Answer:
must be knowing that the shaft mounting the impeller blades is offset to the casing. This means that the area covered in between the impellers and the casing goes on increasing as the fluid travels from the input to the output of the pump.
Before we move onto the actual problem at hand let us first understand the bernoulli principle and continuity equation.
The bernoulli principle states that total energy of an inviscid fluid remains constant. This total energy mainly comprises of kinetic energy, pressure energy and potential energy. In the case of our pump, the potential energy is zero as there is no change in datum level. So only the sum of pressure and kinetic energy is conserved.
The continuity equation states that the mass flow rate is conserved. Meaning, Av= constant in case of liquids.
Back to the centrifugal pump, earlier we established that the area of fluid flow increases as the fluid moves from the inlet to the outlet. When you apply the above principles to this problem we can deduce the following:
1) As the area of flow increases the velocity of fluid decreases.
2) This decrease in fluid velocity corresponds to a decrease in kinetic energy.
3) Because the energy is conserved, a decrease in kinetic head increases the pressure head of the fluid.
This pressure head is basically a resultant of the pressure of the fluid. And hence, the pressure of the fluid increases