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HM 150.20 Operating Principle of a Francis Turbine
Education / GUNT Hamburg / Fluid Mechanics and Hydrology / Fundamentals of Fluid Mechanics /

Water turbines are turbomachines utilising water power. The Francis turbine is part of the reaction turbines which convert the pressure energy of the water into kinetic energy in the control device and in the impeller. The water is fed in the control device by means of a spiral housing. The flowing water is accelerated in the control device by the adjustable guide vanes and directed onto the vanes of the impeller. The redirection and further acceleration of the water in the impeller generates an impulse which is transmitted to the Francis wheel.  

  HM 150.20 is the model of a Francis turbine demonstrating the function of a reaction turbine.

  The experimental unit consists of the Francis wheel, the control device with adjustable guide vanes, a band brake for loading the turbine and a housing with a transparent front panel. The transparent cover enables you to observe the water flow, the wheel and the guide vanes during operation. The angle of incidence and thus the speed of the impeller are modified by adjusting the guide vanes.

 The turbine torque is determined by force measurement on a band brake and is read on spring balances. For measuring the rotational speed, a non-contact speed sensor, e.g. HM 082, is required. A manometer shows the water pressure at the turbine inlet.

  The experimental unit is positioned on the working surface of the HM 150 Base Module in a simple and safe manner. The water supply and flow rate measurement are provided via HM 150. Alternatively, the experimental unit can be operated by the laboratory supply.

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


Learning Objectives / Experiments

- design and function of a Francis turbine
- determination of torque, power and efficiency
- graphical representation of characteristic curves for

  torque, power and efficiency


[1] function of a Francis turbine
[2] transparent front panel for observing the operating area
[3] loading the turbine by use of the band brake
[4] adjustable guide vanes for setting different angles of incidence
[5] marking on brake drum for non-contact speed measurement 
[6] instruments: spring balances for determining the torque, manometer shows pressure at turbine inlet 
[7] flow determination by HM 150 Base Module
[8] water supply using the HM 150 Base Module or via lab supply


Technical Data

- output: 2,8W at n=1.000min-1, approx. 40L/min, 
- Impeller, 7 vanes
  Vane width: 5mm
  External diameter: 50mm
- Guide vanes: 6 vanes, adjustable


Measuring ranges
- braking force (spring balance): 10N
- pressure: 0...0,6bar


Dimensions and Weight
LxWxH: 400x400x630mm
Weight: approx. 12kg
Required for Operation
HM 150 (closed water circuit) or water supply, drainage
Scope of Delivery
1 experimental unit
1 set of instructional material
Order Details

070.15020  HM 150.20  Operating Principle of a Francis Turbine