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Title:

Nonlinear Propagation of Noise Radiated from Supersonic Jets

Accession Number:

01054356

Record Type:

Component

Availability:

Institute of Noise Control Engineering

Iowa State University, 210 Marston Hall
Ames, IA 50011-2153 United States

Abstract:

This paper describes how the role of nonlinearity in the propagation of noise from supersonic jets is not currently well understood, but it is of interest because the noise radiation from military jet aircraft can approach or exceed levels of 150 dB or more at close range. These high noise amplitudes suggest that the inclusion of nonlinear propagation effects in long-range noise estimation models may be of importance in order to correctly assess the environmental impact the aircraft have. A finite-amplitude noise spectrum undergoes an evolution as it propagates, in that energy is transferred from mid to higher frequencies, and in some cases, from mid to lower frequencies, resulting in a spectral broadening. Waveform steepening accounts for the energy transfer to high frequencies as portions of the waveform become more shock-like. If these steepened portions begin to grow, the number of zero crossings decreases, consequently resulting in an energy increase at lower frequencies. The nonlinear propagation of noise has been studied over the past few decades by many others. While many of these studies employed a variety of theoretical and numerical techniques in an attempt to understand and predict the nonlinear spectral evolution, few have included accompanying experimental evidence. Crighton, in particular, has stressed the need for additional aeroacoustic experiments in order to properly assess the relevance and accuracy of the abundance of analytical and numerical work already carried out. Recent laboratory experiments performed on both cold and heat-simulated (HS) model-scale supersonic jets demonstrate evidence of nonlinear propagation effects. This paper represents continued analysis of those data. The experimental setup is first briefly described and is followed by the presentation of power spectral results.

Monograph Accession #:

01054353

Language:

English

Corporate Authors:

Institute of Noise Control Engineering

Iowa State University, 210 Marston Hall
Ames, IA 50011-2153 United States

Transportation Research Board

500 Fifth Street, NW
Washington, DC 20001 United States

Authors:

Gee, Kent L
Petitjean, Benoit P
McLaughlin, Dennis K
Sparrow, Victor W

Editors:

Burroughs, Courtney B
Maling, George C

Pagination:

pp 725-733

Publication Date:

2004

Conference:

Noise-Con 04. The 2004 National Conference on Noise Control Engineering

Location: Baltimore Maryland, United States
Date: 2004-7-12 to 2004-7-14
Sponsors: Institute of Noise Control Engineering; Transportation Research Board

Media Type:

CD-ROM

Features:

Figures (6) ; References (13)

Uncontrolled Terms:

Jets

Subject Areas:

Aviation; Energy; Environment; Vehicles and Equipment

Files:

TRIS, TRB

Created Date:

Jul 26 2007 11:10AM