The measurement and formation of tip clearance loss

doi:10.1115/1.3262264

Journal Article•DOI•

The measurement and formation of tip clearance loss

J. P. Bindon¹•Institutions (1)

01 Jul 1989-Journal of Turbomachinery-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 111, Iss: 3, pp 257-263

TL;DR: In this article, the tip clearance loss from the leading to trailing edge of a linear turbine cascade was measured and the contributions made by mixing, internal gap shear flow, and endwall/secondary flow were identified, separated, and quantified for the first time.

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Abstract: The detailed development of tip clearance loss from the leading to trailing edge of a linear turbine cascade was measured and the contributions made by mixing, internal gap shear flow, and endwall/secondary flow were identified, separated, and quantified for the first time

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Journal Article•DOI•

Turbine blade film cooling using psp technique

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Je-Chin Han¹, Akhilesh P. Rallabandi•Institutions (1)

Texas A&M University¹

07 Jun 2010-Frontiers in Heat and Mass Transfer

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.

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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.

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182 citations

Cites background from "The measurement and formation of ti..."

...Film cooling on the surface of the turbine blade / vane is further complicated by surface curvature, secondary flows such as tipleakage (Bindon (1989)) and horseshoe vortices (Goldstein and Spores (1988)) and unsteady wakes (Mayle (1991)). Effect of Surface Curvature. The results of Ito et al. (1978) and Schwarz et al. (1991) indicate that film cooling effectiveness is relatively subdued on the concave (pressure) side in comparison with the convex (suction side), with the flat plate effectiveness values lying in between. Lift-off occurs at a lower blowing ratio on the concave side. However, the curvature of the concave surface results in a reattachment of the lifted-off coolant on the pressure side, resulting in higher downstream effectiveness. Ethridge et al. (2001) studied the effect of coolant-to-mainstream density ratio on a vane with high curvature. Dittmar et al. (2002) studied different film cooling hole configurations on the suction (convex) side and concluded that shaped holes provide better coverage at higher blowing ratios by resisting jet penetration into the mainstream. Chen et al. (2001) observed an improvement in performance on the concave (pressure) surface due to using compound angled holes instead of simple angled holes at higher blowing ratios....
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...Film cooling on the surface of the turbine blade / vane is further complicated by surface curvature, secondary flows such as tipleakage (Bindon (1989)) and horseshoe vortices (Goldstein and Spores (1988)) and unsteady wakes (Mayle (1991)). Effect of Surface Curvature. The results of Ito et al. (1978) and Schwarz et al. (1991) indicate that film cooling effectiveness is relatively subdued on the concave (pressure) side in comparison with the convex (suction side), with the flat plate effectiveness values lying in between. Lift-off occurs at a lower blowing ratio on the concave side. However, the curvature of the concave surface results in a reattachment of the lifted-off coolant on the pressure side, resulting in higher downstream effectiveness. Ethridge et al. (2001) studied the effect of coolant-to-mainstream density ratio on a vane with high curvature....
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...Film cooling on the surface of the turbine blade / vane is further complicated by surface curvature, secondary flows such as tipleakage (Bindon (1989)) and horseshoe vortices (Goldstein and Spores (1988)) and unsteady wakes (Mayle (1991)). Effect of Surface Curvature. The results of Ito et al. (1978) and Schwarz et al. (1991) indicate that film cooling effectiveness is relatively subdued on the concave (pressure) side in comparison with the convex (suction side), with the flat plate effectiveness values lying in between....
[...]
...Film cooling on the surface of the turbine blade / vane is further complicated by surface curvature, secondary flows such as tipleakage (Bindon (1989)) and horseshoe vortices (Goldstein and Spores (1988)) and unsteady wakes (Mayle (1991))....
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...Film cooling on the surface of the turbine blade / vane is further complicated by surface curvature, secondary flows such as tipleakage (Bindon (1989)) and horseshoe vortices (Goldstein and Spores (1988)) and unsteady wakes (Mayle (1991)). Effect of Surface Curvature. The results of Ito et al. (1978) and Schwarz et al. (1991) indicate that film cooling effectiveness is relatively subdued on the concave (pressure) side in comparison with the convex (suction side), with the flat plate effectiveness values lying in between. Lift-off occurs at a lower blowing ratio on the concave side. However, the curvature of the concave surface results in a reattachment of the lifted-off coolant on the pressure side, resulting in higher downstream effectiveness. Ethridge et al. (2001) studied the effect of coolant-to-mainstream density ratio on a vane with high curvature. Dittmar et al. (2002) studied different film cooling hole configurations on the suction (convex) side and concluded that shaped holes provide better coverage at higher blowing ratios by resisting jet penetration into the mainstream. Chen et al. (2001) observed an improvement in performance on the concave (pressure) surface due to using compound angled holes instead of simple angled holes at higher blowing ratios. An improvement was seen on the suction side at all blowing ratios. Effect of Secondary Flows and Unsteady Wakes. Garg (2000) used an implementation of the k − ω model to simulate a complete film cooled blade. The effects of tip leakage vortices and horseshoe vortices on the film coolant flow-path can be seen. These vortices result in an expansion of the film coolant on the pressure side, and a contraction of the coolant trace on the pressure side, a result confirmed by future tests (Mhetras et al. (2007) and Narzary et al....
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Journal Article•DOI•

Axial Turbine Blade Tips: Function, Design, and Durability

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Ronald Scott Bunker¹•Institutions (1)

General Electric¹

01 Mar 2006-Journal of Propulsion and Power

TL;DR: An overview of the science and technology involved in today's turbine engines is presented with specific focus on the critical rotational-to-stationary interfaces comprising axial turbine blade tips as discussed by the authors.

