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Influence Of Surface Roughness On The Mean And Turbulence Flow Properties Of A Supersonic Boundary Layer
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Book Synopsis Influence of Surface Roughness on the Mean and Turbulence Flow Properties of a Supersonic Boundary Layer by : Robert M. Latin
Download or read book Influence of Surface Roughness on the Mean and Turbulence Flow Properties of a Supersonic Boundary Layer written by Robert M. Latin and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Influence of Surface Roughness on Supersonic High Reynolds Number Turbulent Boundary Layer Flow by : Robert M. Latin
Download or read book The Influence of Surface Roughness on Supersonic High Reynolds Number Turbulent Boundary Layer Flow written by Robert M. Latin and published by . This book was released on 1998-03-01 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive study of rough-wall high speed (M=2.9) high Reynolds number (Re/m = 1.9. 10 to the 7th power) turbulent boundary layer flow was performed consisting of experimental, analytical, and numerical methods. Six wall topologies consisting of a smooth and five rough surfaces (two and three dimensional machined roughness plates; and 80, 36, and 20 grit sand-grain roughened plates) were studied. A confocal laser scan microscope was used to measure the topography of the sand grain roughnesses. The experimental measurement techniques included a convention Pitot pressure probe, laser Doppler velocimetry, hot wire anemometry; color schlieren and laser sheet Mie scattering images. Mean measurements included velocity, Mach number, density, and mass flux. Turbulent measurements included velocity and mass flux turbulence intensities, kinematic Reynolds shear stress, compressible Reynolds shear stress in two planes, and the traverse apparent mass flux. Kinematic turbulent flow statistical properties were found to scale by local mean quantities and displayed a weak dependence on surface roughness. Turbulent flow statistical properties with the explicit appearance of density did not scale by local mean quantities, and had a strong linear dependence on roughness. Surface roughness also had a significant effect on the flow structure size, angles, and energy spectra. A theoretical analysis was performed and a new integral method for the estimation of skin friction was developed. The skin friction estimates were within 4% of compressible semi-empirical relations. A numerical study was performed which used a parabolized Navier Stokes solver with two algebraic turbulence models and the Rotta model for surface roughness. A new method for the estimation of momentum loss improved the numerical flow predictability.
Book Synopsis Supersonic Turbulent Boundary Layers with Periodic Mechanical Non-equilibrium by : Isaac Wesley Ekoto
Download or read book Supersonic Turbulent Boundary Layers with Periodic Mechanical Non-equilibrium written by Isaac Wesley Ekoto and published by . This book was released on 2006 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Roughness topology had a significant effect on the boundary layer mean and turbulent properties due to shock boundary layer interactions. Favorable pressure gradients had the expected stabilizing effect on turbulent properties, but the improvements were less significant for models with surface roughness near the wall due to increased tendency towards flow separation. It was documented that proper roughness selection coupled with a sufficiently strong favorable pressure gradient produced regions of "negative" production in the transport of turbulent stress. This led to localized areas of significant turbulence stress reduction. With proper roughness selection and sufficient favorable pressure gradient strength, it is believed that localized relaminarization of the boundary layer is possible.
Book Synopsis Effect of Distributed Three-dimensional Roughness and Surface Cooling on Boundary-layer Transition and Lateral Spread of Turbulence at Supersonic Speeds by : Albert L. Braslow
Download or read book Effect of Distributed Three-dimensional Roughness and Surface Cooling on Boundary-layer Transition and Lateral Spread of Turbulence at Supersonic Speeds written by Albert L. Braslow and published by . This book was released on 1959 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Influence of Surface Roughness on the Second Order Transport of Turbulence in Non-Equilibrium Boundary Layers by :
Download or read book Influence of Surface Roughness on the Second Order Transport of Turbulence in Non-Equilibrium Boundary Layers written by and published by . This book was released on 2006 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: The principal objective of this project was to gain improved understanding for the mean and turbulent flow physics associated with non-equilibrium, strained, supersonic, compressible boundary layer flow over rough curved surfaces and elevated freestream turbulence levels. Measurements of mean flow and turbulence statistics within such boundary layers has been conducted using Particle Imaging Velocimetry (PIV) technique and the data are reported. Numerical simulation of the flow was also conducted using the eddy-viscosity turbulence models and comparison of the predictions with measurements was performed and reported. This report consists of two parts. The experimental work in this project was subcontracted to R.D.W. Bowersox, Aerospace Engineering Department, Texas A & M University, TX. In Part I, the experimental work done by Bowersox and his group is reported. The pertinent experimental data is given at the end of Part I of this report. The numerical simulation is reported in Part II of this report.
Book Synopsis Boundary Layer Transition at Supersonic Speeds by : E. R. Van Driest
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.
Book Synopsis An Experimental Investigation of the Effects of Several Types of Surface Roughness on Turbulent Boundary Layer Characteristics at Supersonic Speeds by : Felix W. Fenter
Download or read book An Experimental Investigation of the Effects of Several Types of Surface Roughness on Turbulent Boundary Layer Characteristics at Supersonic Speeds written by Felix W. Fenter and published by . This book was released on 1953 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theory is described which can be used to predict accurately the skin friction drag of surfaces with uniform grain-type roughness. The roughness does not necessarily have to extend to the leading edge of the surface for an accurate calculation to be made. Uniform surface roughness composed of spherical beads does not affect the boundary layer in a manner significantly different from grain-type roughness, provided that the grains and the spheres are bonded to the surface in a similar manner. Consequently, the theory accurately predicts the effects of spherical roughness elements on skin friction under these conditions. The effect of a given type of roughness on turbulent boundary layer characteristics is strongly dependent upon the density of distribution of the roughness elements. The effect of maximum density V-grooves on turbulent boundary layer characteristics is dependent upon the sweepback angle. The effect of increasing sweepback is to reduce the skin friction drag. (Author).
