Wednesday, 17 August 2011

Assignment - 3

Fluid Mechanics & Hydraulic Machinery – 3rd UNIT

Assignment - 3

2009

1.         (a) What is coefficient of a venturi meter? Why is its value more than that of an orifice meter?

(b) A Venturimeter of 150mm X 75m is installed in a horizontal pipeline carrying an oil of specific gravity 0.90. The difference of pressure head between the inlet and throat recorded by U tube differential manometer is 175mm of mercury. Determine the discharge through the pipe taking co efficient of discharge of the meter as 0.97  [6+10]

2.         (a) What is a flow nozzle? What are its uses? State the principle on which it works?

(b) A Pitot tube is placed in the center of a 200 mm pipe line carrying water. The difference between the stagnation pressure and static pressure is 40mm of water. The discharge in the pipe is 1.36 m3/minute. The mean velocity in the pipe is 0.83 of the central velocity. Find the coefficient of the Pitot tube.                                           [8+8]

3.         (a) Explain the working of a Venturi meter fitted in a vertical pipe line. Draw a neat sketch and explain. Explain why the coefficient of discharge of venturimeter is more when compared to that of orifice meter.

(b) In a Pitot tube the stagnation pressure is 3 KPa and the static pressure is -2.2Kpa. The fluid flowing is air of mass density 1.2 Kg/m3. Calculate the velocity of flow by taking the instrument coefficient as 0.98.                                                                            [8+8]

4.         (a) Explain how converging cone and diverging cones are proportioned in a Venturi meter with the help of a neat sketch. What will be the ratio of throat diameter and pipe diameter?

(b) A mercury filled U tube differential manometer connected across a 10cm X 5cm Venturimeter records a level difference of 3 cm for the flow of an oil of specific gravity 0.90. Calculate the discharge.                                                                             [8+8]

5.         (a) Describe the Reynold's experiment with the help of a neat sketch.

(b) Two reservoirs with a difference in water surface elevations of 10m are connected by a pipe line ABC which consists of two pipes of AB and BC joined in series. Pipe AB is 10cm in diameter, 20m long and has a value of f=0.02. Pipe BC is of 16cm diameter, 25m long and has f=0.018. The junctions with the reservoirs and between the pipes are abrupt. Calculate the discharge considering all minor losses.                              [6+10] 
           
6.         (a) How do you find the minor losses at the entrance and exit of a pipe line?

(b) Two pipe lines are connected parallelly to carry water with the following details:

Pipe 1: Diameter = 10cm, length = 25m, f = 0.02
Pipe 2: Diameter = 12cm, length = 35m, f = 0.02

If a discharge of 30 lit/sec, is present at the junction of the parallel pipes what will be the discharges in the individual pipe lines.                                                               [6+10]

7.         (a) Differentiate total energy line and hydraulic gradient line. Draw neat sketches and discuss.

(b) Three pipes A, B and C with the details as given below are connected in series:
Pipe
Diameter(cm)
Length(m)
f
A
12
1000
0.032
B
18
800
0.028
C
10
950
0.030

Calculate the size of a pipe of length 850m and f = 0.02 equivalent to the compound pipe ABC.                                                                                                                           [8+8]

2010

1.         (a) Explain Reynold's experiment.
(b) Derive Darcy Weisbach equation.

2.         (a) Derive Dupuit's Equation.
(b) Explain hydraulic gradient and total energy lines.

3.         List the various minor energy losses. Also give the formula for each.

4.         Explain the similarities and differences between a venturimeter and orifice meter.

5.         (a) Derive the equation for discharge of a venturi meter from fundamentals.
            (b) A Venturimeter has its axis vertical and carries petrol of specific gravity 0.78. The inlet and throat diameters are 150mm and 75 mm respectively. The pressure connection at throat 150 mm above that at inlet and actual discharge is 40 lit/sec and Cd=0.96. Calculate pressure difference at inlet and throat in N/m2.                                     [8+8]

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