UPSC Mechanical Engineering PYQs 2022 | Vaidra

1Medium10 marks

Discuss the Expansionist strategy and Wait-and-See strategy for capacity timing and sizing concerning the capacity planning.

2Medium10 marks

Spot welding of two steel sheets each of 1 mm thickness is performed using 20,000 A welding current supplied for 0.15 seconds. Assume that :

(i) interface contact resistance is 200 micro-ohms,

(ii) heat required for melting unit volume of steel is 10 J/mm^3, and

(iii) only 60% of heat generated is used for melting of metal at the interface.

Calculate :

(I) Heat generated, J

(II) Volume of the weld nugget, mm^3

3Medium20 marks

A single-stage impulse turbine rotor has a mean blade ring diameter of 500 mm and rotates at a speed of 10000 r.p.m. The nozzle angle is 20° and the steam leaves the nozzles with a velocity of 900 m/s. The blades are equiangular and the blade friction factor is 0.85. Construct velocity diagrams for the blades and determine the inlet angle of the blades for shockless entry of steam. Also, determine

(i) the diagram power for a steam flow of 750 kg/hr,

(ii) the diagram efficiency,

(iii) the axial thrust and

(iv) the loss of kinetic energy due to friction.

Mechanical Engineering UPSC PYQ 2022

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