Doctoral Dissertations

A. V. Parrett

Abstract

"The problem of acoustic radiation from turbofan engine inlets in flow has not lent itself fully to analysis by numerical means because of the large domains and high frequencies involved. This project has extended the use of finite elements and wave envelope elements, elements which simulate decay and wavelike behaviour in their interpolation functions, from the no-flow case in which they have been proven, to cases incorporating mean flow. By employing an irrotational mean flow assumption, the acoustics problem has been posed in an axisymmetric formulation in terms of acoustic velocity potential, thus minimising computer solution storage requirements. The wave envelope element interpolation functions are derived from the solution for the acoustic field for a harmonic monopole in a uniform mean flow, and the element geometry is based on the ray paths and constant phase surfaces for such a solution. The choice of such a mesh allows simple implementation of a far-field Sommerfeld radiation condition, in a manner similar to the no-flow case.

The results obtained from the numerical procedures agree well with known analytical solutions and static jet engine inflow experimental data. Some discrepancy with flight test data exists but the combined finite element-wave envelope element solution radiation directivity trends are in good agreement with analytical predictions"--Abstract, page ii.

Advisor(s)

Eversman, Walter

Committee Member(s)

Koval, Leslie Robert
Penico, Anthony J., 1923-2011
Batra, R. C.

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering

Sponsor(s)

United States. National Aeronautics and Space Administration

Comments

This work was carried out under NASA Grant NAG-1-198.

Publisher

University of Missouri--Rolla

Publication Date

Spring 1984

Pagination

xiii, 129 pages

Note about bibliography

Includes bibliographical references (pages 111-118).

Rights

© 1984 Alan Vincent Parrett, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Acoustical engineeringAirplanes -- Turbojet enginesFinite element method

Thesis Number

T 5065

Print OCLC #

11699625

Electronic OCLC #

983206522

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