Fast Drag Prediction Method Using Euler Equations

Abstract

A technique to predict the aerodynamic drag from an Euler e ow solution is discussed. The method is based on integration of pressure and skin friction on the surface of the body. For the skin-friction calculation, the van Driest skin-friction model is used. Empirical base drag is also included to the drag calculations. Flow solutions are obtained by an unstructured three-dimensional Euler solver. Supersonic attached e ows are the focus, rather than subsonic and transonice ows. The method cannot be applied to separated and vortical e ows at a high angle of attack. Present calculation technique is applied to three-dimensional supersonic e ows around missile geometries. The technique is applied to three different test cases for validation. The e rst test case is a conventional missile geometry having a e neness ratio of 10 and rectangular e ns. The second test case is another conventional missile geometry having a e neness ratio of 16 and sweptback e ns. The third test case is a missile geometry with a e neness ratio of 13.06 and having cross-oriented sweptback tail e ns and boattail afterbody. Drag coefe cients predicted by the present technique are compared with the experimental results obtained at different Mach numbers and angles of attack.