Aerodynamic Optimisation of Aerofoils for Martian Rotorcraft Using Direct Numerical Simulations

Throughout the last century, designers have worked to optimize aerofoils for a wide range of terrestrial conditions. However, Martian atmospheric density is less than 1% of that on Earth, and Martian surface temperature and atmospheric composition lead to a lower sound speed. Consequently, rotors for a Martian helicopter – such as Ingenuity which flew on Mars in 2021 – must operate in a low Reynolds number compressible regime that is seldom encountered on Earth. Non-conventional aerofoils with sharp edges and flat surfaces have shown improved performance under such conditions, and second-order-accurate Reynolds-averaged Navier-Stokes (RANS) and Unsteady RANS (URANS) solvers have been combined with genetic algorithms to optimise them. However, flow over such aerofoils is characterised by unsteady roll-up of coherent vortices that subsequently break down/transition. Accordingly, RANS/URANS solvers have limited predictive capability, especially at higher angles of attack where the aforementioned physics are more acute. In this seminar I will present recent efforts to overcome this limitation via use of high-order GPU-accelerated Direct Numerical Simulations (DNSs).