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The flow field of supersonic impinging jets is known to be highly unsteady particularly for S/VTOL aircraft configuration. This can have adverse effects such as high noise levels, unsteady acoustic loads and sonic fatigue on the aircraft and surrounding structures, pavement erosion, ingestion of hot gases into the engine nacelle and lift loss of the aircraft. Jet noise from an aircraft has been a problem that significantly impacts aircraft operational procedures and adversely affects the health and safety of the personnel operating nearby and the communities surrounding airports / airbases and flight paths. In the present study, control of the highly resonant flow field associated with supersonic impinging jet by acoustic treatment at the impingement plane has been experimentally investigated. Measurements were made in the supersonic impinging jet facility at the Florida State University for a Mach 1.5 ideally expanded jet. Measurements included unsteady pressures on a surface plate near the nozzle exit and impingement plate, acoustics in the near field and beneath the impingement plane, and velocity field using particle image velocimetry. The passive control involves appropriately designed resonator panel to target discrete impinging tones and broadband noise. Results show that this technique is very effective in attenuating impinging tones and their harmonics in addition to significant broadband reduction.
A Thesis submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Master of Science.
Bibliography Note
Includes bibliographical references.
Advisory Committee
Rajan Kumar, Professor Directing Thesis; Chiang Shih, Committee Member; William Oates, Committee Member.
Publisher
Florida State University
Identifier
FSU_migr_etd-9475
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