ジェット吹出しによる境界層能動制御のメカニズム  [in Japanese] The Mechanism of Active Boundary Layer Control Using Vortex Generator Jets  [in Japanese]

The vortex generator jet method is active control of flow separation that has the ability to provide a time-varying control action. The mechanism for suppressing flow separation was studied experimentally by making a comparison between two effects of steady and pulsed jets on generating longitudinal vortices. The suppression of flow separation is accomplished by transporting high momentum fluid of the freestream to the lower wall by the secondary flow of longitudinal vortices. However, if the vortex detaches from the wall, a counter-rotating vortex of nearly equal strength is induced and, thus, an upwash region is produced by the effect of a vortex pair. The upwash makes ineffective the secondary flow toward the lower wall and as a result streamwise velocity decreases. Pulsed jets enhance the mixing process in comparison with steady jets and indicate effective separation control for the purpose of attaching the vortex to the lower wall.