Investigating the Design Parameters of a Diamond-Shaped Supersonic Airfoil

Abstract

The lifting surfaces of supersonic flying vehicles generally have sharp leading edges. The airfoil sections of such wings produce the desired lift and, more importantly, yield less drag compared with the conventional blunt airfoils commonly used with subsonic flying vehicles. It is evident that, under given flight conditions, the aerodynamic characteristics of a supersonic airfoil namely, its aerodynamic coefficients are strongly dependent on its geometry. More interestingly, the variation in these coefficients is non-monotonic with the variation in the airfoil design. In the present paper, a parametric study is conducted on a diamond-shaped airfoil of a 10% thickness-to-chord ratio. The objective is to investigate the impact of the airfoil design on its performance. A computer code is developed based on the exact shock-expansion theory to estimate the pressure distribution over the airfoil and, hence, its corresponding aerodynamic coefficients. It was found that, the aerodynamic coefficients of the airfoil are sensitive to its design. In addition, the designs for maximum lift and minimum drag coefficients are competing. A nearly-symmetric airfoil would yield a maximum aerodynamic efficiency.