驻涡燃烧室驻涡区三维冷态流动特性数值研究

3-D Numerical Simulation of Cold Flow Characteristics of Cavity in Trapped Vortex Combustor

驻涡燃烧室驻涡区内的流动是影响驻涡燃烧室性能的一个关键因素。首先将数值模拟结果进行与试验测量结果进行对比,确定了最佳的湍流模型,并在此基础上通过数值方法深入研究了驻涡燃烧室驻涡区冷态流动特性。结果发现:通过在驻涡区前壁进气缝中设置一定的矩形挡片可以在驻涡区一定范围内诱发以反向旋转的涡对形式存在的流向涡。对比研究了挡片阻塞比BR(挡片面积与前壁开缝面积之比)分别为0,0.2,0.4时驻涡区内的流动结构,分析了流向涡产生的原因。定量结果表明,当BR=0.2,0.4时,(1)流向涡涡量大小比BR=0时提高了将近100%,BR=0.2对应的流向涡涡量比BR=0.4对应的流向涡涡量略大;(2)在流向涡混合层内,流向涡涡量沿轴向呈先增大后减小的趋势;(3)燃烧室总压损失约比BR=0时大1%。

The flow structure in cavities is a key issue for trapped vortex combustors. Numerical method is verified by experimental results. According to the numerical simulation in this paper, series of stre- amwise vortexes which exist in the form of counter-rotating vortex pairs would be induced by the addi- tion of specific rectangular stacks in the jet slots in the front body of cavities. Three cases in which the stack blockage ratio BR （tab area to jet slot area ratio） are 0,0.2,0.4 respectively are investigated. In cases BR=0. 2,0. 4, the results show that： （1） the streamwise vorticities are significantly increased by nearly 100% compared with that in the case BR=0, and the streamwise vorticities in the case BR=0.2 are slightly stronger than the streamwise vortexes in the cases BR=0.4; （2） in the streamwise vortex mixing layer, the mean streamwise vorticity increases first and then decreases along the axis direction; （3） the total pressure loss of the combustor is about 1% bigger than that in the case BR=0.