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A Computational Investigation Of Tip Leakage Flow And Heat Transfer In Unshrouded Axial Flow Turbines
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Book Synopsis A Computational Investigation of Tip Leakage Flow and Heat Transfer in Unshrouded Axial Flow Turbines by : Senthil Kumar Krishnababu
Download or read book A Computational Investigation of Tip Leakage Flow and Heat Transfer in Unshrouded Axial Flow Turbines written by Senthil Kumar Krishnababu and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Aero-thermal Investigation of Tip Leakage Flow in Unshrouded Axial Turbines by : Zbigniew Schabowski
Download or read book Aero-thermal Investigation of Tip Leakage Flow in Unshrouded Axial Turbines written by Zbigniew Schabowski and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbine Tip and Shroud Heat Transfer by : Darryl E. Metzger
Download or read book Turbine Tip and Shroud Heat Transfer written by Darryl E. Metzger and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unshrouded blades of axial turbine stages move in close proximity to the stationary outer seal, or shroud, of the turbine housing. The pressure difference between the concave and convex sides of the blade drives a leakage flow through the gap between the moving blade tip and adjacent wall. This clearance leakage flow and accompanying heat transfer are of interest because of long obvious effects on aerodynamic performance and structural durability, but understanding of its nature and influences has been elusive. Previous studies indicate that the leakage through the gap is mainly a pressure-driven flow whose magnitude is related strongly to the airfoil pressure loading distribution and only weakly, if at all, to the relative motion between blade tip and shroud. A simple flow and heat transfer model incorporating these features can be used to estimate both tip and shroud heat transfer provided that reasonable estimates of the clearance gap size and clearance leakage flow can be made. The present work uses a numerical computation of the leakage flow to link the model to a specific turbine geometry and operating point for which a unique set of measured local tip and shroud heat fluxes is available. The resulting comparisons between the model estimates and measured heat transfer are good. The model should thus prove useful in the understanding and interpretation of future measurements, and should additionally prove useful for providing early design estimates of the levels of tip and shroud heat transfer that need to be compensated for by active turbine cooling.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721262274 Total Pages :26 pages Book Rating :4.2/5 (622 download)
Book Synopsis Heat Transfer and Flow on the Blade Tip of a Gas Turbine Equipped with a Mean-Camberline Strip by : National Aeronautics and Space Administration (NASA)
Download or read book Heat Transfer and Flow on the Blade Tip of a Gas Turbine Equipped with a Mean-Camberline Strip written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-16 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental and computational studies have been performed to investigate the detailed distribution of convective heat transfer coefficients on the first-stage blade tip surface for a geometry typical of large power generation turbines (greater than 100 MW) In a previous work the numerical heat transfer results for a sharp edge blade tip and a radiused blade tip were presented. More recently several other tip treatments have been considered for which the tip heat transfer has been measured and documented. This paper is concerned with the numerical prediction of the tip surface heat transfer for radiused blade tip equipped with mean-camberline strip (or "squealer" as it is often called). The heat transfer results are compared with the experimental results and discussed. The effectiveness of the mean-camberline strip in reducing the tip leakage and the tip heat transfer as compared to a radiused edge tip and sharp edge tip was studied. The calculations show that the sharp edge tip works best (among the cases considered) in reducing the tip leakage flow and the tip heat transfer. Ameri, A.A. Glenn Research Center NASA/CR-2001-210764, NAS 1.26:210764, E-12693, Rept-2001-GT-0156
Book Synopsis Numerical Investigation of the Unsteady Aerodynamics of Blade Tip Leakage Flow Inside Gas Turbine Engines by : Patricia Phutthavong
Download or read book Numerical Investigation of the Unsteady Aerodynamics of Blade Tip Leakage Flow Inside Gas Turbine Engines written by Patricia Phutthavong and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In today's modern gas turbine engines, the region between the rotor and the stationary shroud has the most extreme fluid-thermal conditions in the entire turbine, and is characterized by a periodically unsteady three-dimensional flow field. Due to the pressure difference across the blade tip, leakage flow enters the gap region from the pressure side and exits from the suction side. Tip leakage flow consists of hot mainstream gas and is highly undesirable since it does not turn, and so does not produce any work. Also, high heat transfer rates in the tip gap region occur as a result of leakage flow due to the formation of very thin boundary layers, which may lead to over-heating of the stationary shrouds. The purpose of the present work is to conduct an unsteady study of the tip leakage flow adjacent to the shroud in real gas turbine engines using an in-house industrial computational fluid dynamics (CFD) code. A turbine stage consisting of the nozzle guide vane (NGV) and rotor was modeled. The effect of tip clearance height, inlet turbulence intensity, inlet total temperature, and rotor angular velocity on the tip leakage aerodynamics will be investigated. To the best of the author's knowledge, time-accurate simulations have not been performed in order to study the effects of flow parameters on tip leakage flow aerodynamics. In addition, the trials of using a commercial CFD package to obtain heat transfer calculations on the shroud will be presented. It was found that the size of the separation bubble on the pressure side of the blade tip is dependent on the inlet total temperature and rotor angular velocity. Also, when the relative height of the separation bubble is large, a small re-circulation zone was found at the suction side of the blade tip. In all cases, flow re-circulation was found near the trailing edge and was due to the combined effect of the shroud relative motion with the secondary cross-flow from the adjacent blade passage.
