Temperature-step Effects on Direct Measurement of Skin-friction Drag PDF Download
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Author: Robert L. P. Voisinet
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 58
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Book Description
Wall-temperature discontinuities can occur in skin-friction balance tests whenever a balance drag element is thermally insulated from the surrounding test surface. An experimental study was conducted to investigate the effects of such a temperature step on the local friction drag. A temperature step was produced by varying the temperature of the NSWC skin-friction-balance drag element above the temperature of the surrounding nozzle wall. Drag-element temperatures ranged from 100 K to 240 K with the surrounding wall maintained at a temperature of 89 K. Nominal Mach numbers were 2.9 and 4.9 over a unit Reynolds number range of 2.6 to 20 million per meter. The results show that the value of the measured shear stress is higher than the cold wall value for a drag element which is at a higher temperature than the surrounding wall temperature and the change in shear stress is proportional to the difference between the drag element and the surrounding wall temperatures. The data has been correlated and corrections to previously published skin-friction results are presented.
Author: Robert L. P. Voisinet
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 58
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Book Description
Wall-temperature discontinuities can occur in skin-friction balance tests whenever a balance drag element is thermally insulated from the surrounding test surface. An experimental study was conducted to investigate the effects of such a temperature step on the local friction drag. A temperature step was produced by varying the temperature of the NSWC skin-friction-balance drag element above the temperature of the surrounding nozzle wall. Drag-element temperatures ranged from 100 K to 240 K with the surrounding wall maintained at a temperature of 89 K. Nominal Mach numbers were 2.9 and 4.9 over a unit Reynolds number range of 2.6 to 20 million per meter. The results show that the value of the measured shear stress is higher than the cold wall value for a drag element which is at a higher temperature than the surrounding wall temperature and the change in shear stress is proportional to the difference between the drag element and the surrounding wall temperatures. The data has been correlated and corrections to previously published skin-friction results are presented.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 492
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 772
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Book Description
Author: Robert L. P. Voisinet
Publisher:
ISBN:
Category : Fluid mechanics
Languages : en
Pages : 144
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Book Description
The results of a detailed experimental investigation of the compressible turbulent boundary layer in a favorable-pressure-gradient flow are presented for zero, moderate and severe heat-transfer conditions. The studies were conducted on a flat nozzle wall at momentum thickness Reynolds numbers from 6,700 to 56,000 and at three wall-to-adiabatic-wall temperature ratios. An attempt was made to hold values of Clauser's pressure-gradient parameter constant. Complete profile measurements were taken with Pitot pressure probes and conical-equilibrium and fine-wire temperature probes. (Modified author abstract).
Author: Robert L. P. Voisinet
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 224
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Book Description
Author: Edwin J. Saltzman
Publisher:
ISBN:
Category : Skin friction (Aerodynamics)
Languages : en
Pages : 52
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Book Description
Author: David L. Brott
Publisher:
ISBN:
Category : Compressibility
Languages : en
Pages : 104
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Book Description
The paper describes the results of a detailed experimental investigation of a two-dimensional turbulent boundary layer in a favorable pressure gradient where the free-stream Mach number varied from 3.8 to 4.6 and the ratio of wall to adiabatic-wall temperature has a nominal value of 0.82. Detailed profile measurements were made with pressure and temperature probes; skin friction was measured directly with a shear balance. The velocity- and temperature-profile results were compared with zero pressure gradient and incompressible results. The skin-friction data were correlated with momentum-thickness Reynolds number and pressure-gradient parameter. (Author).
Author: James R. Bruno
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 42
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Book Description
The development of a skin-friction balance to be used in a wind tunnel with heat-transfer conditions is described. The balance is a null-type device with a floating head element whose temperature can be maintained between 100K and 345K. This is accomplished with a cooled or heated jacket that is placed in direct contact with the friction element. At the desired element temperature the jacket is separated from the element and the shear-force data is taken. The balance was used in a Mach 5 supersonic flow with moderate heat-transfer rates. Shear forces ranging from 0.05 gm/sq cm to 1 gm/sq cm have been measured and higher ranges can be obtained by simply changing a coil spring. (Author).
Author: Wolfgang Rodi
Publisher: Elsevier
ISBN: 0080530958
Category : Science
Languages : en
Pages : 1011
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Book Description
Proceedings of the world renowned ERCOFTAC (International Symposium on Engineering Turbulence Modelling and Measurements).The proceedings include papers dealing with the following areas of turbulence:·Eddy-viscosity and second-order RANS models ·Direct and large-eddy simulations and deductions for conventional modelling ·Measurement and visualization techniques, experimental studies ·Turbulence control ·Transition and effects of curvature, rotation and buoyancy on turbulence ·Aero-acoustics ·Heat and mass transfer and chemically reacting flows ·Compressible flows, shock phenomena ·Two-phase flows ·Applications in aerospace engineering, turbomachinery and reciprocating engines, industrial aerodynamics and wind engineering, and selected chemical engineering problems Turbulence remains one of the key issues in tackling engineering flow problems. These problems are solved more and more by CFD analysis, the reliability of which depends strongly on the performance of the turbulence models employed. Successful simulation of turbulence requires the understanding of the complex physical phenomena involved and suitable models for describing the turbulent momentum, heat and mass transfer. For the understanding of turbulence phenomena, experiments are indispensable, but they are equally important for providing data for the development and testing of turbulence models and hence for CFD software validation. As in other fields of Science, in the rapidly developing discipline of turbulence, swift progress can be achieved only by keeping up to date with recent advances all over the world and by exchanging ideas with colleagues active in related fields.
Author: Anthony W. Fiore
Publisher:
ISBN:
Category : Turbulent boundary layer
Languages : en
Pages : 962
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Book Description
In 1975 the U.S. Air Force and the Federal Republic of Germany signed a Data Exchange Agreement numbered AF-75-G-7440 entitled 'Viscous and Interacting Flow Fields.' The purpose was to exchange data in the area of boundary layer research. It includes both experimental and theoretical boundary layer research at speeds from subsonic to hypersonic Mach numbers in the presence of laminar, transitional, and turbulent boundary layers. The main effort in recent years has been on turbulent boundary layers, both attached and separated in the presence of such parameters as pressure gradients, wall temperature, surface roughness, etc. In the United States the research was conducted in various Department of Defense, NASA, aircraft corporations, and various university laboratories. In the Federal Republic of Germany it was carried out within the various DFVLR, industrial, and university research centers.
