Download or read book Pressure Gradient Effects on Supersonic Boundary Layer Turbulence written by A. J. Laderman and published by . This book was released on 1979 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of mean flow profiles at several streamwise locations in a supersonic turbulent boundary layer growing under a continuous adverse pressure gradient are reported. Tests were performed at a freestream Mach number of 3, for an adiabatic wall, using two curved ramps designed to produce constant pressure gradient flows. The velocity profile data, when transformed to incompressible coordinates, are in good agreement with Coles universal 'wall-wake' velocity profile and they indicate that the boundary layer is in local equilibrium and essentially independent of upstream history. In addition, the Coles wake parameters and Clauser shape factors, characterizing the transformed profiles, are in accord with the results of low speed correlations of adverse pressure gradient flows. The turbulent transport terms were extracted from the mean flow field data and indicate that for a given ramp, the profile of turbulent shear stress normalized by the wall shear, versus distance from the surface, normalized by the local boundary thickness, is severely distored by the pressure gradient although it is apparently insensitive to local conditions.
Download or read book Compressible Turbulence Measurements in a Supersonic Boundary Layer Including Favorable Pressure Gradient Effects written by Raymond S. Miller (CAPT, USAF.) 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 Turbulent Shear Layers in Supersonic Flow written by Alexander J. Smits and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: A good understanding of turbulent compressible flows is essential to the design and operation of high-speed vehicles. Such flows occur, for example, in the external flow over the surfaces of supersonic aircraft, and in the internal flow through the engines. Our ability to predict the aerodynamic lift, drag, propulsion and maneuverability of high-speed vehicles is crucially dependent on our knowledge of turbulent shear layers, and our understanding of their behavior in the presence of shock waves and regions of changing pressure. Turbulent Shear Layers in Supersonic Flow provides a comprehensive introduction to the field, and helps provide a basis for future work in this area. Wherever possible we use the available experimental work, and the results from numerical simulations to illustrate and develop a physical understanding of turbulent compressible flows.
Download or read book Compressible Turbulence Measurements in a Supersonic Boundary Layer Including Favorable Pressure Gradient Effects written by and published by . This book was released on 1994 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of a favorable pressure gradient on the turbulent flow structure in a Mach 2.9 boundary layer (Re/m approx. 1.5 x 10(exp 7)) is investigated experimentally. Conventional flow and hot film measurements of turbulent fluctuation properties have been made upstream of and along an expansion ramp. Upstream measurements were taken in a zero pressure gradient boundary layer 44 cm from the nozzle throat in a 6.35 cm square test section. Measurements are obtained in the boundary layer, above the expansion ramp, 71.5 cm from the nozzle throat. Mean flow and turbulent flow characteristics are measured in all three dimensions. Comparisons are made between data obtained using single and multiple-overheat cross-wire anemometry as well as conventional mean flow probes. Conventional flow measurements were taken using a Pitot probe and a 10 degree cone static probe. Flow visualization was conducted via imaging techniques (Schlieren and shadowgraph photographs). Results suggest that compressibility effects, as seen through the density fluctuations in the Reynolds shear stress are roughly 10% relative to the mean velocity and are large relative to the velocity fluctuations. This is also observed in the total Reynolds shear stress; compressibility accounts for 50 - 75% of the total shear. This is particularly true in the favorable pressure gradient region, where though the peak fluctuation intensities are diminished, the streamwise component of the mean flow is larger, hence the contribution of the compressibility term is significant in the Reynolds shear.
Download or read book Effect of Pressure Gradients on Plate Response and Radiation in a Supersonic Turbulent Boundary Layer written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-02 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the model developed by the author for zero-pressure gradient turbulent boundary layers, results are obtained for adverse and favorable pressure gradients. It is shown that when a flexible plate is located in an adverse pressure gradient area, it vibrates more than if it were in a favorable pressure gradient one. Therefore the noise generated by the plate in an adverse pressure gradient is much greater than that due to the plate in a favorable pressure gradient. The effects of Reynolds number and boundary layer thickness are also analyzed and found to have the same effect in both adverse and favorable pressure gradient cases. Increasing the Reynolds number is found to increase the loading on the plate and therefore acoustic radiation. An increase in boundary layer thickness is found to decrease the level of the high frequencies and therefore the response and radiation at these frequencies. The results are in good qualitative agreement with experimental measurements. Frendi, Abdelkader Langley Research Center NAS1-19700; NAS1-96014; RTOP 537-06-37-20...
Download or read book Effect of Pressure Gradients on Plate Response and Radiation in a Supersonic Turbulent Boundary Layer written by and published by . This book was released on 1997 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Supersonic Boundary Layer Flow in an Adverse Pressure Gradient Including the Effects of Mass Bleed written by David William Mayer and published by . This book was released on 1977 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Aspects of the Structure of Supersonic Turbulent Boundary Layers written by Alexander J. Smits and published by . This book was released on 1988 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Approximate Turbulent Boundary layer Development in Plane Compressible Flow Along Thermally Insulated Surfaces with Application to Supersonic tunnel Contour Correction written by Maurice Tucker and published by . This book was released on 1950 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: As an application of the method, the contour correction of supersonic nozzles for the effects of boundary-layer development is discussed from the requirement of continuity of mass flow and from the requirement of expansion- and shock-wave elimination.
