双台阶超燃冲压发动机燃烧室流场数值模拟

Numerical Simulation of Flow fields in a Scramjet Combustor with Two Steps

采用RNGκ-ε湍流模型以及有限速率化学动力学模型,求解了二维Navier-Stokes方程,分别以氢气和乙烯为燃料数值模拟了具有双台阶单凹槽的超燃冲压发动机燃烧室的流场,并与试验数据进行了对比。计算结果表明:双台阶下游和凹槽处出现了有利于燃烧和火焰稳定的回流区;在隔离段入口马赫数2.0左右时,该燃烧室可以实现在亚燃和超燃两种模态下工作,燃烧效率在0.7以上;数值模拟壁面压力分布的结果与相应的试验结果吻合良好。

Combustor is the key component of a scramjet. In this paper, numerical simulations were performed to study the flow fields of a scramjet combustor with two steps and one cavity. In the simulation, RNG κ-ε turbulence model and finite-rate reaction model was selected to solve the 2-D Navier-Stokes equations. The flowfield with hydrogen fuel injection and ethylene fuel injection was calculated separately and the results were compared with the experiment data. The results show that the recirculation zones, which are helpful for combustion and flame stability, occur at the downstream of the two steps and also inside the cavity. The combustor is in dual-mode, which is ramjet mode and scramjet mode, when the mach number at the entrance of isolator is about 2. 0. The combustion efficiency is above 0. 7. The computation results of static pressure on the lower wall agree well with the corresponding experiment data.