Title page for ETD etd-145110201974500

Type of Document

Master's Thesis

Author

Blanks, Joseph E.

URN

etd-145110201974500

Title

Optimal Design of an Enclosure for a Portable Generator

Degree

Master of Science

Department

Mechanical Engineering

Advisory Committee

Advisor Name	Title
William R. Saunders	Committee Chair
Douglas J. Nelson	none
Harry H. Robertshaw	none

Keywords

acoustic isolation
insertion loss
passive acoustical treatment
close fitting enclosure
optimization
acoustic enclosure

Date of Defense

1997-02-07

Availability

unrestricted

Abstract

A simple, effective design for enclosing portable

generators to reduce the radiated noise is an

idea that seems to be desired by the consumers

in this market. This investigation is to determine

the feasibility of producing such an enclosure for

a generator. Several engineering aspects are

incorporated in the design of the enclosure. The

first, and probably the most paramount, are the

acoustical effects of the enclosure itself. The

investigation follows the theories for insertion

loss of a close fitting enclosure. The thesis

examines the system behavior of a close fitting

enclosure that most acoustic text books ignore

and how the material stiffness, density and

source-to-enclosure distance affect the insertion

loss and effectiveness of the enclosure.

Measured and theoretical sound pressure level

around the generator before and after the

application of the enclosure are presented using

standards described by ISO standard 1344.

The second important consideration for the

enclosure design involves the heat transfer

characteristics. The requirements of cooling air

to the generator are discussed. Also presented

are some acoustic design considerations to

prevent any "direct line of sight" to any of the

necessary openings which will help in the overall

insertion loss. The use of an optimal engineering

design technique is presented, demonstrating its

strengths and weakness in this application. The

optimization method used for the study is the

Hooke and Jeeves, or pattern search method.

This method solved for the optimum material

properties in approximately 30 iterations

depending on the initial starting points and the

desired weighting parameters.

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