Effect of a Cutback Squealer and Cavity Depth on Film-Cooling Effectiveness on a Gas Turbine Blade Tip

Film-cooling effectiveness from shaped holes on the near tip pressure side and cylindrical holes on the squealer cavity floor is investigated. The pressure side squealer rim wall is cut near the trailing edge to allow the accumulated coolant in the cavity to escape and cool the tip trailing edge. Effects of varying blowing ratios and squealer cavity depth are also examined on film-cooling effectiveness. The film-cooling effectiveness distributions are measured on the blade tip, near tip pressure side and the inner pressure side and suction side rim walls using pressure sensitive paint technique. The internal coolant-supply passages of the squealer tipped blade are modeled similar to those in the GE-E 3 rotor blade with two separate serpentine loops supplying coolant to the film-cooling holes. Two rows of cylindrical film-cooling holes are arranged offset to the suction side profile and along the camber line on the tip. Another row of shaped film-cooling holes is arranged along the pressure side just below the tip. The average blowing ratio of the cooling gas is controlled to be 0.5, 1.0, 1.5, and 2.0. A five-bladed linear cascade in a blow down facility with a tip gap clearance of 1.5% is used to perform the experiments. The free-stream Reynolds number, based on the axial chord length and the exit velocity, was 1,480,000 and the inlet and exit Mach numbers were 0.23 and 0.65, respectively. A blowing ratio of 1.0 is found to give best results on the pressure side, whereas the tip surfaces forming the squealer cavity give best results for M=2. Results show high film-cooling effectiveness magnitudes near the trailing edge of the blade tip due to coolant accumulation from upstream holes in the tip cavity. A squealer depth with a recess of 2.1 mm causes the average effectiveness magnitudes to decrease slightly as compared to a squealer depth of 4.2 mm.

[1]  Srinath V. Ekkad,et al.  Numerical Simulation of Flow and Heat Transfer Past a Turbine Blade With a Squealer-Tip , 2002 .

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

[3]  Srinath V. Ekkad,et al.  Numerical Simulation of Film Cooling on the Tip of a Gas Turbine Blade , 2002 .

[4]  Hyung Hee Cho,et al.  Local Heat/Mass Transfer Characteristics on a Rotating Blade With Flat Tip in Low-Speed Annular Cascade—Part I: Near-Tip Surface , 2006 .

[5]  P. Jin,et al.  Local Mass and Heat Transfer on a Turbine Blade Tip , 2003 .

[6]  Karen A. Thole,et al.  Predictions of Cooling From Dirt Purge Holes Along the Tip of a Turbine Blade , 2003 .

[7]  Je-Chin Han,et al.  Heat Transfer Coefficient and Film-Cooling Effectiveness on the Squealer Tip of a Gas Turbine Blade , 2002 .

[8]  Je-Chin Han,et al.  Heat Transfer Coefficient on the Squealer Tip and Near Squealer Tip Regions of a Gas Turbine Blade , 2002 .

[9]  Richard J Goldstein,et al.  Effects of Tip Geometry and Tip Clearance on the Mass/Heat Transfer From a Large-Scale Gas Turbine Blade , 2003 .

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

[11]  Je-Chin Han,et al.  Heat Transfer Coefficients on the Squealer Tip and Near-Tip Regions of a Gas Turbine Blade With Single or Double Squealer , 2003 .

[12]  D. E. Metzger,et al.  Heat Transfer and Effectiveness on Film Cooled Turbine Blade Tip Models , 1995 .

[13]  F. J. Cunha,et al.  Cooling the tip of a turbine blade using pressure side holes - Part 1: Adiabatic effectiveness measurements , 2004 .

[14]  Charles W. Haldeman,et al.  Heat-Flux Measurements and Predictions for the Blade Tip Region of a High-Pressure Turbine , 2006 .

[15]  Ali Ameri,et al.  Effects of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficiency in Axial Turbines , 1998 .

[16]  Ali Ameri,et al.  Effects of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficiency in Axial Turbines , 1998 .

[17]  Y. W. Kim,et al.  Darryl E. Metzger Memorial Session Paper: A Summary of the Cooled Turbine Blade Tip Heat Transfer and Film Effectiveness Investigations Performed by Dr. D. E. Metzger , 1995 .

[18]  D. G. Cherry,et al.  Energy efficient engine. Low pressure turbine test hardware detailed design report , 1982 .

