Abstract
The development of fixed wing aircraft for Mars exploration is desirable, but needs to overcome the challenge of low Reynolds number due to thin Martian atmosphere. Flapped CoFlow jet(FCFJ) airfoil has the potential to achieve an ultra-high cruise lift coefficient with acceptable corrected aerodynamic efficiency of C-L/(C-D + Pc). This study investigates whether FCFJ airfoils and regular CFJ airfoils can have high aerodynamic performance at cruise condition at three cruise Mach number 0.17, 0.26 and 0.4, which have the corresponding Reynolds number of 5.43 x 10(4), 1.42 x 10(5) and 2.18 x 10(5), respectively. The regular CFJ airfoil applies the injection very close to the leading edge at about 2-4% chord location. The FCFJ airfoil has a long flap with the CFJ applied inside the flap as part of the airfoil. The research is based on validated CFD simulation using a 2D RANS solver with Spalart-Allmaras(SA) turbulence model, a third-order WENO scheme for the inviscid fluxes, and second-order central differencing for the viscous terms. At a Mach number of 0.26, numerical simulations show that the FCFJ airfoil can obtain a cruise lift coefficient of 3.74, a lift-to-drag ratio (C-L/C-D) of 172.54, and a corrected aerodynamic efficiency of 20.5. At the Mach number of 0.17, the FCFJ flow is mostly incompressible and the aerodynamic efficiency slightly lower than that at Mach number of 0.26. At freestream Mach number of 0.4, the flow reaches supersonic and makes it very difficult to attach. The study indicates that the FCFJ airfoil is promising for a fixed wing aircraft to fly on Mars.