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Abstract: An overview of the science and technology involved in today's turbine engines is presented with specific focus on the critical rotational-to-stationary interfaces comprising axial turbine blade tips. The purpose is to provide a concise informative review of turbine blade tip functional, design, and durability issues. Neither a historical account nor a bibliography is presented. Attention is paid primarily to the most challenging blade tips in high-pressure, high-temperature gas turbine systems, although most of the science discussed applies equally well to blade tips in low-pressure turbines, as well as steam turbines. As such, a wide range of both aircraft engine and power generating turbine systems are considered. Basic functional requirements, turbine systems design aspects, and transient operational considerations affecting blade tips and affected by blade tips are discussed in light of the multidisciplinary tradeoffs involved in a successful design. The three dominant design philosophies for blade tips in practice today are presented with detailed examination of the aerodynamics, heat transfer, and cooling benefits and detractors. Finally, the in-service durability aspects of turbine blade tips are noted.

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158 citations

Journal Article•DOI•

Large-eddy simulation analysis of mechanisms for viscous losses in a turbomachinery tip-clearance flow

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Donghyun You¹, Meng Wang², Parviz Moin¹, Rajat Mittal³•Institutions (3)

Center for Turbulence Research¹, University of Notre Dame², George Washington University³

10 Sep 2007-Journal of Fluid Mechanics

TL;DR: In this paper, the tip-leakage flow in a turbomachinery cascade is studied using large-eddy simulation with particular emphasis on understanding the underlying mechanisms for viscous losses in the vicinity of the tip gap.

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Abstract: The tip-leakage flow in a turbomachinery cascade is studied using large-eddy simulation with particular emphasis on understanding the underlying mechanisms for viscous losses in the vicinity of the tip gap. Systematic and detailed analysis of the mean flow field and turbulence statistics has been made in a linear cascade with a moving endwall. Gross features of the tip-leakage vortex, tip-separation vortices, and blade wake have been revealed by investigating their revolutionary trajectories and mean velocity fields. The tip-leakage vortex is identified by regions of significant streamwise velocity deficit and high streamwise and pitchwise vorticity magnitudes. The tip-leakage vortex and the tip-leakage jet which is generated by the pressure difference between the pressure and suction sides of the blade tip are found to produce significant mean velocity gradients along the spanwise direction, leading to the production of vorticity and turbulent kinetic energy. The velocity gradients are the major causes for viscous losses in the cascade endwall region. The present analysis suggests that the endwall viscous losses can be alleviated by changing the direction of the tip-leakage flow such that the associated spanwise derivatives of the mean streamwise and pitchwise velocity components are reduced.

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156 citations

Cites result from "The measurement and formation of ti..."

...This trend is a reflection of the streamwise variation of the turbulence intensity and qualitatively quite similar to the experimental measurements in an axial cascade performed by Bindon (1989)....
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Journal Article•DOI•

A Review of Turbine Blade Tip Heat Transfer

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Ronald Scott Bunker¹•Institutions (1)

General Electric¹

25 Jan 2006-Annals of the New York Academy of Sciences

TL;DR: A review of the publicly available knowledge base concerning turbine blade tip heat transfer, from the early fundamental research which laid the foundations of knowledge, to current experimental and numerical studies utilizing engine‐scaled blade cascades and turbine rigs.

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Abstract: This paper presents a review of the publicly available knowledge base concerning turbine blade tip heat transfer, from the early fundamental research which laid the foundations of our knowledge, to current experimental and numerical studies utilizing engine-scaled blade cascades and turbine rigs. Focus is placed on high-pressure, high-temperature axial-turbine blade tips, which are prevalent in the majority of today's aircraft engines and power generating turbines. The state of our current understanding of turbine blade tip heat transfer is in the transitional phase between fundamentals supported by engine-based experience, and the ability to a priori correctly predict and efficiently design blade tips for engine service.

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151 citations

Journal Article•DOI•

Heat Transfer and Pressure Distributions on a Gas Turbine Blade Tip

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Gm. S. Azad¹, Je-Chin Han¹, Shuye Teng¹, Robert J. Boyle²•Institutions (2)

Texas A&M University¹, Glenn Research Center²

08 May 2000-Journal of Turbomachinery-transactions of The Asme

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.

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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 %.

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149 citations

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The measurement and formation of tip clearance loss

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