Book Synopsis A Computational Study of Tip Desensitization in Axial Flow Turbines by :
Download or read book A Computational Study of Tip Desensitization in Axial Flow Turbines written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational investigation of novel tip leakage mitigation methods for high pressure turbine blades by : Mounir B. Ibrahim
Download or read book Computational investigation of novel tip leakage mitigation methods for high pressure turbine blades written by Mounir B. Ibrahim and published by . This book was released on 2014 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of Tip Clearance Flow Fields and Methods of Desensitizing Tip Clearance Effects in Turbines by :
Download or read book Investigation of Tip Clearance Flow Fields and Methods of Desensitizing Tip Clearance Effects in Turbines written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational investigation was carried out during this reporting period to derive the flow field information at various axial and radial locations from the leading to the trailing edge in the tip clearance region of the rotor, and the casing static pressure was measured to derive the trajectory of the leakage vortex and the horseshoe vortex. The data provided here indicates that the tip leakage flow originates at approximately 50% of the chord and is confined to the tip clearance region due to the relative motion between the blade and the wall, as well as the secondary flow in the tip region. Both of these effects are responsible for keeping the tip vortex closer to the suction surface corner of the tip. The leakage flow losses are high, but are confined to an extremely small region near the tip of the suction surface as opposed to the secondary flow, which tends to increase the losses spread over a substantial portion of the passage. Therefore, the information provided here is substantially different from that derived on the basis of cascades testing. Numerical investigation of the flow field in the Penn State rotor based on the utilization of the Navier-Stokes solver has been carried out to gain a better understanding of the secondary and the tip leakage flow development. Analysis of the leakage flow development shows that the relative motion of the blade and the casing wall reduces the propagation of the leakage flow into the mainflow. The tip leakage vortex is confined to the suction surface corner of the casing. Most of the leakage losses are due to the mixing of the tip leakage vortex downstream of the trailing edge.
Book Synopsis Numerical Analysis of Blade Tip Leakage Flow and Shroud Heat Transfer in Gas Turbine Engines by : Md. Hamidur Rahman
Download or read book Numerical Analysis of Blade Tip Leakage Flow and Shroud Heat Transfer in Gas Turbine Engines written by Md. Hamidur Rahman and published by . This book was released on 2008 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Gas Turbine Tip Leakage Flow and Heat Transfer by : Md Hamidur Rahman
Download or read book Gas Turbine Tip Leakage Flow and Heat Transfer written by Md Hamidur Rahman and published by . This book was released on 2011-06 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Computational Study of Tip Leakage Flow and Losses in a Linear Turbine Cascade by : Joan G. Moore
Download or read book A Computational Study of Tip Leakage Flow and Losses in a Linear Turbine Cascade written by Joan G. Moore and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computational study of 3-D flow in the VPI and SU tip leakage turbine cascade is used to show the level of modelling attainable now. Results for the overall flow development are compared with measurements of flow and losses at the exit of the tip leakage gap and downstream of the blade row. Mechanisms for the additional loss due to tip leakage are discussed. Consideration is given to areas where the modelling of fine scale flow structure may be improved. These include the flow in the tip clearance gap, flow in the tip leakage vortex, and flow separation at the trailing edge.
