jntu -aeronautical engineering-fluidmechanics-old question papers

Code No: 07A3EC02 Set No. 3
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) What are the absolute and kinematic viscosities? Derive the equations for
them. Discuss what factors will influence them.
(b) Estimate the pressure inside a water droplet of size of 0.3mm. Assume σ=0.073N/m.
[10+6]
2. (a) What is the criteria to distinguish rotational flow from irrotational flow?
(b) Determine whether the flowing velocity components satisfy the continuity
equation.
i. u = A sin xy, v = −A sin xy
ii. u = x + y, v = x − y. [6+10]
3. (a) Dierentiate between stagnation pressure head and static pressure head with
reference to a pitot tube. Explain with the help of a neat sketch.
(b) A venturimeter of throat diameter 5cm is fitted into a 12.5 cm diameter water
pipe line. The coecient of discharge is 0.96. Calculate the flow in the pipe line
when the reading on a mercury water dierential U tube manometer connected
to the upstream and throat sections shows a reading of 20 cm. [6+10]
4. (a) A 15 cm diameter jet of water strikes a curved vane with a velocity of 40m/sec.
The inlet angle of the vane is zero and the outlet angle is 30 degrees. Calculate
the resultant force on the vane when it is moving with a velocity of 12m/sec
in the direction of the jet.
(b) State the equation used to find out the impact of jet on vanes. Derive the
equation for resultant thrust when a jet strikes a stationary inclined flat plate.
[8+8]
5. (a) What is a run o river plant. What are the dierent parts and arrangements
of such plants? Draw a neat sketch and explain
(b) What is meant by flow duration curve and power duration curve. How do you
dierentiate these two curves? Also explain power duration curve in detail.
[8+8]
6. (a) Dierentiate between:
i. The impulse and reaction turbines,
ii. Radial and axial flow turbines,
Code No: 07A3EC02 Set No. 3
iii. Inward and outward radial flow turbine, and
iv. Kaplan and propeller turbines.
(b) A Pelton wheel is having a mean bucket diameter of 0.8 m and is running at
1000 r.p.m. The net head on the Pelton wheel is 400 m. If the side clearance
angle is 150 and discharge through nozzle is 150 litres/s, find:
i. Power available at the nozzle, and
ii. Hydraulic eciency of the turbine. [16]
7. (a) By means of a neat sketch explain the governing mechanism of Francis Turbine.
(b) A Hydraulic turbine is to develop 845.6 kW when running at 100 r.p.m. under
a head of 10 m. Work out the maximum flow rate and specific speed for the
turbine if the overall eciency at the best operating point is 92 percent. In
order to predict its performance, a 1:10 scale model is tested under a head of
6 m. What would be the speed, power output and water consumption of the
model if it runs under the conditions similar to the prototype? [8+8]
8. (a) What is the eect of acceleration in suction and delivery pipes on indicator
diagram? Does the area of the indicator diagram change as compared to the
area of ideal indicator diagram?
(b) A centrifugal pump impeller whose external diameter and width at the outlet
are 0.8 m and 0.1 m respectively is running at 550 r.p.m. The angle of impeller
vanes at outlet is 40. The pump delivers 0.98 m3 of water per second under an
eective head of 35 m. If the pump is driven by a 500 kW motor, determine:
i. The manometric eciency
ii. The overall eciency, and
iii. The mechanical eciency. Assume water enters the vanes radially at inlet.
[8+8]