Aerodynamic Performance Analysis of a Curved-channel ABLE Airfoil in Supersonic Continuous and Hypersonic Rarefied Flows

An airfoil, equipped with a curved-channel ABLE, is a good alternative to increase the lift-to-drag ratio. For this purpose, a curved-channel artificial blunted leading edge (ABLE) was applied to several supersonic/hypersonic symmetrical airfoils to analyse the aerodynamic performance in low-altitude supersonic continuous flow and high-altitude hypersonic rarefied flow during the process of re-entry into the atmosphere. The compressible Navier-Stokes equations were solved using the finite volume method to analyse the aerodynamic performance and determine the optimal curved-channel ABLE airfoil for supersonic continuous flow. Thereafter, the drag reduction and lift increment efficiency of the optimal ABLE airfoil were analysed in the hypersonic rarefied flow. The variation in the aerodynamic performance of the ABLE airfoil with the Knudsen number and freestream Mach number was determined using the direct simulation Monte Carlo (DSMC) method. The results showed that with suitable ABLE configuration and parameter values, the concept of ABLE can help reduce the drag coefficient, improve the lift coefficient, and obtain a better lift-to-drag ratio in both continuous and rarefied flows without considerable aerothermal penalty. However, the drag reduction effect of the curved-channel airfoil in the rarefied flow is much lower than that in the continuous flow, because of the lower proportion of the wave drag in the total drag, and the overall aerodynamic performance is significantly deteriorated because of the rarefaction effect of the atmosphere.