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Experimental Study Of Boundary Layer Behavior In A Simulated Low Pressure Turbine Nasa Tm 1998 208503 Jan 20 1999
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Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781723575693 Total Pages :216 pages Book Rating :4.5/5 (756 download)
Book Synopsis Experimental Study of Transitional Flow Behavior in a Simulated Low Pressure Turbine by : National Aeronautics and Space Administration (NASA)
Download or read book Experimental Study of Transitional Flow Behavior in a Simulated Low Pressure Turbine written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-24 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed investigation of the flow physics occurring on the suction side of a simulated Low Pressure Turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the pressure distribution of an actual LPT airfoil onto a flat lower plate. The experiments were carried out for the Reynolds numbers of 35,000, 70,000, 100,000 and 250,000 with four levels of freestream turbulence ranging from 1% to 4%. For the three lower Reynolds numbers, the boundary layer on the flat plate was separated and formed a bubble. The size of laminar separation bubble was measured to be inversely proportional to the freestream turbulence levels and Reynolds numbers. However, no separation was observed for the Re = 250,000 case. The transition on a separated flow was found to proceed through the formation of turbulent spots in the free shear layer as evidenced in the intermittency profiles for Re = 35,000, 70,000 and 100,000. Spectral data show no evidence of Kelvin-Helmholtz or Tollmien-Schlichting instability waves in the free shear layer over a separation bubble (bypass transition). However, the flow visualization revealed the large vortex structures just outside of the bubble and their development to turbulent flow for Re = 50,000, which is similar to that in the free shear layer (separated-flow transition). Therefore, it is fair to say that the bypass and separated-flow transition modes coexist in the transitional flows over the separation bubble for certain conditions. Transition onset and end locations and length determined from intermittency profiles decrease as Reynolds number and freestream turbulence levels increase. Sohn, Ki Hyeon and DeWitt, Kenneth J. Glenn Research Center NCC3-288...
Book Synopsis Thermionic Phenomena by : C. Guy Suits
Download or read book Thermionic Phenomena written by C. Guy Suits and published by Elsevier. This book was released on 2013-10-22 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermionic Phenomena is the third volume of the series entitled The Collected Works of Irving Langmuir. This volume compiles articles written during the 1920's and early 1930's, the period when the science of thermionics is beginning to be of importance. This text is divided into two parts. The first part discusses vacuum pumps, specifically examining the effect of space charge and residual gases on thermionic currents in high vacuum. This part also explains fundamental phenomena in electron tubes having tungsten cathodes and the use of high-power vacuum tubes. The second part of this text looks into the electron emission and adsorbed films, specifically studying the relation between contact potentials and electrochemical action and other related topics on electron emission. This publication will be invaluable to those interested in the works of Langmuir, particularly on thermionic phenomena.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721008315 Total Pages :28 pages Book Rating :4.0/5 (83 download)
Book Synopsis Study of Boundary Layer Development in a Two-Stage Low-Pressure Turbine by : National Aeronautics and Space Administration (NASA)
Download or read book Study of Boundary Layer Development in a Two-Stage Low-Pressure Turbine written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-11 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental data from jet-engine tests have indicated that unsteady blade row interactions and separation can have a significant impact on the efficiency of low-pressure turbine stages. Measured turbine efficiencies at takeoff can be as much as two points higher than those at cruise conditions. Several recent studies have revealed that Reynolds number effects may contribute to the lower efficiencies at cruise conditions. In the current study numerical simulations have been performed to study the boundary layer development in a two-stage low-pressure turbine, and to evaluate the transition models available for low Reynolds number flows in turbomachinery. The results of the simulations have been compared with experimental data, including airfoil loadings and integral boundary layer quantities. The predicted unsteady results display similar trends to the experimental data, but significantly overestimate the amplitude of the unsteadiness. The time-averaged results show close agreement with the experimental data.Dorney, Daniel J. and Ashpis, David E. and Halstead, David E. and Wisler, David C.Glenn Research CenterJET ENGINES; TWO STAGE TURBINES; COMPUTERIZED SIMULATION; BALDWIN-LOMAX TURBULENCE MODEL; BOUNDARY LAYER TRANSITION; TRANSITION FLOW; FLOW VISUALIZATION; BOUNDARY LAYER SEPARATION; SEPARATED FLOW; ROTOR BLADES (TURBOMACHINERY); TAKEOFF; CRUISING FLIGHT; COMPUTATIONAL GRIDS; NOZZLE FLOW; SKIN FRICTION; TURBINE BLADES; REYNOLDS NUMBER; FLOW CHARACTERISTICS; FLOW DISTRIBUTION
Book Synopsis An Experimental Investigation of the Compressible Turbulent Boundary Layer with a Favorable Pressure Gradient by : David L. Brott
Download or read book An Experimental Investigation of the Compressible Turbulent Boundary Layer with a Favorable Pressure Gradient written by David L. Brott and published by . This book was released on 1969 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721575466 Total Pages :36 pages Book Rating :4.5/5 (754 download)
Book Synopsis On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions by : National Aeronautics and Space Administration (NASA)
