Concept explainers
Underground water is to be pumped by a 78 percent efficient 5-kW submerged pump to a pool whose free surface is 30 m above the underground water level. The diameter of the pipe is 7 cm on the intake side and 5 cm on the discharge side. Detennine (a) the maximum flow rate of water and (b) the pressure difference across the pump. Assume the elevation difference between the pump inlet and the outlet and the effect of the kinetic energy correction factors to be negligible.
(a)
The maximum discharge of water.
Answer to Problem 88P
The rate of flow of water is
Explanation of Solution
Given information:
The efficiency of the pump is
Write the expression for the maximum discharge.
Here, discharge is
Calculation:
Substitute
Conclusion:
The maximum rate of flow of water is
(b)
The pressure difference across the pump.
Answer to Problem 88P
The pressure difference across the pump is
Explanation of Solution
Given information:
The efficiency of the pump is
Write the expression for the pressure difference across the pump.
Here, pressure at suction side is
Here, discharge is
Calculation:
Velocity in the suction pipe.
Substitute
Velocity in the delivery pipe.
Substitute
Substitute
Conclusion:
The pressure difference across the pump is
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Chapter 5 Solutions
Fluid Mechanics: Fundamentals and Applications
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