Water turbines are turbomachines which convert water energy into mechanical energy. Mostly, they are used for driving generators for power generation purposes. The Kaplan turbine is a reaction turbine with an axial through flow. It has a high specific speed and is suitable for large water flows and small to medium heads. Therefore, the Kaplan turbine is used as a "classic" water turbine in run-of-the-river power stations.

  The HM 421 helps to investigate the characteristic behaviour of a simple-regulated Kaplan turbine during operation. The trainer is provided with a closed water circuit with tank, submersible pump and throttle valve for adjusting the flow rate. The angle of incidence and thus the power output of the impeller are changed by adjusting the guide vanes. The turbine is loaded with a wear-free eddy current brake. 

  The speed is captured by means of an inductive, non-contact position sensor at the turbine shaft. For determining the turbine power, the eddy current brake is equipped with a force sensor for torque measurement. The pressures at the inlet and outlet of the turbine, the temperature and the flow rate are recorded with sensors.   The recorded measured values are displayed digitally and processed further in a PC. The PC is used to calculate the power output data of the examined turbine and to represent them in characteristic curves.

  The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

- Determination of power output curves at different

  speeds 
  * hydraulic power output
  * mechanical power output
- Determination of the head
- Determination of turbine efficiency
- Investigation of the influence of the vane position on

  power output and efficiency