DEPARTMENT OF ELECTRICAL AND INFORMATION ENGINEERING

CAT FEE 252 FLUID MECHANICS

1) A manometer Shown below ,limb A is filled with water of specific gravity 1 and the other

limb with oil of specific gravity 0.95.The area of the enlarged mouth portionis 50 times the

area of the tube portion .if the pressure difference is 22N/m2,calculate the height h. .(4marks)

2) A u-tube with a distance of 120mm between the limbs is filled with a liquid to mid level for

use as a crude accelerometer fixed on a moving vehicle. When the vehicle is accelerated the

difference in level between the limbs was measured as 32mm.Determine the acceleration.

.(3marks)

3) A multiple U-tube manometer is fitted to a pipe with centre at A as shown in the figure

below. Determine the pressure at A.(3marks)

QUESTION 2

1) A trapezoidal 2.5m wide at the bottom and 1.2m deep has slopes 1:1. Determine the total

pressure and centre of pressure on the vertical gate closing the channel when it is full of

water.(4marks)

2) A hydraulic lift shaft of 450mm diameter moves in a cylinder of 451mm diameter with the

length of engagement of 3m. The interface is filled with oil of kinematic viscosity of 2.4 x

10-4

m2/s and density of 900 kg/ m

3.Determine the uniform velocity of movement of the shaft

if the drag resistance is 300N.(3marks)

3) The suction pipe of a pump rises at a slope 2 vertical in 3 along the pipe which is 100mm in

diameter .The pipe is 6.8m long its lower end being just below the water surface in the

reservoir. For design reasons it is desirable that pressure at inlet to the pump shall fall to

more than 70kPa below atmospheric pressure. Neglecting Friction, determine the maximum

discharge the pump may deliver. Take atmospheric pressure as 101.32 kPa.(3 marks)

Use Bernoulli eqution

P1=patm

P2=101.32-70=31.32

Z1=0

Z2=6.8 X 2/3=4.533m

Thus v2=7.15m/s

Maximum discharge Q=A2 X V2= 3.14/4 X 0.12 X 7,15 = 0.056m

3/s

QUESTION 3

1) A vertical s l u i c e gate i s used to cover an opening in a dam. The opening is 2m wide

and 1 .2m h igh . On the upstream of the ga t e , t h e liquid o f specific gravity, 1.45 lies

up to a height of 1.5m, above t h e top of the gate, whereas on the downstream side the

water i s available up to a height t o u ch in g the top of the gate. Find the resultant force

ac t in g o n t h e gate a n d position of centre of pressure. Find also the force acting

h o r i zo n t a l l y at the top of the gate w h i c h i s capable of opening it. Assume that the

gate i s hinged a t the bottom.(5 marks)

1) A vertical gap 2.2 cm wide of infinite exent contains a fluid of viscosity 2Ns/and specific

gravity 0.9specific gravity 0.9. A metallic plate 1.2m x 1.2 m x 0.2 cm is to be lifted up

with a constant velocity of 0.15m/sec, through the gap. If the plate is in the middle of the

gap, find the force required. The weight of the plate is 40 N.(5 marks)

2)