Aerodynamically Induced Pressure Oscillations in Cavities - Physical Mechanisms and Suppression Concepts PDF Download
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Author: Hanno H. Heller
Publisher:
ISBN:
Category :
Languages : en
Pages : 225
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Book Description
This report presents the results of an analytical and experimental research program to (1)improve the understanding of the physical mechanisms that control the occurrence of pressure fluctuations in long and shallow rectangular cavities, exposed to high-speed external flow, and (2)devise and evaluate devices that would either substantially reduce the amplitude of such pressure fluctuations, or totally suppress the occurrence of pressure fluctuations. During this investigation, the understanding of the complex interaction of the external shear layer and the cavity internal fluid medium, which constitutes the generating mechanism of high-intensity periodic pressure fluctuations was substantially furthered. Both the analysis and investigation of the physical mechanisms were aided through extensive shallow-water flow-simulation experiments. Large-scale experiments, using the NASA-Lewis Research Center 8 X 6 ft Supersonic Wind Tunnel were conducted to substantiate some of the analytical predictions and to study in detail the aeroacoustic behavior of cavities in the length-to-depth ratio range, L/D, of 2.3 to 5.5, and the Mach number range of 0. 8 to 2.0. Detailed information was obtained on the normalized levels of the first three resonant modes in the cavity for a range of cavity length-to-depth ratios and freestream Mach numbers. Several concepts for pressure oscillation suppression were developed and evaluated in wind tunnel experiments. The most promising concept utilizes a slanted trailing edge, which stabilizes the free shear flow above the cavity, thus effectively suppressing discrete-tone generation. (Author).
Author: Hanno H. Heller
Publisher:
ISBN:
Category :
Languages : en
Pages : 225
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Book Description
This report presents the results of an analytical and experimental research program to (1)improve the understanding of the physical mechanisms that control the occurrence of pressure fluctuations in long and shallow rectangular cavities, exposed to high-speed external flow, and (2)devise and evaluate devices that would either substantially reduce the amplitude of such pressure fluctuations, or totally suppress the occurrence of pressure fluctuations. During this investigation, the understanding of the complex interaction of the external shear layer and the cavity internal fluid medium, which constitutes the generating mechanism of high-intensity periodic pressure fluctuations was substantially furthered. Both the analysis and investigation of the physical mechanisms were aided through extensive shallow-water flow-simulation experiments. Large-scale experiments, using the NASA-Lewis Research Center 8 X 6 ft Supersonic Wind Tunnel were conducted to substantiate some of the analytical predictions and to study in detail the aeroacoustic behavior of cavities in the length-to-depth ratio range, L/D, of 2.3 to 5.5, and the Mach number range of 0. 8 to 2.0. Detailed information was obtained on the normalized levels of the first three resonant modes in the cavity for a range of cavity length-to-depth ratios and freestream Mach numbers. Several concepts for pressure oscillation suppression were developed and evaluated in wind tunnel experiments. The most promising concept utilizes a slanted trailing edge, which stabilizes the free shear flow above the cavity, thus effectively suppressing discrete-tone generation. (Author).
Author: Leonard L. Shaw
Publisher:
ISBN:
Category : Oscillations
Languages : en
Pages : 68
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Book Description
A flight test program was performed to gain further insight into the phenomenon of flow-induced cavity pressure oscillations and to evaluate the effectiveness of suppression concepts in eliminating or reducing the pressure oscillations. The cavities tested were rectangular with approximate dimensions of 17 inches long, 8.5 inches deep, and 8.75 inches wide and were instrumented with microphones, static pressure ports, and a thermocouple. The flight speeds ranged from Mach number 0.6 to 1.3 at pressure altitudes of 3,000, 20,000, and 30,000 feet. The suppression devices included leading edge spoilers and deflectors and trailing edge ramps and deflectors. Several combinations of these were tested. The results indicate that the flow-induced pressure oscillations in a cavity of the dimensions tested and for the speed range tested can be significantly reduced with leading edge spoilers in conjunction with a trailing edge ramp. Reductions as large as 30 dB were achieved for the predominant model frequency for a one-third octave band. Other combinations of the suppression devices afforded some reduction, but the spoiler ramp combination proved most effective. (Author).
