High speed test rig

High Speed Closed Loop Test Rig

Axial And Radial Stages

For the aim of research programs on axial turbines and centrifugal compressors a closed loop test rig for axial and centrifugal turbomachines has been launched in 2001 at LFM.

The test rig is equipped with:

      1.  section for centrifugal turbomachines

      2. cooling section

      3. Venturi nozzle for the flow rate measurement

      4. filtering section

      5. flow rate can be exhausted either in the by pass line or in the axial section

Flow rate regulation can be performed by two throttling valve sections (ref. 9, 10). The test rig can be operated under closed conditions or forcing the outlet or the inlet of the axial section to the atmospheric pressure;

The maximum power available at the centrifugal section is 800 kW while 400 kW are available at the axial one; the maximum rotational speed is 20000 Rpm for both the sections. The two reversible DC engines allow a continuous rotational speed regulation and the electrical power generated at the turbine brake is reversed to the centrifugal section engine, leading to significant savings in electrical running costs.

Maximum centrifugal impeller diameter is 560 mm; maximum outer/internal diameters of the axial turbomachine are 400/280 mm.

The test rig is instrumented in order to allow the over-all performance evaluation of both installed turbomachines. Both sections are equipped with traversing systems for the measurement of the flow field inside and downstream of the turbomachines; optical accesses for LDV measurements are also provided.

At the present time, the centrifugal section is equipped with a centrifugal compressor characterized by a nominal compression ratio of 2.6 at 5 kg/s (inlet at atmospheric condition) at a rotational speed of 18000 rpm.

The axial section is equipped with an axial turbine (figure 3) representative of a modern HP stage characterized by a leaned stator and a bowed rotor rotating at 12000 Rpm; the casing diameter is 400mm and the blade height is 50 mm.

Unsteady effects in axial turbine

FRAPP measurements downstream rotor blades

Impeller-Vaned diffuser in centrifugal compressor

Interactions between rotor and diffuser

Combustor-Turbine interactions

Entropy wave propagation in turbine stage