Drag prediction at subsonic and transonic speeds using Euler methods

A technique for the evaluation of aerodynamic drag from flow field solutions based on Euler equations is discussed. The technique is based on the application of the momentum theorem to a control surface enclosing the configuration and it allows the decomposition of the total drag into induced drag and wave drag. Consequently, it provides more physical insight into the drag sources than the conventional surface-pressure integration technique. The induced drag is obtained from the integration of the kinetic energy of the trailing vortex system on a wake plane and the wave drag is obtained from the integration of the entropy jump over the shocks. The drag-evaluation technique is applied to three-dimensi onal steady flow field solutions for the ONERA M6 wing as well as an AR-7 wing with an elliptic spanwise chord distribution and a NACA 0012 section shape. Comparisons between the drag obtained with the present technique and the drag based on the integration of surface pressures are presented for several Euler codes.