In order to investigate the potential of a transonic High-Pressure turbine (HPT), a highspeed turbine rig called HWSS (High-Work Single-Stage) was designed by Rolls-Royce Deutschland (RRD), installed at DLR Göttingen and investigated experimentally. First a single-stage HPT was investigated followed by a second measurement campaign where the turbine was extended to a 1.5-stage turbine.
An extensive measurement program was specified, including boundary layer measurements at the HP inlet as well as rakes and multi-hole probes for measuring time-dependent radial distributions of pressure and temperature at several planes in the test section. Additional pressure transducers in the annulus were used to monitor the circumferential periodicity. The tip clearance was measured throughout the whole measurement program and found to be very close to the specified value. Stator and rotor were delicately equipped with Kulite pressure transducers which -in the case of the rotor by means of a telemetry- monitored time-dependent pressure distributions at 15%, 50% and 90% blade height. The whole blade instrumentation comprises 90 pressure transducers (some of them redundant), 18 strain gauges and three thermal sensors, resulting in a highly complex set-up.While the aerodynamic design and instrumentation of the blades was done at RRD, the design of the test section, manufacturing of all parts and the testing program were carried out at DLR Göttingen.
The HWSS HPT was installed in the wind-tunnel RGG. The facility is a closed-loop wind-tunnel, equipped with a 4-stage radial compressor and capable of inlet temperatures between 295K and 450K and compressor delivery pressure ratios up to 6. However, the maximum allowable pressure ratio for the HWSS runs was limited to 4.5. Also, the maximum rotational speed of 14,500 rpm was reduced to 11,000 rpm in the experiments. Turbine power was picked up by a 1200kW motor, acting as a generator and fed back into the grid. Data for power measurements was provided by a shaft encoder and a torque meter, yielding a torque measurement accuracy of <0.15%. The mass flow in the main passage was determined redundantly, using a calibrated Venturi nozzle and static pressure tappings in the HP inlet. The remaining flows such as film coolant and leakage air were measured with orifice plates.
The test program was split into performance and traverse measurements. Performance was measured within a range of 30 - 110% nominal speed and between 10-100% nominal power for two different tip clearances. During the area traverse measurements, three steady probes and one unsteady (Kulite) probe were simultaneously installed at defined axial and circumferential positions.
This work was carried out within the German government funded research project LuFo-3 “Transonic Single-Stage High-Pressure Turbine” under the reference number 20T0301A.
Publication:T. Wolf, E. Janke, R. Benton, F. Kost, F. Haselbach, S. Gegg:DESIGN AND TEST OF A HIGHLY LOADED SINGLE-STAGE HIGH PRESSURE TURBINEASME paper GT2011-45342, ASME Turbo Expo 2011, June 6-10, 2011, Vancouver, British Columbia, Canada