Curvature and nonparallel effects in 3-D compressible transition analysis

Abstract

The objective of this work is to investigate the surface curvature and nonparallel effects in stability calculations and transition predictions. The surface curvature terms are included in the linear stability equations derived from the Navier-Stokes equations expressed in a curvilinear orthogonal coordinate system. The nonparallel effects are analyzed by including the nonparallel mean flow terms into the linear stability equations and by taking into account harmonic and nonharmonic variations of the perturbations in the direction perpendicular to the wing leading edge. The resulting equations are solved using a perturbation technique. The results obtained with this method have been validated by comparisons with solutions obtained by Cebeci et al. (1994), Langlois et al. (1997), and Malik and Masad (1994) for 3D incompressible flows over infinite swept wings, and with solutions obtained by Salinas and Casalis (1997) for 2D compressible flows over a flat plate. It is shown that surface curvature and nonparallel effects can have a significant influence on the stability characteristics of compressible flows. Comparisons with experimental data are presented, and the expected improvement in the consistency of the critical n-factor is quantified. (Author)