关键词: 钝体火焰;燃烧不稳定性;火焰传递函数;声场;热释放波动;速度波动

Abstract: In view of the gas turbine being easy to produce combustion instability problems under the condition of lean burning premixed combustion，the effects of different hydrogen contents on the combustion instability of hydrogen-methane mixture bluff body flame were researched to obtain control method of combustion instability. With the help of the flame transfer function to describe the response characteristics of sound field， several devices were adopted to receive flame picture，such as the image intensifier cameras（ICCD）， photomultiplier tubes（PMT）and cassegrain fixed-point sampling device. Thus the general law of influence under different speed fluctuation of 4 hydrogen contents （0%，10%，20%，40%）on the combustion instability was obtained， and the action mechanism of hydrogen content change on the heat release rate of mixture was analyzed. The experiment results show that the combustion instability strengthens with the increasing of velocity fluctuation A. When A is smaller， amplitude of flame transfer function |H| reduces rapidly.When A is greater than 0.3， the decline of |H| tends to be flat， and the flame transfer function reaches saturation. Under the same velocity fluctuation， the opposite conclusion is obtained after studying the flame under the action of 90Hz and 140Hz. When the hydrogen content increases at 90Hz， flame transfer function amplitude |H| increases.The heat release fluctuation is in phase with the velocity fluctuation phase and the phase difference is close to 0°，and the combustion instability is weakened. At 140Hz， the addition of hydrogen makes |H| decrease while the phase difference is far away from 0°.The following variation of heat release fluction and velocity fluctuation is poor， the combustion instability is enhanced.

Key words: Bluff-body flame;Combustion instability;Flame transfer functions;Acoustic excitation;Heat release fluctuation;Velocity fluctuation