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Characterization of the Flow-Field for Dual Normally Impinging Axi-Symmetric Jets

Title: Characterization of the Flow-Field for Dual Normally Impinging Axi-Symmetric Jets.
Name(s): Harmon, Malcolm Jerrod, author
Alvi, Farrukh S., professor directing thesis
Kumar, Rajan (Professor of Mechanical Engineering), committee member
Collins, Emmanuel G., committee member
Florida State University, degree granting institution
College of Engineering, degree granting college
Department of Mechanical Engineering, degree granting department
Type of Resource: text
Genre: Text
Master Thesis
Issuance: monographic
Date Issued: 2017
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource (80 pages)
Language(s): English
Abstract/Description: In this study, the flow and acoustic field characteristics of dual high-speed axi-symmetric impinging jets will be examined. Initially, the short takeoff and vertical landing (STOVL) facility was redesigned by adding a second jet to the existing model there by achieving a dual jet configuration. This modified facility was designed to simulate aircraft hover in proximity to the ground. Emphasis is placed on the complex behavior of the jets as the nozzle pressure ratio (NPR) is varied to produce over-expanded, ideally-expanded and under-expanded jet flows. Two nozzle configurations were chosen to simulate dual impinging jets: 1) two converging nozzles (Mach design, Md = 1.00) and 2) a converging nozzle (Md = 1.00) and a converging-diverging (CD) nozzle (Md = 1.50). The experimental results described in this thesis include shadowgraph flow visualization, surface pressure measurements, and near-field acoustic measurements. Shadowgraph flow visualization was used to observe the acoustic field and the coupling between dual jets for various NPR combinations. Mean surface pressure measurements were obtained for impinging jet configurations which analyzed the jet behavior for ground plane separations ranging from x/D = 2 to 10. These measurements provided information regarding the footprint of the flow-field, particularly the fountain flow behavior. It was found that there is a shift in the fountain flow region which occurs when the NPR of one jet was substantially higher than the supplementary jet. Unsteady pressure measurements and near-field acoustic measurements investigated the presence of a feedback loop that occurs for both free and impinging jets, under certain conditions. The presence of tones, either screech or impingement, was clearly evident from the spectral peaks in the near-field noise spectra. When such tones are present, the corresponding flow-field images show strong acoustic waves.
Identifier: FSU_SUMMER2017_Harmon_fsu_0071N_14049 (IID)
Submitted Note: A Thesis submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Master of Science.
Degree Awarded: Summer Semester 2017.
Date of Defense: June 20, 2017.
Keywords: Characterization, Dual, FCAAP, Impinging, Malcolm, Thesis
Bibliography Note: Includes bibliographical references.
Advisory Committee: Farrukh Alvi, Professor Directing Thesis; Rajan Kumar, Committee Member; Emmanuel Collins, Committee Member.
Subject(s): Mechanical engineering
Aerospace engineering
Persistent Link to This Record:
Host Institution: FSU

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Harmon, M. J. (2017). Characterization of the Flow-Field for Dual Normally Impinging Axi-Symmetric Jets. Retrieved from