Book Synopsis Receptivity and Transition to Turbulence of Supersonic Boundary Layers with Surface Roughness by : Nicola De Tullio
Download or read book Receptivity and Transition to Turbulence of Supersonic Boundary Layers with Surface Roughness written by Nicola De Tullio and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A deeper understanding of the different factors that influence the laminar-turbulent transition in supersonic boundary layers will help the design of efficient high-speed vehicles. In this work we study the effects of surface roughness on the stability and transition to turbulence of supersonic boundary layers. The investigation is carried out by direct numerical simulations (DNS) of the compressible Navier-Stokes equations and focuses on the modifications introduced in the transition process by localised roughness elements, for Mach numbers M∞ = 6.0 and M∞ = 2.5, and distributed slender pores at M∞ = 6.0. The first part of the investigation into the effects of localised roughness deals with the receptivity and initial exponential amplification of disturbances in boundary layers subjected to small external perturbations. Different transition scenarios are investigated by considering different free-stream disturbances and roughness elements with different heights. The results show that, for roughness heights approaching the local displacement thickness, transition is dominated by the growth of a number of instability modes in the roughness wake. These modes are damped by wall cooling and their receptivity is found to be more efficient in the case of free-stream disturbances dominated by sound. At M∞ = 6 the growth of Mack modes in the boundary layer is found to play a crucial role in the excitation of the most unstable wake modes. An investigation into the nonlinear stages of transition shows that the breakdown to turbulence starts with nonlinear interactions of the wake instability modes. This leads to the formation of a turbulent wedge behind the roughness element, which spreads laterally following mechanisms similar to those observed for the evolution of compressible turbulent spots. An oblique shock impinging on the transitional boundary layer significantly accelerates the breakdown process and leads to a wider turbulent wedge. The study ends with an analysis of porous walls as a passive method for transition control, which is carried out using a temporal DNS approach. The results show damping of both the primary, of second or Mack mode type, and secondary instabilities and indicate that, despite the high Mack number, first mode waves regain importance in this modified transition scenario.
Book Synopsis Brief aan Willem Bentinck (heer van Rhoon) by :
Download or read book Brief aan Willem Bentinck (heer van Rhoon) written by and published by . This book was released on 1748 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Experimental Investigation of the Effects of Several Types of Surface Roughness on Turbulent Boundary Layer Characteristics at Supersonic Speeds by : Felix W. Fenter
Download or read book An Experimental Investigation of the Effects of Several Types of Surface Roughness on Turbulent Boundary Layer Characteristics at Supersonic Speeds written by Felix W. Fenter and published by . This book was released on 1958 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulent Shear Layers in Supersonic Flow by : Alexander J. Smits
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.
Book Synopsis Surface Roughness Effects on the Hypersonic Turbulent Boundary Layer by : Dale Evan Berg
Download or read book Surface Roughness Effects on the Hypersonic Turbulent Boundary Layer written by Dale Evan Berg and published by . This book was released on 1977 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of the response of a hypersonic turbulent boundary layer to a step change in surface roughness has been performed. The boundary layer on a flat nozzle wall of a Mach 6 wind tunnel was subjected to abrupt changes in surface roughness and its adjustment to the new surface conditions was examined. Both mean and fluctuating flow properties were acquired for smooth-to-rough and rough-to-smooth surface configurations. (Author).
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Problem of Roughness Drag at Supersonic Speeds by : K. R. Czarnecki
Download or read book The Problem of Roughness Drag at Supersonic Speeds written by K. R. Czarnecki and published by . This book was released on 1966 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterizing the Streamwise Development of Surface Roughness Effects on a Supersonic Boundary Layer by : Brian Douglas Kocher
Download or read book Characterizing the Streamwise Development of Surface Roughness Effects on a Supersonic Boundary Layer written by Brian Douglas Kocher and published by . This book was released on 2018 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-component particle image velocimetry was employed to measure the effects of the mechanical distortions caused from surface roughness topologies on a Mach 2 boundary layer. The first goal of this study was to characterize the mechanical responses of the supersonic boundary layer to various roughness topologies. These responses were characterized in ensemble averaged mean velocity characteristics as well as turbulent intensity responses through the Reynolds Stresses. The second goal was to characterize the streamwise development of the mechanical distortions over a diamond roughness topology. Measurements were taken at three streamwise measurement locations to measure the streamwise mechanical distortion development. Lastly, near-wall streamwise-elongated coherent structures were characterized utilizing a streamwise-spanwise oriented laser sheet. Instantaneous velocity vector fields and two point autocorrelations were used to characterize the spatial orientation of the near-wall coherent structures. Baseline characteristics of the supersonic boundary layer were determined over a hydraulically smooth floor insert. The mean and turbulent statistics compare well to other results when scaled by the roughness friction velocity. Ensemble averaged outer-scaled streamwise velocity profiles showed a velocity deficit in the near-wall region. Inner-scaled boundary layer profiles showed a downward vertical shift of 3 and 4.5 for the diamond roughness and realistic roughness topologies, respectively. These values show similar mechanical responses to the results seen by Ekoto et al.(3) in a Mach 2.86 boundary layer. The roughness effects were shown to increase in magnitude along the streamwise distance.
Book Synopsis AIAA Journal by : American Institute of Aeronautics and Astronautics
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2003 with total page 938 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1973 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:
