Yashwantrao Chavan Maharashtra Open University 2006 Certification TML Strength of Materials - Question Paper

TML054/EE/20070818
Hydraulic Machines
Time : 180 minutes Marks : 100
Instructions for the students :
1. All ques. are compulsory.
2. “Long ans kind ques. (LAQ)” is a supply kind ques. of 20 marks,
which require typical ans of about 60-80 lines in about 32-40 minutes.
3. “Short ans kind ques. (SAQ)” is a supply kind ques. of five marks,
which require typical ans of about 15-20 lines in about 08-10 minutes.
4. Use of non-programmable kind of scientific calculator is allowed.
5. Draw neat diagrams wherever necessary.
6. presume suitable data if necessary.

Long ans kind ques. (LAQ’s)
1. (a) How do you classify water turbines ? Differentiate ranging from
impulse and reaction turbines ? discuss the various
efficiencies of a water turbine.
(b) A Kaplan turbine develops 22000 kW at an avg. head of
35 m. Assuming a speed ratio of 2, flow ratio of 0.6, diameter
of the boss equal to 0.35 times the diameter of the runner
and an overall efficiency of 88%, compute the diameter
speed and specific speed of the turbine.


2. (a) discuss the construction and working of hand pump and jet
pump.
(b) A centrifugal pump rotating at 1500 rpm delivers 0.2 m3/s at a
head of 15 m. compute the specific speed of the pump and
the power input. Assuming overall efficiency of the pumps as
0.68. If this pump were to operate at 900 rpm, what would be
the head, discharge and power needed for homologous
conditions ? presume overall efficiency remains unchanged at
new rpm.


3. (a) What do you mean by stalling and surging in an axial flow
compressor ?

(b) A 2 stage single acting reciprocating compressor takes in air
at the rate of 0.2 m3/s. The intake pressure and temperature
of air are 0.1 mPa and 160C. The air is compressed to a final
pressure of 0.7 mPa. The intermediate pressure is ideal and
intercooling is perfect and the compression index in both the
stages is 1.25 and the compressor runs at 600 rpm.
Neglecting clearance,
determine :
i) The intermediate pressure
ii) The total quantity of every cylinder
iii) The power needed to drive the compressor
Take Cp = 1.005 kJ/kg k and R = 0.287 kJ/kgk.
10
4. (a) A pelton turbine produces 10 mw when it is working under a
head of 500 m and is running at 300 rpm with overall
efficiency equal to 0.80. compute the power output speed,
efficiency and discharge of the turbine when it is working
under a head of 350 m.
(b) A model turbine of 1m in diameter acting under a head of 2m
runs at 150 rpm. Estimate the scale ratio of the prototype
developes 20 mv under a head at 225m with a specific speed
of 100. Also compute the power developed by the model.

1
Short ans kind ques. (SAQ’s)

5. discuss the functions of a draft tube. 5
6. discuss the working of Hydraulic accumulator. 5
7. What is an intercooler ? elaborate its advantages ? 5
8. discuss the working of Rotameter.

Earning:   Approval pending.