Total No. of Questions 10]
[Total No. of Pages 4
[5353] 118
T.E. (Mechanical Engineering) (Semester II)
TURBO MACHINES
(2012 Pattern)
Time :2½ Hours] [Max. Marks :70
Instructions to the candidates:
Answer Q.1 Q.2, Q.3 Q.4, Q.5 Q.6, Q.7 Q.8, Q.9 Q.10.
Figures to the right indicate full marks.
Use of non programmable scientific calculator is allowed.
Assume data wherever necessary and mention it.
Draw neat and suitable figures wherever necessary.
P3255
SEAT No.
P.T.O.
[5353] 118 2
Q4) A Kaplan turbine runner has outer diameter of 4.5 m and the diameter of
the hub is 2m. lt is required ton develop 20.6 MW when running at 150
rpm, under a head of 21m . Assuming hydraulic efficiency of 94% and
overall efficiency of determine the runner vane angle at inlet and
exit at the mean diameter of the vane.
Define following terms: nozzle efficiency, stage efficiency, blade efficiency,
coefficient of discharge.
Q5) Explain following heads in centrifugal pump
Suction lift
ii) Delivery lift
iii) Centrifugal head
iv) Manometric head
The impeller of the centrifugal pump has an outer diameter of 250mm
and an effective area of the 0.017m2.The blades are bent backward so
that the direction of outlet relative velocity makes an angle of 148 deg
with the tangent drawn in the direction of impeller rotation. The diameters
of suction and delivery pipes are 150mm and 100mm respectively. The
pump delivers 0.031 m3/s at 1450 rpm when suction and delivery lifts are
4.6m and 18m respectively. The head losses in the suction and delivery
pipes are 2m and 2.9m respectively. The motor driving the pump delivers
10kW. Assuming that water enters the pump without shock and whirl
Determine: 1. Manometric efficiency and 2.The overall Efficiency of the
pump.
OR
Q6) A centrifugal pump running at 800rpm is working against a total head of
20.2m. The external diameter of the impeller is 480mm and outlet width
60mm. lf the vanes angle at outlet is 40 deg and Manometric efficiency is
Determine: Flow velocity at outlet ii) Absolute velocity of water
leaving the vane iii)Angle made by the absolute velocity at outlet with
direction of motion at outlet and iv)Rate of flow through pump.
Discuss the significance of the effect of outlet blade angle on performance
of centrifugal pump.
[5353] 118 3
Q7) Classify centrifugal compressor and discuss its applications.
Differentiate between centrifugal and axial flow compressors.
A gas compressor compresses the gas at the rate of 2Kg/s from inlet
static pressure of 1 bar to a static pressure of 4bar.The power input to a
compressor is 400kW.The velocity of air at entry to the impeller blades
is 100m/s and at exit of the impeller is 160m/s. Determine the stagnation
pressures and temperatures at inlet and exit of the compressor, diameter
of the suction pipe required and adiabatic efficiency based on the static
and total values. Assume γ 1.4, Cp=1.05 kJ/kgK and R=300Nm/kgK.
The temperature at inlet of the impeller is taken as 280 K.
OR
Q8) A centrifugal compressor delivers 10 m3/s of air when running at 10000
rpm. The air is drawn in at 1 bar and 300K and delivered at 4 bar. The
isentropic efficiency is 80%.The blades are radial at outlet and constant
flow velocity is 64 m/s. The outer dia. Of the impeller is twice the inner
dia. And slip factor may be taken as 0.9. Calculate l.Temperature of air at
outlet of impeller 2. Power required driving the compressor 3. Impeller
diameters at inlet and outlet 4.Impeller blade angle at inlet 5. Diffuser
blade angle at inlet.
Discuss the performance characteristic curves of the centrifugal
compressor.
Q9) Show that for 50% Degree of Reaction of axial flow compressors blades
are symmetrical.
An axial compressor stage has following data; temperature 300 K and
pressure 1 bar at entry, degree of reaction mean blade ring diameter
36 cm, rotational speed 18000 rpm. blade height at entry 6 cm, air angles
at rotor and stator exit 250,axial velocity 180m/s, work done factor 0.88,
mechanical efficiency 96.7 Determine Air angles at the rotor and
stator entry The mass flow rate of air The power required to drive
the compressor The loading coefficient, assume R 287 J/kgK.
OR
[5353] 118 4
Q10)a) Draw neat sketch of axial flow compressor and Explain flow processes
through Axial flow compressor with h-S diagram for single stage.
An eight stage axial flow compressor takes in air at a temperature of
293k at the rate of 3 kg/sec. The pressure ratio is 6 and isentropic
efficiency is 0.89. The compressor is designed for 50 reaction. The
blade speed for each stage may be assumed to be constant as 180 m/sec
and the flow velocity is 100 m/sec. Determine the power required to
drive the compressor and the direction of air at entry and exit from the
rotor and stator. Assume that the total work is equally shared between
the stages. Assume γ 1 .4 and Cp 1 .005kJ/kg K.