Aerothermal Impact of Stator-Rim Purge Flow and Rotor-Platform Film Cooling on a Transonic Turbine Stage

The sealing of the stator-rotor gap and rotor-platform cooling are vital to the safe operation of the high-pressure turbine. Contrary to the experience in subsonic turbines, this paper demonstrates the potential to improve the efficiency in transonic turbines at certain rim seal rates. Two types of cooling techniques were investigated: purge gas ejected out of the cavity between the stator rim and the rotor disk, and cooling at the rotor-platform. The tests were carried out in a full annular stage fed by a compression tube at M 2is = 1.1, Re = 1.1 × 10 6 , and at temperature ratios reproducing engine conditions. The stator outlet was instrumented to allow the aerothermal characterization of the purge flow. The rotor blade was heavily instrumented with fast-response pressure sensors and double-layer thin film gauges. The tests are coupled with numerical calculations performed using the ONERA's code ELSA. The results indicate that the stator-rotor interaction is significantly affected by the stator-rim seal, both in terms of heat transfer and pressure fluctuations. The flow exchange between the rotor disk cavity and the mainstream passage is mainly governed by the vane trailing edge shock patterns. The purge flow leads to the appearance of a large coherent vortex structure on the suction side of the blade, which enhances the overall heat transfer coefficient due to the blockage effect created. The impact of the platform cooling is observed to be restricted to the platform, with negligible effects on the blade suction side. The platform cooling results in a clear attenuation of pressure pulsations at some specific locations. The experimental and computational fluid dynamics results show an increase in the turbine performance compared with the no rim seal case. A detailed loss breakdown analysis helped to identify the shock loss as the major loss source. The presented results should help designers improve the protection of the rotor platform while minimizing the amount of coolant used.

[1]  S. Aoki,et al.  Film Cooling on a Gas Turbine Rotor Blade , 1991 .

[2]  Steven R. Manwaring,et al.  Endwall Cavity Flow Effects on Gaspath Aerodynamics in an Axial Flow Turbine: Part I — Experimental and Numerical Investigation , 2000 .

[3]  R. P. Roy,et al.  Pressure Field and Main-Stream Gas Ingestion in a Rotor-Stator Disk Cavity , 2001 .

[4]  Roger W. Ainsworth,et al.  Improved fast-response heat transfer instrumentation for short-duration wind tunnels , 2004 .

[5]  Jürgen F. Mayer,et al.  Simulation of the Interaction of Labyrinth Seal Leakage Flow and Main Flow in an Axial Turbine , 2002 .

[6]  L. Cambier,et al.  elsA - An efficient object-oriented solution to CFD complexity , 2002 .

[7]  Tony Arts,et al.  Investigation of the flow field downstream of a turbine trailing edge cooled nozzle guide vane , 1996 .

[8]  Reza S. Abhari,et al.  An Experimental Study of Film Cooling in a Rotating Transonic Turbine , 1994 .

[9]  R. P. Roy,et al.  Experiments on Gas Ingestion Through Axial-Flow Turbine Rim Seals , 2004 .

[10]  Je-Chin Han,et al.  Film-Cooling Effectiveness on a Rotating Blade Platform , 2006 .

[11]  Dieter Bohn,et al.  Experimental and Numerical Investigation of the Influence of Rotor Blades on Hot Gas Ingestion Into the Upstream Cavity of an Axial Turbine Stage , 2000 .

[12]  M. F. Blair.  An Experimental Study of Heat Transfer and Film Cooling on Large-Scale Turbine Endwalls , 1974 .

[13]  H. Schlichting.  Boundary Layer Theory , 1955 .

[14]  T. Yasa,et al.  Determination of the Efficiency of a Cooled HP Turbine in a Compression Tube Facility , 2006 .

[15]  T. Yasa,et al.  Accurate Turbine Inertia Measurement , 2007 .

[16]  R. P. Dring,et al.  An Experimental Investigation of Film Cooling on a Turbine Rotor Blade , 1980 .

[17]  Remo Marini,et al.  The Effect of Blade Leading Edge Platform Shape on Upstream Disk Cavity to Mainstream Flow Interaction of a High-Pressure Turbine Stage , 2007 .

