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Low Pressure Turbine Separation Control
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Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721512393 Total Pages :26 pages Book Rating :4.5/5 (123 download)
Book Synopsis Low-Pressure Turbine Separation Control by : National Aeronautics and Space Administration (NASA)
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
Book Synopsis Numerical Investigation of Low-pressure Turbine Blade Separation Control by : D. Postl
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:
Book Synopsis Separation Control in Low Pressure Turbines Using Plasma Actuators with Passing Wakes by : Debashish Burman
Download or read book Separation Control in Low Pressure Turbines Using Plasma Actuators with Passing Wakes written by Debashish Burman and published by . This book was released on 2013 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Separation Control on Low-pressure Turbine Airfoils Using Synthetic Vortex Generator Jets by : Ralph J. Volino
Download or read book Separation Control on Low-pressure Turbine Airfoils Using Synthetic Vortex Generator Jets written by Ralph J. Volino and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Plasma Actuators for Separation Control of Low Pressure Turbine Blades by : Junhui Huang
Download or read book Plasma Actuators for Separation Control of Low Pressure Turbine Blades written by Junhui Huang and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Control of Low-pressure Turbine Separation Using Vortex Generator Jets by : Jeffrey P. Bons
Download or read book Control of Low-pressure Turbine Separation Using Vortex Generator Jets written by Jeffrey P. Bons and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Separation and Transition Control on Ultra-high-lift Low Pressure Turbine Blades in Unsteady Flow by : Xue Feng Zhang
Download or read book Separation and Transition Control on Ultra-high-lift Low Pressure Turbine Blades in Unsteady Flow written by Xue Feng Zhang and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Brief van Berkhout's Academische Boekhandel en Antiquariaat N.V aan Wilhelmus Johannes Maria Antonius Asselbergs (1903-1968) by :
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:
Book Synopsis Investigation of Separation Control in Low Pressure Turbine Using Pulsed Vortex Generator Jets (Postprint). by :
Download or read book Investigation of Separation Control in Low Pressure Turbine Using Pulsed Vortex Generator Jets (Postprint). written by and published by . This book was released on 2006 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The periodic fluctuation of velocity in the boundary layer due to forcing of Vortex Generator Jets (VGJs) injected over the suction surface of the Pack-B turbine blade is reported. Blade Reynolds numbers in the turbine cascade match those that occur in aircraft engines while at high altitude cruise. The blowing ratio, a ratio of the jet velocity to the freestream velocity, was set to 2. The VGJs are pitched at 30 degrees and have a skew angle of 90 degrees to the freestream and are located in two rows at 45% and 63% axial chord. PIV data phase locked to the VGJ forcing was used to obtain planar velocity data around the blade. The phase locked PIV images reveal the fluctuation of the flow velocity in the boundary layer with respect to the pulsing period of the VGJ. This sheds light on the mechanism by which the VGJs suppress laminar separation over the blade suction surface.
Book Synopsis Active Flow Control of Low Pressure Turbine Blade Separation Using Plasma Actuators by : Karthik Ramakumar
Download or read book Active Flow Control of Low Pressure Turbine Blade Separation Using Plasma Actuators written by Karthik Ramakumar and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Visualization of Flow Control Devices (VGJs) for Low Pressure Turbine Separation Control Using Stero PIV. by :
Download or read book Visualization of Flow Control Devices (VGJs) for Low Pressure Turbine Separation Control Using Stero PIV. written by and published by . This book was released on 2004 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: An AFOSR-sponsored collaborative effort in low-pressure turbine (LPT) flow control is currently underway to capitalize on recent laboratory successes using vortex generating jets (VGJs). AFRL/PRTT, the University of Arizona, and Brigham Young University (BYU) are all players in this effort to enhance the understanding of the effect of VGJs on separating LPT boundary layers. AFRL/PRTT has the design task (under Drs. Richard Rivir and Rolf Sondergaard) to integrate flow control strategies into the Air Force's jet engine inventory. To make the transition of VGJs from the laboratory to the design process will require a greatly improved understanding of the fundamental physics, so that accurate models can be developed and incorporated into LPT design codes. Dr. Hermaun Fasel (University of Arizona) has an AFOSR grant to develop computational models as building blocks for this design integration process. The necessary experimental data to validate these models is being obtained from wind tunnel testing at BYU (Dr. Jeffrey Bons as PI).
Book Synopsis Integrated Flow Control Devices for the Design of Enhanced Low Pressure Turbines by :
Download or read book Integrated Flow Control Devices for the Design of Enhanced Low Pressure Turbines written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow separation limits the efficiency of low-pressure turbines (LPTs) in aircraft engines. Recent experiments with vortex generator jets (VGJs), conducted in AFRL's low-speed cascade at Wright-Patterson AFB, have demonstrated dramatic reductions in separation losses. The critical science that wilt enable this design innovation to reach its potential is a comprehensive understanding of the effect of VGJs on a separating boundary layer. Experiments are underway at BYU to better understand the basic physics of the separation control phenomenon and establish the quantitative links between the underlying flow physics and LPT performance. Two-component velocity measurements of VGJ evolution have been made along a flat wall with no freestream pressure gradient and at pressure gradient conditions typical of a low pressure turbine suction surface. Initial measurements are also being taken in a linear cascade for comparison with the flat wall studies. Data clearly show the presence of streamwise vortices which provide the necessary boundary layer mixing to inhibit separation. Vortex development is modified when jet injection occurs in an adverse pressure gradient. The effects of freestream turbulence will also be considered. These detailed flow measurements are suitable for code validation.
