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An Investigation Of Using Tip Leakage Interrupter And Blade Slit To Mitigate Aerodynamic Losses In Axial Turbine Stage
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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 Axial Turbine Loss Analysis and Efficiency Prediction Method by : Yong S. Hong
Download or read book Axial Turbine Loss Analysis and Efficiency Prediction Method written by Yong S. Hong and published by . This book was released on 1966 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method is presented to predict axial stage turbine efficiency using detailed aerodynamic component losses. Suitable computer programs were set up for the more time consuming portions of the calculations. Boundary layer theory plus empirical test data was used to obtain numerical values for the flow losses. The method was applied to typical Boeing turbine tests and stage efficiencies were compared with the measured values. Calculated and measured stage efficiencies agreed within plus or minus one percent in all cases. This achievement proved to be far superior to existing prediction methods which yielded efficiency accuracies ranging from 2 to 7 percent. Using the developed method, the performance of a given turbine stage can be optimized without spending an excessive amount of time for numerical calculations by evaluating various combination of aspect ratio, solidity, number of blades, trailing edge thickness, and rotor tip clearance. All the investigated cases were checked for only single stage axial turbines. The accuracy of the method for multi-stage application has yet to be verified by experiment. (Author).
Book Synopsis Effect of Rotor Tip Clearance on the Performance of a 5-inch Single Stage Axial Flow Turbine by : Donald E. Holeski
Download or read book Effect of Rotor Tip Clearance on the Performance of a 5-inch Single Stage Axial Flow Turbine written by Donald E. Holeski and published by . This book was released on 1969 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of the Effects of Low Reynolds Number Operation on the Performance of a Single-Stage Turbine with a Downstream Stator by : Robert E. Forrette
Download or read book Investigation of the Effects of Low Reynolds Number Operation on the Performance of a Single-Stage Turbine with a Downstream Stator written by Robert E. Forrette and published by . This book was released on 1959 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbine Blade Tip Design and Tip Clearance Treatment by : Tony Arts
Download or read book Turbine Blade Tip Design and Tip Clearance Treatment written by Tony Arts and published by . This book was released on 2004 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement and Prediction of Tip Leakage Losses in an Axial-flow Transonic Turbine by : M. Wehner
Download or read book Measurement and Prediction of Tip Leakage Losses in an Axial-flow Transonic Turbine written by M. Wehner and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine & Aeroengine Congress & Exhibition, Orlando, FL, Jun 2 - Jun 5, 1997.
Book Synopsis An Investigation Into Turbine Blade Tip Leakage Flows at High Speeds by : Zainab Jabbar Saleh
Download or read book An Investigation Into Turbine Blade Tip Leakage Flows at High Speeds written by Zainab Jabbar Saleh and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbine Blade Tip Leakage Loss Investigation by : Ayman Abou-Salem
Download or read book Turbine Blade Tip Leakage Loss Investigation written by Ayman Abou-Salem and published by . This book was released on 2016 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Blade Tip Geometry on the Tip Leakage Flow in Axial Turbine Cascades by : F. J. G. Heyes
Download or read book Effect of Blade Tip Geometry on the Tip Leakage Flow in Axial Turbine Cascades written by F. J. G. Heyes and published by . This book was released on 1991 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most critical components of gas turbine engines, rotor blade tip and casing, is exposed to high thermal load. It is a significant challenge to the designer to protect the turbine material from this severe situation. Leakage flow over the blade tip is also one of the important issues to improve the turbine performance. To understand the detailed phenomena and natures of the heat transfer on the turbine blade tip and casing in association with the tip leakage flow under actual turbine operating conditions, both steady and unsteady simulations have been conducted. A single stage gas turbine engine was modeled and simulated using commercial CFD solver ANSYS CFX R.11. The modeled turbine stage has 30 vanes and 60 blades with a pressure ratio of 3.2 and a rotational speed of 9500 rpm. The predicted isentropic Mach number and adiabatic wall temperature on the casing showed good agreement with available experimental data under the close operating condition. Through the steady simulations, the typical tip leakage flow structures and heat transfer rate distributions were analyzed. The tip leakage flow separates and recirculates just around the pressure side edge of the blade tip. This coverage of the recirculating flow results in low heat transfer rates on the tip surface. The leakage flow then reattaches on the tip surface beyond the flow separation zone. This flow reattachment has shown enhanced heat transfer rates on the tip. The leakage flow interaction with the reverse cross flow, induced by relative casing motion, is found to have significant effect on the casing heat transfer rate distribution. Critical region of high heat transfer rate on the casing exists near the blade tip leading edge and along the pressure side edge. Whereas near the suction side the heat transfer rates are relatively low due to the coverage of the reverse cross flow. The effects of the tip clearance heights and rotor rotating speeds were also investigated. The region of recirculating flow increases with the increase of clearance heights. The flow incidence changes and the casing relative motion is enhanced with higher rotation speeds. As a result, the high heat transfer rate regions have been changed with these two parameters. Unsteady simulations have been performed to investigate time dependent behaviors of the leakage flow structures and heat transfer on the rotor casing and blade tip. The effects of different time steps, number of sub iteration and number of rotor vane passing were firstly examined. The periodicity of the tip leakage flow and heat transfer rate distribution is observed for each vane passing. The relative change in the position of the vane and the vane trailing edge shock alters the inlet flow conditions of the rotor part. It results in the periodic variations of the leakage flow structures and heat transfer rate distributions. The higher heat transfer rates were observed at the region where the trailing edge shock reached. The maximum amplitude of the pressure fluctuation in the tip region is about 20% of the averaged rotor inlet pressure. The maximum amplitude of the heat transfer rate fluctuation on the blade tip, caused by the unsteady leakage flow variations, reaches up to about 25% of the mean heat transfer rate. The effects of tip clearance heights and rotor speeds have also been analyzed and compared one with respect to others. Same typical patterns of leakage flow structures and heat transfer rate distribution can be obtained in both steady and unsteady simulations. However, steady simulation underpredicted the highest heat transfer rate. Because it couldn't capture the critical local high heat transfer phenomena caused by the unsteady stator-rotor interactions.
