摘要
针对马赫数2.92,总压2.6MPa和总温1530K的超声速来流条件,基于主动喷注乙烯的燃料喷注方案,在后缘突扩凹腔燃烧室中开展了激光诱导等离子体点火实验研究。通过采集50kHz的CH*基自发辐射图像,详细观测了火焰传播过程并进而研究了主动式燃料喷注方案对点火过程的影响。研究表明,在激光诱导等离子体点火以后,CH*基强度沿时间的变化会呈现出不同的阶段性特征,大体可以分为四个不同的发展变化阶段(激光激发阶段、初始火焰阶段、过渡阶段和全局火焰阶段)。对于采用凹腔主动式燃料喷注方案,都会经历一个类似的初始火焰形成、减弱、增长和迅速发展成全局火焰的过程,区别在于采用凹腔后壁面燃料喷注方案的初始火焰要更加微弱,而且要经历一个难以观测到CH*基信号的初始火焰沉寂阶段。在全局当量比0.03～0.07的条件下,凹腔前壁面燃料喷注方案要比凹腔后壁面燃料喷注方案更加利于初始火焰的发展,但在形成全局火焰以后会引起较大的波动不利于火焰稳定。
Experimental investigation on the laser-induced plasma(LIP)ignition based on direct fueling schemes was conducted in an ethylene fueled model scramjet combustor with a rear-wall-expansion cavity in a Ma=2.92 supersonic inflow with a stagnation pressure of 2.6 MPa and a stagnation temperature of 1530 K.To study the effect of cavity direct fueling schemes on LIP ignition processes,flame motions were studied by recording the CH* chemiluminescence images at the frame rate of 50 kHz.It is indicated that there exists different stages during a LIP ignition process,which could be classified into four different periods as laser excitation,initial flame,transition and complete flame periods.As for the cavity direct fueling scheme,it is observed that there always exist similar initial flame formation,weakening,growing and fast transition processes.Furthermore,an initial flame quiescent phenomenon will occur under the cavity direct fueling scheme with rear-wall injection,during which the CH* signal is hardly to be recorded.At global equivalence ratios between 0.03 and 0.07,the cavity direct fueling scheme with fore-wall injection is more favorable for the initial flame propagation,however,it will also cause oscillations during the flame stabilization process.
作者
蔡尊
朱家健
孙明波
王振国
CAI Zun;ZHU Jia-jian;SUN Ming-bo;WANG Zhen-guo(Science and Technology on Scramjet Laboratoly,National University of Defense Technology,Changsha 410073,China)
出处
《推进技术》
EI
CAS
CSCD
北大核心
2019年第1期115-122,共8页
Journal of Propulsion Technology
基金
国家自然科学基金(91541101
51606217)
