为了揭示非定常等离子体激励在压气机内流近壁区的流动控制机理,建立了等离子体激励流动控制的计算模型,采用基于shear stress transport(SST)湍流模型的尺度自适应雷诺平均/大涡(RANS/LES)混合模拟方法进行非定常数值模拟,研究了非定常等离子体激励的耦合作用机理。结果表明:机匣近壁区转子吸力面流动分离导致叶顶泄漏涡破碎并触发转子内部流动失稳。非定常等离子体激励与机匣近壁区流场相互作用产生诱导涡,诱导涡与叶顶泄漏涡发生耦合作用,促使叶顶泄漏涡产生周期性的振荡,抑制叶顶泄漏涡向转子前缘移动,机匣近壁区流场抵抗逆压力梯度的能力增强,有效地抑制转子吸力面流动分离,与定常等离子体激励相比流动控制效果更好。
The computational modeling used for flow control simulation was established to investigate the mechanism of internal flow control near wall region in an axial compressor with unsteady plasma actuation. Unsteady numerical simulation was performed using a scale adaptive hybrid Reynolds-average Navier-Stokes/large eddy (RANS/LES) method based on shear stress transport(SST) turbulence model. The phenomenological model was used to model the body force over the region of the plasma and added to the momentum equations. The results show that the flow separation at the blade suction surface near wall region is responsible for the tip leakage vortex breakdown and compressor instability. The plasma actuator injects momentum into the flow near wall region. The induced vortex is created due to the interaction between the boundary layer and the high-energy flow near wall region. The induced vortex is created and dissipates periodically, prompting the tip leakage vortex to oscillate periodically. The flow near wall region effectively resists the inverse pressure gradient. The tip leakage vortex spillage ahead of the rotor leading edge and the flow separation at the blade suction sur- face are suppressed. This allows the compressor to operate at lower mass flow rates. Compared with steady plasma actuation, unsteady plasma actuation improves compressor stability more effectively.