Book Synopsis Turbine Tip Clearance Loss Mechanisms by : Steven Andrew Mazur
Download or read book Turbine Tip Clearance Loss Mechanisms written by Steven Andrew Mazur and published by . This book was released on 2013 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional numerical simulations (RANS and URANS) were used to assess the impact of two specific design features, and of aspects of the actual turbine environment, on turbine blade tip loss. The calculations were carried out for a subsonic high pressure turbine stage. The loss mechanism examined is that due to tip clearance vortex mixing. The effects examined were three-dimensional blade stacking, downstream transition duct geometry, and unsteadiness due to an upstream nozzle guide vane. Tip leakage loss changes due to three-dimensional blade stacking (bowing or reverse bowing) are verified to be associated with changes in the magnitude of blade tip loading, which create differences in the leakage flow exit velocities. The effect of a downstream diffusing transition duct on tip leakage losses is small; there was a 3.6% increase in tip leakage loss for a 65% increase in duct exit-to-inlet area ratio compared to a constant area duct. For unsteadiness arising from an upstream nozzle guide vane, it is shown that substantial temporal fluctuations in vortex core velocity and loss generation exist. However, the time average tip leakage loss differed less than 5% from the tip leakage loss calculated on a steady flow basis. Based on the computations, the mechanism for tip leakage vortex loss in the three different situations examined appears to be similar to that which is seen for an isolated turbine blade.
Book Synopsis Analysis of the Tip Leakage Flow Field in an Axial Turbine by : C. Scott Anderson
Download or read book Analysis of the Tip Leakage Flow Field in an Axial Turbine written by C. Scott Anderson and published by . This book was released on 1999-06-01 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comparisons of experimental laser-Doppler-velocimetry measurements using the Naval Postgraduate School cold-flow turbine test rig were made with 3D viscous computational fluid dynamics flow solutions. The turbine tested was the first stage of the Pratt and Whitney designed High Pressure Fuel Turbopump for the Space Shuttle Main Engine. The laser anemometer was modified to incorporate a field stop, which acted as a spatial filter to limit reception of undesired blade reflections. The laser measurements were made in the endwall region of the test turbine, at three axial locations, and at three radial depths. For each location, absolute flow angle, axial and tangential velocity ratios, turbulence intensities and correlation coefficients were measured. The computational effort encompassed modeling a single blade passage of both the stator and the rotor and computing flow solutions of the stage using NASA software. Exit plane and endwall flow property profiles showed good agreement when compared with experimental data.
Book Synopsis The Development of Axial Turbine Leakage Loss for Two Profiled Tip Geometries Using Linear Cascade Data by : George Morphis
Download or read book The Development of Axial Turbine Leakage Loss for Two Profiled Tip Geometries Using Linear Cascade Data written by George Morphis and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: To assess the possibility of tip clearance loss reduction and to explore the nature and origin of tip clearance loss, blade tip geometries that reduce the roughly 40 percent of total loss occurring within the gap were studied. The shapes investigated aimed at reducing or avoiding the gap separation bubble thought to contribute significantly to both internal gap loss and to the endwall mixing loss. It was found that radiusing and contouring the blade at gap inlet eliminated the separation bubble and reduced the internal gap loss but created a higher mixing loss to give almost unchanged overall loss coefficients when compared with the simple sharp-edged flat-tipped blade. The separation bubble does not therefore appear to influence the mixing loss. Using a method of assessing linear cascade experimental data as though it were a rotor with work transfer, one radiused geometry, contoured to shed radial flow into the gap and reduce the leakage mass flow, was found to have a significantly higher efficiency. This demonstrates the effectiveness of the data analysis method and that cascade loss coefficient alone or gap discharge coefficient cannot be used to evaluate tip clearance performance accurately. Contouring may ultimately lead to better rotor blade performances.
Book Synopsis Prediction of Tip-leakage Losses in Axial Turbines by : Metin I. Yaras
Download or read book Prediction of Tip-leakage Losses in Axial Turbines written by Metin I. Yaras and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Existing methods for predicting the tip-leakage losses in turbomachinery are based on a variety of assumptions, many of which have not been fully verified experimentally. Recently, several detailed experimental studies in turbine cascades have helped to clarify the physics of the flow and provide data on the evolution of the losses. The paper examines the assumptions underlying the prediction methods in the light of these data. An improved model for the losses is developed, using one of the existing models as the starting point.
Book Synopsis Investigation of Tip Losses for Axial Flow Fans by : W. B. Bryant
Download or read book Investigation of Tip Losses for Axial Flow Fans written by W. B. Bryant and published by . This book was released on 1943 with total page 250 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 Blade Tip Clearance Effect on the Performance and Flow Field of a Three Stage Axial Turbine by : Sharef Aly Abdel-Fattah
Download or read book Blade Tip Clearance Effect on the Performance and Flow Field of a Three Stage Axial Turbine written by Sharef Aly Abdel-Fattah and published by . This book was released on 2003 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
