A study of the aerodynamic characteristics of a propeller and wing including the effect of ground proximity

Harris, Andrew Peter (1993) A study of the aerodynamic characteristics of a propeller and wing including the effect of ground proximity. University of Southampton, Doctoral Thesis.

Abstract

This thesis presents a study of the aerodynamic interaction between a tractor propeller, nacelle and wing in combination, with and without high lift devices deployed on the wing, including the effect of ground proximity.

A wind tunnel investigation was undertaken with the model positioned on the wind tunnel centre line and also in close proximity to the ground. Surface pressure distributions were measured on the wing and nacelle when the propeller was operating and with the propeller blades removed. The thrust and torque produced by the propeller were also recorded. The propeller slipstream enhanced the loading on the upwash side of the clean wing due to the swirl and increase in total pressure within the propeller slipstream combining together. On the downwash side, the two effects opposed each other resulting in a comparatively small change in the wing loading. The propeller slipstream produced a similar asymmetric effect on the wing when the trailing edge flap was deployed. An increase in loading was also produced on both sides of the flap centre line with a greater lift increment occurring on the upwash side. The development of the leading edge slat significantly reduced the asymmetric effect of the propeller slipstream on the wing, although the flap aerodynamic characteristics were not affected. A significant side force was produced by the nacelle when the propeller was operating which varied with propeller advance ratio and wing angle of attack. The effect of ground proximity increased the pressure on the lower surface of the wing and around the surface of the nacelle. An oil based flow visualization technique illustrated the spanwise distortion of the propeller slipstream as it passed around the model, with the flow tending to migrate in the direction of the slipstream rotation on both the upper and lower surfaces of the wing.

In addition, a three-dimensional panel method was developed in order to predict the effect of the propeller slipstream on the aerodynamic characteristics of the wing and nacelle, as well as the reciprocal effect of the wing and nacelle on the aerodynamic performance of the propeller.

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