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Aeroacoustic Characteristics of Supersonic Impinging Jets

Title: Aeroacoustic Characteristics of Supersonic Impinging Jets.
Name(s): Worden, Theodore James, author
Alvi, Farrukh S., professor co-directing dissertation
Shih, Chiang, professor co-directing dissertation
Liang, Zhiyong Richard, university representative
Collins, Emmanuel G., committee member
Gustavsson, Jonas, committee member
Kumar, Rajan (Professor of Mechanical Engineering), committee member
Michalis, Krista, 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
Doctoral Thesis
Issuance: monographic
Date Issued: 2017
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource (376 pages)
Language(s): English
Abstract/Description: High-speed impinging jets are often generated by the propulsive systems of aerospace launch vehicles and tactical aircraft. In many instances, the presence of these impinging jets creates a hazard for flight operations personnel due to the extremely high noise levels and unsteady loads produced by fluid-surface interaction. In order to effectively combat these issues, a fundamental understanding of the flow physics and dominant acoustic behavior is essential. There are inherent challenges in performing such investigations, especially with the need to simulate the flowfield under realistic operational conditions (temperature, Mach number, etc.) and in configurations that are relevant to full-scale application. A state-of-the-art high-temperature flow facility at Florida State University has provided a unique opportunity to experimentally investigate the high-speed impinging jet flowfield at application-relevant conditions. Accordingly, this manuscript reports the findings of several experimental studies on high-temperature supersonic impinging jets in multiple configurations. The overall objective of these studies is to characterize the complex relationship between the hydrodynamic and acoustic fields. A fundamental parametric investigation has been performed to document the flowfield and acoustic characteristics of an ideally-expanded supersonic air jet impinging onto a semi-infinite flat plate at ambient and heated jet conditions. The experimental program has been designed to span a widely-applicable geometric parameter space, and as such, an extensive database of the flow and acoustic fields has been developed for impingement distances in the range 1d to 12d, impingement angles in the range 45 degrees to 90 degrees, and jet stagnation temperatures from 289K to 811K (TTR=1.0 to 2.8). Measurements include point-wise mean and unsteady pressure on the impingement surface, time-resolved shadowgraphy of the flowfield, and fully three-dimensional near field acoustics. Aside from detailed documentation of the flow and acoustic fields, this work aims to develop a physical understanding of the noise sources generated by impingement. Correlation techniques are employed to localize and quantify the spatial extent of broadband noise sources in the near-impingement region and to characterize their frequency content. Additionally, discrete impingement tones are documented for normal and oblique incidence angles, and an empirical model of the tone frequencies has been developed using velocity data extracted from time-resolved shadowgraphy together with a simple modification to the conventional feedback formula to account for non-normal incidence. Two application-based studies have also been undertaken. In simulating a vertical take-off and landing aircraft in hover, the first study of a normally-impinging jet outfitted with lift-plate characterizes the flow-acoustic interaction between the high-temperature jet and the underside of an aircraft and documents the effectiveness of an active flow control technique known as `steady microjet injection' to mitigate high noise levels and unsteady phenomena. The second study is a detailed investigation of the jet blast deflector/carrier deck configuration aimed at gaining a better understanding of the noise field generated by a jet operating on a flight deck. The acoustic directionality and spectral characteristics are documented for a model-scale carrier deck with particular focus on locations that are pertinent to flight operations personnel.
Identifier: FSU_SUMMER2017_Worden_fsu_0071E_13997 (IID)
Submitted Note: A Dissertation submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Summer Semester 2017.
Date of Defense: June 23, 2017.
Keywords: acoustic, aeroacoustic, flow noise, impingement, jet, supersonic
Bibliography Note: Includes bibliographical references.
Advisory Committee: Farrukh Alvi, Professor Co-Directing Dissertation; Chiang Shih, Professor Co-Directing Dissertation; Richard Liang, University Representative; Emmanuel Collins, Committee Member; Jonas Gustavsson, Committee Member; Rajan Kumar, Committee Member; Krista Michalis, Committee Member.
Subject(s): Aerospace engineering
Mechanical engineering
Persistent Link to This Record:
Owner Institution: FSU

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Worden, T. J. (2017). Aeroacoustic Characteristics of Supersonic Impinging Jets. Retrieved from