fludmechanics-jntu-old papers

Code No: 07A3EC02 Set No. 1
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) Discuss the influence of the following fluid properties on fluid motion
i. Viscosity
ii. Specific gravity
iii. Surface tension
iv. Bulk modulus
(b) If the surface tension at air water interface is 0.073N/m, What is the pressure
dierence between inside and outside of an air bubble of diameter 0.01mm?
[10+6]
2. (a) Describe stream line and stream tube with the help of neat sketches.
(b) For steady incompressible flow verify whether the following values of u and v
are possible:
i. u = 4xy + y2, v = 6xy + 3x
ii. u = 2x2 + y2, v = −4xy
iii. u = −x/ (x2 + y2), v = −y/(x2 + y2). [6+10]
3. (a) What are the construction details of a pitot tube and explain how it works?
(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 50 lit/sec. [6+10]
4. (a) A nozzle of 56 mm diameter delivers a stream of water at 30 m/sec perpen-
dicular to a plate that moves away from the jet at 8 m/sec. Find the work
done and eciency of the jet.
(b) Prove that the force exerted by a jet of water on a fixed curved vane when the
jet strikes at the centre is F = ρav2 (1+cosθ) where
ρ = Mass density of water
a = Area of cross section of the jet
v = Velocity of the jet
θ = Angle of the curved plate at the out let. [8+8]
5. (a) Explain the inherent advantages, which make Hydropower more attractive.
(b) A runo stream with an installed capacity of 12000KW operates at 15% load
factor when it serves as a peak load station. What should be the lowest
discharge in the stream so that the station may serve as the base load station.
It is given that plant eciency is 70% when working under a head of 18m.
Also calculate maximum load factor of the plant when the discharge in the
stream rises to 18 cumecs [8+8]
6. (a) Define the terms: speed ratio, flow ratio and jet ratio
(b) An inward flow reaction turbine has external and internal diameters as 1.2 m
and 0.6 m respectively. The velocity of flow through the runner is constant
and is equal to 1.8 m/s. Determine:
i. Discharge through the runner, and
ii. Width at outlet if the width at inlet = 20 cm [16]
7. (a) Give the range of specific speed values of the Kaplan, Francis turbines and
Pelton wheels. What factors decide whether Kaplan, Francis, or a Pelton type
turbine would be used in a hydroelectric project ?
(b) A Kaplan turbine working under a head of 25 m develops 16000 kW shaft
power. The outer diameter of the runner is 4 m and hub diameter is 2 m. The
guide blade angle is 35. The hydraulic and overall eciency are 90% and 85%
respectively. If the velocity of whirl is zero at outlet, determine: (i) runner
vane angles at inlet and outlet, and speed of turbine. [8+8]
8. (a) What do you understand by characteristic curves of a pump? What is the
significance of the characteristic curves? Explain them in detail.
(b) The diameter of a centrifugal pump, which is discharging 0.035 m3/s of water
against a total head of 25 m is 0.05m. The pump is running at 1200 r.p.m.
Find the head, discharge and ratio of powers of a geometrically similar pump
of diameter 0.3 m when it is running at 2000 r.p.m. [8+8]