Download or read book Flow Induced Pressure Oscillations in Shallow Cavities written by Hanno H. Heller and published by . This book was released on 1970 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of an experimental wind-tunnel study of flow-induced pressure oscillations in shallow cavities (length-to-depth ratio from 4 to 7). A variable-depth rectangular cavity was exposed to tangential flow over the open surface in the Mach-number range from 0.8 to 3, with flow stagnation pressures varying from 2 to 15 psia. The cavity was tested in an empty stage and with one or two stores. Third-octave band and narrowband fluctuating-pressure spectra were obtained at various locations within the cavity and under the approaching boundary layer; these spectra yielded information on broadband and resonant response characteristics. Information on the longitudinal and lateral energy distribution, on recirculating-flow velocities, and on temperatures within the cavity was also obtained. This information was used to develop a scheme for predicting resonant frequencies and associated pressure-mode shapes, as well as discrete-frequency and broadband pressure amplitudes.

Download or read book Suppression of Flow induced Pressure Oscillations in Cavities written by M. E. Franke and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aerodynamically Induced Pressure Oscillations in Cavities Physical Mechanisms and Suppression Concepts written by Hanno H. Heller and published by . This book was released on 1975 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).

Download or read book An Experimental Investigation Into the Suppression of Flow induced Pressure Oscillations in Two dimensional Open Cavities written by Randall S. Mainquist (1LT, USAF.) and published by . This book was released on 1978 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation to Suppress Flow Induced Pressure Oscillations in Open Cavities written by and published by . This book was released on 1989 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: High speed tangential flow over open cavities (e.g. aircraft weapon bays) can invoke large pressure oscillations within the cavity. These large oscillations can damage the cavity structure as well as items placed within the cavity. The purpose of this experimental study was to determine the effectiveness of suppressing pressure oscillations by manipulating the shear layer over a two-dimensional cavity with a length-to-depth ratio of two. Two methods, a frequency controllable control surface (fence) and pulsating secondary airflow at the cavity leading edge, were used to manipulate the shear layer. The suppression effectiveness of the fence utilized in both passive and active modes (zero to 120 Hz) was evaluated at six airflow Mach numbers (0.62, 0.76, 0.90, 1.07, 1.28, 1.53). The effectiveness of pulsating secondary airflow was evaluated at one airflow Mach number (1.28) and two flow injection angles (parallel and 45 degrees to the flow) at frequencies ranging from zero to 80 Hz. The effect of steady flow injection was also evaluated at mass flow rates per unit width ranging from 0.323 to 1.27 (lbm/sec/ft). Pressure recordings from within the cavity were made for each test. The effectiveness of a pulsating fence in suppressing the peak mode pressure oscillations proved to be less than that achievable with the fence static. The pulsed secondary flow injection technique was most effective when pulsed at a 45 degree angle to the external flow. Theses.

Download or read book Investigation for Suppressing Flow induced Pressure Oscillations in an Open Cavity written by Fa-li Yang (CAPT, CAF.) and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow induced Resonance of Screen covered Cavities written by Paul T. Soderman and published by . This book was released on 1990 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Induced Resonance of Screen Covered Cavities written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-03 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of screen-covered cavities exposed to airflow tangent to the screen is described. The term screen refers to a thin metal plate perforated with a repetitive pattern of round holes. The purpose was to find the detailed aerodynamic and acoustic mechanisms responsible for screen-covered cavity resonance and to find ways to control the pressure oscillations. Results indicate that strong cavity acoustic resonances are created by screen orifices that shed vortices which couple resonance by choosing hole spacings such that shed vortices do not arrive at a downstream orifice in synchronization with cavity pressure oscillations. The proper hole pattern is effective at all airspeeds. It was also discovered that a reduction of orifice size tended to weaken the screen/cavity interaction regardless of hole pattern, probably because of viscous flow losses at the orifices. The screened cavities that resonated did so at much higher frequencies than the equivalent open cavity. The classical large eddy phenomenon occurs at the relatively small scale of the orifices (the excitation is typically of high frequency). The wind tunnel study was made at airspeeds from 0 to 100m/sec. The 457-mm-long by 1.09-m-high rectangular cavities had length-to-depth ratios greater than one, which is indicative of shallow cavities. The cavity screens were perforated in straight rows and columns with hole diameters ranging from 1.59 to 6.35 mm and with porosities from 2.6 to 19.6 percent. Soderman, Paul T. Ames Research Center RTOP 505-61-11...

Download or read book Suppression of Aerodynamically Induced Cavity Pressure Oscillations written by Leonard L. Shaw and published by . This book was released on 1979 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).

Download or read book Mechanics of Flow Induced Sound and Vibration V1 written by William K. Blake and published by Elsevier. This book was released on 2012-12-02 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Flow Induced Oscillations in Rectangular Cavities written by Alan J. Bilanin and published by . This book was released on 1970 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation of Flow induced Cavity Resonance written by Paul Zoccola (Jr., J.) and published by . This book was released on 2000 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanics of Flow Induced Sound and Vibration Volume 1 written by William K. Blake and published by Academic Press. This book was released on 2017-06-13 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Engineering Model of Unsteady Flow in a Cavity written by R. C. Bauer and published by . This book was released on 1991 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: A mathematical model was assembled from fundamental fluid dynamic relations and turbulent single-stream mixing zone relations to predict spectra, i.e., the frequency and amplitude, of unsteady pressures acting in a rectangular cavity exposed to an external flow parallel to the cavity opening. Characteristics of the approaching boundary layer are expected as inputs, thereby allowing computation of spectra for cases of mass-injection upstream of the cavity. The equations were compiled as a code (CAP) that can be run in less than 15 sec on a personal computer. Maximum dynamic loads acting on the contents of the cavity can be estimated, in addition to the primary frequencies of oscillation.

Download or read book Cavity Unsteady Pressure Measurements at Subsonic and Transonic Speeds written by Maureen B. Tracy and published by . This book was released on 1997 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Theoretical Study of Cavity Acoustics written by R. E. Dix and published by . This book was released on 2000 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Between 1986 and 1990, a large database was compiled at AEDC from the results of a series of wind tunnel experiments investigating the aerodynamics of flow over open cavities. The database, known as the Weapons Internal Carriage and Separation (WICS) database, covered four experiments that were completed in the AEDC wind tunnels. The initial database documentation focused on the test and data, but included very little analysis of the results. The purpose of the present work is to report analysis of the cavity acoustics and trajectory data. In addition, an updated engineering mathematical model for cavity aeroacoustics is presented.

Download or read book Flow Induced Vibration written by S. Ziada and published by CRC Press. This book was released on 2000-01-01 with total page 863 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow-induced vibrations and noise continue to cause problems in a wide range of engineering applications ranging from civil engineering and marine structures to power generation and chemical processing. These proceedings bring together more than a hundred papers dealing with a variety of topics relating to flow-induced vibration and noise. The cont