Simulation of Propeller Slipstream and Its Effect on Wing

In this paper, a specific configuration of tilt-rotor eVTOL with the propeller installed in front of the wing was analyzed. We do the coupling design of pylon and wing and then unsteady RANS CFD method with sliding mesh strategy was applied for the rotation domain, and attention was paid to the propeller-wing coupling effect. For the propeller, compared with the isolated condition, the inner propeller thrust decreased slightly (about -2.1% at alpha = 0 degrees) and the efficiency reduced a little (about 1% at alpha = 0 degrees) in the case of coupling with the wing, but the outer propeller thrust increased by 2.3%, presenting a symmetric situation, and the cruise efficiency remains unchanged. For the main wing, the direction of rotation of the outer propeller affects its aerodynamic characteristics: When the rotation direction is inboard-up, the lift coefficient of the whole aircraft was increased by 5.6%, and the lift-drag ratio is reduced by 2.9%. The aerodynamic efficiency of inboard-up is higher than that of the inboard-down, because the propeller slipstream introduced by the propeller whose rotation direction opposite to the wingtip vortex cancels out part of the downwash effect of the wingtip vortex, resulting in lower induced drag. This counteracting effect is also transmitted to the upstream propellers in reverse. The propeller slipstream also changes the angle of attack and velocity of the local air flow on the wing, so the surface pressure distribution and circulation distribution are changed. The installation position and rotation direction of propeller have a profound effect on slipstream, wingtip vortex, etc.