Correct Answer - Option 4 : All of the above
Explanation:
Cavitation is the phenomenon of the formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below the vapour pressure of the fluid and the sudden collapse of these bubbles in the region of higher pressure.
In centrifugal pumps, the cavitation may occur at the inlet of the impeller of the pump or at the suction side of the pump where the pressure is considerably low. So to avoid cavitation pressure on the suction side should be high. In order to determine whether cavitation will occur in any portion of the suction side of the pump, the critical value of Thoma’s cavitation factor is calculated.
The hydraulic machines subjected to cavitation are reaction turbines and centrifugal pumps.
Cavitation in turbine: In a reaction turbine (Francis Turbine) the cavitation may occur at the outlet of the runner or at the inlet of the draft tube where the pressure is considerably reduced.
Cavitation in Centrifugal Pump: In centrifugal pumps, the cavitation may occur at the inlet of the impeller of the pump or at the suction side of the pumps, where the pressure is considerably reduced.
Cavitation also occurs in reciprocating pumps if there is a high-velocity suction or discharge.
