Turbulent wake influence on sailplane performance

Abstract

A Computational Fluid Dynamics (CFD) study was conducted to investigate the influence of a turbulent wake flow on the aerodynamic performance of the JS-1 sailplane. The Menter (1992c) SST k − ω turbulence model was coupled with the γ − Reθ transition model to model a transitional and turbulent wake flow on the JS-1. As a necessary step, the SST k − ω turbulence and γ − Reθ transition model was validated. The validation process comprised of four stages which ascertained the ability of the physical model to predict a transitional and turbulent wake flow on sailplane geometries. The validated CFD tool was used and it was observed that the source of the turbulent wake is a separated turbulent boundary layer from the wing-fuselage junction. A boundary layer analysis was conducted on the JS-1 fin and it was seen that approximately 23.6% of the total fin height is immersed in the turbulent wake. A quantitative drag force analysis showed that the turbulent wake has a significant contribution towards the total drag force on the JS-1 sailplane during thermal flight. The implementation of a combined low wing and high tail configuration with high aspect ratio fin was suggested as the optimal design option to enhance the performance of the JS-1 sailplane during thermal flight.