Inverse method with geometric constraints for transonic aerofoil design

Abstract

SUMMARYAn engineering method for the design of aerofoils having a prescribed pressure distribution in subsonic or transonic flow is described. The method is based on an iterative procedure of 'residual-correction' type. In each iteration step, the difference between a current and a target pressure distribution (residual) is determined by a fast (multi-grid) finite-volume full-potential code. Corrections to the geometry driving the pressure residual to zero ate determined by a global, inverse, thin-aerofoil theory based method for the subsonic part of the flow field, and by means of a local, inverse, wavy-wall theory based formula for the supersonic part of the flow field. The determination of the geometry correction has been formulated as a minimization problem in the sense that pressure distribution and geometry requirements may be balanced in a weighted least squares sense. The method is described briefly, including the basic mathematical/physical formulation and the main computational aspects. The capabilities of the method are illustrated by means of examples of aerofoil designs.

Airfoil design and optimization methods: recent progress at NLR

“…At NLR, successful computational methods for the design of airfoils and wings in subsonic and transonic flow have been developed following the residual-correction approach [1]. Essentially, these methods are based on solving an inverse problem, determining an airfoil or wing shape such that it will generate a priori prescribed surface pressure distributions at given operating conditions.…”