Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 7th Sem 2171917 Steam And Gas Turbines Previous Question Paper
Seat No.: ________
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?VII (NEW) EXAMINATION ? WINTER 2020
Subject Code:2171917 Date:02/02/2021
Subject Name:Steam and Gas Turbines
Time:10:30 AM TO 12:30 PM Total Marks: 56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of Steam table and Molliar diagram is permitted.
MARKS
Q.1 (a) Describe different types of nozzle with neat sketch. State the function
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of nozzle.
(b) With help of S.F.E.E. prove that
. Neglect
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initial velocity of steam. Where C2 is outside velocity of steam from
nozzle (h1 ?h2) is heat drop in nozzle.
(c) What is critical pressure? Derive the expression for critical pressure
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ratio in flow through nozzles. Calculate its value for superheated
steam.
Q.2 (a) What is function of governing system of steam turbine? Compare
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throttle and Nozzle Governing.
(b) Derive an expression for exit velocity of steam in terms of enthalpy of
04
fluid at inlet and at exit and the velocity of steam at inlet.
(c) Show that in a 50 % reaction turbine stage, the maximum efficiency
07
is (22) / (1 + 2). where is the nozzle angle.
Q.3 (a) Explain with neat sketch any one method of attachment of blade to
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turbine rotor.
(b) Why compounding of impulse turbine is necessary? What are various
04
methods of reducing rotor speed? Explain anyone method with neat
diagram.
(c) The following particulars refer to a stage of a Parson's steam turbine
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comprising one ring of fixed blades and one ring of moving blades.
Mean diameter of blade ring = 70 cm, Steam velocity at exit from
blades = 160 m/s, R.P.M. = 3000, Blade outlet angle =200, steam
flow through blades = 7 kg/s. Draw the velocity diagram and find the
following: -
(a) Blade inlet angle, (b) Tangential force on ring of moving blades,
(c) Power developed in stage.
Q.4 (a) Compare the impulse and reaction turbines.
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(b) Enlist different losses in steam turbine.
04
(c) Draw p-v &T-s diagram for gas turbine cycle with: (1) Intercooler,
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(2) Reheating (3) Regeneration. Also state the difference between
Intercooler and Reheating gas turbine cycle.
Q.5 (a) State the difference between steam turbine and gas turbine.
03
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(b) Find the efficiency of constant pressure closed cycle gas turbine.
04
(c) In an open cycle regenerative gas turbine plant, the air enters the
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compressor at 1 bar, 32 0C and leaves at 6.9 bar. The temperature at
the end of combustion chamber is 816 0C. the isentropic efficiencies
of compressor and turbine are respectively 0.84 and 0.85. combustion
efficiency is 90 % and the regenerator effectiveness is 60 %,
Determine Thermal efficiency of the plant.
Q.6 (a) State the different applications of Gas turbine.
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(b) Describe any four requirements of a typical combustion chamber of
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the gas turbine power plant.
(c) A simple gas turbine takes air at 1.01 bar and 15.5 0C and compresses
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it through a pressure ratio 5:1, the adiabatic efficiency of compression
being 85 %. The gases enter the turbine at a temperature 540 0C and
expand to 1.01 bar, the turbine efficiency being 80. Estimate the flow
of air and gases in kg/s, for a net power of 1500 kW, making the
following assumptions,
Fall of pressure through the combustion system is 0.07 bar, Cp for
both air and combustion gases =1.047 kJ/kgK, k = 1.4. Neglect
additional mass flow due to fuel.
Q.7 (a) Explain the working of turboprop engine with neat sketch. State its merits
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and demerits.
(b) Explain effect of operating variables on work ratio in gas turbine
04
power plant.
(c) Draw & Explain Can type combustor with swirl floe flame stabilizer.
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Q.8 (a) Give classification of propulsive engine.
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(b) Differentiate between (i) Turbojet engine and Turboprop engine
04
(ii) Ramjet engine and Pulsejet engine
(c) What is the principle of jet-propulsion? Explain Thrust, Thrust power,
07
Propulsive power and Propulsive Efficiency.
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This post was last modified on 04 March 2021