THE PERFORMANCE OF A GENERIC NON-AXISYMMETRIC END WALL IN A SINGLE STAGE, ROTATING TURBINE AT ON AND OFF-DESIGN CONDITIONS

The application of non-axisymmetric end walls in turbine stages has gained wide spread acceptance as a means to improve the performance of turbines in both power generation and aero-derivative applications. Non-axisymmetric end walls are aimed at the control of secondary flows and to a large extent have been developed through the use of computational fluid dynamics and detailed measurements in linear and annular cascades and proven in full scale engine tests. Little or no literature is available describing their performance at conditions other than design. This study utilises 5-hole probe measurements in a low speed, model turbine in conjunction with computational fluid dynamics to gain a more detailed understanding of the influence of a generic end wall design on the structure of secondary flows at both on and off-design flow conditions. Results indicate a 0.4% improvement in rotor efficiency at design but this was reduced at off design and at higher loading the rotor efficiency was reduced by 0.5%. Stage efficiencies were improved for all conditions but with a declining trend as load was increased. Experimental and CFD results are examined to investigate these findings further.

[1]  Reza S. Abhari,et al.  Improving Efficiency of a High Work Turbine Using Nonaxisymmetric Endwalls—Part II: Time-Resolved Flow Physics , 2010 .

[2]  C. H. Sieverding,et al.  Recent Progress in the Understanding of Basic Aspects of Secondary Flows in Turbine Blade Passages , 1985 .

[3]  Martin G. Rose,et al.  Improving the Efficiency of the Trent 500 HP Turbine Using Non-Axisymmetric End Walls: Part II — Experimental Validation , 2001 .

[4]  Martin G. Rose,et al.  Improving the Efficiency of the Trent 500 HP Turbine Using Non-Axisymmetric End Walls: Part 1 — Turbine Design , 2001 .

[5]  Grant Ingram,et al.  An automated instrumentation system for flow and loss measurements in a cascade , 2006 .

[6]  T. W. von Backström,et al.  Turbulence model comparisons for a low pressure 1.5 stage test turbine , 2009 .

[7]  Martin G. Rose,et al.  Improving Turbine Efficiency Using Non-Axisymmetric End Walls: Validation in the Multi-Row Environment and With Low Aspect Ratio Blading , 2002 .

[8]  Glen C Snedden,et al.  The Application of Non-Axisymmetric Endwall Contouring in a Single Stage, Rotating Turbine , 2009 .

[9]  Dwain Dunn,et al.  CHARACTERISATION OF A REFURBISHED 1½ STAGE TURBINE TEST RIG FOR FLOWFIELD MAPPING BEHIND BLADING WITH NON-AXISYMMETRIC CONTOURED ENDWALLS , 2007 .

[10]  Martin G. Rose,et al.  Improving Efficiency of a High Work Turbine Using Non-Axisymmetric Endwalls: Part I—Endwall Design and Performance , 2008 .

[11]  Heinz-Peter Schiffer,et al.  Non-Axisymmetric End Wall Profiling in Transonic Compressors—Part I: Improving the Static Pressure Recovery at Off-Design Conditions by Sequential Hub and Shroud End Wall Profiling , 2009 .

[12]  Paloma González,et al.  Low Pressure Turbine Design for Rolls-Royce Trent 900 Turbofan , 2006 .

[13]  Steen A. Sjolander,et al.  Measurements of Secondary Losses in a High-Lift Front-Loaded Turbine Cascade With the Implementation of Non-Axisymmetric Endwall Contouring , 2009 .

[14]  J. D. Denton.  Loss mechanisms in turbomachines. Part II: Loss generation in turbomachines , 1999 .

[15]  Steen A. Sjolander,et al.  Measurements of Secondary Losses in a Turbine Cascade With the Implementation of Non-Axisymmetric Endwall Contouring , 2008 .

[16]  I. Popovic,et al.  Comparative Investigation of Three Highly Loaded LP Turbine Airfoils: Part I — Measured Profile and Secondary Losses at Design Incidence , 2007 .

[17]  Richard J Goldstein,et al.  Flow visualization in a linear turbine cascade of high performance turbine blades , 1995 .

[18]  John D. Denton,et al.  The 1993 IGTI Scholar Lecture: Loss Mechanisms in Turbomachines , 1993 .

[19]  Ali Mahallati,et al.  Aerodynamics of a Low-Pressure Turbine Airfoil at Low-Reynolds Numbers: Part 1 — Steady Flow Measurements , 2007 .

[20]  Martin G. Rose,et al.  Improving the Efficiency of the Trent 500-HP Turbine Using Nonaxisymmetric End Walls—Part I: Turbine Design , 2003 .

[21]  David Gregory-Smith,et al.  Nonaxisymmetric Turbine End Wall Design: Part I— Three-Dimensional Linear Design System , 2000 .

[22]  Steen A. Sjolander,et al.  Application of Non-Axisymmetric Endwall Contouring to Conventional and High-Lift Turbine Airfoils , 2007 .

[23]  David Gregory-Smith,et al.  Non-Axisymmetric Turbine End Wall Design: Part II — Experimental Validation , 1999 .

[24]  Richard J Goldstein,et al.  Flow visualization in a linear turbine cascade of high performance turbine blades , 1995 .

[25]  Steen A. Sjolander,et al.  Measurements of Secondary Losses in a Turbine Cascade With the Implementation of Nonaxisymmetric Endwall Contouring , 2008 .

[26]  David Gregory-Smith,et al.  Nonaxisymmetric Turbine End Wall Design: Part II—Experimental Validation , 2000 .

[27]  L. Langston,et al.  Secondary Flows in Axial Turbines—A Review , 2001, Annals of the New York Academy of Sciences.

[28]  Grant Ingram.  Endwall profiling for the reduction of secondary flow in turbines , 2003 .

[29]  Reza S. Abhari,et al.  Improving Efficiency of a High Work Turbine Using Non-Axisymmetric Endwalls: Part II—Time-Resolved Flow Physics , 2008 .