中心分级预混旋流火焰燃烧噪声的实验研究

Experimental Research on Combustion Noise of Centrally Staged Premixed Swirl Flame

关键词:  航空发动机  中心分级  旋流火焰  燃烧噪声  火焰宏观结构  预混甲烷火焰  贫预混燃烧

Key words:  Aeroengine  Centrally staged  Swirl flame  Combustion noise  Flame macrostructure  Premixed methane flame  Lean premixed combustion

摘要:

针对中心分级旋流燃烧器中预混甲烷火焰在常温常压下的燃烧噪声进行了实验研究，主要关注实验工况和限制域结构对燃烧噪声的影响。用声级计测量了燃烧噪声声压级，用带有CH*滤镜的单反相机拍摄火焰的平均图像。实验结果表明，在主、预燃级空气流量恒定时，总当量比与分层比对燃烧噪声产生了显著的影响，氢气掺入对燃烧噪声无明显影响；预燃级当量比对于燃烧噪声的产生起关键作用，预燃级当量比越接近1.00燃烧噪声越大；相同工况下，预燃级空气流量分配越多，产生的燃烧噪声越大。改变火焰限制域的结构，使用锥形火焰筒可以减少燃烧噪声的产生。本研究还结合带有CH^*滤镜的摄像机拍摄的火焰图像，初步分析了燃烧噪声与火焰宏观结构之间的对应关系。

Abstract:

An experimental study on the combustion noise of a premixed methane flame in a centrally-staged swirl burner at atmospheric temperature and pressure is carried out， focusing on the effects of experimental conditions and confinement structure on the combustion noise. The combustion noise sound pressure level was measured with a sound level meter， and the time-averaged images of the flame were taken with a DSLR camera with a CH* filter. The experimental results show that when the airflow of the main and pilot stages keeps constant， the total equivalence ratio and the stratification ratio have a significant effect on combustion noise， but the hydrogen addition seems to have no obvious effect. The pilot stage equivalence ratio plays a key role in the generation of combustion noise. As a result， the closer the pilot stage equivalence ratio is to 1.00， the greater the combustion noise. Under the same operating conditions， the combustion noise increases with the increase of the air split ratio. Changing the structure of the dump confinement with conical confinement can reduce the level of combustion noise. In this study， the corresponding relationship between combustion noise and flame macrostructure was preliminarily analyzed by combining flame images captured by a camera with a CH* filter.