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Book Experimental Cavity Pressure Measurements at Subsonic and Transonic Speeds Static Pressure Results

Download or read book Experimental Cavity Pressure Measurements at Subsonic and Transonic Speeds Static Pressure Results written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 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...

Book Three dimensional Cavity Flow Fields at Subsonic and Transonic Speeds

Download or read book Three dimensional Cavity Flow Fields at Subsonic and Transonic Speeds written by Elizabeth B. Plentovich and published by . This book was released on 1990 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Experimental Cavity Pressure Distributions at Supersonic Speeds

Download or read book Experimental Cavity Pressure Distributions at Supersonic Speeds written by and published by . This book was released on 1987 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Effect of sweep on cavity flow fields at subsonic and transonic speeds

Download or read book Effect of sweep on cavity flow fields at subsonic and transonic speeds written by and published by . This book was released on 2012 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book An Experimental Investigation of the Effects of a Base Cavity on the Near wake Flowfield of a Body at Subsonic and Transonic Speeds

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:

Book Subsonic and Transonic Transitional Cavity Flows

Download or read book Subsonic and Transonic Transitional Cavity Flows written by J. Henderson and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Effect of Depth on a Three dimensional Rectangular Cavity in Subsonic Flow

Download or read book The Effect of Depth on a Three dimensional Rectangular Cavity in Subsonic Flow written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A cavity was inserted into a 20 m/s subsonic flow. The flow had a freestream turbulence level of 0.5%. The cavity had an aspect ratio of 2.0 and was capable of reaching depths from 0.0 to 2.35L. Velocity and turbulence measurements were acquired in the shear layer over the cavity and upstream of the cavity in the approaching boundary layer using hotwire anemometry. These measurements showed that the approaching boundary layer approximated a universal fully turbulent boundary layer. The hotwire was also used to acquire energy spectra in the boundary and free shear layers as well as in the freestream in order to examine the frequency content of the flow. Finally condenser microphones were installed into the cavity and used to acquire energy spectra by measuring the unsteady pressure inside the cavity at various locations. Significant effort was made to identify the causes for each mode. The author has found evidence to suggest that tones generated by the cavity can be driven either acoustically or fluid dynamically. However, acoustics appear to dominate in the current cavity geometry and the current flow speed. The data acquired agrees well with past experiments. However, several new trends were noted that the author has not found mentioned in past work. First, shear layer velocity and turbulence profiles indicate the presence of a recirculation region at the upstream cavity lip. Second, relative sound pressure levels indicate that the total energy inside the cavity decreases as depth increases from D/L = 0.5 to 2.1. This loss of energy coincides with an increase in energy in the shear and boundary layers at the same depths. However, at cavity depths greater than D/L = 2.1 the trend reverses itself as a second vortex cell begins to form beneath the primary vortex.

Book An Experimental Study of Low Speed Open Cavity Flows

Download or read book An Experimental Study of Low Speed Open Cavity Flows written by Abraham Joseph Meganathan and published by . This book was released on 2000 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Flow Field Dynamics in Subsonic Cavity Flows

Download or read book Flow Field Dynamics in Subsonic Cavity Flows written by Nathan E. Murray and published by . This book was released on 2006 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subsonic flow over a rectangular cavity with a length-to-depth ratio of 6 and an 8.0 mm depth is studied experimentally to gain insight into the relationship between the wall-pressure loads and the flow field dynamics. The data was collected along the centerline of the cavity at free-stream Mach numbers ranging from 0.2 to 0.8 using wall mounted pressure transducers, 2-D Particle Image Velocimetry (PIV), and spark Schlieren photography. The cavity flow data is analyzed using Proper Orthogonal Decomposition (POD), two-point time-dependent correlations, and the modified Quadratic Stochastic Estimation (mQSE) which allows the temporal dynamics of the flow to be estimated using the measured wall-pressure fluctuations as estimators. These analyses are used to determine the flow field sources that are related to the wall-pressure loads and determine how these sources are related to the periodic nature of a resonating cavity. The mQSE estimation demonstrates the phenomenon of mode-switching and shows how the wall-pressure loads are related to vortex motion as well as downstream and upstream propagating density gradients which move with the shear-layer convection and the acoustic speed respectively. In general that the shear-layer oscillation, vortex convection, and flow impingement are shown to be directly related to the measured pressure loads. Following Kraichnan (1956), Poisson's equation is applied to the estimated velocity fluctuations to calculate the wall-pressure loads resulting from the linear and non-linear source terms. The results show that the linear term has a much stronger impact on the wall-pressure and exhibits the periodicity associated with the Rossiter modes. In contrast, the non-linear contribution is found to be smaller in magnitude and primarily broadband in nature.

Book Experimental and Theoretical Studies of the Effect of Gas Content on Unsteady Cavity Flows

Download or read book Experimental and Theoretical Studies of the Effect of Gas Content on Unsteady Cavity Flows written by Robert J. Van Houten and published by . This book was released on 1982 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: A partially cavitating two-dimensional hydrofoil was oscillated in pitch while air was bled into the cavity at a controlled rate. By varying the ambient pressure and air flow rate simultaneously, a constant ventilation number was maintained for a series of cavity air partial pressures. Unsteady forces and cavity pressures were measured, and photographs taken. It was found that cavity air caused fluctuating cavity pressures, and tended to stabilize cavity length. Its effect on force coefficients was relatively modest. These trends were also found from a parallel theoretical investigation in which a computer program which predicts unsteady cavitation of 2-D foils was modified to allow for cavity gas. (Author).

Book Effect of L D and Yaw Angle on Flow Oscillations in Subsonic Rectangular Cavities

Download or read book Effect of L D and Yaw Angle on Flow Oscillations in Subsonic Rectangular Cavities written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was undertaken to examine the effect of cavity depth and yaw angle on flow oscillations that occur in an open cavity placed within a subsonic boundary layer. A rectangular cavity was placed within a thick turbulent boundary layer with a corresponding Reynolds number based on the cavity length of 61,935. Pressure time histories were acquired at five separate cavity depths (or L/D values) at each yaw angle from 5 degree to 90 degree using microphone-type pressure transducers. The spectral character of these signals was analyzed, and pressure level and dominant frequencies were determined. This study indicates that large changes in the pressure level occur as L/D varies from 0.5 to 2.1 and as the yaw angle varies from 5 to 90 deg. Relative sound pressure level calculations indicate that the energy within the cavity compared with that of the boundary layer was observed to increase by approximately 22 percent at L/D=2.1 and 2.2 times at yaw angle=60 deg.