DESCRIPTION

Technical Description

Pelton turbines are types of impulse turbine. They are driven by free jet nozzles. In the nozzles, the water is strongly accelerated. Ambient pressure exists at the nozzle outlet.  

The experimental unit is placed upon the base unit HM 290. The two units together provide the basic experiments to get to know the operating behaviour and the most important characteristic variables of Pelton turbines.

The water jet is accelerated in a nozzle and hits the Pelton wheel tangentially. In the blades on the circumference of the Pelton wheel the water jet is deflected by approximately 180°. The impulse of the water jet is transmitted to the Pelton wheel.

HM 289 consists of a Pelton wheel and a needle nozzle, mounted in a transparent housing. The needle nozzle can be adjusted during operation. The loading device is outside of the housing. The eddy current brake generates a defined load. The eddy current brake is specially developed by GUNT. It is wear-free and can be finely adusted.

The torque delivered by the turbine is determined via an electronic force sensor. The speed is measured with an optical speed sensor. The measuring values are transferred to the base unit HM 290.

The water supply and the flow rate measurement are realised with the base unit HM 290. A pressure control included in HM 290 enables the recording of characteristics at a constant head.

All the advantages of software-supported experiments and evaluation are offered by the GUNT software in HM 290.  

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

Learning Objectives / Experiments

- principle of operation of a Pelton turbine
- characteristic at constant head
  * relationship between torque and speed
  * efficiency dependent on speed
  * flow rate dependent on speed
  * hydraulic power and mechanical power dependent on speed

- evaluation of measuring values and characteristics based on the theory
- partial load behaviour with needle control in comparison to throttle control