With the execution of major river valley projects in India, the hydraulic and mechanical engineer is faced with intricate turbine design for high heads, the most important phenomenon to be guarded against, being cavitation. By testing the model of the proposed runner and its casing in a water tunnel, it has become easier to locate points subject to cavitation and modify them suiting particular site conditions. The paper describes briefly the cavitation phenomenon and characteristics as it happens in turbine testing. Performance tests of hydraulic turbines have also been discussed. Phenomenon like vortex formations at low loads in Francis turbines and vibrations in turbines have been narrated. Field tests for performance and efficiency, particularly the famous Gibson method have been outlined. The paper will prove useful in guiding hydraulic engineer in making a preliminary selection of the turbine and to understand the cavitation on turbines.