Download or read book On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study, which is the first of a series of investigations dealing with specific issues of low pressure turbine (LPT) boundary layer aerodynamics, is aimed at providing detailed unsteady boundary flow information to understand the underlying physics of the inception, onset, and extent of the separation zone. A detailed experimental study on the behavior of the separation zone on the suction surface of a highly loaded LPT-blade under periodic unsteady wake flow is presented. Experimental investigations were performed at Texas A&M Turbomachinery Performance and Flow Research Laboratory using a large-scale unsteady turbine cascade research facility with an integrated wake generator and test section unit. To account for a high flow deflection of LPT-cascades at design and off-design operating points, the entire wake generator and test section unit including the traversing system is designed to allow a precise angle adjustment of the cascade relative to the incoming flow. This is done by a hydraulic platform, which simultaneously lifts and rotates the wake generator and test section unit. The unit is then attached to the tunnel exit nozzle with an angular accuracy of better than 0.05 , which is measured electronically. Utilizing a Reynolds number of 110,000 based on the blade suction surface length and the exit velocity, one steady and two different unsteady inlet flowconditions with the corresponding passing frequencies, wake velocities and turbulence intensities are investigated using hot-wire anemometry. In addition to the unsteady boundary layer measurements, blade surface pressure measurements were performed at Re=50,000, 75,000, 100,000, and 125,000 at one steady and two periodic unsteady inlet flow conditions. Detailed unsteady boundary layer measurement identifies the onset and extent of the separation zone as well as its behavior under unsteady wake flow. The results presented in ensemble-averaged and contour plot forms contribute to understanding t
Author :National Aeronautics and Space Adm Nasa Publisher :Independently Published ISBN 13 :9781729231623 Total Pages :48 pages Book Rating :4.2/5 (316 download)
Book Synopsis Planetary Boundary Layer Simulation Using Tass by : National Aeronautics and Space Adm Nasa
Download or read book Planetary Boundary Layer Simulation Using Tass written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-25 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boundary conditions to an existing large-eddy simulation model have been changed in order to simulate turbulence in the atmospheric boundary layer. Several options are now available, including the use of a surface energy balance. In addition, we compare convective boundary layer simulations with the Wangara and Minnesota field experiments as well as with other model results. We find excellent agreement of modelled mean profiles of wind and temperature with observations and good agreement for velocity variances. Neutral boundary simulation results are compared with theory and with previously used models. Agreement with theory is reasonable, while agreement with previous models is excellent. Schowalter, David G. and DeCroix, David S. and Lin, Yuh-Lang and Arya, S. Pal and Kaplan, Michael Langley Research Center NCC1-188; RTOP 538-04-11-11
Book Synopsis Turbine Design and Application by : Arthur J. Glassman
Download or read book Turbine Design and Application written by Arthur J. Glassman and published by . This book was released on 1972 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of Turbulent Boundary Layers by : Tuncer Cebeci
Download or read book Analysis of Turbulent Boundary Layers written by Tuncer Cebeci and published by Elsevier. This book was released on 2012-12-02 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculating two-dimensional and axisymmetric laminar and turbulent boundary layers. This book will be useful to readers who have advanced knowledge in fluid mechanics, especially to engineers who study the important problems of design.
Book Synopsis Boundary Layer Effects by : Anthony W. Fiore
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.
Book Synopsis Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers by : Gazi Hasanuzzaman
Download or read book Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers written by Gazi Hasanuzzaman and published by Cuvillier Verlag. This book was released on 2022-01-18 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental investigation in turbulent boundary layer flows represents one of the canonical geometries of wall bounded shear flows. Utmost relevance of such experiments, however, is applied in the engineering applications in aerospace and marine industries. In particular, continuous effort is being imparted to explore the underlying physics of the flow in order to develop models for numerical tools and to achieve flow control. Flow control experiments have been widely investigated since 1930’s. Several flow control technique has been explored and have shown potential benefit. But the choice of control technique depends largely on the boundary condition and the type of application. Hence, friction drag of subsonic transport aircraft is intended to be reduced within the scope of this Ph. D. topic. Therefore, application of active control method such as microblowing effect in the incompressible, zero pressure gradient turbulent boundary layer was investigated. A series of experiments have been performed in two different wind tunnel facilities. Wind tunnel from Department of Aerodynamics and Fluid Mechanics (LAS) was used for the measurements for moderate Reynolds number range in co-operation with the wind tunnel from Laboratoire de M´ecanique de Feiret Lille for large Reynolds number range. Measurements are conducted with the help of state-of-the-art techniques such as Laser Doppler Anemometry, Particle Image Velocimetry and electronic pressure sensors.