Book Synopsis On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions by :
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:
Book Synopsis Separation Flow Control with Vortex Generator Jets Employed in an Aft-loaded Low-pressure Turbine Cascade with Simulated Upstream Wakes by : Kyle Adler Gompertz
Download or read book Separation Flow Control with Vortex Generator Jets Employed in an Aft-loaded Low-pressure Turbine Cascade with Simulated Upstream Wakes written by Kyle Adler Gompertz and published by . This book was released on 2009 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Detailed pressure and velocity measurements were acquired at Rec = 20,000 with 3% inlet free stream turbulence intensity to study the effects of position, phase and forcing frequency of vortex generator jets employed on an aft-loaded low-pressure turbine blade in the presence of impinging wakes. The L1A blade has a design Zweifel coefficient of 1.34 and a suction peak at 58% axial chord, making it an aft-loaded pressure distribution. At this Reynolds number, the blade exhibits a non-reattaching separation region beginning at 60% axial chord under steady flow conditions without upstream wakes. Wakes shed by an upstream vane row are simulated with a moving row of cylindrical bars at a flow coefficient of 0.91. Impinging wakes thin the separation zone and delay separation by triggering transition in the separated shear layer, although the flow does not reattach. Instead, at sufficiently high forcing frequencies, a new time-mean separated shear layer position is established which begins at approximately 72%Cx. Reductions in area-averaged wake total pressure loss of more than 75% were documented. One objective of this study was to compare pulsed flow control using two rows of discrete vortex generator jets (VGJs). The VGJs are located at 59%Cx, approximately the peak Cp location, and at 72%Cx. Effective separation control was achieved at both locations. In both cases, wake total pressure loss decreased 35% from the wake only level and the shape of the Cp distribution indicates that the cascade recovers its high Reynolds number (attached flow) performance. The most effective separation control was achieved when actuating at 59%Cx where the VGJ disturbance dominates the dynamics of the separated shear layer, with the wake disturbance assuming a secondary role only. On the other hand, when actuating at 72%Cx, the efficacy of VGJ actuation is derived from the relative mean shear layer position and jet penetration. When the pulsed jet actuation (25% duty cycle) was initiated at the 72%Cx location, synchronization with the wake passing frequency (8.7Hz) was critical to produce the most effective separation control. A 20% improvement in effectiveness over the wake-only level was obtained by aligning the jet actuation between wake events. A range of blowing ratios was investigated at both locations to maximize separation reduction with minimal mass flow. The optimal control parameter set for VGJ actuation at 72%Cx does not represent a reduction in required mass flow compared to the optimal parameter set for actuation at 59%Cx. Differences in the fundamental physics of the jet interaction with the separated shear layer are discussed and implications for the application of flow control in a full engine demonstrator are reviewed. Evidence suggests that flow control using VGJs will be effective in the highly unsteady LPT environment of an operating gas turbine, provided the VGJ location and amplitude are adapted for the specific blade profile.
Book Synopsis A Study of Separated Flow Through a Low-pressure Turbine Cascade by :
Download or read book A Study of Separated Flow Through a Low-pressure Turbine Cascade written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-pressure turbines (LPT) experience large changes in chord Reynolds number as the turbine engine operates from take-off to cruise conditions. Due to prevailing conditions at high altitude cruise, the Reynolds number reduces drastically. At low Reynolds numbers, the flow is largely laminar and tends to separate easily on the suction surface of the blade, and this laminar separation in particular leads to significant degradation of engine performance due to large re-circulation zones. Therefore, a better understanding of low-Reynolds number flow transition and separation is very critical for an effective design of LPT blade, and in exploring various possibilities for implementing flow control techniques, passive or active, to prevent or delay the flow separation in the low-pressure turbine. The objective of the present study is to understand the three-dimensional flow separation that occurs inside an LPT cascade at very low Reynolds numbers, and a high-order accurate numerical solution procedure is used to attain the same. A multi-block, periodic, structured grid generated by the grid generation software, GRIDPRO, is used to represent the flow domain. A MPI-based higher-order, parallel, chimera version of the FDL3DI flow solver, developed by the Air Force Research Laboratory at Wright Patterson Air Force Base, is extended for the present turbomachinery application. A sixth-order accurate compact-difference scheme is used for the spatial discretization, along with second-order accurate temporal discretization. Up to tenth-order filtering has been applied to minimize the numerical oscillations, and maintain numerical stability. Simulations have been performed for Reynolds numbers (based on inlet velocity and axial chord) 10,000 and 25,000. The effect of these low-Reynolds numbers on the flow physics for a low-pressure turbine cascade has been studied in detail. At Re = 10,000, the flow undergoes more separation than at Re = 25,000 as expected and the separation remains significant over the entire blade for both the Reynolds number. The location of the onset of separation matches with an available LES simulation and with the available experimental data. In addition to the above simulations, another study was carried out to understand the effect of two different sets of inflow/outflow boundary conditions on the flow solution. The two sets of boundary conditions include static inflow with extrapolated outflow (BC1), and dynamic inflow (BC2) that accounts for upstream influence in the subsonic flow. The computed Cp distribution for the LPT flow shows good agreement with the available experimental data. Application of BC2 boundary condition predicted a bounded region of separation, while BC1 boundary condition predicted significant separation over the entire blade of an LPT.
Book Synopsis Experimental Investigation of Boundary Layer Behavior in a Simulated Low Pressure Turbine by : Ki-Hyeon Sohn
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:
Book Synopsis On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions by : Meinhard Schobeiri
Download or read book On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions written by Meinhard Schobeiri and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
