BOUNDARY LAYER SEPARATION CONTROL USING VORTEX GENERATOR JETS

通过墙壁上的小孔进入自由流的射流已被证明在控制边界层分离方面是有效的。纵向涡流是由喷流与自由流相互作用产生的。通过比较定常射流和脉冲射流对纵向涡产生的影响，从实验上研究了气流分离的抑制机理。研究了射流俯仰角和射流与自由流速度比对抑制流动分离的影响。对下游多个位置的二次流进行了测量，以了解纵向涡的行为。实现分离控制抑制的最重要的结果是不仅旋涡很强，而且它们继续靠近壁面，涡流发生器射流可以适应各种流动变化。与固体涡流发生器的情况相比，这是一个有利的特性。基于对分离控制机理的认识，开发了一种主动分离控制反馈系统。该系统已在多个流动条件下实际应用，取得了良好的应用效果。

Jets issuing through small holes in a wall into a freestream have proven effective in the control of boundary layer separation. Longitudinal vortices are produced by the interaction between the jets and the freestream. The mechanism for suppressing flow separation was studied experimentally by making a comparison between the effect of steady jets and that of pulsed jets on generating longitudinal vortices. The effect of the jet pitch angle and jet to freestream velocity ratio on suppressing flow separation was studied. Secondary flow fields at several downstream locations were measured to know the behavior of longitudinal vortices. The most important results for attaining the suppression of separation control are that not only the vortices are strong but also they continue to be near the wall.Vortex generator jets can be adapted for various flow changes. This is an advantageous characteristic compared with the case of solid vortex generator. An active separation control feedback system was developed based on the knowledge on the separation control mechanism. The system has been actually applied to several flow conditions and has been confirmed to be useful.