Book Synopsis Investigation of a Cavity Simulating the Clearance Gap at the Grooved Tips of Axial High Pressure Turbines by : Amirhasan Jafari
Download or read book Investigation of a Cavity Simulating the Clearance Gap at the Grooved Tips of Axial High Pressure Turbines written by Amirhasan Jafari and published by . This book was released on 2015 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Modern gas turbines operate at high overall pressure ratio and high gas temperature. The presence of tip clearance flows together with the high gas temperature will result in high aerodynamic losses and high heat transfer and can be detrimental to the blade tip. This work simulates the flow and heat transfer through the clearance gap for base line flat tip and cavity tip geometries with a stationary and moving shroud. Various parameters were investigated to assess the possibility of minimizing tip heat flux and aerodynamic losses. Those parameters include: 1) Cavity depth-to-width ratio, 2) Clearance-to-width ratio, 3) Different shroud speeds. The Computational Fluid Dynamics (CFD) code ANSYS Fluent was used to perform the calculations. Turbulence was modeled using Spalart-Allmaras (SA) model which was available in Fluent and the Reynolds number investigated is 15,000 which is based on inlet velocity and cavity height. Areas of high heat transfer rate were identified on the blade tip and the change of gas leakage for different tip treatments were examined. Also, the effect of tip injection on tip desensitization was assessed for four different jet blowing ratios (0.5, 1.0, 2.0, and 3.0), three different jet angles (30°, 90°, and 150°), and three different jet locations (Camber Line (CL), Pressure Side (PS), and Suction Side (SS)). It is shown that injecting air to the tip gap region always reduces the aerodynamic loss across the tip due to leakage flow. Higher blowing ratios are more effective in reducing the mass flow rate through the tip gap. One of the finding of the present study shows that blowing ratio has the highest effect on the flow in the region compared to the other two parameters examined (jet angle and jet location). The present study shows that a jet at lower blowing ratios such as M=0.5 and M=1.0 reduces heat flux to the surface by reducing the heat transfer coefficient. However, at higher velocities such as M=2.0 and M=3.0 cause more disturbance in the jet downstream and increase the heat transfer rates and are detrimental for the blade. It is shown that blowing air at a shallow angle like 30° reduces the heat transfer coefficient values more effectively in comparison with a more steeper angle like 90°. Blowing in the opposite direction of the mainstream flow does not improve the heat transfer coefficient significantly. Finally, it was found out that jets at pressure side are more effective in reducing heat transfer values of the cavity wall in comparison with central and suction side jets.
Book Synopsis Gas Turbine Tip Region Leakage Flow and Heat Transfer by :
Download or read book Gas Turbine Tip Region Leakage Flow and Heat Transfer written by and published by . This book was released on 2005 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: New, detailed flow field measurements and high resolution Nusselt number (Nu) distributions are presented for a very large low-speed cascade representative of a high-pressure turbine rotor blade with turning of 110 degrees and blade chord of 1.0 m. Data was obtained for tip leakage and passage secondary flow at a Reynolds number of 4.0 x 1 %%, based on exit velocity and blade axial chord. Tip clearance levels ranged from 0% to 1.68% of blade span (0% to 3% of blade chord). The relative motion between the casing and the blade tip was simulated using a motor-driven moving belt system. Particle Image Velocimetry (PIV) was used to obtain flow field maps of several planes parallel and normal to the tip surface within the tip gap, and adjacent passage flow. Secondary flow was measured at planes normal to the blade exit angle at locations upstream and downstream of the trailing edge. An infrared camera made detailed temperature measurements on a constant heat flux tip surface. The interaction between the tip leakage vortex and passage vortex is clearly defined, revealing the dominant effect of the tip leakage flow on the tip endwall secondary flow. A reduction in the magnitude of the under-tip flow near the endwall due to the moving wall is observed and the effect on the tip leakage vortex examined. The moving belt endwall significantly shifts the region of high Nu distribution and reduces the overall averaged Nu on the tip surface by up to 13.3%. The addition of a suction side squealer tip significantly reduced local tip heat transfer and resulted in a 32% reduction in averaged Nu.
