Unit 4 Performance characteristics and testing of I

Unit : 4 Performance characteristics and testing of I. C. Engine

Q. 1 If N is the rpm number of power stroke / min in four stroke engine is a) 2 N c) N b)N/2 d) 4 N ANS: b) N/2

Q. 2 Turbocharging engine are those in which charge density is increased by a) Separate air compressor c) Cooling air inlet b) Compressor driven by exhaust gas turbine d) None of above ANS: b) Compressor driven by exhaust gas turbine

Q. 3 The volumetric efficiency of a well-designed engine is in the range a) 30 to 40% c) 60 to 70% b) 40 to 60% d) 75 to 85 % ANS: d) 75 to 85 %

Q. 4 For SI engine with engine speed torque Decrease b) increase c) Increase and then decrease d) None of above a) ANS: c) Increase and then decrease

Q. 6 Efficiency of turbocharger engine compared to naturally aspired engine a) More b) Same c) less d) can not predict ANS: a) More

Q. 7. Power developed within the cylinder is called a) I. P. b) B. P. c) Both A and B d) F. P. ANS: a) I. P.

Q. 8 Power available at output of the shaft is called (a) Indicated power (b) Break power (c) Frictional power (d) All of above ANS: (b) Break power

Q. 9 Mechanical losses in engine equal to (a) B. P. /I. P (b) I. P. /B. P. (c) I. P. -B. P. (d) B. P. -I. P. ANS: (c) I. P. -B. P.

Q. 10 Indicator diagram is used to measure (a) ) imep (b) speed (c) temperature (d) F. P. ANS: a) imep

Q. 11 Best method of measurement of B. P. is (a) Rope brake dynamometer (b) Prony brake dynamometer (c) Hydraulic dynamometer (d) all are equal ANS: (c) Hydraulic dynamometer

Q. 12 Which of the dynamometer cannot be used for measurement of B. P. at high speed (a) Prony Brake (b) Hydraulic (c) Swing field (d) All of above ANS: (a) Prony Brake

Q. 13 Which of the following dynamometer is suitable to measure B. P. of an aircraft (a) Prony Brake (b) Hydraulic (c) Swing field (d) Eddy curent ANS: (d) Eddy curent

Q. 14 F. P. ------With increase in speed increase b) remain same c) decrease d) can not predict a) ANS: a) increase

Q. 15 Which of the best way to measure F. P. of I. C. Engine a) Willan’s line method Morse test b) c) Motoring test d) All are equally effective a) ANS: b) Morse test

Q. 16 Morse test in multi cylinder engine is used to determine a) Mechanical efficiency b) Thermal efficiency c) Air standard efficiency d) Relative efficiency ANS: b) Thermal efficiency

Q. 17 Morse test is applicable to a) Single cylinder S. I. engine b) Single cylinder C. I. engine c) Multicylinder S. I. Engine d) All of above ANS: c) Multicylinder S. I. Engine

Q. 18) A Fuel flow meter shows that an engine consumed 100 cc of fuel in 20 sec of specific gravity 0. 78. the mass flow rate of fuel in kg/hr is about a) b) c) 14 41 Density of fuel =specific gravity * density of water =0. 78*1000 23 d) 32 =780 Kg/m 3 Mf = (volume/time)*density of fuel =(100*106 / 20)*780 Kg/ sec = 14. 04 kg/hr ANS: a) 14

Q. 19 An S. I. engine a compression ratio of 6 and has an indicated thermal efficiency of 0. 3, its relative efficiency is about………. a) 0. 154 b) 0. 586 c) 1. 705 d) None of above ANS: b) 0. 586

Q. 20 An engine has output of 50 Kw and consumes ¼ kg of fuel per min, its sfc equal to…. . kg/kwh a) 1/200 b) 50/4 c) 0. 3 d) None of above ANS: c) 0. 3

Q. 21 Brake Thermal efficiency of C. I. engine is about a) 20 -28% b) 30 -40% c) 40 -50% d) more than 50% ANS: b) 30 -40%

Q. 22 B. P. of 4 cylinder, 4 stroke engine is measured by brake dynamometer which develops a torque of 1000 Nm at 4200 rpm. The B. P. is about a) 440 KW b) 1760 KW c) 4. 4*105 KW d) None of above ANS : a) 440 KW

Q. 23 In an eight cylinder engine the fuel supplied was 4000 kg in 2 hour and the output 8000 kw. Its bfsc is about a) 0. 5 kg/kwh b) 1 kg/kwh c) 0. 25 kg/kwh d) 0. 12 kg/kwh ANS: c) 0. 25 kg/kwh

Q. 24 For 4 cylinder engine , the I. P. =100 KW , B. P. =20 KW/Cylinder , Its mechanical efficiency is a) 0. 2 b) 0. 4 c) 0. 8 d) Can not predict ANS: c) 0. 8

Q. 25 For 4 cylinder engine , the I. P. =100 KW , B. P. =20 KW/Cylinder , Its mechanical efficiency is a) 67 % b) 33% c) 75 % d) None of the above ANS: c) 0. 8

Q. 26 Supercharging is process of increasing the a) Pressure in the cylinder b) Suction pressure of charge c) Temperature of charge d) Charge density ANS: d) Charge density