Francis Turbine

Francis Turbine

The Francis Turbine is a laboratory-scale reaction turbine for use with Digital Hydraulic Bench.

The turbine has a sturdy base which sits on the top of the hydraulic bench. The turbine connects to the pumped supply of the hydraulic bench. The bench measures the flow rate. A mechanical gauge measures the inlet pressure to the turbine. Adjustable guide vanes in the turbine alter the flow rate and direction of flow to the impeller (runner) of the turbine. The end of the turbine outlet tube (draft) is in the open-water channel of the hydraulic bench. Included with the turbine is a weir plate to create a shallow reservoir in the water channel of the bench. This ensures that water covers the end of the draft during tests. A band brake with spring balances measures the torque at the turbine shaft. A stroboscope with speed display or an optical tachometer can measure the speed of the turbine. The stroboscope can also ‘freeze’ the image of the turbine and water flow to improve students’ understanding of the turbine. 

Students test the turbine at different flow rates, loads and guide vane settings. They use the flow, torque, pressure and speed measurements to calculate hydraulic power input and mechanical (shaft) power at the turbine. They use these to create performance curves for the turbine.