The Application of Ultra High Lift Blading in the BR715 LP Turbine

The original LP turbine of the BR715 engine featured High Lift blading, which achieved a 20-percent reduction in aerofoil numbers compared to blading with conventional levels of lift, reported in Cobley et al. (1997). This paper describes the design and test of a re-bladed LP turbine with new Ultra High Lift aerofoils, achieving a further reduction of approximately 11 percent in aerofoil count and significant reductions in turbine weight. The design is based on the successful cascade experiments of Howell et al. (2000) and Brunner et al. (2000). Unsteady wake-boundary layer interaction on these low-Reynolds-number aerofoils is of particular importance in their successful application. Test results show the LP turbine performance to be in line with expectation. Measured aerofoil pressure distributions are presented and compared with the design intent. Changes in the turbine characteristics relative to the original design are interpreted by making reference to the detailed differences in the two aerofoil design styles.

[1]  Howard P. Hodson,et al.  Development of Blade Profiles for Low-Pressure Turbine Applications , 1997 .

[2]  Howard P. Hodson,et al.  Wake-separation bubble interaction in low pressure turbines , 1994 .

[3]  Howard P. Hodson,et al.  Prediction of the Becalmed Region for LP Turbine Profile Design , 1998 .

[4]  Howard P. Hodson,et al.  Boundary Layer Development in Axial Compressors and Turbines: Part 3 of 4— LP Turbines , 1997 .

[5]  Stefan Brunner,et al.  Comparison of Two Highly Loaded Low Pressure Turbine Cascades Under the Influence of Wake-Induced Transition , 2000 .

[6]  Howard P. Hodson,et al.  High Lift and Aft-Loaded Profiles for Low-Pressure Turbines , 2001 .

[7]  Michael J. Brear,et al.  Pressure Surface Separations in Low Pressure Turbines: Part 1 of 2 — Midspan Behaviour , 2001 .

[8]  I. Raab,et al.  Controlling the secondary flow in a turbine cascade by three-dimensional airfoil design and endwall contouring , 1999 .

[9]  Howard P. Hodson,et al.  An Investigation of Boundary Layer Development in a Multistage LP Turbine , 1994 .

[10]  C. H. Sieverding,et al.  Blade row interference effects in axial turbomachinery stages - Lecture Series 1998-02 , 1998 .

[11]  Michael J. Brear,et al.  Pressure Surface Separations in Low-Pressure Turbines—Part 1: Midspan Behavior , 2002 .

[12]  Michael J. Brear,et al.  Pressure Surface Separations in Low Pressure Turbines: Part 2 of 2 — Interactions With the Secondary Flow , 2001 .

[13]  Michael J. Brear,et al.  Pressure Surface Separations in Low-Pressure Turbines—Part 2: Interactions With the Secondary Flow , 2002 .

[14]  Norbert Arndt,et al.  Design of New Three Stage Low Pressure Turbine for the BMW Rolls-Royce BR715 Turbofan Engine , 1997 .

[15]  Howard P. Hodson,et al.  The role of research in the aerodynamic design of an advanced low-pressure turbine , 1999 .

[16]  Howard P. Hodson,et al.  Wake passing in LP turbine blades , 1995 .

[17]  Howard P. Hodson,et al.  Unsteady Wake-Induced Boundary Layer Transition in High Lift LP Turbines , 1996 .

[18]  Howard P. Hodson,et al.  Boundary Layer Development in Axial Compressors and Turbines: Part 2 of 4 — Compressors , 1995 .

[19]  Howard P. Hodson,et al.  Boundary Layer Development in the BR710 and BR715 LP Turbines: The Implementation of High Lift and Ultra High Lift Concepts , 2001 .