Analysis of PSP Results Obtained for the VFE-2 65° Delta Wing Configuration at Sub- and Transonic Speeds

The objectives of the International Vortex Flow Experiment 2 (VFE-2) are to perform new wind-tunnel tests on a delta wing by using modern measurement techniques and to compare these data with results of numerical state-of-the-art codes. In the present paper results of the first part of the VFE-2 experiments carried out at DLR Göttingen on a NASA wind tunnel model are described. These investigations comprise pressure distribution measurements by means of the Pressure Sensitive Paint (PSP) technique which captures the complete model surface giving much more insights in details of the flow topology than would be possible by discrete pressure taps. The delta wing of 65° sweep angle was equipped with sharp as well as with rounded leading edges. The pressure distributions are analyzed for two Mach numbers M = 0.4 and 0.8 and two Reynolds numbers 2 and 3 million. Dependent on the angle of attack (10º -25º) the aerodynamics are described with emphasis to secondary vortex formation and vortex breakdown. For the rounded leading edge the aerodynamics are also described with regard to attached flow, onset of outer primary vortex and particularly the formation of an inner primary vortex