涡旋射流控制逆压梯度平板边界层分离的涡结构研究

为了研究涡旋射流控制边界层分离的物理机理,设计、搭建了涡旋射流控制逆压梯度平板边界层分离实验台,在此基础上对低雷诺数下平板边界层分离及射流控制进行了实验和数值研究.通过对比不同射流控制方式的统计特性及射流控制效果,揭示了射流流场大尺度相干结构的演化规律.射流瞬时流动细节的研究表明:发卡涡和类发卡涡是逆压梯度环境下直射流和斜射流中比较典型的涡结构;在斜射流中,随着类发卡涡的发展,射流孔下游发展成熟的类发卡涡涡腿外侧出现了不断增强的次生流向涡结构;次生涡结构对壁面附近能量的增大和质量的输运、耗散具有重要的作用.经对比发现,斜射流控制流动分离的效果明显优于直射流.

Study on the Special Vortical Structure Development During Flow Separation Control by VGJs in Boundary Layer of Flat Plate with Adverse Pressure Gradient

Experimental and numerical studies were performed at low Reynolds number using VGJs on flat plates with adverse pressure gradient to investigate the physical mechanism of flow separation control by VGJs in boundary layers.The control effects and the statistical characteristics of different control modes were analyzed to explore the development of the large-scale coherent structure.The instantaneous flow analyses show that the hairpin or hairpin-like vortices are two classical vortical structures formed from vertical and angled VGJs in adverse pressure gradient.In downstream of angled VGJs,the additional flow structures are generated as a consequence of the hairpin-like vortices.Its formation could increase the transport of energy and mass,and then improve the dissipation effectively.In addition,the angled VGJs provides more effective separation control than the vertical VGJs.