Variable-Pressure Wind Tunnel Test of Airfoils at Low Reynolds Numbers Designed for Mars Exploration Aircraft

Abstract

Recently, aerial Mars exploration systems have been actively researched. Because the atmospheric density of Mars is almost one-hundredth to that of Earth's, the flight Reynolds number becomes low (Re = 10⁴ ~ 10⁵). In low Reynolds numbers, the flow around a wing tends to separate and conventional airfoils cannot satisfy the given performance requirements for Mars exploration aircraft. In recent years, Sasaki et al. researched new airfoils that have high lift-to-drag ratio at low Reynolds number using evolutionary multi-objective optimization and computational fluid dynamics. In this research, two-dimensional wind tunnel test of three airfoils proposed by Sasaki et al. is conducted to investigate their actual aerodynamic characteristics at Reynolds number 2.0 × 10⁴. The Ishii airfoil with good performance at low Reynolds number is used as the benchmark. The result of the wind tunnel test showed that the lift curve of the three airfoils is linear, and their maximum lift coefficient and stall angle are larger than those of Ishii. Particularly, the three airfoils' lift-to-drag ratio is superior to the Ishii airfoil by more than 30%.