Effect of plasma excitation on aerodynamic characteristics of airfoil in Martian atmosphere

The aerodynamic characteristics of the airfoil for the Martian unmanned aerial vehicles (UAVs) need to be improved because of the low density and the low pressure in the Martian atmosphere. The active flow control technology with plasma excitation was used to enhance the airfoil lift and reduce the airfoil drag in the Martian atmosphere. Effects of plasma excitation positions, excitation power, and angle of attack on the lift and drag of the airfoil were studied at a low Reynolds number on Mars. It is found that the plasma excitation increases the airfoil lift in the region of the trailing edge of the lower surface with a maximum increase of 37% and reduces the airfoil drag in the region of the leading edge of the lower surface with a maximum drag reduction of 8%. The lift-drag ratio of the airfoil significantly raises when increasing the excitation power and decreasing the angle of attack. The pressure wave induced by the plasma excitation generates a pressurized zone and a depressurized zone in the upstream and downstream regions of the excitation, respectively. Therefore, pressurized and depressurized surfaces appear on the airfoil. When the excitation gets close to the trailing edge, the pressurized surface enlarges, which leads to a higher pressure difference across the upper and lower surfaces of the airfoil and increases the airfoil lift. When the excitation is located near the leading edge, the depressurized surface expands, which reduces the pressure difference of the airfoil and decreases the airfoil drag.