BOUNDARY LAYER SEPARATION CONTROL USING VORTEX GENERATOR JETS

射流通过壁面小孔进入自由流，在控制边界层分离方面已被证明是有效的。纵向涡是由射流和自由流相互作用产生的。通过对比稳态射流和脉冲射流对纵向涡的抑制作用，研究了抑制流动分离的机理。研究了射流螺距角和射流与自由流速度比对抑制流动分离的影响。测量了下游几个位置的二次流场，以了解纵向涡的行为。实现分离控制抑制的最重要结果是，不仅涡流强度大，而且涡流持续在壁面附近。涡发生器射流可以适应各种流动变化。与固体涡发生器相比，这是一个有利的特点。基于对分离控制机理的了解，开发了一种主动分离控制反馈系统。该系统已实际应用于几种流动工况，效果良好。

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.