1) Bernoulli’s Assumptions
▶️(i) Steady flow
(ii) Ideal fluid
(iii)Irrotational flow
2) If the flow is steady means acceleration is zero than how can a fluid flow?
▶️Acceleration of a fluid particle contains two components one is local acceleration and other is convective acceleration.
*For a steady flow local acceleration is zero because velocity is not changing with time.
*But there is convective acceleration which depends upon the cross section of the flow.If it is uniform convective acceleration will be zero and if it is varying there will be convective acceleration due to which fluid can flow.
3) What is ideal fluid?
▶️~A fluid which has no viscosity and is incompressible and has zero shear stress and exerts normal stresses.
4) Assumptions of Hegen Poiseuille equation.
▶️(i)fluid is incompressible and Newtonian.
(ii)flow is laminar through a pipe of constant circular cross-section.
5) Why we use Haigen poissulle equation?
▶️To calculate head loss due to friction in a pipe for an fully developed laminar flow.
6) What is Cavitation?
▶️It happens in suction lift, due to low pressure in suction pipe the boiling point of water decreases and it may start boling at the temperature at which process is happening
Due to this vapours are formed and therefore there are bubbles in the impeller. When these bubbles collapse on the surface of pump, there is a jerk and this cause a cavity in the surface
This is called cavitation.
7) How to eliminate Cavitation?
▶️Cavitation can be eliminated by
Increasing the npsh available by increasing height of section side.
8) Define NPSH. How cavitation can be eliminated in a pump?
▶️To avoid cavitation, the pressure at the pump inlet must exceed the vapour pressure by a certain value, called the net positive suction head.
9) What is Priming?
▶️Priming is a process of filling suction pipe, casing, delivery pipe upto delivery valve with water.
10) Why we use it?
▶️We use it to remove air from these parts.