Download or read book Experimental Investigation of Separation on Low Pressure Turbine Blades written by Brian Hollon and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Separation in a Low Pressure Turbine Blade Cascade Model written by Brian Hollon and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Boundary Layer Behavior in a Simulated Low Pressure Turbine written by Ki-Hyeon Sohn and published by . This book was released on 1998 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Heat Transfer Transition and Separation on Turbine Blades at Low Reynolds Number and High Turbulence Intensity written by and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of turbulence intensity on the heat transfer distribution, transition and flow separation on a turbine blade was investigated at low Reynolds numbers. Measurements were performed in linear cascades (at both UCDavis and the USAF Academy) at low Reynolds number (67,000 to 144,000) representative of low pressure turbine stages at high altitude. Nominal turbulence intensities of 1% and 10% (generated with biplane lattice grids) were used. The heat transfer was measured with the uniform heat flux (UHF) or heated-coating method. The heated-coating was a gold-film and liquid crystals were used for the surface temperature measurement. A novel laser-tuft surface flow visualization method was also used. For low turbulence levels (1%) the pressure side of the blade exhibited streaks of varying heat transfer possibly associated with Taylor-Gortler vortices. With grid turbulence (10%) these streaks disappeared on the pressure side and the heat transfer nearly doubled. Gird turbulence also increased the heat transfer on the leading edge and suction surface, while advancing the location of boundary layer transition. Good agreement was generally found between the UCDavis and USAFA data. These cascade results compare favorably to those that have been reported with rotation.
Download or read book Experimental and Numerical Investigation of Losses in Low Pressure Turbine Blade Rows written by Daniel J. Dorney and published by . This book was released on 2000 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions written by and published by . This book was released on 2003 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Brief van Berkhout s Academische Boekhandel en Antiquariaat N V aan Wilhelmus Johannes Maria Antonius Asselbergs 1903 1968 written by and published by . This book was released on 1960 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Pressure Turbine Separation Control written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work details a computational study, using the Glenn HT code, that analyzes the use of vortex generator jets (VGJs) to control separation on a low-pressure turbine (LPT) blade at low Reynolds numbers. The computational results are also compared with the experimental data for steady VGJs. It is found that the code determines the proper location of the separation point on the suction surface of the baseline blade (without any VGJ) for Reynolds numbers of 50,000 or less. Also, the code finds that the separated region on the suction surface of the blade vanishes with the use of VGJs. However, the separated region and the wake characteristics are not well predicted. The wake width is generally over-predicted while the wake depth is under-predicted. Garg, Vijay K. Glenn Research Center NASA/CR-2002-211689, NAS 1.26:211689, E-13419, GT-2002-30229
Download or read book Numerical Investigation of Low pressure Turbine Blade Separation Control written by D. Postl and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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
Download or read book Control of Flow Separation on a Turbine Blade by Utilizing Tail Extensions written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted in a two-dimensional linear cascade, focusing on the suction surface of a low pressure turbine blade. Flow Reynolds numbers, based on exit velocity and suction surface length were varied from 50,000 to 300,000. The axial chord of the blades was varied using tail extenders from 0% to 15% beyond design. The effects of Reynolds number on a low pressure turbine cascade blade with tail extensions was investigated. This study has shown that for certain cases, changing the axial chord of a low pressure turbine blade by utilizing tail extensions provided a clear improvement in boundary layer behavior which results in better overall performance. There was no additional advantage when the tail extensions were longer than 6.1% of the axial chord. The shortest tail extension resulted in the greatest zone of performance enhancement. The longer tail extension resulted in a smaller region of performance enhancement.
Download or read book Experimental Study of Flow Past Turbine Blades written by E. Eckert and published by . This book was released on 1949 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbine-blade-section tests were made in a low-speed two-dimensional cascade tunnel using a Mach-Zehnder interferometer. Pressure distributions and forces were calculated from density gradients given by the interference patterns. The central blade was heated to improve the definition of boundary layer separation. Reynolds number was varied from 11,800 to 54,000 and spacing ration from 0.687 to 1.141.
