Improved modeling of propeller-wing interactions with a lifting-line approach

Abstract

Propellers have a high propulsive efficiency and can help in the reduction of fuel consumption of aircraft. For propellers which are mounted in front of the wing, the interaction of the slipstream with the lifting surfaces can alter the lift distribution significantly. In the use of modern optimization tools, fast and accurate analysis of the wing aerodynamics is needed, including the influence of the propeller slipstream. Current potential flow based wing analysis tools, such as the lifting-line and vortex lattice method, highly overestimate the lift increase due to the axial induced velocity component in the slipstream, compared to wind tunnel and CFD data. The shortcomings of the existing wing analysis tools are found in the approach of adding the slipstream velocities to the wing induced circulation. At the wing segments that are submerged in the propeller slipstream, it is assumed that the slipstream is infinity large. To account for the effect of the finite slipstream dimensions on the lift distribution, potential flow methods based on the image vortex technique, are used to correct the existing analysis tools. These tools were validated using CFD simulations using the Euler equations. From the validation process, one method was found to produce a good agreement with the CFD data and this can be used to improve the modeling of propeller-wing interactions.