Seat No.:
Enrolment No.
--- Content provided by FirstRanker.com ---
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER-VII (NEW) EXAMINATION - WINTER 2020
Subject Code:2171917
Subject Name:Steam and Gas Turbines
Time:10:30 AM TO 12:30 PM
--- Content provided by FirstRanker.com ---
Instructions:
- Attempt any FOUR questions out of EIGHT questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
- Use of Steam table and Molliar diagram is permitted.
--- Content provided by FirstRanker.com ---
Q1 (a) Describe different types of nozzle with neat sketch. State the function of nozzle. MARKS 03
(b) With help of S.F.E.E. prove that C2 = 44.72v(h1 — h2). Neglect initial velocity of steam. Where C2 is outside velocity of steam from nozzle (h1 —h2) is heat drop in nozzle. 04
(c) What is critical pressure? Derive the expression for critical pressure ratio in flow through nozzles. Calculate its value for superheated steam. 07
Q2 (a) What is function of governing system of steam turbine? Compare throttle and Nozzle Governing. 03
Q3 (a) Derive an expression for exit velocity of steam in terms of enthalpy of fluid at inlet and at exit and the velocity of steam at inlet. 04
--- Content provided by FirstRanker.com ---
(b) Show that in a 50 % reaction turbine stage, the maximum efficiency is (2cos2a) / (1 + cos2a). where a is the nozzle angle. 07
(c) Explain with neat sketch“any one method of attachment of blade to turbine rotor. 03
Q4 (a) Why compounding of impulse turbine is necessary? What are various methods of reducing rotor speed? Explain anyone method with neat diagram. 04
(b) The following particulars refer to a stage of a Parson’s steam turbine 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. 07
Q5 (a) Compare the impulse and reaction turbines. 03
--- Content provided by FirstRanker.com ---
(b) Enlist different losses in steam turbine. 04
(c) Draw p-v &T-s diagram for gas turbine cycle with: (1) Intercooler, (2) Reheating (3) Regeneration. Also state the difference between Intercooler and Reheating gas turbine cycle. 07
(@ State the difference between steam turbine and gas turbine. 03
Date:02/02/2021 Total Marks: 56
--- Content provided by FirstRanker.com ---
(¢) In an open cycle regenerative gas turbine plant, the air enters the compressor at 1 bar, 32 °C and leaves at 6.9 bar. The temperature at the end of combustion chamber is 816 °C. 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. 04
Q.6 (a) State the different applications of Gas turbine. 03
(b) Describe any four requirements of a typical combustion chamber of the gas turbine power plant. 04
(c) A simple gas turbine takes air at 1.01 bar and 15.5 °C and compresses it through a pressure ratio 5:1, the adiabatic efficiency of compression being 85 %. The gases enter the turbine at a temperature 540 °C 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. 07
Q.7 (a) Explain the working of turboprop engine with neat sketch. State its merits and demerits. 03
--- Content provided by FirstRanker.com ---
(b) Explain effect of operating variables on work ratio in gas turbine power plant. 04
(c) Draw & Explain Can type combustor with swirl floe flame stabilizer. 07
Q.8 (a) Give classification of propulsive engine. 03
(b) Differentiate between (i) Turbojet engine and Turboprop engine (i) Ramjet engine and Pulsejet engine 04
(c) What is the principle of jet-propulsion? Explain Thrust, Thrust power, Propulsive power and Propulsive Efficiency. 07
--- Content provided by FirstRanker.com ---
This download link is referred from the post: GTU B.Tech 2020 Winter Question Papers || Gujarat Technological University
--- Content provided by FirstRanker.com ---