等离子体气动激励特性及其抑制叶栅流动分离的实验研究

Experimental research on the characteristic of plasma aerodynamic actuation and flow separation control on a compressor cascade

为揭示纳秒脉冲等离子体气动激励特性及其抑制高负荷压气机叶栅流动分离的作用效果与影响规律,利用PIV流场测试、高速纹影和压力测试开展实验研究。结果表明,纳秒脉冲等离子体气动激励诱导出垂直向上的冲击流动,冲击波的持续时间为80μs左右;纳秒脉冲激励能够有效抑制高负荷压气机叶栅流动分离,其流动控制效果随激励电压和下表面电极宽度的增大以及电极形状改变为弯曲电极而提高,可最大降低总压损失8.4%;激励频率是叶栅等离子体流动控制效果的重要影响因素,端壁横向激励的最佳激励频率为4.0kHz;吸力面流向激励主要改善中间叶高流动特性,而抑制角区流动分离的能力较弱;端壁横向激励通过抑制横向流动,较大程度上减弱了低能流体在角区的积聚,抑制角区流动分离能力较强;组合激励结合了吸力面流向激励和端壁横向激励的作用优势,因而流动控制效果最好。

To discover the characteristic of nanosecond pulsed plasma aerodynamic actuation（PAA） as well as the effect and influence law of flow separation control on a highly loaded compressor cascade by PAA, experimental investigations of PIV measurements, high-speed Schlieren visualization and pressure measurements were conducted. Results show that a shock wave is induced by nanosecond pulsed PAA to spread outward and can last only about 80μs. Nanosecond pulsed PAA can effectively prevent the flow separation in a highly loaded compressor cascade, and the control effect enhances with the increase of lower electrode width and actuation discharge as well as the shape of curved electrodes. The relative reduction of pitch-averaged total pressure loss coefficient is up to 8.4%. The actuation frequency is one key factor affecting the control effect of nanosecond pulsed PAA, and the optimal actuation frequency is 4kHz. The streamwise PAA on the suction surface can mainly change the flow characteristic at midspan, but has weak impact on corner separation. The pitchwise PAA on the endwall can reduce the accumulation of low-energy fluids at the suction surface and endwall corner by inhibiting the cross flow. The control effect of streamwise PAA on the suction surface combined with pitchwise PAA on the endwall is the best.