关键词: 燃烧室;凹腔结构+;横向燃料喷流+;超音速燃烧;火焰稳定性;平面激光诱导荧光+

Abstract: Several cavities with different geometry parameters including the length-to-depth ratio(L/D),depth(D) and aft ramp angle(θ) were placed inside a supersonic duct just downstream of the fuel injection port,respectively.A helium jet adulterated with acetone vapor and a hydrogen jet were employed to simulate the fuel jet under non-combusting and combusting conditions.Acetone and hydroxyl radical fluorescence images at different planes of the flowfield were imaged by the planar laser-induced fluorescence(PLIF) technique.The non-combusting flowfield was simulated numerically.The results show that cavity geometry parameters can affect the static pressure distribution in the cavity through influencing the transmitting characteristics of the high-pressure disturbance from the cavity back wall to the cavity front wall and then affect the flow of the fuel jet.Less L/D or deeper(larger D) or steeper(larger θ) cavities are helpful in transmitting the high-pressure disturbance that can cause the fuel not easy to turn to the cavity and prevent the fuel mass from entering the cavity.Larger L/D and deeper cavities can increase the range of the low speed back flowing regions in the cavity which can enhance the combustion in the cavity and the flame-holding ability.It seems that the cavity aft ramp angle has little influence on the combustion of the fuel.

Key words: Combustion chamber;Cavity geometry+;Transverse fuel jet+;Supersonic combustion;Flame stability;Planar laser-induced fluorescence(PLIF)+