Parametric Study of the Performance of a Biplane Joined at the Tips

Abstract

A parametric investigation has been conducted on a new multiple lifting surface configuration. This new configuration is a biplane joined at the tips with flow guides. This paper will explain the effects due to geometric parametric variation in stagger and gap on the performance of fourteen different rectangular planform flat plate profile biplane models joined at the tips by flow guides. The purpose of the present study is to examine the possibility of further increasing the aerodynamic efficiency of a biplane configuration by adding winglets both computationally and experimentally. The experimental integrated force data were obtained from wind-tunnel tests performed in the University of Dayton low-speed wind tunnel (LSWT) at Reynolds number 60,000 and 120,000. Test conditions varied angle of attack by ±25° . The computational study used the Athena Vortex Lattice (AVL) code based on the Vortex Lattice Method (VLM). Then, the computed results were verified by comparison with the experimental data and the two were found to compare quite well under some conditions, and not well under other conditions. The results show that both gap and stagger have positive effects on the coefficient of lift and aerodynamics efficiency. The models with positive stagger show higher lift coefficient and higher aerodynamic efficiency compared to the models with negative stagger. This effect of changing stagger from positive to negative values becomes less important at higher values of gap, due to the smaller interactions between the two wings. Curves of lift coefficient versus angle of attack show a change in the lift slope around the angle of attack of maximum aerodynamic efficiency. At highest Reynolds number, the trend of performance increase diminished.