Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 6th Semester (Sixth Semester) 2018-2019 RME601 Fluid Machinery Question Paper
Printed Paesz02 Sub Code: RME601
Papermz? Rollel | | | I I I I I I I
B TECH
(SEM?VI) THEORY EXAMINATION 2018-19
FLUID MACHINERY
T ime: 3 Hours T 0tal Marks: 70
Note: 1. Attempt all Sections. If require any missing data; then choose suitably.
SECTION A
1. Attempt all questions in brief. 2 x 7 = 14
a. What is the difference between ?uid mechanics and ?uid machinery?
b Why are turbines more efficient than pumps?
0. What is whirl velocity in a turbine? Give the significance of whirl velocity.
d Why do impulse turbine need high head and low ?ow rate and the reverse is needed
for reaction turbine?
What is NPSH? Why do we need to calculate NPSH?
Why the reciprocating pump is called positive displacement pump?
3'5.?
Why do we use an accumulator in a hydraulic system?
SECTION B
2. Attempt any three of the following: 7 x 3 = 21
a. A jet of water having velocity of 11.5 m/s impinges a vane, which is moving with a
velocity of 4.5 m/s. The vane is so shaped that the jet is de?ected through 1150. Find
the angle of the jet so that there is no shock at inlet. What is the absolute velocity of
the jet at exit in magnitude and direction and the work done per second per unit weight
of striking per second? Assume that the vane is smooth.
b. Show that the hydraulic efficiency for a Francis turbine having velocity of ?ow
through runner as constant, is given by the relation:
1
?tanza
1-(223)
Where a = the guide blades angle and 0 = vane angle of the runner and there is no
friction on the blades.
The turbine is having radial discharge at outlet.
If the vanes are radial at inlet, then show that,
2
m1 _ 2 + tanza
0. Why are centrifugal pumps used sometimes in series and sometimes in parallel? Give
the operational dif?culties commonly experienced in centrifugal pumps and their
remedies.
d. What is the effect of acceleration of piston on velocity and pressure in the suction and
delivery pipe of reciprocating pump? Obtain an expression for the pressure head due to
acceleration in the suction and delivery pipes.
e. What is function of torque converter? Describe with the help of a neat sketch its
constructional features and working. Discuss its characteristics. State its merits,
limitations and applications.
77h:
1+
SECTION C
3. Attempt any one part of the following: 7 x 1 = 7
(a) What do you understand by the term ?jet of water?? Develop an expression for the
efficiency of a series of moving curved plates when the jet of water strikes the plate at
one of the tips.
(b) Explain why a notch is made in lips of Pelton turbine buckets. A Pelton wheel is
working under a head of 550 m and produces 10000 kW at 450 rpm. If the efficiency
of the wheel is 85%, determine the discharge of the turbine, diameter of the wheel and
diameter of nozzle (assume coefficient of velocity as 0.98 and speed ratio as 0.45.
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RME601
4. Attempt any one part of the following: 7 x 1 = 7
(a)
(b)
What is cavitation? How does it affect the performance of hydraulic machines? How
can it be avoided in reaction turbines? Define Thoma?s cavitation number.
An inward ?ow reaction turbine works under an average head of 160 m with a
discharge of 80 m3/s. The inlet and outlet diameters of the turbine are 4 m and 2 m,
respectively. The runner blade angle at the inlet is 120?. Radial discharge velocity at
the outlet is 15 m/s. Assuming constant breadth of wheel and 90% hydraulic
ef?ciency, determine the HP produced in megawatt and the revolution per minute of
the machine.
5. Attempt any one part of the following: 7 x 1 = 7
(a)
(b)
Explain why priming is necessary to start pumping by centrifugal pump. Brie?y
explain the signi?cance of similarity parameters in centrifugal pump.
A centrifugal pump has an impeller of 0.5 m outer diameter and when running at 600
rpm, it discharges at the rate of 8000 l/m against a head of 8.5 m. The water enters the
impeller without whirl and shock. The inner diameter is 0.25 m and the vanes are set
back at outlet at an angle 0f 450 and the area of ?ow which is constant from inlet to
outlet of the impeller is 0.06 m2. Determine the
(i) Manometric efficiency of the pump
(ii) Vane angle at outlet
(iii) Least speed at which the pump commences to work.
6. Attempt any one part of the following: 7 x 1 = 7
(a)
(b)
Show that work saved in overcoming friction in pipelines by fitting air vessels in a
reciprocating pump is 39.2% for double acting pump.
A double acting pump runs at 85 double strokes per minute in a harmonic motion. This
pump?s piston has a diameter of 0.120 m and stroke of 0.220 m. If the pump has a
vertical suction pipe which is 5 m long and 110 mm in diameter, then compute the
maximum permissible suction lift, assuming that separation occurs at 2m of absolute.
Use atmospheric head of water as 10.3 m.
7. Attempt any one part of the following: 7 x 1 = 7
(a)
(b)
What is function of hydraulic press? Describe with the help of a neat sketch its
constructional features and working. Discuss its characteristics. State its merits,
limitations and applications.
An accumulator is loaded with 400 kN weight. The ram has a diameter of 300 mm and
stroke of 6 m. Its friction may be taken as 5%. It takes 2 minute to fall through its full
stroke. Find the total work supplied and power delivered to the hydraulic appliance by
the accumulator, when 0.0075 m3/s of liquid is being delivered by a pump, while the
accumulator descends with stated velocity.
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This post was last modified on 29 January 2020