Analytical method for the computation of the noise from a pusher propeller

Abstract

The noise of a pusher propeller is significantly different from that of a tractor propeller, because of the aerodynamic interference between the inflow, which is disturbed by engine exhausts and wakes from upstream airframe parts, and the propeller blades. In this paper a fast and easy-to-use method is presented for the computation of the noise of a pusher propeller. An analytical description is derived for the interaction noise caused by a steady, non-uniform inflow into a propeller. The method is based on a Fourier-decomposition of the inflow, and a lifting-line description of the unsteady forces on the propeller blades. This analytical description has been implemented in a computer program and applied to a test case. Comparison of the results to results from a fully computational approach yields a reasonable agreement in a qualitative sense, which suggests that the method at least captures the physics of the problem. A limited parameter study is presented. © 2010 by National Aerospace Laboratory NLR. Published by the American Institute of Aeronautics and Astronautics, Inc.