[18]  S. P. Harasgama,et al.  Film Cooling Research on the Endwall of a Turbine Nozzle Guide Vane in a Short Duration Annular Cascade: Part 1—Experimental Technique and Results , 1992 .

[19]  Bruce V. Johnson,et al.  The Flow Field and Main Gas Ingestion in a Rotor-Stator Cavity , 2007 .

[20]  D. L. Rhode,et al.  Thermal Details in a Rotor–Stator Cavity at Engine Conditions With a Mainstream , 1992 .

[21]  Guillermo Paniagua,et al.  Novel 2D Transient Heat Conduction Calculation in a Cooled Rotor: Ventilation Preheating — Blowdown Flux , 2008 .

[22]  O. Popp,et al.  Steady and Unsteady Heat Transfer in a Transonic Film Cooled Turbine Cascade , 1999 .

[23]  Michael F. Blair.  An Experimental Study Heat Transfer in a Large-Scale Turbine Rotor Passage , 1994 .

[24]  U. Okapuu,et al.  A Mean Line Prediction Method for Axial Flow Turbine Efficiency , 1982 .

[25]  R. Dénos,et al.  Effect of the hub endwall cavity flow on the flow-field of a transonic high-pressure turbine , 2004 .

[26]  Jonathan Corpus Ong,et al.  The Effect of Coolant Injection on the Endwall Flow of a High Pressure Turbine , 2012 .

[27]  Je-Chin Han,et al.  Film-Cooling Effectiveness on a Rotating Turbine Platform Using Pressure Sensitive Paint Technique , 2010 .

[28]  John D. Denton,et al.  The Control of Shroud Leakage Loss by Reducing Circumferential Mixing , 2006 .

[29]  G. Gyarmathy,et al.  Flow Interaction From the Exit Cavity of an Axial Turbine Blade Row Labyrinth Seal , 2001 .

[30]  U. Ghia,et al.  High-Re solutions for incompressible flow using the Navier-Stokes equations and a multigrid method , 1982 .

[31]  J. Dunham,et al.  Improvements to the Ainley-Mathieson Method of Turbine Performance Prediction , 1970 .

[32]  S. H. Moustapha,et al.  Off-Design Performance of a Single-Stage Transonic Turbine , 1999 .

[33]  Michael F. Blair,et al.  An Experimental Study of Heat Transfer in a Large-Scale Turbine Rotor Passage , 1992 .

[34]  Nicholas J. Hills,et al.  Measurement and Analysis of Ingestion Through a Turbine Rim Seal , 2003 .

[35]  T. Yasa,et al.  Performance analysis of a transonic high-pressure turbine , 2007 .

[36]  Simon Hogg,et al.  Interaction of rim seal and annulus flows in an axial flow turbine , 2004 .

[37]  E. Laroche,et al.  A Combined Experimental and Numerical Investigation of the Flow in a Heated Rotor/Stator Cavity, With a Radial Inflow , 1999 .

[38]  U. P. Phadke,et al.  Aerodynamic aspects of the sealing of gas-turbine rotor-stator systems , 1988 .

[39]  Cengiz Camci,et al.  Mainstream Aerodynamic Effects Due to Wheelspace Coolant Injection in a High-Pressure Turbine Stage: Part I—Aerodynamic Measurements in the Stationary Frame , 2001 .

[40]  Je-Chin Han,et al.  Film Cooling Effectiveness on the Leading Edge of a Rotating Turbine Blade , 2004 .

[41]  H. Hodson,et al.  Heat Transfer Committee Best Paper of 1995 Award: Distribution of Film-Cooling Effectiveness on a Turbine Endwall Measured Using the Ammonia and Diazo Technique , 1996 .

[42]  Tony Arts,et al.  The VKI Compression Tube Annular Cascade Facility CT3 , 1992 .

[43]  Dieter Bohn,et al.  Experimental and Theoretical Investigations of Heat Transfer in Closed Gas-Filled Rotating Annuli , 1993 .

[44]  Francesco Montomoli,et al.  Interaction of Wheelspace Coolant and Main Flow in a New Aeroderivative LPT , 2006 .