Experimental Investigation of the Wing-Body Juncture Flow on the DLR-F6 Configuration in the ONERA S2MA Facility

Abstract

An experimental aerodynamic investigation of the DLR F6 generic transport aircraft configuration has been conducted in the S2MA wind tunnel facility of ONERA in Modane, France, in a collaboration between DLR and ONERA in November 2008. The test with the DLR-F6 configuration is a follow-on study of tests in this tunnel in the 1990s, as well as of recent tests with the same configuration in NASA NTF facility in 2007, which has been carried out by NASA and DLR as a contribution to the AIAA Drag Prediction Workshop activities. While the test campaign in the NASA NTF covered the wing/body, the wing/body/fairing, and the wing/body/nacelle/pylon configuration for Reynolds-numbers of Re=3 x 10 6 and 5 x 10 6 , the present experimental investigation is limited to the wing/body configuration with and without a side-of-body fairing for a Reynolds-number of Re=3 x 10 6 . The main purpose of the test is to address specific issues and findings from the previous NASA NTF test, as well as to provide more detailed and additional flow field information of the wing/body juncture flow for these two configurations with different measurement techniques. The contribution is confined to the analysis of results of the ONERA S2MA wind tunnel. The measurements of force and moment data, as well as static pressure distributions on the wing and on the fuselage of the wing/body configuration show a satisfying long term repeatability over a time period of 18 years. Flow features at the wing/body junction of the wing/body and the wing/body/fairing configuration have been analyzed in more detail by evaluating inboard pressure distributions as well as pressure sensitive paint to determine the complete pressure field on the wing surface and link it to the information of the pressure distributions. The aerodynamic impact of the side-of-body fairing has been analyzed for design and off design conditions given by a Mach number of 0.80. At off-design conditions adverse drag increments have been observed for the configuration with fairing. Oil flow visualization pictures have been used to investigate the size and formation of the side-ofbody separation. It is shown that the flow inside the separation bubble is mainly fed by the lower wing surface flowfield. For unsteady pressure measurements Kulites sensors have been inserted at the side of the body to analyze the degree of unsteadiness inside and in the vicinity of the separation bubble that is present in the rear part of the wing/body junction.