Accession Number:

ADA193387

Title:

The Influence of Surface Rounding on Trailing Edge Noise,

Descriptive Note:

Corporate Author:

BBN LABS INC CAMBRIDGE MA

Personal Author(s):

Report Date:

1988-01-01

Pagination or Media Count:

48.0

Abstract:

An analysis is made of the sound produced by low Mach number turbulent flow over an asymmetrically rounded trailing edge of an airfoil. Such airfoils are used in experimental studies of trailing edge noise and vortex shedding phenomena, and have a flat pressure side and a rounded, or beveled, suction surface at the trailing edge, so that in the immediate vicinity of the edge the airfoil has a wedge shaped profile. There are two principal interaction noise sources a lift dipole associated with the unsteady transverse forces exerted on the airfoil, and a thickness dipole which radiates preferentially in the plane of the airfoil. The latter is usually negligible except possibly at low frequencies, and at large included angles of the trailing edge wedge. Detailed results are given for included angles of 90 deg and less. It is concluded that, for given turbulence intensity, surface beveling has a significant effect on the radiation only at sufficiently high frequencies that the trailing edge may be regarded as a straight-sided wedge over distances of the order of the turbulence length scale.

Subject Categories:

  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE