JNTU, B-Tech,I-Semester,Fluid Mechanics , November 2008


JNTU, B.Tech,I-Semester,

Fluid Mechanics

 November 2008

(Civil Engineering)



1. (a) Define the terms “Vapour Pressure” and capillarity.

(b) A 90 mm diameter shaft rotates at 1200 rpm in a 100 mm long journal bearing

of 90.5 mm internal diameter. The annular space in the bearing is filled with

oil having a dynamic viscosity of 0.12 Pa-s. Estimate the power dissipated.


2. A cylinder 30 cm in diameter and 100 cm in height is fixed centrally on the top of

a large cylinder of 100 cm diameter and 60 cm length. Both the cylinders are filled

with water. Calculate

(a) total pressure at the bottom of the cylinder

(b) weight of total volume of water. What is the hydrostatic paradox between the two results?


3. (a) Is the flow net analysis applicable to rotational flow? If not, Why?

(b) A two-dimensional flow can be described by u = ?y /b2 , v = x /a2 Verify that this

is the flow of an incompressible fluid and that the ellipse x2 /a2 + y2 / b2 = 1 is a streamline.


4. (a) Derive the Euler’s equation of motion for flow of steady incompressible fluid.

State the assumptions.

(b) A 2.5 cm nozzle is connected to a 7.5 cm diameter pipe. If the pressure at the

upstream end of the nozzle is 550 kN/m2 gauge, what will be the force exerted

by the nozzle on the water, if the water is discharged into the atmosphere.


5. (a) Differentiate between

i. Stream line body and bluff body

ii. Friction drag and pressure drag.

(b) A kite 60cm x 60cm weighing 2.943 N assumes an angle of 10o to the horizontal.

If the pull on the string is 29.43N when the wind is flowing at a speed of 40 km/hr. Find the corresponding coefficient of drag and lift. Density of air is given as 1.25 kg/m3.


6. (a) Show that discharge per unit width between two parallel plates distance b apart, when one plate is moving at velocity U while the other one is held stationary, for the condition of zero shear stress at the fixed plate is q = bu/3.

(b) A horizontal pipe line 20cm in diameter, 70m long conveys oil of specific

gravity 0.95 and viscosity 0.23 NS/m2. If the velocity of the oil is 1.38 m/sec,

find the difference in pressure between the two ends of the pipe.


7. A pipe 0.15 m diameter taking off from a reservoir suddenly expands to 0.3 m at the end of 16 m and continues for another 15 m. If the head above the inlet of the pipe is 4.88 m determine the actual velocity at the exit, taking into consideration all the losses. Take f= 0.04 for the complete pipe line.


8. A venturimeter having inlet diameter 100 mm and throat diameter 25 mm is fitted

in a vertical pipe, throat is 0.3 m below the inlet, for measuring the flow of petrol

of specific gravity 0.78. Pressure gauges are fitted at inlet and throat. Taking loss

of head between inlet and throat as 36 times the velocity head at inlet, find cd of

the meter and the discharge when the inlet gauge reads 274.68 KN/m2

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