Effects Of The Flow Characteristics On The Flameholder Vortex Shedding In Afterburner

The oscillating combustion is self-oscillation feedback phenomenon generated due to theperiodic changes of burning rate and heat release rate caused by pulsating exothermic reaction ofcombustion and combustion chamber characteristics of the acoustic inter-coupling. Periodic changesof pressure caused by vortex shedding of stabilizer is an important factor of pulsating heat ofcombustion. For integrated afterburner, the vortex shedding is a key factor in causing oscillatingcombustion. This paper numerical simulation the vortex shedding process and it is influence on thecombustion stability in integrated afterburner meanwhile the factors which effect the vortex sheddingwere analyzed. The main research work carried out in this paper are as follows:Numerical simulation of the unsteady vortex shedding process is performed. The alternatingperiods of vortex generation, development, growth and shedding after flame-holder, and flow chartthrough a complete cycle drawn vortex shedding frequency, which is monitoring flame-holder liftfrequency obtained is consistent. After the flame-holder,the points pressure and speed magnitudeand the pulsation frequency is not the same, a point near the center axis of the pressure pulsation closeto the vortex shedding frequency.The research of the factors witch effect the vortex shedding behind the flame-holder,it wasconcluded that the flame-holder length along the flow has no effect on the recirculation zone,but thelength of the recirculation zone increase by16%by the tail slope,while too large tail slope makes therecirculation zone disappeared.The steam velocity did not influence the recirculation zone length andthe pressure,velocity distribution in the flow filed,but the larger stream velocity the grater vortexshedding frequency. Plus disturbance will have some impact on vortex shedding frequency, when lowplus pulse disturbance a lower frequency disturbance,the vortex shedding frequency focused on valuelarger than the original, while higher plus disturbance frequency the vortex shedding frequency isconcentrated at a value less than the original.According to the process of combustion simulation, it is found that the flow field parameterdistribution is approximately same as the cold simulation in the internal and external region ofrecirculation zone formed by the vortex shedding，and the pressure，velocity fluctuation periodical orquasi-periodic change effected by the periodical vortex shedding. Further more, the externaldisturbance exert a minor effect on fluctuation frequency of pressure and velocity. The results showthat the heat release fluctuation induced only with the vortex shedding behind flame holder and the external disturbance.