空气加热器喷雾燃烧流场仿真模拟

Simulation on spray combustion flow field of the air heater

为研究喷注压降对空气加热器喷雾燃烧流场的影响规律,采用DPM离散相模型,结合考虑湍流燃烧效应的涡耗散模型对酒精/液氧/空气三组元加热器进行仿真计算,并与理论计算及试验结果进行对比,验证模型的准确性。仿真结果表明:在保持三组元流量恒定的条件下,提高空气喷注压降能够缩短酒精喷雾的雾化距离与火焰长度,当空气喷注压降提高后,能使喷雾距离缩短50%,火焰长度缩短40%,燃烧室内温度分布更加均匀,有利于提供满足试验需求的均匀热气流;同时,降低酒精喷注压降能够减小酒精喷雾的穿透距离,使火焰更加集中于燃烧室轴线处;当空气喷注压降超出工作范围时,火焰无法附着在喷嘴出口,容易造成加热器熄火;过高的酒精喷注压降会使燃烧火焰周期性摆动,不利于燃烧室热防护。

In order to study the influence of injection pressure drop on the spray combustion flow field and combustion stability of the air heater.Discrete phase model(DPM)and eddy dissipation model considering the turbulent combustion effect were used to simulate the C 2H 5OH/LOx/Air tripropellant air heater,the simulation results were in good agreement with theoretical calculation and experiment,thereby the accuracy of the numerical models was verified.As the results shown,under the condition of maintaining a constant mass flow of the three-component propellant,increasing the air injection pressure drop could shorten the alcohol spray atomization distance and flame length,when the air injection pressure drop is increased to the critical pressure,the spray distance is shortened by 50 and the flame length is shortened by 40.And the temperature distribution in the combustion chamber was more uniform,which could provide a uniform hot air flow to meet the test needs;reducing the alcohol injection pressure drop could reduce the alcohol spray penetration distance,and the flame was more concentrated on the axis of the combustion chamber.In addition,when the air injection pressure drop exceeded the working range,the flame would not be anchored to the injector outlet,which could cause the heater to shut down.Excessively high alcohol injection pressure drop would cause the combustion flame to oscillate periodically,which was not conducive to the thermal protection of the combustion chamber.