Book Synopsis Gas Turbine Tip Leakage Flow and Heat Transfer by : Pepe Palafox
Download or read book Gas Turbine Tip Leakage Flow and Heat Transfer written by Pepe Palafox and published by . This book was released on 2006 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Investigation of Using Tip Leakage Interrupter and Blade Slit to Mitigate Aerodynamic Losses in Axial Turbine Stage by : Veerandra Chakkarava Andichamy
Download or read book An Investigation of Using Tip Leakage Interrupter and Blade Slit to Mitigate Aerodynamic Losses in Axial Turbine Stage written by Veerandra Chakkarava Andichamy and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow field near the blade tip in a turbine stage is highly three dimensional with multiple vortical systems. They are a major source of energy loss in the turbine passage. The current study uses two new concepts called Blade Slit and Tip Leakage Interrupters (TLI) to mitigate some of the adverse effects of these vortical structures and improve the efficiency of an axial turbine stage.A Blade Slit is a small cut (slit) is made on the blade to facilitate high momentum fluid on the pressure side of the blade to pass through the blade and reach the suction side. This flow, on reaching the suction side, acts as a jet and interacts with the local vortical structures. The slit, when strategically placed, facilitates the jet to impinge the core of the low momentum vortex systems. This interaction effectively reduces the strength of these vortices and thereby reduces the aerodynamic loss in the turbine passage.TLIs are a system of vortex generators attached to the suction side of the turbine blade tip. They operate by inducing controlled vortical structures originating from strategically shaped/oriented multiple and sub-miniature vortex generators. They also act as a flow obstruction for the existing vortex system in the passage. When properly placed on the blade surface, these TLIs interact with the tip leakage vortex and passage vortex present in the turbine passage. This interaction reduces the damaging aerodynamic effects of these vortices. Both of these designs are developed as proof of concepts and their aerodynamic loss mitigation characteristics are studied in this thesis. In this investigation, the design parameters associated with these concepts such as their local orientation and location on the blade surface are varied. The influence of these design parameters over the loss reduction properties of the Blade Slit and TLI is studied. Both of these designs are experimentally and computationally analyzed in this study. The experiments in this study are carried out in a single-stage, low-speed axial turbine facility, while the computational work is performed using one to one computational model of the experimental configuration. The results from the Blade Slit design show that not all the fluid exiting the slit imparts high momentum to the vortical structures. Some of these fluids interact with the main flow on the suction side and creates additional aerodynamic losses in the turbine passage. In the case of TLI, the orientation of TLI with respect to the local blade surface determines the nature of interaction between the TLI and the vortical structures in the passage and hence its ability to reduce the aerodynamic losses. The study draws conclusions about the significance of individual design parameters associated with Blade Slit and TLI. It also shows that significant loss reduction might be possible with simple modifications to the blade geometry. All the modifications on the blade should be limited to the highly vortical region near the blade tip. Any modification which changes the flow properties of the main flow results in an additional aerodynamic loss in the turbine passage. In addition to analyzing Blade Slit and TLI design, the aerodynamic influence of blade tip modifications and the blade tip clearances in a turbine passage have also been studied.
Book Synopsis Performance Evaluation of a Two-stage Axial-flow Turbine for Two Values of Tip Clearance by : Milton G. Kofskey
Download or read book Performance Evaluation of a Two-stage Axial-flow Turbine for Two Values of Tip Clearance written by Milton G. Kofskey and published by . This book was released on 1968 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbine Aerodynamics by : Ronald H. Aungier
Download or read book Turbine Aerodynamics written by Ronald H. Aungier and published by American Society of Mechanical Engineers. This book was released on 2006 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a thorough description of actual, working aerodynamic design and analysis systems, for both axial-flow and radial-flow turbines. It describes the basic fluid dynamic and thermodynamic principles, empirical models and numerical methods used for the full range of procedures and analytical tools that an engineer needs for virtually any type of aerodynamic design or analysis activity for both types of turbine. The book includes sufficient detail for readers to implement all or part of the systems. The author provides practical and effective design strategies for applying both turbine types, which are illustrated by design examples. Comparisons with experimental results are included to demonstrate the prediction accuracy to be expected. This book is intended for practicing engineers concerned with the design and development of turbines and related machinery.