[19]  Karen A. Thole,et al.  Cooling the Tip of a Turbine Blade Using Pressure Side Holes—Part I: Adiabatic Effectiveness Measurements , 2005 .

[20]  Je-Chin Han,et al.  Detailed heat transfer coefficient distributions on a large-scale gas turbine blade tip , 2001 .

[21]  Je-Chin Han,et al.  Heat transfer coefficients on the squealer tip and near squealer tip regions of a gas turbine blade , 2003 .

[22]  Jeremy Clyde Bailey,et al.  Effect of Squealer Cavity Depth and Oxidation on Turbine Blade Tip Heat Transfer , 2001 .

[23]  Je-Chin Han,et al.  Heat Transfer and Flow on the Squealer Tip of a Gas Turbine Blade , 2000 .

[24]  Je-Chin Han,et al.  Film-Cooling Effectiveness on Squealer Rim Walls and Squealer Cavity Floor of a Gas Turbine Blade Tip Using Pressure Sensitive Paint , 2005 .

[25]  Richard J Goldstein,et al.  Local Mass/Heat Transfer on Turbine Blade Near-Tip Surfaces , 2003 .

[26]  Srinath V. Ekkad,et al.  Effect of Blade Tip Geometry on Tip Flow and Heat Transfer for a Blade in a Low-Speed Cascade (2003-GT-38176) , 2004 .

[27]  Srinath V. Ekkad,et al.  Flow and Heat Transfer Predictions for a Flat-Tip Turbine Blade , 2002 .

[28]  J. P. Downs,et al.  A SUMMARY OF THE COOLED TURBINE BLADE TIP HEAT TRANSFER AND FILM EFFECTIVENESS INVESTIGATIONS PERFORMED BY DR.D.E.METZGER , 1994 .

[29]  Michael G. Dunn,et al.  Turbine Tip and Shroud Heat Transfer , 1991 .

[30]  Je-Chin Han,et al.  Numerical Prediction of Film Cooling and Heat Transfer With Different Film-Hole Arrangements on the Plane and Squealer Tip of a Gas Turbine Blade , 2004 .

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

[32]  Je-Chin Han,et al.  Heat Transfer Coefficients and Film-Cooling Effectiveness on a Gas Turbine Blade Tip , 2003 .

[33]  Je-Chin Han,et al.  Effect of Squealer Geometry Arrangement on a Gas Turbine Blade Tip Heat Transfer , 2002 .

[34]  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 .

[35]  A. A. Ameri,et al.  Heat Transfer and Flow on the First-Stage Blade Tip of a Power Generation Gas Turbine: Part 2—Simulation Results , 2000 .

[36]  Je-Chin Han,et al.  Heat-Transfer Coefficients of a Turbine Blade-Tip and Near-Tip Regions , 2002 .

[37]  Je-Chin Han,et al.  Heat Transfer Coefficient and Film-Cooling Effectiveness on a Gas Turbine Blade Tip , 2002 .

[38]  Hugh W. Coleman,et al.  Experimentation and Uncertainty Analysis for Engineers , 1989 .

[39]  J. Bell,et al.  Pressure-sensitive paint in aerodynamic testing , 1993 .

[40]  Charles W. Haldeman,et al.  Time-Averaged Heat Flux for a Recessed Tip, Lip, and Platform of a Transonic Turbine Blade , 2000 .

[41]  Je-Chin Han,et al.  Heat Transfer Coefficients and Film Cooling Effectiveness on the Squealer Tip of a Gas Turbine Blade , 2003 .

[42]  H. Cho,et al.  Local Heat/Mass Transfer Characteristics on a Rotating Blade With Flat Tip in a Low-Speed Annular Cascade—Part II: Tip and Shroud , 2006 .

[43]  Je-Chin Han,et al.  Film-Cooling Effectiveness on a Gas Turbine Blade Tip Using Pressure-Sensitive Paint , 2005 .

[44]  D. Rigby,et al.  A Numerical Analysis of Heat Transfer and Effectiveness on Film Cooled Turbine Blade Tip Models , 1999 .

[45]  F. J. Cunha,et al.  Cooling the Tip of a Turbine Blade Using Pressure Side Holes—Part II: Heat Transfer Measurements , 2005 .

[46]  Je-Chin Han,et al.  Assessment of Steady State PSP, TSP, and IR Measurement Techniques for Flat Plate Film Cooling , 2005 .