中心分级预混旋流火焰燃烧噪声的实验研究

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.