Experimental Cavity Pressure Measurements at Subsonic and Transonic Speeds. Static-Pressure Results PDF Download
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Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722386801 Category : Languages : en Pages : 80
Book Description
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...
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722386801 Category : Languages : en Pages : 80
Book Description
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...
Author: National Aeronautics and Space Adm Nasa Publisher: ISBN: 9781730955280 Category : Languages : en Pages : 84
Book Description
An experimental investigation was conducted to expand the data base and knowledge of flow fields in cavities over the subsonic and transonic speed regimes. A rectangular, 3-D cavity was tested over a Mach number range from 0.30 to 0.95 and at Reynolds numbers per foot from 1 x 10 to the 6th power to 4.2 x 10 to the 6th power. Two sizes of cavities were tested with length-to-height ratios (l/h) of 4.4 and 11.7 and with rectangular and nonrectangular cross-sections. Extensive static pressure data on the model walls were obtained and a complete tabulation of the data are presented. The boundary layer approaching the cavity was turbulent and the thickness was measured with a total pressure rake. The static pressure measurements obtained with the deep cavity configuration (l/h = 4.4) at Reynolds numbers greater than 3.0 x 10 to the 6th power per foot showed large fluctuations during the data sampling time. For the deep cavity, at lower Reynolds numbers, and for all conditions tested with the shallow cavity, the data showed much less unsteadiness. Though mean static pressure distributions have been used in past cavity analysis at transonic free stream conditions, the data presented here indicates that it is necessary to consider the instantaneous pressure distributions. The data also indicated that the shallow cavity static pressure measurements were sensitive to the thickness of the boundary layer entering the cavity. Plentovich, E. B. Langley Research Center...
Author: Publisher: ISBN: Category : Languages : en Pages : 79
Book Description
An experimental investigation of turbulent flow over a cavity in an aerodynamic surface has been conducted. The test was carried out at nominal Mach numbers of 4 and 8, with Reynolds numbers based on free-stream conditions and length of body ahead of the cavity of 8.0 x 10 to the 6th power and 11.0 x 10 to the 6th power, respectively. Two conditions of wall-to-free-stream stagnation temperature ratio, 0.4 and 0.8, were tested at M(inf) = 8.09, whereas at M(inf) =3.99, the temperature ratio was 0.75. For all tests, the ratio of initial boundary-layer thickness to cavity depth was approximately 0.2. Measurements were made of surface pressure and temperature, and flow field surveys of pitot and static pressures and total temperature were performed. The test results showed that the recirculating fluid temperature was not less than 0.7 times the free-stream stagnation temperature despite decrease of the wall temperature to 0.4 the free-stream value. A satisfactory correlation was obtained between the experimental velocities and the error function profile of Goertler, and the distribution of total temperature across the mixing layer was adequately described by Crocco's linear relation of total temperature and velocity. A value of the mixing coefficient near 12 was found regardless of Mach number or wall- to-free-stream stagnation temperature ratio.
Author: National Aeronautics and Space Administration (NASA)
Author: E. B. Plentovich
Author: National Aeronautics and Space Administration (NASA)
Author: Maureen B. Tracy
Author: National Aeronautics and Space Adm Nasa
Author: 
Author: Robert L. Stallings (Jr.)
Author: Elizabeth B. Plentovich
Author: 
Author: 
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