UPSC Mechanical Engineering 2021

(a) What is the supporting force system at A for the cantilever beam shown in the figure ? Neglect the weight of the beam. (10 marks) (b) The velocity of a particle, moving in the…

(a) In a slider-crank mechanism, the lengths of the crank and connecting rod are 150 mm and 600 mm respectively. Locate all the I-centres of the mechanism for the position when th…

(a) What is the purpose of tempering of hardened steel? Explain the principle of tempering using suitable schematics including heating temperature requirement and microstructural…

(a) Find out the value of atomic packing factor for the FCC crystal structure. Calculate the radius of an iridium (Ir) atom, given that Ir has an FCC crystal structure, a density…

(a) TIG welding of two sheets of 5 mm thickness is performed using welding current (I) of 200 A and arc voltage (V) of 12 V. Assume 70% of generated arc heat is utilised for melti…

(a) Five jobs A, B, C, D and E need to be processed on a machine. Processing time (in days) and due date (from now) are given below : | Jobs | Processing Time (in days) | Due Date…

A car servicing company is interested in reducing the waiting time for its customers. They select four customers randomly each day and find the waiting time for each customer whil…

The frontal working area of the electrode is 2000 mm² in a certain ECM operation in which the applied current = 1800 amps and the voltage = 12 volts. The material being cut is nic…

(a) Discuss briefly the functional differences between a fan, a blower and a compressor. (10 marks) (b) Prove that shock cannot occur in subsonic flow. (10 marks) (c) Consider a l…

(a)(i) 3 kg of air is compressed in a reversible steady flow polytropic process from 100 kPa, 40°C to 1000 kPa. During this process the law of compression followed is PV^1.25 = C.…

(a)(i) Show that the effective conductance, (A_1F̄₁₂) for two black, parallel plates of equal area connected by re-radiating walls at constant temperature is A_1F̄₁₋₂ = A₁((1+F₁₋₂…

(a) Two walls A and B are maintained at temperatures T_A and T_B, respectively. One end of a metal rod of length l is embedded in the wall A, while the other end is fixed to wall…

(a) What do you understand by the term EGR? Explain how EGR reduces NOₓ emission in CI engines. (10 marks) (b) The flue gas composition measured by Orsat apparatus for a boiler bu…

(a) (i) How does the mixture combustion in the combustion chamber of a C.I. engine differ from that of an S.I. engine? (ii) What is meant by combustion induced swirl? Show with sk…

(a) (i) A single stage impulse steam turbine rotor has a diameter of 1·2 m and runs at 3000 rpm. The nozzle angle is 18°. The blade speed ratio is 0·42. The relative velocity at t…

(a) An ammonia vapour compression refrigeration system works between temperature limits of −6·7°C and 26·7°C. The vapour is dry at the end of compression and there is no under coo…