Book Synopsis An Experimental Study of the Thick Turbulent Boundary Layer Near the Tail of a Body of Revolution by : Virendrakumar Chaturbhai Patel
Download or read book An Experimental Study of the Thick Turbulent Boundary Layer Near the Tail of a Body of Revolution written by Virendrakumar Chaturbhai Patel and published by . This book was released on 1973 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed measurements of pressure distributions, mean velocity profiles and Reynolds stresses were made in the thick incompressible axisymmetric turbulent boundary layer near the tail of a body of revolution. The results indicate a number of important differences between the behavior of a thick and a thin boundary layer. Significant variations of static pressure and a low level of turbulence are noted. Thus in order to predict the behavior of the flow in the tail region of a body of revolution it does not appear possible to use conventional thin-boundary-layer calculation procedures. (Author Modified Abstract).
Book Synopsis Summary of Laminar Boundary Layer Control Research by : Northrop Corporation Boundary Layer Research Section
Download or read book Summary of Laminar Boundary Layer Control Research written by Northrop Corporation Boundary Layer Research Section and published by . This book was released on 1964 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: At subsonic speeds, full length laminar flow and low drags were obtained up to high length Reynolds numbers on a thin straight, on a swept laminar suction wing and on a suction body of revolution. Moderately increased suction rates in the most critical region of a straight and a swept laminar suction wing enabled full chord laminar flow in the presence of external sound. Theoretical investigatiions are concerned with nonlinear boundary layer oscillations and stability investigations (assuming small disturbances) of a supersonic laminar boundary layer on a flat plate up to high supersonic speeds as well as on a highly swept supersonic low drag suction wing of low wave drag. On a supersonic flat laminar suction plate with and without weak incident shock waves, extensive laminar flow and low equivalent drags were obtained at M = 3 up to length Reynolds numbers of 26 x 1000000. Further supersonic low drag suction experiments on a suction body of revolution, on a 36 degree supersonic yawing wing, as well as on a 72 degree supersonic yawing wing (swept behind the Mach cone) of low wave drag, are described. The latter wing showed full chord laminar flow with a subsonic type pressure distribution at M = 2 and R sub C approximately equal to 1000000. (Author).
Book Synopsis Measurements of Upstream History Effects in Compressible Turbulent Boundary Layers by : David F. Gates
Download or read book Measurements of Upstream History Effects in Compressible Turbulent Boundary Layers written by David F. Gates and published by . This book was released on 1973 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report describes an experimental study of compressible turbulent boundary layers for which the upstream history was systematically varied. A series of experiments was conducted using both a supersonic half nozzle and a conventional flat plate for which the nozzle throat and flat plate leading edge can be temperature controlled. The supersonic nozzle provided a favorable upstream pressure gradient together with a controlled thermal history at the throat. The flat plate provided upstream temperature control with no pressure history. Velocity and temperature profile and heat-transfer measurements were made in a downstream region of zero-pressure-gradient and constant wall temperature. (Modified author abstract).
Book Synopsis Measurements of a Supersonic Favorable-pressure-gradient Turbulent Boundary Layer with Heat Transfer by : Robert L. P. Voisinet
Download or read book Measurements of a Supersonic Favorable-pressure-gradient Turbulent Boundary Layer with Heat Transfer written by Robert L. P. Voisinet and published by . This book was released on 1973 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).
Book Synopsis IUTAM Symposium on One Hundred Years of Boundary Layer Research by : Hans-Joachim Heinemann
Download or read book IUTAM Symposium on One Hundred Years of Boundary Layer Research written by Hans-Joachim Heinemann and published by Springer Science & Business Media. This book was released on 2006-12-20 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book collects peer-reviewed lectures of the IUTAM Symposium on the 100th anniversary of Boundary Layer research. No other reference of this calibre, on this topic, is likely to be published for the next decade. Covers classification, definition and mathematics of boundary layers; instability of boundary layers and transition; boundary layers control; turbulent boundary layers; numerical treatment and boundary layer modelling; special effects in boundary layers.
Book Synopsis Influence of Surface Static-pressure Orifices on Boundary-layer Transition by : Dan M. Somers
Download or read book Influence of Surface Static-pressure Orifices on Boundary-layer Transition written by Dan M. Somers and published by . This book was released on 1982 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Study of Boundary-layer Flows with Pressure Gradient and Mass Transfer by a Simple Integral Method by : Tse-Fou Zien
Download or read book Study of Boundary-layer Flows with Pressure Gradient and Mass Transfer by a Simple Integral Method written by Tse-Fou Zien and published by . This book was released on 1971 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: A refined Karman-Pohlhausen method previously generalized by Zien to include the effects of mass transfer is further explored and its application is extended to cases involving both pressure gradients and surface mass transfer. The case with piece-wise suction (or blowing) is also included. The study is restricted to plane, incompressible, laminar boundary layers. Configurations of flat plates and circular cylinders are chosen to illustrate the application of the method. Results are given mainly in terms of skin frictions, and they are presented entirely in closed forms. The calculations for the porous plate case are carried out using rather elaborate velocity profiles, but the results differ negligibly from previous ones with very simple profiles. A linear velocity profile is then used to carry out some exploratory calculations for more complex flows. The method is shown to be a potentially efficient tool for handling the problem of boundary-layer control by means of surface mass transfer. (Author).
