Experimental and numerical analysis of the transonic vortical flow over a generic lambda wing configuration

Abstract

Transonic flows over the generic lambda wing configuration SACCON are considered for Mach numbers in the range 0.5 ≤ M∞ ≤ 0.8. These flows are governed by an interaction of compressibility effects and vortical flows. In order to analyze the related flow physics, experimental and numerical approaches are combined. In wind tunnel tests, performed in the transonic tunnel DNW-TWG, the SACCON configuration was tested at a reduced scale of 1:20.5 at Reynolds numbers 2.1·106 ≤ Re ≤ 2.8·106. Surface oil flow visualizations provide information on separation and reattachment lines, and thus also on vortex systems on the lee side of the model. In addition, schlieren images showing vortex structures and shock waves provide a first impression of the three-dimensional flow field. Detailed information on threedimensional flow fields have been obtained from numerical simulations carried out with the DLR TAU-Code. CFD results obtained with different turbulence models have been validated by comparison with skin friction lines of surface oil flow visualizations. Based on CFD results it is shown that at higher Mach numbers the presence of supersonic flow regimes limits the propagation of information and in this manner strongly influences vortex flows on the wing. Furthermore, at high angles of attack the particular design of the SACCON configuration results in strong shock-vortex interactions. These features lead to complex flow phenomena that can affect flight characteristics of the SACCON configuration over the entire flight envelope.