Characteristics of a powerful Francis turbine

Optimal view of the operating area of the turbine

Adjustable guide vanes for setting the output The Francis turbine belongs to the reaction turbines which convert pressure energy of the working medium into kinetic energy in the guide vanes and in the rotor. Francis turbines are used for medium heads. The turbine power is controlled by adjusting the guide vanes. In practice, Francis turbines are used in run-of-river power plants and in pumped storage plants. Enables examinations of the function and operating behaviour of a Francis turbine. The closed water circuit consists of a tank with optional cooling, a centrifugal pump and a flow control valve for adjusting the inlet pressure. The dimensions of the trainer guarantee realistic measured values.

The transparent Operating area of the turbine enables an optimal view of water flow, rotor and guide vanes during operation. An asynchronous machine is used as a generator for loading the turbine. A pump with variable speed via frequency converter provides for an energy efficient operation. By adjusting the guide vanes the angle of attack, the cross-section and thus the output of the turbine are changed. 

The generator is equipped with a pendulum bearing and with a force sensor to determine the torque. The pressures at the inlet and outlet of the turbine, the temperature and the flow rate are recorded by sensors. The speed of the turbine is recorded by means of an inductive, non-contact position sensor at the generator shaft. The measured values are displayed digitally and can be processed further on a PC. The output data of the examined turbine are determined and can be represented by characteristic curves.

Learning objectives/experiments

Determination of the mechanical power and hydraulic power of the turbine

Determination of efficiency

Investigation of the influence of the guide vane position

Investigation of the conversion of hydraulic into mechanical energy

Recording of characteristic curves

Velocity triangles.

Specification:

Investigation of a Francis turbine

Digital display for temperature, flow rate and ressures (additional manometer within scope of supply), speed, torque and electrical power of generator

Closed water circuit with pump, motor, flow control valve and tank with optional cooling

Pump with variable speed via frequency converter

Rotor and guide vanes of the turbine completely visible

Adjustment of flow rate via flow control valve

Loading the turbine by use of the asynchronous machine as generator

Non-contact speed measurement at the generator haft and force sensor for measuring the driving torque

Adjustable guide vanes for setting different angles of attack.