The effect of strut geometry on propeller-strut interaction tone noise

This paper investigates the effect of strut geometry on the interaction tones produced by a propeller operating above a strut using analytical, computational, and experimental methods. Simple analytical models are presented to predict the unsteady loading on the propeller due to its interaction with the bound potential field of the strut and on the strut due to its interaction with the bound potential field of the propeller. The radiated sound field is then predicted using Farassat’s Formulation 1A. These predictions show that the periodic noise produced when a propeller operates in close proximity to a downstream strut is strongly impulsive. This impulsive noise is highly directional and strongly dependent on the distance between the strut and the propeller. The effect of changing the strut geometry to de-phase the impulsive sound radiated from different locations on the propeller and strut is explored.