Control of vortical flow over a rounded leading-edge delta wing

An attempt is made for fluidic control of the vortical flow and its related vortex breakdown phenomenon over a delta wing with a particular geometry. The model has a sweep angle of Lambda = 60 deg and a rounded leading edge. The control system is based on four rectangular slots along the portside leading edge, and it provides continuous or pulsed jets normal to the leading-edge surface and parallel to the leeward side plane. The mass flow rate and the frequency of injection can be varied independently. The results are compared to a reference case defined by a microflap fixed along the leading edge and set perpendicular to it. Qualitative measurements are obtained with surface flow visualizations and boundary-layer transition detections with acenaphten. Quantitative data consist in mean and instantaneous surface pressure distributions measurements under the primary vortex axis and in mean three-dimensional velocity held measurements. The control effect is analyzed by means of laser sheet visualizations to detect the vortex breakdown position and by normal force and rolling moment measurements with a five-component balance.