CUED Publications database

The effect of scarfing and curved lip geometry on the radiation from an intake

Keith, GM and Peake, N (1999) The effect of scarfing and curved lip geometry on the radiation from an intake. In: UNSPECIFIED.

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© 1999 by G.M. Keith & . N. Peake. Published by the American Institute of Aeronautics and Astronautics, Inc. In this paper we describe an analytic approach to predicting the effect of intake geometry on the scattering of fan noise propagating forwards in an aeroengine duct. This approach, based on the Geometrical Theory of Diffraction, is applicable in the high frequency regime appropriate to fan noise and offers an efficient and flexible prediction scheme for determining the external field scattered by intake geometries intractable to other methods. Scarfing is one proposal for a class of intake geometry in which an attempt is made to direct sound away from the ground and into the sky. This paper summarises previous work which looked at the effect of scarfing on infinitely thin walled cylinders and extends it to describe methodologies and preliminary results in the case of walls of finite thickness with curved intake lips. The indications are that scarfing, as expected, reduces the total radiated sound below the horizontal by reflecting more of the incident sound field upwards. However, the level of the noise that remains directed downwards is not necessarily reduced. The effect of scarfing on the maximum intensity in a given downward direction depends on a complex interaction of the incident mode and intake geometry, which emphasises the need for full three dimensional analysis.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Divisions: Div A > Energy
Depositing User: Cron Job
Date Deposited: 11 Dec 2018 01:38
Last Modified: 07 Mar 2019 17:59