2-stage Air-Axial-Turbine "Olivia"

 

A two-stage axial air-turbine is used as the test carrier. Due to the modular design of the test turbine, systematic variation of the configurations to be examined can be carried out with comparatively little time and material effort. Both blade and sealing strip rings are used in the housing as well as in the rotor in order to be able to realize a simple variation of the axial spacing between the blade rows, as well as a variation of the foot overhang of the blades and the shroud cavities by replacing the sealing strip rings. In the housing, blade and sealing strip rings are fixed in their axial position by means of a tensioning device. The probes can only be moved in radial direction. In order to be able to measure a guide vane pitch, the guide vane rings are rotated in circumferential direction by means of an adjusting mechanism. The hub contour at the inlet and outlet sides is a two-part design and can be adapted by different inserts of the current configuration. A perforated plate is used at the turbine inlet in order to ensure reproducible and circumferentially symmetrical inlet boundary conditions. The water brake is mounted on the outlet side of the turbine and serves for both, speed regulation and power determination, which can be calculated by means of a force measurement via a lever arm. The pendulum bearing design also allows the bearing loss performance to be recorded. Via the speed, it is possible to realize partial and overload conditions variably by changing the enthalpy parameter.

The test turbine is supplied with air from the compressor installation of the institute. The compressor system consists of two radial compressors. In order to meet the requirements for reynolds and Mach number similarity in the test turbine, this is compared with the real machine in the charged and closed circuit. This ensures the widest independence of operation from environmental influences

 

Applications

  • Investigation of aerodynamic questions with regard to rotor - stator interaction
  • Examination of different blading types by high flexibility
  • Examination of multi-stage effects
  • Investigation of non-stationary aerodynamics in turbines
  • Axial gap investigations
  • Examination of different sealing configurations between rotating and stationary system
 

Measurement Technology

  • Stationary and transient pressure measurements
  • High Precision Temperature Measurement Technology (Thermocouple Type K and PT100)
  • Use of stationary and transient measuring miniaturized flow probes
  • Recording of high-precision probe adjustment devices for the 2D measurement of the flow field in three measuring planes with 3-hole probes, 5-hole probes and temperature probes
  • Fixed pressure combs in the exit plane
  • Detection of the profile pressure distribution on different heights
  • Eddy current measurement for determining the radial gap over the cover band
  • Measurement of pressure drop in the cavities
 

Technical design data of the air turbine (current design)

Inlet pressure [bar]

3.2

Pressure ratio [-]

1.4

Turbine inlet temperature [°C]

90

Mach number [-]

0.15

Speed [1/min]

4775

Massflow [kg/s] 12.82
Flow-coefficient φ [-] 0.5
Enthalpy number Ψh [-] 2.62