Heat Transfer Coefficients and Film-Cooling Effectiveness on a Gas Turbine Blade Tip
01 Jun 2003-Journal of Heat Transfer-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 125, Iss: 3, pp 494-502
TL;DR: In this article, the detailed distributions of heat transfer coefficient and film cooling effectiveness on a gas turbine blade tip were measured using a hue detection based transient liquid crystals technique on a five-bladed linear cascade with blow-down facility.
Abstract: The detailed distributions of heat transfer coefficient and film cooling effectiveness on a gas turbine blade tip were measured using a hue detection based transient liquid crystals technique. Tests were performed on a five-bladed linear cascade with blow-down facility. The Reynolds number based on cascade exit velocity and axial chord length was 1.1 × 10 6 and the total turning angle of the blade was 97. 7°. The overall pressure ratio was 1.2 and the inlet and exit Mach numbers were 0.25 and 0.59, respectively. The turbulence intensity level at the cascade inlet was 9. 7%. The blade model was equipped with a single row of film cooling holes at both the tip portion along the camber line and near the tip region of the pressure side. All measurements were made at the three different tip gap clearances of 1.0%, 1.5%, and 2.5% of blade span and the three blowing ratios of 0.5, 1, and 2
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TL;DR: In this article, the pressure sensitive paint (PSPSPP) mass transfer analogy is used to determine the film cooling effectiveness. But the PSP method is not suitable for high-temperature applications, as it does not take into account the conduction error in high thermal gradient regions near the hole.
Abstract: Film cooling is widely used to protect modern gas turbine blades and vanes from the ever increasing inlet temperatures. Film cooling involves a very complex turbulent flow-field, the characterization of which is necessary for reliable and economical design. Several experimental studies have focused on gas turbine blade, vane and end-wall film cooling over the past few decades. Measurements of heat transfer coefficients, film cooling effectiveness values and heat flux ratios using several different experimental methods have been reported. The emphasis of this current review is on the Pressure Sensitive Paint (PSP) mass transfer analogy to determine the film cooling effectiveness. The theoretical basis of the method is presented in detail. Important results in the open literature obtained using the PSP method are presented, discussing parametric effects of blowing ratio, momentum ratio, density ratio, hole shape, surface geometry, free-stream turbulence on flat plates, turbine blades, vanes and end-walls. The PSP method provides very high resolution contours of film cooling effectiveness, without being subject to the conduction error in high thermal gradient regions near the hole.
182 citations
TL;DR: In this paper, a two-dimensional model of a first stage gas turbine rotor blade with a profile of the GE-E 3 aircraft gas turbine engine rotor blade was used to measure heat transfer coefficients and film cooling effectiveness.
Abstract: Experimental investigations were performed to measure the detailed heat transfer coefficients and film cooling effectiveness on the squealer tip of a gas turbine blade in a five-bladed linear cascade. The blade was a two-dimensional model of a first stage gas turbine rotor blade with a profile of the GE-E 3 aircraft gas turbine engine rotor blade. The test blade had a squealer (recessed) tip with a 4.22% recess. The blade model was equipped with a single row of film cooling holes on the pressure side near the tip region and the tip surface along the camber line. Hue detection based transient liquid crystals technique was used to measure heat transfer coefficients and film cooling effectiveness. All measurements were done for the three tip gap clearances of 1.0%, 1.5%, and 2.5% of blade span at the two blowing ratios of 1.0 and 2.0. The Reynolds number based on cascade exit velocity and axial chord length was 1.1×10 6 and the total turning angle of the blade was 97. 9 deg. The overall pressure ratio was 1.2 and the inlet and exit Mach numbers were 0.25 and 0.59, respectively. The turbulence intensity level at the cascade inlet was 9.7%. Results showed that the overall heat transfer coefficients increased with increasing tip gap clearance, but decreased with increasing blowing ratio. However, the overall film cooling effectiveness increased with increasing blowing ratio. Results also showed that the overall film cooling effectiveness increased but heat transfer coefficients decreased for the squealer tip when compared to the plane tip at the same tip gap clearance and blowing ratio conditions.
104 citations
TL;DR: The most important contributions on turbine blade cooling studies at Texas A&M University's Turbine Heat Transfer Laboratory from 1980 to 2004 are summarized in this article, where the focus is on the effect of rotation on rotor blade coolant passage heat transfer with rib turbulators, pin fins, dimples, and impinging jets.
