Abstract
This dissertation presents the first high-fidelity numerical study of CoFlow Jet (CFJ) active flow control at low Reynolds number (Re ~ 10^5), enabling flight in the thin Martian atmosphere and at ultra-high Earth altitudes. Conventional airfoils suffer massive separation and cannot sustain the lift required for compact Mars vehicles. The target is MAGGIE (Mars Aerial and Ground Global Intelligent Explorer), a solar-powered fixed-wing VTOL aircraft enabled by ultra-high lift CFJ airfoils. To unify hover and cruise, flapped CFJ (FCFJ) wings place CFJ on the flaps, forming a Deflected Slipstream that turns flow 90 degrees down at hover and retracts for cruise, avoiding tilt-wing or tilt-rotor mechanisms. A 21% thick airfoil is shown feasible for low-Re flight for the first time.
Simulations use the in-house FASIP solver with RANS, 3D IDDES, and LES, validated against low-Re experiments. IDDES and LES reveal that FCFJ generates an extreme adverse pressure gradient (EAPG) at the flap shoulder about 36.8 times stronger than baseline, where turbulent diffusion dominantly counters the EAPG, confirmed by RANS, IDDES, and for the first time by LES. Upstream of injection the boundary layer stays laminar under a favorable pressure gradient and remains attached; injection then triggers laminar-to-turbulent transition, with spanwise spectra showing steep laminar decay and Kolmogorov -5/3 scaling downstream.
At Martian cruise (M = 0.17, Re = 5.63 x 10^4), an FCFJ wing of aspect ratio 20 with a circular tip cap achieves CL = 3.53 and (CL/CD)c = 7.44. Tandem FCFJ wings boost total lift 1.9-fold with under 1% sensitivity to stagger and gap. For hover, modest nose-up tilting cuts CFJ power by 65 to 70% while meeting lift targets, proving fixed-wing feasibility for Mars.