基于高速摄影图像处理统计分析的点火过程试验

针对空气来流马赫数为2.1、总温为846K,总压为0.7MPa的条件下凹腔内的强迫点火过程,利用高速摄影观测了凹腔主动喷注方式的乙烯强迫点火试验.基于高速摄影图像的合成分析和概率统计,提出了能够定量分析出点火过程凹腔火焰稳定和燃烧室火焰分布的试验研究方法;利用该研究方法,采用主动喷注方式在全局当量比为0.15和0.17(相应的主动喷注当量比分别为0.04和0.06)的条件下,对比研究了采用凹腔后壁面喷注的喷注方案和采用凹腔前壁喷注和后壁面喷注相结合的喷注方案的点火试验过程;定量分析了这两种喷注方案点火后的凹腔火焰稳定和燃烧室内的火焰分布.当凹腔主动喷注当量比为0.04时,点火凹腔内并没有形成良好的局部压力反馈,火焰在点火凹腔内常以不连续形式稳定存在.当主动喷注当量比达到0.06时,整个燃烧室的火焰分布要更加均匀.针对超声速来流条件下的点火过程瞬态图像,该方法能够有效地开展定性分析和定量研究. 

Experiment of ignition process based on statistical analysis of image processing

As for the ignition process at the inflow conditions of Mach 2.1 with stagnation temperature of 846K and pressure of 0.7MPa high speed photography was used to observe the ethylene ignition experiments with the active cavity injection. Based on the high speed photography image synthesis and statistical analysis, a new method for analyzing the cavity flame stabilization and the flame distribution quantitatively was proposed. At the overall equivalent ratio of 0.15 and 0.17(the active injection equivalent ratio of 0.04 and 0.06 correspondingly), the ignition process of the scheme using ramp injection and the scheme using a combined parallel and ramp injection were compared by applying this method. Besides, the cavity flame stabilization and the flame distribution of the ignition schemes were investigated in quantitatively. At the active equivalent ratio of 0.04, the local pressure feedback is weak and the flame exists in a discontinuous form. At the active equivalent ratio of 0.06, the flame distribution of the combustor is more even. As for the ignition process transient images in a supersonic flow, qualitative and quantitative analysis could be made effectively by using this method.