Stall characteristics analyses and stall lift robustness inverse design for high-lift devices of a wide-body commercial aircraft

Abstract

Stall is an important cause closely associated with the flight accidents of commercial aircrafts, and stall lift robustness of HLD (high-lift devices) plays a significant role in flight safety issues. In this study, stall characteristics of the HLD of a wide-body commercial aircraft are simulated and analyzed via DES (detached eddy simulation) method, and the impacts of geometric parameters of the HLD on stall lift characteristics are investigated. Afterwards, stall lift robustness design for the HLD is performed via a proposed inverse method which combines the GRNN (generalized regression neural network) method and PCA (principal component analysis) method. Then the inverse design model is established with the aerodynamic parameters as input and the geometric parameters as output. The PCA method is introduced to reduce the dimension of the input data, while the GRNN is employed to predict the geometric parameters. The design process is iterated with new sample points added in. The validated results via DES method indicate that the finally designed HLD configuration conforms with the design targets very well, and thus the stall lift robustness is improved obviously. More specifically, the average lift coefficient near the stall AoA (angle of attack) is improved by 1.4%, and the variance of the lift coefficients near the stall AoA is reduced by 79%, while the stall AoA remains unchanged.