Wind tunnel model support and wall interference corrections in DNW-HST- ensuring high data quality standards -
The DNW High Speed wind Tunnel HST is a closed-circuit, pressurized transonic facility used by industry to support the development of new aircraft and launch vehicles at close to actual flight Reynolds numbers. Test section dimensions are 2.0m* 1.8m (width*height). As part of a continuous effort to increase measurement accuracy a dedicated project together with NLR and Embraer has been successfully completed focusing on further refinement of tunnel model support and wall interference corrections. As part of this joined project, results from various wind tunnel test activities and numerical analysis were applied to validate the improved correction procedures, tailored to the rear sting set-up in the HST test section with slotted walls. The picture below shows the wind tunnel model upside down on a dorsal sting during support interference measurements to assess the effect of the dummy rear model support. The rear support consists of a straight rear sting and the double roll boom (green part). The shape of the newly manufactured dorsal sting is based on an aerodynamically optimized design of NLR. In order to better understand the support and wall interference phenomena occurring in the HST test section, individual effects were measured for the rear sting as well as the double roll boom. Wall pressures were analysed in a systematic way to establish the wall interference effects. This resulted in a very effective and accurate methodology. The accuracy of the corrected measured model drag, lift and pitching moment appeared to be within the uncertainty range of the model load balance. The paper will discuss the adopted support interference and wall interference procedures. Final measured data will be compared with available data measured in other wind tunnels and CFD.