New Hybrid Method to Correct for Wind Tunnel Wall- and Support Interference On-line

Authors: B. J. C. Horsten, L. L. M. Veldhuis

Abstract:

Because support interference corrections are not properly understood, engineers mostly rely on expensive dummy measurements or CFD calculations. This paper presents a method based on uncorrected wind tunnel measurements and fast calculation techniques (it is a hybrid method) to calculate wall interference, support interference and residual interference (when e.g. a support member closely approaches the wind tunnel walls) for any type of wind tunnel and support configuration. The method provides with a simple formula for the calculation of the interference gradient. This gradient is based on the uncorrected measurements and a successive calculation of the slopes of the interference-free aerodynamic coefficients. For the latter purpose a new vortex-lattice routine is developed that corrects the slopes for viscous effects. A test case of a measurement on a wing proves the value of this hybrid method as trends and orders of magnitudes of the interference are correctly determined.

Keywords: Hybrid method, support interference, wall interference, wind tunnel corrections.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1072187

References:

[1] B.F.R. Ewald, AGARDograph 336: Wind Tunnel Wall Correction. Canada Communication Group Inc., 1998.
[2] B.J.C. Horsten and L.L.M. Veldhuis, Experimental and Numerical Results on Cavity Effects in Juncture Flow. Conference Proceeding of the 38th Fluid Dynamics Conference and Exhibit, Seattle, Washington, United States, 2008.
[3] D. Eckert, Correction of Support Influence on Measurements with Sting Mounted Wind Tunnel Models. AGARD FDP Conference, Brussels, Belgium, 1993.
[4] X. Vaucheret, Vortex Lattice Code For Computation of Any Wind Tunnel and Support Effects on Models. La Recherche Aerospatiale, vol. 1(2), pp. 39-51, 1991.
[5] M. Mokry, Evaluation of Combined Wall- and Support-Interference on Wind Tunnel Models. AGARD-CP-535, 1994.
[6] K. Pettersson and A. Rizzi, Aerodynamic scaling to free flight conditions: Past and present. Progress in Aerospace Sciences vol. 44(4), pp. 295-313, 2008.