Use of Navier-Stokes Methods to Predict Circulation Control Airfoil Performance

摘要

The predictive capability of the two-dimensional compressible mass-averaged Navier-Stokes equations was investigated for a typical circulation control air-foil. The governing equations were solved using the implicit approximate factorization algorithm of Beam-Warming with the turbulence model of Baldwin-Lomax. To account for the unique characteristics of circulation control airfoils, an empirical turbulence model correction due to Bradshaw was used. This thesis is unique in that the predictive capability of the computational method is explored by examining the importance of the empirical Bradshaw curvature correction constant on the computed results. Using a generic value of the curvature constant at various blowing coefficient levels, the computational method was able to accurately predict airfoil pitching moment and lift curve slope due to blowing. Predicted levels of airfoil lift coefficient, although reasonable, were found to be consistently low compared with experiment due to the generic curvature constant providing premature jet detachment from the Coanda surface. Computed and measured airfoil drag results followed the same trends, but lack of overall drag coefficient agreement was disappointing. Lift coefficient was found to be quite sensitive, pitching moment not sensitive, and drag coefficient moderately sensitive to the value of the curvature constant used. For the highest blowing coefficient case considered, the value of curvature constant required for the computational lift coefficient to match the experimental lift coefficient was also determined. Keywords: Boundary layer control. (edc)