Navier-Stokes analysis of tunnel wall interference effects on pitching delta wings

A numerical method for the assessment and correction of tunnel wall interference effects in forced-oscillation testing is presented. The method is based on the wall pressure signature method using computed wall pressure distributions. The wall pressure field is computed using unsteady three dimensional full Navier-Stokes solver for a 70-degree pitching delta wing in a wind tunnel. Approximate-factorized alternate direction implicit (AF-ADI) scheme is advanced in time by solving block tri-diagonal matrices. The algebraic Baldwin-Lomax turbulence model is included to simulate the turbulent flow effect. Also, dual time sub-iteration with local time stepping is implemented to improve the convergence. The computed wall pressure field is then imposed as boundary conditions for Euler resimulation to obtain the interference flow field. Comparisons between the full Navier-Stokes solutions and thin layer Navier-Stokes solutions were made. The static computation shows good agreement with experiments. The dynamic computation demonstrates reasonable physical phenomena with a good convergence history. The effects of the tunnel wall in upwash and blockage are analyzed using the computed interference flow field for various reduced frequencies and amplitudes. The corrected results by pressure signature method agree well with the results of free air conditions.