Abstract: Gas turbines are used extensively for aircraft propulsion, land-based power generation, and industrial applications. Developments in turbine cooling technology play a critical role in increasing the thermal efficiency and power output of advanced high-temperature gas turbine engines. Gas turbine blades are cooled internally by passing the coolant through several rib-enhanced serpentine passages to remove heat conducted from the outside surface. External cooling of turbine blades by film cooling is achieved by injecting relatively cooler air from the internal coolant passages out of the blade surface to form a protective layer between the blade surface and hot gas-path flow. The most important research contributions on turbine blade cooling studies at Texas A&M University's Turbine Heat Transfer Laboratory from 1980 to 2004 are summarized. For turbine blade internal cooling, the focus is on the effect of rotation on rotor blade coolant passage heat transfer with rib turbulators, pin fins, dimples, and impinging jets. For turbine blade external cooling, the focus is on unsteady high freestream turbulence effects on film-cooling performance with a special emphasis on turbine blade edge region heat transfer and cooling problems.
101 citations
TL;DR: In this article, a literature survey of blade tip leakage flow and heat transfer, as well as research of external and internal cooling technologies, is presented, where the tip clearance gap is defined as the point where the complex tip leakage flows and local high heat loads prevail.
Abstract: Gas turbines are widely used for aircraft propulsion, land-base power generation, and other industrial applications like trains, marines, automobiles, etc. To satisfy the fast development of advanced gas turbines, the operating temperature must be increased to improve the thermal efficiency and output work of the gas turbine engine. However, the heat transferred to the turbine blade is substantially increased as the turbine inlet temperature is continuously increased. Thus, it is very important to cool the turbine blades for a long durability and safe operation. Cooling the blade must include cooling of the key regions being exposed to the hot gas. The blade tip region is such a critical area and is indeed difficult to cool. This results from the tip clearance gap where the complex tip leakage flow occurs and thereby local high heat loads prevail. This paper presents a literature survey of blade tip leakage flow and heat transfer, as well as research of external and internal cooling technologies. The pres...
100 citations
Cites background from "Heat Transfer Coefficients and Film..."
...Kwak and Han [81] measured heat transfer coefficient and film cooling effectiveness on the squealer tip of a gas turbine blade in a five-bladed linear cascade....
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...Kwak and Han [39] and Kwak et al. [40] conducted a series of measurements on the tip and near-tip region heat transfer coefficients of a turbine blade with flat or squealer tip, and the effects of rim location and height as well as tip clearance on heat transfer were measured....
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...Kwak and Han [82] also measured the distributions of heat transfer coefficient and film cooling effectiveness on a turbine blade tip....
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...Good agreement with experimental data of Ekkad and Han [113] was achieved....
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...Han et al. [60] analyzed numerically 3D flow fields near the tip region in an annular cascade with tip clearance and rotation and in a linear cascade with the validation of numerical results by flow visualization....
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TL;DR: In this article, the heat transfer coefficient distributions on a gas turbine squealer tip blade were measured using a hue detection based transient liquid crystals technique, and the results showed that the lower heat transfer coefficients on the blade tip and the shroud were significantly reduced.
Abstract: Detailed heat transfer coefficient distributions on a gas turbine squealer tip blade were measured using a hue detection based transient liquid crystals technique. The heat transfer coefficients on the shroud and near tip regions of the pressure and suction sides of a blade were also measured. Squealer rims were located along (a) the camber line, (b) the pressure side, (c) the suction side, (d) the pressure and suction sides, (e) the camber line and the pressure side, and (f) the camber line and the suction side, respectively. Tests were performed on a five-bladed linear cascade with a blow down facility. The Reynolds number based on the cascade exit velocity and the axial chord length of a blade was 1.1×106 and the overall pressure ratio was 1.2. Heat transfer measurements were taken at the three tip gap clearances of 1.0%, 1.5% and 2.5% of blade span. Results show that the heat transfer coefficients on the blade tip and the shroud were significantly reduced by using a squealer tip blade. Results also showed that a different squealer geometry arrangement changed the leakage flow path and resulted in different heat transfer coefficient distributions. The suction side squealer tip provided the lowest heat transfer coefficient on the blade tip and near tip regions compared to the other squealer geometry arrangements.Copyright © 2003 by ASME
97 citations
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01 Jan 1995
TL;DR: This chapter discusses the development of Hardware and Software for Computer Graphics, and the design methodology of User-Computer Dialogues, which led to the creation of the Simple Raster Graphics Package.
