jntu- aeronautical-fluidmechanics-old questionpapers

Code No: 07A3EC02 Set No. 4
II B.Tech I Semester Regular Examinations, November 2008
FLUID MECHANICS AND HYDRAULIC MACHINERY
( Common to Electrical & Electronic Engineering and Production
Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Define dynamic viscosity and kinematic viscosity. What are their units? Ex-
plain the significance of viscosity on fluid motion.
(b) Find the pressure in N/m2 represented by a column of
i. 10cm of water
ii. 5 cm of oil of relative density 0.75
iii. 2cm of mercury. [8+8]
2. (a) Derive the equation of continuity in dierential form.
(b) Determine whether the following velocity components satisfy the continuity
equation:
i. u = 2x2 + zy, v = −2xy + 3y3 + 3zy, w = −3/2 z2
− 2xy − 6yz
ii. u = −cx/y, v = c log xy. [6+10]
3. (a) Explain how do you measure the velocity of flowing water in a stream using
pitot tube.
(b) An oil of relative density 0.90 flows through a vertical pipe of diameter 20cm.
The flow is measured by a 20cm × 10cm venturimeter. The throat is 30cm
above the inlet section. A dierential U tube manometer containing mercury
is connected to the throat and the inlet. If coecient of discharge is 0.99 what
is the manometer reading for a flow of 50lit/sec. [6+10]
4. (a) A 15 cm diameter jet of water with a velocity of 20 m/sec strikes a plate
normally. If the plate is moving with a velocity of 8m/sec in the direction of
the jet, calculate the work done per second on the plate and the eciency of
the energy transfer.
(b) Prove that the force exerted by a jet of water on a fixed hemispherical curved
vane when the jet strikes at the centre is F = ρav2 where
ρ = Mass density of water
a = Area of cross section of the jet
v = Velocity of the jet. [8+8]
5. (a) What are valves used in a penstock. Explain with neat sketches, various types
of valves with their suitability under various conditions.
(b) What is intake structures. Explain dierent types with the help of neat
sketches.
[8+8]
6. (a) How will you classify the turbines? Explain
(b) A Pelton wheel is to be designed for the following specifications. Power
=735.75 kW S.P. Head = 200 m, Speed = 800 r.p.m., η0 = 0.86 and jet
diameter is not to exceed one-tenth of the wheel diameter. Determine :
i. Wheel diameter,
ii. The number of jets required, and
iii. Diameter of the jet. Take Cv = 0.98 and speed ratio = 0.45. [16]
7. (a) What is cavitation? How can it be avoided in reaction turbine?
(b) What is governing and how it is accomplished for dierent types of water
turbines?
[8+8]
8. (a) Draw an indicator diagram, considering the eect of acceleration and friction
in suction and delivery pipes. Find an expression for the work done per second
in case of single-acting reciprocating pump.
(b) A single-acting reciprocating pump having a bore of 150 mm and a stroke of
300 mm is raising water to height of 20 m above the sump level. The pump
has an actual discharge of 0.0052 m3/s. The eciency of the pump is 70%. If
the speed of pump is 60 r.p.m. Determine:
i. Theoretical discharge
ii. Theoretical power
iii. Actual power, and
iv. Percentage slip. [8+8]