1. Home Assignment BS-ME (5th semester)
Date: 17-09-2012
Subject: Fluid Mechanics-II Due Date: 01-10-2012
Q 1: A centrifugal pump is required to lift water against total head of 40 m at the rate of
50.liters per second. Find the power of the pump, if the overall efficiency is 62%.
Q 2: A centrifugal pump having outer diameter equal to two times the inner diameter and
running at 1000 rpm, works against a total head of 40 m. The velocity of flow through the
impeller is constant and equal to 2.5 m/s. The vanes are set back at an angel of 40° at
outlet. If the outer diameter of the impeller is 50 mm and width at the outlet is 50 mm,
determine.
1. Vane angle at inlet
2. Work done by impeller on water per second
Q 3: A centrifugal pump impeller has diameter of 60 cm and width of 6 cm at the outlet.
The pump runs at 1450 rpm and delivers, 0.8 m3/s against a head of 80 m. The leakage
loss after the impeller is 4% of discharge, the external mechanical loss is 10 kW and
hydraulic efficiency is 80%. Determine the blade angle at outlet, the power required and the
overall efficiency of the pump.
Q4: The internal and external diameters of the impeller of a centrifugal pump are 200 mm
and 400 mm respectively. The pump is running at 1200 rpm. The vane angles of the
impeller at inlet and outlet are 20° and 30° respectively. The water enters the impeller
radially and velocity of flow is constant. Determine the work done by the impeller per unit
weight of water.
Q5: water is pumped with a centrifugal pump, and measurements made on the pump
indicate that for a flow rate of 240 gpm the required input power is 6 hp. For a pump
efficiency of 62%, what is the actual head rise of the water being pumped?
Q6: A centrifugal pump with a 7 in diameter impeller is used to pump water at 100 oF, and
the pump inlet is located 12 ft above the open water surface. When the flow rate is 200
gpm the head loss between the water surface and the pump inlet is 6 ft of water. Would you
expect cavitation in the pump to be a problem at 11 ft of NPSHr.
Note: The rough work and vector/flow diagram for these questions will also be counted.