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Institute of Turbomachinery and Fluid Dynamics
Logo Leibniz Universität Hannover
Institute of Turbomachinery and Fluid Dynamics
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Axial Turbine

Field of Application

  • Investigation of aerodynamic problems in single and multi-stage axial turbines
  • Investigation of different blade designs due to high flexibility
  • Investigation of forced and aeroelastically-excited blade vibrations in axial turbines
  • Investigation of multi-stage effects
  • Investigation of unsteady aerodynamics in axial turbines
  • Acoustic transportation in axial turbines
  • Investigation of axial gaps

Measurement Techniques

  • Steady and unsteady pressure measurement techniques
  • High precision temperature measurement technique (thermocouple Typ K and PT100)
  • Application of steady and unsteady measuring miniaturized flow vector probes
  • Up to 8 radial probes traversing with flow vector probes simultaneously possible
  • Permanent recording of inlet and outlet conditions by pressure rakes
  • Blade instrumentation (steady/unsteady)
  • Speaker and microphone measurement technique for inserting acoustic noise and measuring the acoustic transportation
  • CTA probes for measuring velocity vectors and flow field turbulence
  • Endoscopic 3-component Particle Image Velocimetry (PIV) for determining the flow field
  • Several circumferential traversing sensors for high-resolution measurements

Description

The air turbine test rig at the TFD has been successfully used for scientific experiments in the field of axial turbines in pilot plant scale for decades.

The test rig can hold various scaled bladings for high-, medium- and low-pressure turbines due to its flexible design.

The relatively long axial design of the rotor allows the investigation of up to seven turbine stages which can be installed on different rotor designs. For this reason, the test rig is suitable for investigations into multi-stage effects such as in the field of flow path optimization or overall unsteady stage effects (aeroacoustic, aeroelastic).

The main component of the test rig is the pressure-retaining turbine casing in classic steam turbine design with its peripheral installations. The turbine casing can include different turbine configurations by substituting the stator vane-carrier and rotor. Consequently investigations with project-specific blading are possible.

The propulsion of the turbine is supplied by compressed air. The blading transfer the effective work to the turbine rotor and the rotor is coupled via a high-precision torquemeter to the dynamometer. In the current setup a spur gear in combination with a DC-generator/-motor is used. Through the loading machine the rotational speed of the turbine can controlled independently of the set mass flow through the turbine. The DC machine provides a smooth transition between load and towing operation of the system.

In addition to basic studies on the flow field in low-pressure turbines like rotor-stator interaction, investigations into aeroelastic problems and the study of multi-stage effects are carried out, for example on modern high-pressure steam turbine blades. Particularly with regard to partial and low-load operation, the test vehicle is able to reproduce the flexible driving operation of real gas and steam turbines. As part of the acquisition and enforcement of public projects, and financed by external funding projects the monitoring and the lubricating grease and sealing air supply to the test rig were recently renewed and equipped with measurement instrumentation. This includes new 256-channel pressure measurement instrumentation, 90-channel high-precision temperature measurement technique, new unsteady measurement technique for measurements with a sampling frequency of up to 200 MHz inclusive amplifier on up to 32 channels, a high-precision torquemeter, new and flexible measurement programs and a new operating point control to stabilize operating parameters. For real time monitoring the IfTA  ARGUS OMDS system is used.

Specifications (current setup)

  • Stagenumber/ configurations:
  • Rotor design:
     
  • Max. rotational speed:
  • Max. inlet pressure:
  • Max. inlet temperature:
  • Max. flow rate/ mass flow:
  • Max. Power
  • Min. hub diameter:
  • Max. casing diameter:
  • Weight incl. blading:
 
  1. 1; 1.5; 2; 4; 5; 7
  2. two versions of a 1-7 stage rotor
  3. 1-stage blisk tie rod rotor
  4. 7 500 1/min
  5. 3 bar
  6. 180 °C
  7. 9.2 kg/s
  8. 1 350 kW (eletric)
  9. 270 mm
  10. 500 ... 600 mm
  11. 6 000 kg
 

Contact

Dipl.-Ing. Simon Bittner