Blade Tip Heat Transfer and Aerodynamics in a Large Scale Turbine Cascade With Moving Endwall

High resolution Nusselt number distributions were measured on the blade tip surface of a large, 1.0 m chord, low-speed cascade representative of a high-pressure turbine. Data were obtained at a Reynolds number of 4.0×105 based on exit velocity and blade axial chord. Tip clearance levels ranged from 0.56% to 1.68% design span or equally from 1% to 3% of the blade chord. An infrared camera, looking through the hollow blade, made detailed temperature measurements on a constant heat flux tip surface. The relative motion between the endwall and the blade tip was simulated by a moving belt. The moving belt endwall significantly shifts the region of high Nusselt number distribution and reduces the overall averaged Nusselt number 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 Nusselt number. Analysis of pressure measurements on the blade airfoil surface and tip surface along with particle image velocimetry velocity flow fields in the gap gives an understanding of the heat transfer mechanism.

[1]  D. G. Gregory-Smith,et al.  Secondary Flow Measurements in a Turbine Cascade With High Inlet Turbulence , 1992 .

[2]  Terry V. Jones,et al.  An Investigation on Turbine Tip and Shroud Heat Transfer , 2002 .

[3]  A. Yamamoto,et al.  Interaction Mechanisms Between Tip Leakage Flow and the Passage Vortex in a Linear Turbine Rotor Cascade , 1988 .

[4]  S. A. Sjolander,et al.  Effects of Simulated Rotation on Tip Leakage in a Planar Cascade of Turbine Blades: Part I — Tip Gap Flow , 1991 .

[5]  J. E. LaGraff,et al.  PIV Maps of Tip Leakage and Secondary Flow Fields on a Low Speed Turbine Blade Cascade With Moving Endwall , 2005 .

[6]  D. E. Metzger,et al.  HEAT TRANSFER AT THE TIP OF AN UNSHROUDED TURBINE BLADE , 1982 .

[7]  Steen A. Sjolander,et al.  Prediction of Tip-Leakage Losses in Axial Turbines , 1990 .

[8]  Je-Chin Han,et al.  Heat Transfer and Pressure Distributions on a Gas Turbine Blade Tip , 2000 .

[9]  P. R. Dodge,et al.  Rotor-Tip Leakage: Part I—Basic Methodology , 1982 .

[10]  Ali Ameri,et al.  Heat Transfer and Flow on the First-Stage Blade Tip of a Power Generation Gas Turbine: Part 1—Experimental Results , 2000 .

[11]  A. Yamamoto,et al.  Endwall Flow/Loss Mechanisms in a Linear Turbine Cascade With Blade Tip Clearance , 1989 .

[12]  Howard P. Hodson,et al.  The Effect of Blade Tip Geometry on the Tip Leakage Flow in Axial Turbine Cascades , 1991 .

[13]  Roger W. Ainsworth,et al.  An investigation of the heat transfer and static pressure on the over-tip casing wall of an axial turbine operating at engine representative flow conditions. (II). Time-resolved results , 2004 .

[14]  Richard J Goldstein,et al.  Effect of Endwall Motion on Blade Tip Heat Transfer , 2003 .

[15]  Jeffery P. Bindon,et al.  Pressure Distributions in the Tip Clearance Region of an Unshrouded Axial Turbine as Affecting the Problem of Tip Burnout , 1987 .

[16]  Steen A. Sjolander,et al.  Effects of Simulated Rotation on Tip Leakage in a Planar Cascade of Turbine Blades: Part II — Downstream Flow Field and Blade Loading , 1991 .

[17]  Minking K. Chyu,et al.  Heat Transfer in the Tip Region of Grooved Turbine Blades , 1989 .

[18]  John Moore,et al.  Tip leakage flow in a linear turbine cascade , 1987 .

[19]  J. P. Bindon,et al.  The measurement and formation of tip clearance loss , 1989 .