Hydraulic Turbines parameters should be set such that at any point of flow static pressure may not fall below the vapor pressure of the liquid. These parameters to control cavitation are pressure head, flow rate and exit pressure of the liquid. The control parameters for cavitation free operation of hydraulic turbines can be obtained by conducting tests on model of the turbine under consideration. The parameters beyond which cavitation starts and turbine efficiency falls significantly should be avoided while operation of hydraulic turbines. Flow separation at the exit of the turbine in the draft tube causes vibrations which can damage the draft tube. To dampen the vibration and stabilize the flow air is injected in the draft tube. To totally avoid the flow separation and cavitation in the draft tube it is submerged below the level of the water in tailrace.