[01- 2210] IIIIV B.E. DEGREE EXAMINATION. Second Semester FLUID MECHANICS

-I

(Common for Civil and Civil Environmental Engineering) (Common with MS Civil Engineering) (Effective from the admitted batch of 2006-2007)

Maximum: 70 marks

Time: Three hours

Answer any FIVE questions. Question No.1 is compulsory.

All questions carry equal marks.

1.

(a)

Viscosity of liquids decreases with increase in temperature, while that of gases increases with increase in temperature. Why?

(b)

Distinguish

between

atmospheric pressures.

standard

and local

(c)

Define stream line, path line and streak line.

3.

(a)

Determine the horizontal and vertical componentsoftotal pressure due to water on

(d)

Differentiate between Stream line body and bluff body.

a tainter gate shown in figure 1. Width of gate is 4m.

2.

(e)

List the minor losses of energy in pipes.

(f)

What is moment of momentum equation?

(g)

What is Cippoletti weir?

(a)

Derive an eXpression-for the capillary rise of

a liquid having surface tension

0'

J

and

contact 8 angle between two vertical parallel plates a distance "d" apart. If the plates are of glass, what will be the capillary rise of water

having

0'

= 0.073

N/m

= 00.

Figure. 1

Take

d =lmm? (b) (b)

A pipe 50 cm in diameter branches .into two

Prove that the total pressure exerted by a

pipes

static liquid on an inclined plane submerged surface is same as the force exerted on a

respectively as shown in figure 2. If the

vertical plane surface as long as the depth of

of diameters

25 em and 20 cm

average velocity of 50 cm diameter pipe is 4m1sec find

centre of gravity of the surface is unaltered.

2

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.

(i)

Discharge through 50 em diameter pipe and

(ii)

velocity in 20 em diameter pipe if the average velocity in 25 em pipe is 3 mlsec.

5.

-

(a)

Derive the Darcy Weisbach equation for friction head loss in a pipe. .

(b)

Water is flowing'through a horizantal pipe line 1500 m long and 200 mm in diameter, Pressures at the two ends ofthe pipe line are

t t

respec~vely 12k.pa and 2 kpa. If f

6.

(a)

Derive the formula for velocity of flow. through an.orifice.

(b)

A 4 em diameter orificein the vertical side of a tank disch81'geswater. The water surface in the tank is at a constant level of 2m above the center of the orifice. If the head loss in the orifice is p.2 m and the coefficient of contraction can be assumed to be 0.63 estimate.

Figure. 2

4.

and derive Bernoullis theorem, mentioning clearly the assumptions underlying it.

(a) State

A 450 red1.Jcingbend is connected in a pipe

(b) .

line, the diameters at the inlet and outlet of the bend being 40 cm and 20 cm respectively. Find the force exerted by water on the bend if the intensity of pressure at inlet of bend is 21.58N/cm2. The rate of flow of water is 500 lit! sec. 4

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.

t

i

= 0.015,

determine the discharge through the pipe in litres per minute. Consider only frictional loss.

(i)

The values of the coefficient of velocity and coefficient of discharge

(ii)

The discharge through orifice and

(iii) Location of point of impact of the jet on a horizontal plane located 0.5 m below the center of orifice.

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7.

(a)

A lawn sprinkler has two nozzles of diameters 8 mm each at the end of a rotating arm and the velocity of flow of water from each nozzles is 12m/s.One nozzle discharges water in the downward direction and other in vertically upward direction. The nozzles are 40 cm from the centre of.the rotating arm. Determine the torque required to hold the rotating arm stationary. Also determine the constant speed of rotation arm, if it is free to rotate.

(b)

What is the need for momentum and energy correction factors? Derive the expression for

the factors.

8.

.

The population of a city is 8 x 105 and it is to be supplied with water from a reservoir 6.4 km away. Water is to be supplied at the rate of 0.14m3per head per day and half the supply is to be delivered in 8 hours. The full supply level of the reservoir is R.t 180.00 and its lowest water level is R.t 105.00. The delivery end of the main is at R.t 22.50 and the head required there is 12m. Find the diameter ofthe pipe. Take f = 0.04.

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