Post-Stall Prediction of Multiple-Lifting-Surface Configurations Using a Decambering Approach

Abstract

A novel scheme is presented for an iterative decambering approach to predict the post-stall characteristics of wings using known section data as inputs. The new scheme differs from earlier ones in the details of how the residual in the Newton iteration is computed. With earlier schemes, multiple solutions are obtained for wings at high angles of attack as the final converged solution depends on the initial conditions used for the iteration. With this scheme, multiple solutions at high angles of attack are brought to light right during the computation of the residuals for the Newton iteration. In general, the new scheme is found to be more robust at achieving convergence. Experimental validation is provided using experimental airfoil lift curves from Naik and Ostowari for three different aspect ratios of rectangular wings. Results are presented from a study of the stall characteristics of wings of different planform shapes and two configurations of a wing-tail and a wing-canard configuration. Results are also presented from a study to investigate possible asymmetric lift distributions when the iterations were started with an initial asymmetric distribution of the decambering.