Aerodynamic Loads on an Aft-Mounted Propeller Induced by the Wing Wake

Abstract

This paper presents an experimental and numerical study of the aerodynamic in-plane and out-of-plane loads of a propeller which are induced by the wake of an upstream wing impinging on the lower half of the propeller disk. A propeller was installed behind a wing model in a low-speed wind-tunnel and measurements were taken with an external balance and a rotating shaft balance to determine the aerodynamic characteristics of the wing and propeller. The installation of the wing shows negligible changes in propeller thrust coefficient at low advance ratios, while at medium thrust conditions (C
T ≈ 0.3), the wing shows a small increase in propeller thrust in the order of 1%. The installation of the propeller aft of the wing shows a change on propeller efficiency ranging from ∆η
p =–0.01 to +0.04. The location of the wake impingement at the propeller plane is shown to play an important factor for the time averaged and unsteady propeller loads. The radial location where the largest change in load occurs due to wake impingement, coincides with the location of highest propeller loading. A simplified and computationally efficient method is presented for estimation of these unsteady propeller loads in non-uniform inflow. The method shows good agreement for the integral unsteady blade thrust and integral propeller for different wake impingement locations.