Abstract: 1 Introduction Image Processing as Picture Analysis The Advantages of Interactive Graphics Representative Uses of Computer Graphics Classification of Applications Development of Hardware and Software for Computer Graphics Conceptual Framework for Interactive Graphics 2 Programming in the Simple Raster Graphics Package (SRGP)/ Drawing with SRGP/ Basic Interaction Handling/ Raster Graphics Features/ Limitations of SRGP/ 3 Basic Raster Graphics Algorithms for Drawing 2d Primitives Overview Scan Converting Lines Scan Converting Circles Scan Convertiing Ellipses Filling Rectangles Fillign Polygons Filling Ellipse Arcs Pattern Filling Thick Primiives Line Style and Pen Style Clipping in a Raster World Clipping Lines Clipping Circles and Ellipses Clipping Polygons Generating Characters SRGP_copyPixel Antialiasing 4 Graphics Hardware Hardcopy Technologies Display Technologies Raster-Scan Display Systems The Video Controller Random-Scan Display Processor Input Devices for Operator Interaction Image Scanners 5 Geometrical Transformations 2D Transformations Homogeneous Coordinates and Matrix Representation of 2D Transformations Composition of 2D Transformations The Window-to-Viewport Transformation Efficiency Matrix Representation of 3D Transformations Composition of 3D Transformations Transformations as a Change in Coordinate System 6 Viewing in 3D Projections Specifying an Arbitrary 3D View Examples of 3D Viewing The Mathematics of Planar Geometric Projections Implementing Planar Geometric Projections Coordinate Systems 7 Object Hierarchy and Simple PHIGS (SPHIGS) Geometric Modeling Characteristics of Retained-Mode Graphics Packages Defining and Displaying Structures Modeling Transformations Hierarchical Structure Networks Matrix Composition in Display Traversal Appearance-Attribute Handling in Hierarchy Screen Updating and Rendering Modes Structure Network Editing for Dynamic Effects Interaction Additional Output Features Implementation Issues Optimizing Display of Hierarchical Models Limitations of Hierarchical Modeling in PHIGS Alternative Forms of Hierarchical Modeling 8 Input Devices, Interaction Techniques, and Interaction Tasks Interaction Hardware Basic Interaction Tasks Composite Interaction Tasks 9 Dialogue Design The Form and Content of User-Computer Dialogues User-Interfaces Styles Important Design Considerations Modes and Syntax Visual Design The Design Methodology 10 User Interface Software Basic Interaction-Handling Models Windows-Management Systems Output Handling in Window Systems Input Handling in Window Systems Interaction-Technique Toolkits User-Interface Management Systems 11 Representing Curves and Surfaces Polygon Meshes Parametric Cubic Curves Parametric Bicubic Surfaces Quadric Surfaces 12 Solid Modeling Representing Solids Regularized Boolean Set Operations Primitive Instancing Sweep Representations Boundary Representations Spatial-Partitioning Representations Constructive Solid Geometry Comparison of Representations User Interfaces for Solid Modeling 13 Achromatic and Colored Light Achromatic Light Chromatic Color Color Models for Raster Graphics Reproducing Color Using Color in Computer Graphics 14 The Quest for Visual Realism Why Realism? Fundamental Difficulties Rendering Techniques for Line Drawings Rendering Techniques for Shaded Images Improved Object Models Dynamics Stereopsis Improved Displays Interacting with Our Other Senses Aliasing and Antialiasing 15 Visible-Surface Determination Functions of Two Variables Techniques for Efficient Visible-Surface Determination Algorithms for Visible-Line Determination The z-Buffer Algorithm List-Priority Algorithms Scan-Line Algorithms Area-Subdivision Algorithms Algorithms for Octrees Algorithms for Curved Surfaces Visible-Surface Ray Tracing 16 Illumination And Shading Illumination Modeling Shading Models for Polygons Surface Detail Shadows Transparency Interobject Reflections Physically Based Illumination Models Extended Light Sources Spectral Sampling Improving the Camera Model Global Illumination Algorithms Recursive Ray Tracing Radiosity Methods The Rendering Pipeline 17 Image Manipulation and Storage What Is an Image? Filtering Image Processing Geometric Transformations of Images Multipass Transformations Image Compositing Mechanisms for Image Storage Special Effects with Images Summary 18 Advanced Raster Graphic Architecture Simple Raster-Display System Display-Processor Systems Standard Graphics Pipeline Introduction to Multiprocessing Pipeline Front-End Architecture Parallel Front-End Architectures Multiprocessor Rasterization Architectures Image-Parallel Rasterization Object-Parallel Rasterization Hybrid-Parallel Rasterization Enhanced Display Capabilities 19 Advanced Geometric and Raster Algorithms Clipping Scan-Converting Primitives Antialiasing The Special Problems of Text Filling Algorithms Making copyPixel Fast The Shape Data Structure and Shape Algebra Managing Windows with bitBlt Page Description Languages 20 Advanced Modeling Techniques Extensions of Previous Techniques Procedural Models Fractal Models Grammar-Based Models Particle Systems Volume Rendering Physically Based Modeling Special Models for Natural and Synthetic Objects Automating Object Placement 21 Animation Conventional and Computer-Assisted Animation Animation Languages Methods of Controlling Animation Basic Rules of Animation Problems Peculiar to Animation Appendix: Mathematics for Computer Graphics Vector Spaces and Affine Spaces Some Standard Constructions in Vector Spaces Dot Products and Distances Matrices Linear and Affine Transformations Eigenvalues and Eigenvectors Newton-Raphson Iteration for Root Finding Bibliography Index 0201848406T04062001
5,692 citations
TL;DR: In this article, the tip flow and heat transfer on the GE-E 3 first-stage turbine was simulated using the k-ω turbulence model and a two-dimensional cavity problem was calculated.
