Transonic Test Turbine Facility (TTTF)

Within the research programs at the Institute for Thermal Turbomachinery and Machine Dynamics, in 1995 design and building of a transonic test turbine facility was started. In November 1999 the turbine test facility was run for the first time. This facility is driven by a compressor station of 3 MW power and allows testing of transonic gas turbine stages in full flow similarity. The test stand gives access of conventional pressure and temperature probes as well as of optical measurement devices such as Laser-Doppler-Velocimetry (LDV) and Particle-Image-Velocimetry (PIV) systems. Changing demands from research projects resulted in several modifications. Since the commissioning hundreds of hours of test runs with many different transonic turbine stages were performed.

The following picture shows the main component of the facility. Pressurized air, delivered by a separate electrically driven compressor station with 3 MW power, is fed to the turbine stage to be tested. The test turbine drives the brake compressor shown at right. The pressurized air from the brake compressor can be added to the air from the compressor station in a mixing chamber. The air from the compressor station may be cooled to about 50 °C, whereas the temperature of the brake compressor air depends on the pressure ratio.  The exhaust air from the turbine normally flows through an exhaust line directly to the silencers in the exhaust tower. Optionally a suction blower driven by a 750 kW engine (previously a helicopter engine) may be inserted into the exhaust line to reduce the turbine back pressure and thus increase the turbine overall pressure ratio.

TTTF Main Components

Mechanical and Operational Features:

  • Continuously operating cold flow test facility in open cycle.
  • Use of a compressor as brake for enhancing mass flow.
  • Wide adjustable speed range of the test rig with the first bending mode of the two shafts below 7000 rpm and the second bending mode sufficiently higher than the maximum speed of 11550 rpm.
  • Stable tilting pad bearings also at the turbine shaft.
  • Overhung-type turbine shaft for easy disk assembly.
  • All casing parts horizontally split for easy maintenance (except diffuser inserts).
  • Modular design for quick modification of test setup.
  • Possible cooling air flow supply of blades and cavity.
  • Test section with high flexibility of meridional path [mm]:
    • Stage inlet adapters starting at inner diameter Dinner = 360 and outer diameter Douter = 620
    • Test section inserts maximum diameter D = 800
    • Diffuser insert flanges Di  = 720
    • Test section length L = 406
    • Diffuser length LDiff = 620
  • Test turbine stage operational limits:
    • Inlet pressure max. 4.6 bar (5 bar)
    • Inlet temperature max. 185°C
    • Outlet pressure 0.97 without or 0.80 bar with suction blower operation
    • Maximum mass flow: 9.5 kg/s without and about 20 kg/s with air of brake  compressor
    • Maximum speed 11550 rpm
  • GHH brake compressor:
    • Nominal speed 11175 rpm
    • Nominal outlet temperature 229°C
    • Maximum coupling power 2.5 MW at -15° IGV position

In the download section you can find some publications regarding the details, design and construction of the TTTF as well as results of some tests.

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Institute of Thermal Turbomachinery and Machine Dynamics

Graz University of Technology
Inffeldgasse 25/A
A-8010 Graz

Tel: +43 (0)316 873 - 7226
Fax: +43 (0)316 873 - 7239