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

Abstract

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 second part of the VFE-2 experiments carried out at DLR Göttingen on a NASA wind tunnel model are described. These investigations comprise velocity field measurements by means of Particle Image Velocimetry (PIV). The delta wing of 65^° sweep angle was equipped with sharp as well as with rounded leading edges. Two Mach numbers M = 0.4 and 0.8 and two Reynolds numbers 2 and 3 million are investigated for 10^°, 13^°, 20^° and 25^° angle of attack. PIV results are presented and the flow is described with emphasis to primary and secondary vortex formation as well as vortex breakdown. For the rounded leading edge the aerodynamics are described with regard to the transition from attached flow to the formation of an inner primary vortex and the onset of the outer primary vortex.