Abstract: Calculations were performed to simulate the tip flow and heat transfer on the GE-E 3 first-stage turbine, which represents a modern gas turbine blade geometry. Cases considered were a smooth tip, 2 percent recess, and 3 percent recess. In addition, a two-dimensional cavity problem was calculated. Good agreement with experimental results was obtained for the cavity calculations, demonstrating that the k-ω turbulence model used is capable of representing flows of the present type. In the rotor calculations, two dominant flow structures were shown to exist within the recess. Also areas of large heat transfer rate were identified on the blade tip and the mechanisms of heat transfer enhancement were discussed. No significant difference in adiabatic efficiency was observed for the three tip treatments investigated.
180 citations
TL;DR: In this paper, a combined experimental and computational study has 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 (> 100 MW).
Abstract: A combined experimental and computational study has 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 (> 100 MW). This paper is concerned with the design and execution of the experimental portion of the study, which represents the first reported investigation to obtain nearly full surface information on heat transfer coefficients within an environment that develops an appropriate pressure distribution about an airfoil blade tip and shroud model. A stationary blade cascade experiment has been run consisting of three airfoils, the center airfoil having a variable tip gap clearance. The airfoil models the aerodynamic tip section of a high-pressure turbine blade with inlet Mach number of 0.30, exit Mach number of 0.75, pressure ratio of 1.45, exit Reynolds number based on axial chord of 2.57 x 10{sup 6}, and total turning of about 110 degrees. A hue detection based liquid crystal method is used to obtain the detailed heat transfer coefficient distribution on the blade tip surface for flat, smooth tip surfaces with both sharp and rounded edges. The cascade inlet turbulence intensity level took on values of either 5 or 9%.more » The cascade also models the casing recess in the shroud surface ahead of the blade. Experimental results are shown for the pressure distribution measurements on the airfoil near the tip gap, on the blade tip surface, and on the opposite shroud surface. Tip surface heat transfer coefficient distributions are shown for sharp edge and rounded edge tip geometries at each of the inlet turbulence intensity levels.« less
154 citations
TL;DR: In this paper, the static and heat transfer coefficient of a first stage gas turbine rotor blade with a profile of a GE-E(sup 3) aircraft gas turbine engine rotor blade was investigated.
Abstract: Heat transfer coefficient and static pressure distributions are experimentally investigated on a gas turbine blade tip in a five-bladed stationary linear cascade. The blade is a 2-dimensional model of a first stage gas turbine rotor blade with a blade tip profile of a GE-E(sup 3) aircraft gas turbine engine rotor blade. The flow condition in the test cascade corresponds to an overall pressure ratio of 1.32 and exit Reynolds number based on axial chord of 1.1 x 10(exp 6). The middle 3-blade has a variable tip gap clearance. All measurements are made at three different tip gap clearances of about 1%, 1.5%, and 2.5% of the blade span. Heat transfer measurements are also made at two different turbulence intensity levels of 6.1 % and 9.7% at the cascade inlet. Static pressure measurements are made in the mid-span and the near-tip regions as well as on the shroud surface, opposite the blade tip surface. Detailed heat transfer coefficient distributions on the plane tip surface are measured using a transient liquid crystal technique. Results show various regions of high and low heat transfer coefficient on the tip surface. Tip clearance has a significant influence on local tip beat transfer coefficient distribution. Heat transfer coefficient also increases about 15-20% along the leakage flow path at higher turbulence intensity level of 9.7% over 6.1 %.
149 citations