Download or read book Experimental Investigation of Supersonic Boundary Layer Including Favorable Pressure Gradient Effects written by Joel J. Luker and published by . This book was released on 1995 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of an Adverse Pressure Gradient on the Behavior of a Flat Plate Supersonic Turbulent Boundary Layer written by E.M. Fernando and published by . This book was released on 1987 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of the Influence of a Favorable Pressure Gradient on the Basic Structure of a Mach 5 0 High Reynolds Number Supersonic Turbulent Boundary Layer written by Nathan R. Tichenor and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High-speed high Reynolds number boundary layer flows with mechanical non-equilibrium effects have numerous practical applications; examples include access-to-space ascent, re-entry and descent, and military hypersonic systems. However, many of the basic turbulent flow processes in this regime are poorly understood and are beyond the realm of modern direct numerical simulations Previous studies have shown that curvature driven pressure gradients significantly alter the state of the turbulence in high-speed boundary layers; the turbulence levels have been shown to decrease by large amounts (up to 100 percent) and the Reynolds shear stress has been shown to change sign. However, most of our understanding is based on point measurement techniques such as hot-wire and Laser Doppler anemometry acquired at low to moderate supersonic Mach numbers (i.e., M = 2-3). After reviewing the available literature, the following scientific questions remain unanswered pertaining to the effect of favorable pressure gradients: (1) How is state of the mean flow and turbulence statistics altered? (2) How is the structure of wall turbulence; break-up, stretch or a combination? (3) How are the Reynolds stress component production mechanisms altered? (4) What is the effect of Mach number on the above processes? To answer these questions and to enhance the current database, an experimental analysis was performed to provide high fidelity documentation of the mean and turbulent flow properties using two-dimensional particle image velocimetry (PIV) along with flow visualizations of a high speed (M4.88=), high Reynolds number (Re[is almost equal to]36,000) supersonic turbulent boundary layer with curvature-driven favorable pressure gradients (a nominally zero, a weak, and a strong favorable pressure gradient). From these data, detailed turbulence analyses were performed including calculating classical mean flow and turbulence statistics, examining turbulent stress production, and performing quadrant decomposition of the Reynolds stress for each pressure gradient case. It was shown that the effect of curvature-driven favorable pressure gradients on the turbulent structure of a supersonic boundary layer was significant. For the strong pressure gradient model, the turbulent shear stress changed sign throughout the entire boundary layer; a phenomena was not observed to this magnitude in previous studies. Additionally, significant changes were seen in the turbulent structure of the boundary layer. It is believed that hairpin vortices organized within the boundary layer are stretched and then broken up over the favorable pressure gradient. Energy from these hairpin structures is transferred to smaller turbulent eddies as well as back into the mean flow creating a fuller mean velocity profile. It was determined that the effects of favorable pressure gradients on the basic structure of a turbulent Mach 5.0 boundary layer were significant, therefore increasing the complexity of computational modeling.
Download or read book Boundary Layer Transition at Supersonic Speeds written by E. R. Van Driest and published by . This book was released on 1961 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments carried out in the 12-inch supersonic wind tunnel to investigate the effect of three dimensional roughness elements (spheres) on boundary-layer transition on a 10-degree (apex angle) cone without heat transfer are described. The local Mach number for these tests was 2.71. The data show clearly that the minimum (effective) size of trip required to bring transition to its lowest Reynolds number varies power of the distance from the apex of the cone to the trip. Use of available data at other Mach numbers indicates that the Mach number influence for effective tripping is taken into account by a simple expression. Some remarks concerning the roughness variation for transition on a blunt body are made. Finally, a general criterion is introduced which gives insight to the transition phenomenon and anticipates effects of external and internal disturbances, Mach number transfer.
Download or read book Supersonic Turbulent Boundary Layer in an Adverse Pressure Gradient written by Emerick Manley Fernando and published by . This book was released on 1988 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Anomalous Effects of Pressure Gradient on Supersonic Turbulent Boundary Layers written by P. Bradshaw and published by . This book was released on 1972 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Boundary Layer Characteristics in Supersonic Streams Having Adverse Pressure Gradients written by George H. McLafferty and published by . This book was released on 1959 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inestigations were conducted to determine the thickness and profile shape characteristics of turbulent boundary layers in supersonic streams having adverse pressure gradients similar to those which are encountered in supersonic inlets. The program included tests conducted at Mach numbers from 2.0 to 3.5 using two-dimensional and axisymmetric curved-surface models to produce the adverse pressure gradients. The magnitude of the gradients relative to the boundary layer thickness at the beginning of the gradient was varied by employing models having different radii of curvature and by changing the boundary layer thickness at the beginning of the gradient. The over-all pressure rise in most cases was greater than the value which would cause a turbulent boundary layer to separate if the pressure rise were created by an oblique shock wave. Some tests were conducted to determine the effect of boundary layer removal from the curved surfaces on boundary layer growth and on the pressure gradients which could be realized without separation. An analytical investigation was also conducted so that the results of the experimental investigation could be applied to the prediction of cases outside the range of the experiments. (Author).
Download or read book Boundary Layer Effects written by Anthony W. Fiore and published by . This book was released on 1978 with total page 962 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
