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 Nelson, Douglas J. Robertshaw, Harry H. Saunders, William R. Committee Chair Keywords
- close fitting enclosure
- passive acoustical treatment
- insertion loss
- acoustic isolation
- acoustic enclosure
Date of Defense 1997-02-07 Availability unrestricted AbstractA 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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