热激励器对超声速圆管射流的控制机理

CONTROL MECHANISM OF THERMAL ACTUATOR IN SUPERSONIC ROUND JET

采用大涡模拟方法研究了热激励器对马赫1.3超声速圆管射流涡结构的影响,采用加入净热源的方法模拟了热激励器的热效应,分析了不同激励模态(m=±1和m=±4)的降噪和增加射流掺混的效果.研究发现:(1)射流在受到激励作用时,产生了更大的径向和周向速度扰动,这有利于流向涡的形成,m=±1激励模态下流向涡的发展更快,特别是在摆动面上会有更大的增长速度;(2)气动噪声分布的频带很宽,激励作用对抑制高频气动噪声有较强的作用;(3)对于在喷管壁面处产生的固壁噪声,m=±4模态下的激励作用一定程度上加强了固壁噪声.

Large eddy simulation（LES） is applied to study the effect of the thermal actuators on the vertical structures with a Mach 1.3 round jet. The thermal actuators are modelled as heat sources inside the groove. The noise reduction and mixing enhancement at two different actuation modes（m = ±1 and m = ±4） are explored. Results show that radial and circumferential velocity fluctuations are increased due to the actuation effect. It promotes the formation of streamwise vertical structure especially on the flapping plane at the mode m = ±1. The aerodynamic noise distribution covers a wide range of frequencies with high amplitude at high frequencies. It is found that the actuation weakens aerodynamic noise in the range of high frequencies while the wall noise may be increased due to the actuation effect.