Gasdynamic Knowledge Base for High Speed Flow Modelling

Abstract

This chapter is intended to illustrate a fragment of developments toward systematic high speed design, that is here aerodynamics in the regime of transonic and supersonic Mach numbers. The purpose is to show the modelling background of a combination of gasdynamics and geometry in the development of modern software for aerodynamic design in the virtual environment of personal and workstation computers. Here it is not intended to once more derive the basics for algorithm development in numerical simulation (CFD): only a simplified model of the basic equations is briefly mentioned because they paved the way to a better understanding of local flow phenomena, or as a consequence, of the requirements for detailed shaping of surface geometry in order to control local inviscid flow phenomena. In the transonic as well as in the supersonic regime, these phenomena are dominated by the interaction of surface geometry and surfaces within the flow field, for instance the boundary between locally subsonic and locally supersonic flow. These sonic surfaces, but also shock wave surfaces may be seen as part of the complete geometry set consisting of configuration and important flow features under design conditions. Motivation of this contribution is therefore to explain the gasdynamic background of some practical geometry tools for aerodynamic design, which take into account sonic and shock surfaces as part of the boundary conditions. Building on the pioneering basics of Guderley [76] and Oswatitsch [77], the ideas underlying the outlined concepts have been developed within the author’s past theoretical work in transonics at DLR in Göttingen.