PREVIOUS YEAR ESE&GATE OBJECTIVE QUESTIONS COVERED PREVIOUS YEAR ON STEAM TURBINES PART1 ESE MECHANICAL PRESENTED BY DEEPALI NAMDEO
About ME GATE Qualified. I also have an experience of 11 months teaching Engineering subjects like Industrial, Thermodynamics, SOM, HMT. Currently working as a Design Engineer at "Cameron-A Schlumberger Company" B.tech with honors from M.I.T.S Gwalior. I am pursuing my Post graduate Diploma in Design Engineering for Oil and Gas Industry
1. Given, Vb- Blade speed IGATE-1998] V = Absolute velocity of steam entering the blade, a = Nozzle angle. The efficiency of an impulse turbine is maximum when (a)% = 0.5V cos (c) V,-0.5V" cos (b)V, = V cos (d)V, V cosa 1. Ans. (a) 2. For a single stage impulse turbine with a rotor diameter of 2 m and a speed of 3000 rpm when the nozzle angle is 20 , the optimum velocity of steam in m/s is (a) 334 IGATE-19941 (b) 356 use u (c) 668 DN (d) 711 VcoSa and u 6 2.Ans. (c Just 2
3. The Rateau turbine belongs to the category of GATE-2001] (a) Pressure compounded turbine (c) Velocity compounded turbine (b) reaction turbine (d) redial flow turbine 3. Ans. (a) 4. Match the following [GATE-2003] P. Curtis Q. Rateau R. Kaplan S. Francis 1. Reaction steam turbine 2. Gas turbine 3. Velocity compounding 4. Pressure compounding 5. Impulse water turbin<e 6. Axial turbine 7. Mixed flow turbine 8. Centrifugal pump Code: P QR S 6 P Q R S 3 (a) 2 3 (d) 3 6 4. Ans. (d)
Steam enters a De Laval steam turbine with an inlet velocity of 30 m/s and leaves with an outlet velocity of 10 m/s. The work done by 1kg of steam is (a) 400 Nm 5. ," (b) 600 Nm (c) 800 Nm (d) 1200Nm [IES-2003] 5. Ans. (a) The work done by lkg of steam isvV)x1x(302-102) 400 Nm
6. In the velocity diagram shown below, u-blade velocity, C- absolute fluid velocity and = relative velocity of fluid and the subscripts 1 and 2 refer to inlet and outlet. (a) an impulse turbine (b) a reaction turbine (c) a centrifugal compressor (d) an axial flow compressor Ci C2 GATE-2005] 6.Ans. (d)
7. A steam turbine receives steam steadily at 10 bar with an enthalpy of 3000 kJ/kg and discharges at 1 bar with an enthalpy of 2700 kJ/kg. The work output is 250 kJ/kg. The changes in kinetic and potential energies are negligible. The heat transfer from the turbine casing to the surroundings is equal to (a) 0 kJ [GATE-2000] (b) 50 kJ 7. Ans. (b) Enthalpy drop = Power output + losses (c) 150 kJ (d) 250 kJ Or 3000-2700 = 250 + losses or losses = 50 kJ to the surrounding
8.In an ideal impuise turbine, the LIES-19931 (a) Absolute velocity at the inlet of moving blade is equal to that at the outlet (h) Relative velocity at the inlet of the moving blade s equal to that at the outlet (c) Axial, velocity at the inlet is cqual to that at the outlet (d) Whirl vclocity at the inlet is cqual to that at the outlet Ans. (b) For an ideal impulse turbine, relative velocity at inlet of the moving blade is equal to that at the outlet. 9.Which one of the following sketches represents an impulse turbine blade? IES-1995] Ans. (a) Figure at (a) is for impulse turbine blade. As no pressure change from inlet to outlet no area change is allowed.
10.The given figure shows the variation of certain steam parameter in case of a simple impulse turbine. The curve A-B- C represents the variation of (a) pressure in nozzle and blades (b) velocity in nozzle and blades (c) temperature in nozzle and blades (d) enthalpy in nozzle and blades Nozzle IES-2001] Ans. (b)
11 Which one of the following velocity triangles represents the one at the exit IES-1994] of a radial impeller with forward curved blades? v-absolute velocity, w relative velocity) (u peripheral velocity. V2 W. u2 U 2 2 Ans. (b) Veloeity triangle at (b) is correct. Actual velocity ve is at right angle and angle between ug and w is acute
Which one of the following is used to bring down the speed of an impulse steam turbine to practical limits? (a) A centrifugal governor (c) A large flywheel 13. [IES-2006] (b) Compounding of the turbine (d) A gear box 13. Ans. (b) Why is compounding of steam turbines done? (a) To improve efficiency (c) To reduce exit losses 14. [IES-2005] (b) To reduce the speed of rotor (d) To increase the turbine output 14. Ans. (b)
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I have done my bachelor's in mechanical engineering from M.I.T.S Gwalior. Currently I am Design Engineer at Cameron, a Schlumberger Company.