Aerodynamic characteristics of airfoils with Gurney flaps in the Martian atmospheric environment

Rotorcraft operating in the thin and cold Martian atmosphere typically encounter unique aerodynamic conditions characterized by low Reynolds numbers and high Mach numbers, resulting in degraded performance compared to Earth operations. This study investigated the aerodynamic characteristics of the CLF5605 low-Reynolds-number airfoil under Martian atmospheric conditions through three-dimensional unsteady incompressible Reynolds-averaged Navier-Stokes simulations using the k-ω SST turbulence model. The analysis reveals unsteady laminar separation at the airfoil trailing edge, leading to periodic vortex formation and shedding, low-frequency lift and drag oscillations, and overall aerodynamic performance deterioration. To address these challenges, we proposed implementing Gurney flaps on the trailing edge. A comprehensive study was conducted to evaluate the aerodynamic performances of airfoils equipped with 2% chord-length Gurney flaps across varying Reynolds numbers, Mach numbers, and angles of attack. The results demonstrate that Gurney flaps effectively suppress unsteady laminar separation and enhance lift generation. However, their effectiveness is constrained to specific operational regimes: Reynolds numbers ranging from 5000 to 30000, Mach numbers below 0.65, and angles of attack between 0° and 3°. Additionally, while lift is improved, the lift-to-drag ratio remains unaffected due to proportional increases in drag. Furthermore, we developed and analyzed three Gurney flap-integrated rotor designs, which exhibited superior thrust generation, torque characteristics, and hovering efficiency compared to clean rotors. These findings provide critical insights and practical design guidelines for optimizing rotor performance of Mars unmanned aerial vehicles.