零度和逆向压力梯度环境下涡激励射流的数值模拟
Numerical simulations of particle image velocimetry (PIV) experiments con-ducted with vortex generating jets (VGJs) on a °at plate, at a Reynolds numberbased on plate length of 50,000, were performed for three °ow conditions using atime-accurate hybrid Navier-Stokes solver. Time-averaged steady blowing of angledjets, subjected to a zero pressure gradient, yielded excellent agreement with the PIVdata in terms of vortex formation and strength. Observed °ow features include pri-mary and secondary vortices, where the primary vortex eventually dominates thedownstream region. A shell wall structure, created by smaller vortical structures sur-rounding the developing vortices, was also observed. A pulsed jet in a zero pressuregradient was then initialized from a no-control case. A qualitative comparison be-tween averaged experimental and instantaneous numerical results was performed withgood agreement in terms of the convected size and distance of the wake. Analysisof the instantaneous numerical °ow ¯ eld agreed well with various °ow visualizationexperiments describing the formation of \kidney" vortices. Various indicators pointto the production of a primary vortex by the reduced mass °ow of the pulsed jet.Finally, an adverse pressure gradient was applied, inducing a laminar separation zoneon the plate. A pulsed angled jet induced strong spanwise vortices in the separatedshear layer which appear to weaken the separation zone and allow the bulk jet °uidto °ush the remaining low-momentum °uid out of the domain. It is reasonable toassume that reduced blowing ratios and duty cycles would produce similar shear layervortices and comparable loss reductions. In°uences of both turbulent transition anddominant vortical structures were observed, though the spanwise shear layer vorticesappear to be critical to the laminar separation reduction scenarios observed in thisstudy.