Navier-Stokes Analysis of Tunnel-Wall Interference Effects on Pitching Delta Wings

摘要

A numerical method for the analysis of tunnel-wall interference effects in forced-oscillation testing is presented. The method is based on the wall-pressure signature concept and utilizes the computed wall-pressure distributions. The induced wall pressure field is computed by using an unsteady three-dimensional full Navier-Stokes solver for a 70-deg pitching delta wing in a wind tunnel. To validate the code, the computed static results are shown to have good agreement with the experimental data of Wentz in lift and drag coefficients. On the other hand, the computed static and dynamic normal force coefficients are, in general, higher than those in a second set of data. However, the predicted hysteresis curves of normal force coefficient in large-amplitude-oscillation testing agree reasonably well with this second set of data. The computed unsteady pressures on the tunnel walls and floor are used to generate the interference flow field that is analyzed for the upwash and blockage corrections. The corrected results are shown to agree well, in the slope and magnitude of hysteresis loops, with the computed results in free-air conditions. It is also shown that the hysteresis in upwash and blockage corrections increases with the reduced frequency.