Improvement of Drag Prediction for Transonic Transport Aircraft Configuration Using Hybrid Unstructured Navier-Stokes Solver

In general, an unstructured grid technique has a good flexibility for a complex geometry, and already its usefulness has been demonstrated for full aircraft computations. In the case of three-dimensional, high Reynolds number viscous flow calculations, however, the very fine and stretched grids are required to resolve accurately thin boundary layers developed along the body surface, and so we often have some difficulties in high quality grid generation. A hybrid unstructured grid technique is incorporated into CASPER, a CFD-based design system developed at TRDI-JDA. In this paper, transonic and high Reynolds number flows around an ONERA Model M5 configuration are computed using the CASPER. To validate the present code, with respect to pressure distributions, longitudinal forces and moment coefficients, and transition lines, the present computed results are quantitatively compared with the other computed results and wind-tunnel testing data. Furthermore, some approaches are discussed for reliable drag prediction using CFD method.