凹腔燃烧截面波系及温度场同步显示研究

Simultaneous Visualization of Cross Section Wave System and Temperature Field in Cavity Combustion

关键词:  超燃冲压发动机  燃烧室  剪切层  流场  聚焦纹影

Key words:  Scramjet  Combustor  Shear layer  Flow field  Focused schlieren

摘要:

凹腔作为超声速燃烧室的典型构型，对燃烧状态下的相关物理量进行准确诊断，有利于定量分析和研究超声速燃烧的机理。相对此前采用激光纹影等通程积分密度场显示方法，研究设计了一套锐聚焦深度<1mm的激光聚焦纹影，用于显示凹腔截面的燃烧流场波系结构，同时，利用羟基平面激光诱导荧光（OH-PLIF）和聚焦纹影同步诊断同一截面的温度场和密度场。试验结果表明，所显示截面内的波系结构清晰，得到了更多流场细节，同时也标记出了该截面内氢气燃烧状态，二者具有较好的一致性。该同步诊断结果可以更好地了解剪切层在燃烧室的运动和发展轨迹、以及不同参数的氢气喷射对剪切层和燃烧状态的影响等。获取同一截面的波系结构和燃烧状况同步数据，对于研究燃料喷射以及凹腔燃烧等具有一定的参考价值。

Abstract:

Cavity is a typic configuration of supersonic combustor， it is beneficial to the basic research and analysis on the mechanism of supersonic combustion， through accurately diagnosing the relevant physical parameters in the combustion state. Compared to the previous method of full path integral for density field diagnose， such as laser schlieren， a set of laser focused schlieren with the sharp focus depth less than 1mm was designed， which was used to visualize the wave system structure of combustion cross section of cavity， meanwhile the temperature field and density field for the same section were diagnosed simultaneously by focused schlieren and OH-PLIF. The experimental results showed that the wave structure in the cross-section was clear， and more details such as the hydrogen combustion state were obtained also， and the two results have a good consistency. The joint results are helpful for better understanding of the movement and development of the shear layer， the effects of hydrogen injection with different parameters on shear layer and combustion state. To obtain the synchronous information of both the wave structure and the combustion state for the same cross section has certain reference value for fuel injection and cavity combustion research.