液体燃料脉冲爆震发动机点火方法研究

Ignition method for liquid-fueled pulse detonation engine

关键词:  两相爆轰  脉冲爆震发动机  火焰射流  爆燃向爆震转变

Key words:  Two phase detonation  PDE  Flame jet  DDT

摘要:

目前脉冲爆震发动机的起爆主要采用爆燃向爆震转变的方式实现,而爆燃波发展缓慢,消耗了循环周期的很长一段时间。为缩短爆燃向爆震转变的时间和距离,本文研究了一种新型蒸发管点火系统,用蒸发管对两相混合物进行预蒸发,在预燃室内点火形成火焰射流进入主爆震室,实现主爆震室内两相混合物的快速短距离起爆。热态实验在内径120mm,长2500mm的爆震室上进行。与火花塞直接在主爆震室点火相比起爆时间可以从12.5ms缩短到2～3ms,起爆距离可以从1350mm缩短到775mm。预燃室长度和个数对起爆过程也具有非常明显的影响,长度和个数的增加都有利于爆震波的起爆。

Abstract:

Ignition method based on turbulent hot jet is developed for two-phase pulse detonation engine (PDE). It is used to enhance a deflagration to detonation transition (DDT) time and distance. The turbulent hot jet is created by combustion in a pre-combustor which has a spark plug and a vaporizing tube. The vaporizing tube breathes and vaporizes two-phase mixture from main combustor to form combustible mixture, which is ignited by the spark to produce transverse hot turbulent jet into main combustor. In order to show the feasibility of this new ignition system, multi-cycle tests are carried on a pulse detonation engine model of 120mm in I.D. and 2500mm in length filled with gasoline-air mixture. By comparing with conventional spark system the new ignition method can shorten initiation time from 12.5 ms to 2 ms and DDT distance from 1350 mm to 775 mm. The effectiveness of the length and number of the pre-combustor on DDT has been conducted as well. A detailed study of the mechanism of detonation initiation by a turbulent jet of combustion products was demonstrated by shadowgraph observations in a 60 mm×60 mm square tube. Experimental results show that the turbulent hot jet can accelerate flame in combustible mixtures much faster than by spark directly.