Adiabatic and conjugate cooling effectiveness analysis of a new hybrid scheme

Abstract The adiabatic film cooling effectiveness and flow characteristics for a new hybrid scheme and a circular hole were investigated numerically. The new film cooling scheme is proposed for high temperature gas turbine engines in aerospace and electric power generation applications. The hybrid scheme included two consecutive film hole configurations with interior bending to direct the secondary flow in stream-wise direction. The film cooling performance with flow-field analysis for the hybrid scheme and the circular hole were investigated at blowing ratio of 0.5, 1.0 and 2.0 for 0.95 density ratios. The results showed that the hybrid scheme provided a superior local and average film cooling effectiveness performance that was enhanced for further increase in blowing ratio. Moreover, the new scheme enhanced the downstream overall area-average film cooling effectiveness compared to the circular film hole. Subsequently, film cooling and conjugate heat transfer were combined to investigate the cooling effectiveness of the hybrid scheme at Br = 0.5 and 1.0 for different flow arrangements, specifically: parallel flow and jet impingement with two different gap heights (0.8  d and 1.2  d ). The hybrid scheme presented a high cooling effectiveness by combining film cooling and conjugate heat transfer. The jet impingement configuration enhanced the upstream flow circulation which has a significant effect on convective heat transfer. Furthermore, a large gap height with jet impingement enhanced the downstream cooling effectiveness compared to other conjugate and adiabatic cases studied. The conjugate configuration with large gap height provided the highest overall laterally averaged cooling effectiveness compared to other conjugate and adiabatic cases studied. As a result, the hybrid scheme is able to minimize the cooling flow rate significantly since it provided superior cooling effectiveness at a lesser secondary flow rate, thus increasing overall engine efficiency.

[1]  Y. Okita,et al.  Film Effectiveness Performance of an Arrowhead-Shaped Film-Cooling Hole Geometry , 2007 .

[2]  İbrahim Koç.  Experimental and numerical investigation of film cooling effectiveness for rectangular injection holes , 2007 .

[3]  H. Cho,et al.  Local Heat/Mass Transfer With Various Rib Arrangements in Impingement/Effusion Cooling System With Crossflow (2004-GT-53686) , 2004 .

[4]  Sigmar Wittig,et al.  Free-Stream Turbulence Effects on Film Cooling With Shaped Holes , 2002 .

[5]  Jing Ren,et al.  Systematic Investigation on Conjugate Heat Transfer Rates of Film Cooling Configurations , 2005 .

[6]  Jr-Ming Miao,et al.  Numerical approach to hole shape effect on film cooling effectiveness over flat plate including internal impingement cooling chamber , 2006 .

[7]  B. Jubran,et al.  Film cooling effectiveness from trenched shaped and compound holes , 2008 .

[8]  Jane E. Sargison,et al.  A converging slot-hole film-cooling geometry - Part 1: Low-speed flat-plate heat transfer and loss , 2002 .

[9]  M. Ghorab,et al.  Simulation of a Multi-Stage Cooling Scheme for Gas Turbine Engines: Part I , 2007 .

[10]  F. Durst,et al.  Monte Carlo simulation of a nephelometric experiment , 2001 .

[11]  B. Sundén,et al.  A numerical,and experimental investigation of the slot film-cooling jet with various angles , 2005 .

[12]  James D. Heidmann,et al.  Conjugate Heat Transfer Effects on a Realistic Film-Cooled Turbine Vane , 2003 .

[13]  Minking K. Chyu,et al.  Film Cooling Effectiveness and Heat Transfer Coefficient Distributions Around Diffusion Shaped Holes , 2002 .

[14]  Mohamed Gaber Ghorab.  Experimental investigation of advanced film cooling schemes for a gas turbine blade , 2009 .

[15]  Xianchang Li,et al.  Effects of Various Modeling Schemes on Mist Film Cooling Simulation , 2007 .

[16]  Hyung Hee Cho,et al.  Enhancement of Film Cooling Performance Using a Shaped Film Cooling Hole with Compound Angle Injection , 2001 .

[17]  R. J. Goldstein,et al.  Effects of hole geometry and density on three-dimensional film cooling , 1974 .

[18]  A. Khanicheh,et al.  Film Effectiveness Downstream of a Row of Compound Angle Film Holes , 2005 .

[19]  Zdzislaw Mazur,et al.  Analysis of conjugate heat transfer of a gas turbine first stage nozzle , 2006 .

[20]  Dieter Bohn,et al.  Double-Jet Ejection of Cooling Air for Improved Film Cooling , 2007 .

[21]  Achmed Schulz,et al.  Assessment of Various Film-Cooling Configurations Including Shaped and Compound Angle Holes Based on Large-Scale Experiments , 2003 .

[22]  Srinath V. Ekkad,et al.  Film cooling from a row of holes supplemented with anti vortex holes , 2007 .

[23]  P. Jiang,et al.  Conjugate heat transfer analysis of film cooling flows , 2006 .

[24]  Dieter Bohn,et al.  Improvement of a Film-Cooled Blade by Application of the Conjugate Calculation Technique , 2006 .

[25]  Srinath V. Ekkad,et al.  A Novel Antivortex Turbine Film-Cooling Hole Concept , 2008 .