Download or read book An Experimental Investigation of Subsonic Cavity Flows Without and with Forcing written by Jesse Clayton Little and published by . This book was released on 2005 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Grazing flow over a shallow cavity is characterized by a shear layer instability feedback loop that induces strong pressure fluctuations at discrete frequencies. Examples include flow over aircraft weapons bays, aircraft landing gear openings and transmission or reception optical ports on aircraft. In the first application, this behavior can result in decreased accuracy of weapons delivery, fatigue failures and lowered efficiencies. Because of the variety of unwanted effects inherent to cavity flows, their control is of interest to both military and commercial aircraft applications. The complex nature of cavity flow has been explored since the mid-20th century with accelerated study over the past 25 years in hopes of understanding and controlling major pressure fluctuations within the cavity. A key to developing a successful control scheme for this fluidic system is a detailed understanding of the physics that govern the flow-acoustic coupling mechanisms. This work provides both qualitative and quantitative measurements for use in characterizing the fluid and acoustic physics that govern the resonance phenomenon. Focus is placed on the subsonic regime with an emphasis on Mach 0.30 flow and its control. Results include the analysis of surface pressure spectra and spatial correlations, flow visualization and velocity measurement using particle image velocimetry (PIV) in various controlled and baseline (unforced) cases. These results show that a well chosen actuation scheme at or near the receptivity region of the cavity shear layer can interrupt or weaken the acoustic feedback loop and significantly reduce the sound pressure level in the cavity. Physically, this amounts to modifying the development and evolution of the coherent structures spanning the cavity and thereby changing the frequency at which these vortices impact the trailing edge of the geometry. In addition, simultaneous dynamic surface pressure and planar velocity measurements are used in low dimensional modeling for closed-loop controller design purposes. Modeling using this method allows design of accurate models from experimental results rather than relying on numerical data, which is incapable of resolving the complex nonlinear production of acoustics in the low subsonic cavity flows at this time.
Download or read book An Experimental Investigation of High Subsonic Flow Over an Off Axis Longitudinal Cavity with Antiresonance Devices written by Kenneth Vaccaro (2LT, USAF.) and published by . This book was released on 1974 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Theoretical and Experimental Investigation of the Acoustic Response of Cavities in an Aerodynamic Flow written by H. E. Plumblee and published by . This book was released on 1962 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Theoretical and Experimental Investigation of the Acoustic Response of Cavities in an Aerodynamic Flow written by H. E. Plumblee and published by . This book was released on 1962 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory is developed for the resonant frequencies and pressure amplifications of a rectangular cavity of arbitrary dimensions in a flow field. An intermediate step involves the derivation of radiation impedance for a cavity at all Mach numbers, using the concepts of retarded pot ntial t eory. Experim ntal results are given for small cavities tested in the subsonic regime and for cavities up to 8 in. in length at supersonic Mach numbers from 1.75 to 5 0. Comparisons are drawn between theoretical and experimental frequency and amplitude response, indicating that the theory developed gives very good definition of the problem.
Download or read book Experimental Cavity Pressure Measurements at Subsonic and Transonic Speeds Static Pressure Results written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11-06 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted to determine cavity flow-characteristics at subsonic and transonic speeds. A rectangular box cavity was tested in the Langley 8-Foot Transonic Pressure Tunnel at Mach numbers from 0.20 to 0.95 at a unit Reynolds number of approximately 3 x 10(exp 6) per foot. The boundary layer approaching the cavity was turbulent. Cavities were tested over a range of length-to-depth ratios (l/h) of 1 to 17.5 for cavity width-to-depth ratios of 1, 4, 8, and 16. Fluctuating- and static-pressure data in the cavity were obtained; however, only static-pressure data is analyzed. The boundaries between the flow regimes based on cavity length-to-depth ratio were determined. The change to transitional flow from open flow occurs at l/h at approximately 6-8 however, the change from transitional- to closed-cavity flow occurred over a wide range of l/h and was dependent on Mach number and cavity configuration. The change from closed to open flow as found to occur gradually. The effect of changing cavity dimensions showed that if the vlaue of l/h was kept fixed but the cavity width was decreased or cavity height was increased, the cavity pressure distribution tended more toward a more closed flow distribution. Plentovich, E. B. and Stallings, Robert L., Jr. and Tracy, M. B. Langley Research Center...
Download or read book An Experimental Investigation of the Effects of a Base Cavity on the Near wake Flowfield of a Body at Subsonic and Transonic Speeds written by Richard William Kruiswyk and published by . This book was released on 1988 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Supersonic Internal Cavity Flows written by Kazuyuki Sakamoto and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Airflow Over a Cavity with Antiresonance Devices written by Donald A. Buell and published by . This book was released on 1971 with total page 84 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 An experimental investigation of cavity flow written by Richard M. Cannon and published by . This book was released on 2003 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Pressure Oscillations in Axi Symmetric Cavity Flows written by V. Sarohia and published by . This book was released on 1977 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted of subsonic turbulent flows over shallow, axi-symmetric cavities located downstream of the leading edge of a flat-nosed fuse contour and on an ellipsoidal nose contour. The objective was to evaluate cavity performance in terms of pressure oscillations inside the cavity for various cavity configurations and other pertinent parameters for various modes of cavity operation. Free-stream velocities over the contours ranged up to 650 ft/sec, and Reynolds numbers based on maximum diameter of the contour ranged between 10000 and about 1000000. It was found that pressure signals at the base of the cavity for an oscillating cavity flow as high as 150 dB, could be obtained and that a total acoustic power as high as 20 W was estimated. Furthermore, pressure oscillations existed for cavity depths as small as 0.050 in. It may be that this is not the minimum depth for which oscillations are generated, since the next smaller depth tested was 0.020 in. For the smallest depth, of 0.020 in., pressure oscillations in the cavity did not occur. Cavity oscillations were more pronounced when the cavity was located in the favorable (negative) pressure gradient region of the axi-symmetric body. Instant spark shadowgraphs taken for both laminar and for turbulent boundary layer flow separation at the upstream cavity corner showed the presence of large, organized vortex structures in the oscillating shear layer. Mean velocity measurements of an oscillating cavity shear layer indicated an entrainment rate as large as 0.046 as compared to a non-oscillating cavity shear layer entrainment of approximately 0.021.
Download or read book Experimental Investigation of Porous floor Effects on Cavity Flow Fields at Supersonic Speeds written by and published by . This book was released on 1990 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Porous floor Effects on Cavity Flow Fields at Supersonic Speeds written by Floyd J. Wilcox and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Porous floor Effects on Cavity Flow Fields at Supersonic Speeds written by Floyd J. Wilcox 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 Theoretical and Experimental Investigation of the Subsonic flow Fields Beneath Swept and Unswept Wings with Tables of Vortex induced Velocities written by William J Alford (Jr) and published by . This book was released on 1956 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Three Dimensional Modes in Perdiodically Driven Cavity Flow written by Jonathan J. F. Leung and published by . This book was released on 2004 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1990 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
