A Field-Panel Approach for Flow Calculation about 3D Transonic Configurations
D. Fokin, L. Gebhardt, Th. Lutz and S. Wagner
Proceedings BEM 23 Conference, May 7-9, 2001, Lemnos, Greece
The purpose of the present work is to develop a mathematically sound and efficient field-panel method for the analysis of inviscid transonic flow over 3D aircraft configurations taking the effects of (weak) shock waves into account. The problem is reduced to a system of two nonlinear integro-differential equations for the disturbance potential in the field and the singularity distribution on a reference surface. An iteration procedure incorporating the boundary element method to satisfy the impermeability conditions on the body (Neumann formulation), coupled with a correction for compressibility effects based on the full potential equation has been developed. The artificial viscosity concept is used to stabilize the process for transonic cases. Exemplary results of test calculations for transonic 3D wings with shock waves are presented. The method was applied to investigate the effect of a local geometry modification of the wing section (shock control bump) in order to reduce the shock intensity for given off-design conditions. A parametric study was performed to find proper bump height and position.