An accurate and efficient interactive boundary-layer method for analysis and design of airfoils

Abstract

An accurate, comprehensive interactive boundary-layer (IBL) method has been coupled with an analytic-based Euler equation solution method for the analysis and design of airfoils. The goal of this development effort is an efficient design process which includes all necessary physics and which can ultimately be applied to high-lift systems. It takes full advantage of the efficiency afforded by an inverse boundary-layer method for predicting viscous effects. The boundary-layer method includes an improved Cebeci-Smith eddy viscosity formulation and computes transition onset using either the e-method or Michel's formula. The inviscidflow method is significantly more efficient than the conventional CFD (Computational Fluid Dynamics) approach for inviscid flow prediction and provides full compressibility effects. It uses a sequence of transformations, mappings and asymptotic methods which places the Euler equations in the form of a boundary value problem amenable to analytic solution using classical mathematical techniques. Furthermore, aerodynamic sensitivity derivatives for design can be evaluated analytically by differentiating and using the same mathematical solution techniques. Results are presented which demonstrate the potential improvements that can be realized by this approach.