DRAG PREDICTION AT SUBSONIC AND TRANSONIC SPEEDS USING EULER METHODS

A technique for the evaluation of aerodynamic drag from flowfield solu tions based on Euler equations is discussed. The technique is based on the application of the momentum theorem to a control surface enclosin g the configuration and it allows the decomposition of the total drag into induced drag and wave drag. Consequently, it provides more physic al insight into the drag sources than the conventional surface-pressur e integration technique. The induced drag is obtained from the integra tion of the kinetic energy of the trailing vortex system on a wake pla ne and the wave drag is obtained from the integration of the entropy j ump over the shocks. The drag-evaluation technique is applied to three -dimensional steady flowfield solutions for the ONERA M6 wing as well as an AR-7 wing with an elliptic spanwise chord distribution and a NAC A 0012 section shape. Comparisons between the drag obtained with the p resent technique and the drag based on the integration of surface pres sures are presented for several Euler codes.