JNTU Mechanics Of Fluids Exam Paper Nov 2008


JNTU Mechanics Of Fluids Exam Paper Nov 2008

(Aeronautical Engineering)


1. (a) Write a note on viscosity and compressibility.

(b) Calculate the velocity gradient at distances of 0,10,15 cm from the boundary

if the velocity profile is a parabola given by u =Ay2 + By + C and with

the vertex 15cm from the boundary, where the velocity is 100 cm/sec. Also

calculate the shear stress at these points if the fluid has a viscosity of 8.2 poise.



2. (a) What are the methods available for describing the fluid flow? and explain

each method.

(b) A circular pipe 10 cm in diameter has 2 m length which is porous, In this

porous section the velocity of exit is known to be constant. If the velocities

at the inlet and outlet of the porous section are 2.0 m/sec and 1.2 m/sec

respectively, estimate (i) the discharge emitted out through the walls of the

porous pipe and (ii) the average velocity of this emitted discharge. [8+8]


3. (a) State the momentum equation. How will you apply momentum equation for

determining the force exerted by a flowing liquid on a pipe bend?

(b) A nozzle at the end of a 80 mm hose produces a jet 40 mm in diameter.

Determine the force on the joint at the base of the nozzle when it is discharging

1200 liters of water per minute. [8+8]


4. (a) Describe with the help of neat sketch, the variation of drag coefficient for a

cylinder over a wide range of Reynolds number.

(b) Oil with a free stream velocity of 3 m/s flows over a thin plate 1.25-m wide

and 2 m long. Determine the boundary layer thickness and the shear stress

at mid ? length and calculate the total, double-sided resistance of the plate.

Take Density = 860 kg/m3andv = 10?3. [8+8]


5. (a) What is the relation between pressure and density of a compressible fluid for

(i) Isothermal (ii) adiabatic process

(b) Air ,thermodynamic state of which given by pressure

P = 230 kN/m2 and temperature = 300 K is moving at a velocity

V= 250 m/s .Calculate the stagnation pressure if

(i) compressibility is neglected (ii) compressibility account for. [8+8]


6. (a) Derive an expression for mean velocity of flow for laminar flow through inclined


(b) Derive the necessary condition for mean velocity for the laminar flow between

parallel flat plates when both the plates are at rest. [8+8]


7. (a) Explain the terms Pipes in parallel, Equivalent pipe and Equivalent size of

the pipe.

(b) Determine the difference in the elevations between the water surfaces in the

two tanks which are connected by a horizontal pipe of diameter 30cm and

length 400m. The rate of flow of water through the pipe is 300 lit/sec. Neglect

the minor losses and take the value of f=0.008 . [8+8]


8. (a) A pipe containing water at 172 kN/m2 pressure is connected by a differential

gage to another pipe 1.5 m lower than the first pipe and containing water at

high pressure. If the difference in heights of the two mercury columns of the

gage is equal to 75 mm, what is the pressure in the lower pipe? G of mercury

= 13.6.

(b) Obtain an expression for inclined manometer and explain its use.


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