An Investigation of the Trailing Vortex System Generated by a Jet‐Flapped Wing Operating at High Wing Lift Coefficients

The purpose of this investigation was to measure the geometry of the trailing vortex generated behind a jet‐flapped wing. Such vortices can pose a serious hazard to aircraft that penetrate them. Previous investigations performed on conventional wings indicate that these vortices persist far some time and have maximum tangential velocities which increase linearly with the lift coefficient. As future aircraft may employ high lift devices such as jet‐flapped wings, the vortices generated could be even stronger. Two semispan models of a jet‐flapped wing were tested in a subsonic wind tunnel. Parameters varied during testing included the jet flap angle, angle of attack, aspect ratio, and jet momentum coefficient. Vortex measurements were obtained using a vortex meter which measured the rotational speed of the fluid within the vortex. Values obtained were numerically integrated to yield the tangential velocity and circulation distribution through the vortex. Experimental results indicate that the maximum tongential velocity increases to a maximum and then decreases with continually increasing jet blowing. At high values of jet blowing, the vortex was found to decay rapidly downstream.