Author: M. E. Franke
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: William K. Blake
Publisher: Elsevier
ISBN: 0323149618
Category : Technology & Engineering
Languages : en
Pages : 459
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Book Description
Mechanics of Flow-Induced Sound and Vibration: Volume 1 discusses a broad selection of flow sources that are widely encountered in many applications of subsonic flow engineering and provides combined physical and mathematical analyses of each of these sources. It classifies each of the leading sources of vibration and sound induced by various types of fluid motion and unifies the disciplines essential to describing each source. The book considers sources such as jet noise, flow-induced tones and self-excited vibration, dipole sound from rigid and flexible acoustically compact surfaces, random vibration of flow-excited plates and cylindrical shells, cavitation noise, acoustic transmission characteristics and sound radiation from bubbly liquids, splash noise, throttling and ventilation system noises, lifting surface flow noise and vibration, and tonal and broadband sounds from rotating machinery. It also integrates the fundamentals of the subject with the many practicalities of the design of quiet vibration-free machinery. This book caters to advanced students well-versed in applied mathematics, fluid mechanics, and vibrations, strength of materials, acoustics, and statistical methods.
Author: Gullapalli Sivaramakrishna
Publisher: Springer Nature
ISBN: 9811923787
Category : Technology & Engineering
Languages : en
Pages : 633
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Book Description
This book presents the select proceedings of the 3rd National Aerospace Propulsion Conference (NAPC 2020). It discusses the recent trends in the area of aerospace propulsion technologies covering both air-breathing and non-air-breathing propulsion. The topics covered include state-of-the-art design, analysis and developmental testing of gas turbine engine modules and sub-systems like compressor, combustor, turbine and alternator; advances in spray injection and atomization; aspects of combustion pertinent to all types of propulsion systems and nuances of space, missile and alternative propulsion systems. The book will be a valuable reference for beginners, researchers and professionals interested in aerospace propulsion and allied fields.
Author:
Publisher:
ISBN:
Category : Shock (Mechanics)
Languages : en
Pages : 232
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 432
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Author: William K. Blake
Publisher: Academic Press
ISBN: 0128122897
Category : Science
Languages : en
Pages : 504
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Book Description
Mechanics of Flow-Induced Sound and Vibration, Volume 1: General Concepts and Elementary Sources, Second Edition, enables readers to fully understand flow-induced vibration and sound, unifying the disciplines of fluid dynamics, structural dynamics, vibration, acoustics, and statistics in order to classify and examine each of the leading sources of vibration and sound induced by various types of fluid motion. Starting with classical theories of aeroacoustics and hydroacoustics, a formalism of integral solutions valid for sources near boundaries is developed and then broadened to address different source types, including jet noise, flow tones, dipole sound from cylinders, and cavitation noise. Step-by-step derivations clearly identify any assumptions made throughout. Each chapter is illustrated with comparisons of leading formulas and measured data. Along with its companion, Mechanics of Flow-Induced Sound and Vibration, Volume 2: Complex Flow-Structure Interactions, the book covers everything an engineer needs to understand flow-induced sound and vibration. This book will be essential reading for postgraduate students, and for engineers and researchers with an interest in aerospace, ships and submarines, offshore structures, construction, and ventilation. Presents every important topic in flow-induced sound and vibration Covers all aspects of the topics addressed, from fundamental theory, to the analytical formulas used in practice Provides the building blocks of computer modeling for flow-induced sound and vibration
Author: Arun K. Saha
Publisher: Springer
ISBN: 8132227433
Category : Technology & Engineering
Languages : en
Pages : 1638
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Book Description
This volume comprises the proceedings of the 42nd National and 5th International Conference on Fluid Mechanics and Fluid Power held at IIT Kanpur in December, 2014.The conference proceedings encapsulate the best deliberations held during the conference. The diversity of participation in the conference, from academia, industry and research laboratories reflects in the articles appearing in the volume. This contributed volume has articles from authors who have participated in the conference on thematic areas such as Fundamental Issues and Perspectives in Fluid Mechanics; Measurement Techniques and Instrumentation; Computational Fluid Dynamics; Instability, Transition and Turbulence; Turbomachinery; Multiphase Flows; Fluid‐Structure Interaction and Flow‐Induced Noise; Microfluidics; Bio‐inspired Fluid Mechanics; Internal Combustion Engines and Gas Turbines; and Specialized Topics. The contents of this volume will prove useful to researchers from industry and academia alike.
Author: Chinese Aeronautical Society
Publisher: Springer Nature
ISBN: 9819988640
Category : Technology & Engineering
Languages : en
Pages : 742
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Book Description
This book contains the original peer-reviewed research papers presented at the 6th China Aeronautical Science and Technology Conference held in Wuzhen, Zhejiang Province, China, in September 2023. Topics covered include but are not limited to Navigation/Guidance and Control Technology, Aircraft Design and Overall Optimisation of Key Technologies, Aviation Testing Technology, Airborne Systems/Electromechanical Technology, Structural Design, Aerodynamics and Flight Mechanics, Advanced Aviation Materials and Manufacturing Technology, Advanced Aviation Propulsion Technology, and Civil Aviation Transportation. The papers presented here share the latest findings in aviation science and technology, making the book a valuable resource for researchers, engineers and students in related fields.
