinder combustion process.The results show that knocking severity is significantly increased with the increase of initial intake pressure.There is no absolute relationship between pressure wave generation and ignition method,and the amplitude of pressure oscillations mainly depends on end-gas mixture thermodynamic state before auto-ignition occurrence.Mild and weak knocking combustion are induced by end-gas auto-ignition,and the larger area of unburned mixture zone when auto-ignition occurs,the stronger the knocking severity.The formation of super-knock is caused by the propagation of supersonic autoigniting flame that leads to the convergence of pressure wave in front of flame front.And eventually,a transition from the deflagration to the detonation mode is induced,which is accompanied by extremely high pressure oscillations.