Download or read book EXPERIMENTAL INVESTIGATION OF BOUNDARY LAYER BEHAVIOR IN A SIMULATED LOW PRESSURE TURBINE NASA TM 1998 207921 SEP 15 1998 written by United States. National Aeronautics and Space Administration and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Use of Dimples to Suppress Boundary Layer Separation on a Low Pressure Turbine Blade written by Kurt P. Rouser and published by . This book was released on 2002-12-01 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow separation on a low pressure turbine blade is explored at Reynolds numbers of 25k, 45k and 100k, Experimental data is collected in a low- speed, draw-down wind tunnel using a cascade of eight Pak-B blades, Flow is examined from measurements of blade surface pressures, boundary layer parameters, exit velocities, and total pressure losses across the blade, Two recessed dimple shapes are assessed for suppressing flow separation and associated losses, One dimple is spherical, and the second is asymmetric, formed from a full dimple spanwise half-filled, A single row of each dimple shape is tested at 50%, 55% and 65% axial chord, Symmetric dimples reduce separation losses by as much as 28%, while asymmetric dimples reduce losses by as much as 23%, A complementary three-dimensional computational study is conducted to visualize local flow structure, Computational analysis uses Gridgen v13,3 as a mesh generator, Fluent v6,O as a flow solver and FIELDVIEW - v8,0 for graphic display and analysis, Computational results for Pak-B blades at a Reynolds number of 25k indicate that both dimple shapes cause a span-wise vortex to rollup within the dimple and provide a localized pressure drop,
Download or read book Experimental Study of the Effects of Wakes on Separation in Low Pressure Turbine Flow written by Burak Öztürk and published by . This book was released on 2003 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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...
Download or read book Combined Effects of Reynolds Number Turbulence Intensity and Periodic Unsteady Wake Flow Conditions on Boundary Layer Development and Heat Transfer of a Low Pressure Turbine Blade written by Burak Ozturk and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed experimental investigation has been conducted to provide a detailed insight into the heat transfer and aerodynamic behavior of a separation zone that is generated as a result of boundary layer development along the suction surface of a highly loaded low pressure turbine (LPT) blade. The research experimentally investigates the individual and combined effects of periodic unsteady wake flows and freestream turbulence intensity (Tu) on heat transfer and aerodynamic behavior of the separation zone. Heat transfer experiments were carried out at Reynolds number of 110,000, 150,000, and 250,00 based on the suction surface length and the cascade exit velocity. Aerodynamic experiments were performed at Re = 110,000 and 150,000. For the above Re-numbers, the experimental matrix includes Tus of 1.9%, 3.0%, 8.0%,13.0% and three different unsteady wake frequencies with the steady inlet flow as the reference configuration. Detailed heat transfer and boundary layer measurements are performed with particular attention paid to the heat transfer and aerodynamic behavior of the separation zone at different Tus at steady and periodic unsteady flow conditions. The objectives of the research are (a) to quantify the effect of Tu on the aero-thermal behavior of the separation bubble at steady inlet flow condition, (b) to investigate the combined effects of Tu and the unsteady wake flow on the aero-thermal behavior of the separation bubble, and (c) to provide a complete set of heat transfer and aerodynamic data for numerical simulation that incorporates Navier-Stokes and energy equations. The analysis of the experimental data reveals details of boundary layer separation dynamics which is essential for understanding the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number and Tu. To provide a complete picture of the transition process and separation dynamics, extensive intermittency analysis was conducted. Ensemble averaged maximum and minimum intermittency functions were determined leading to the relative intermittency function. In addition, the detailed intermittency analysis reveals that the relative intermittency factor follows a Gaussian distribution confirming the universal character of the relative intermittency function.
