Flow Management of a Plane Turbulent Wall Jet by a Streamwise Vortex Pair with Periodic Variation in Strength and Radius

抄録

Flow management of a plane turbulent wall jet has been studied experimentally by utilizing a streamwise vortex pair with periodic variation in strength and radius. The magnitudes of the streamwise vorticity and secondary current induced by the vortex pair are weakened by the periodic variation. The integrated streamwise momentum flux is increased by the introduction of the streamwise vortex pair which consists of two counter-rotating longitudinal vortices into the shear layer. Despite the weakening of the vorticity and secondary current caused by the periodic variation, the increment rate of the momentum flux is slightly increased due to the periodic variation. In an analysis with triple velocity decomposition and phase averaging, it is evident that the periodic fluctuating velocity component contributes significantly to the production of the Reynolds shear stress.