ATD-Advanced technology demostration MCQ Unit -3

Q1-Scavenging air in diesel engine means
A) Air used for combustion sent under pressure
B) Forced air for cooling cylinder
C) Burnt air containing products of combustion
D) Air used for forcing burnt gases out of engine's cylinder during the exhaust period

Answer D

Q2-The pressure at the end of compression in the case of diesel engine is of the order of 

A 6 kg/cm2 

B 12 kg/cm2 

C 20 kg/cm2

 D 35 kg/cm2 

Answer D

 Q3-The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will 

A Increase

 B Decrease 

C Be independent 

D May increase or decrease depending on other factors 

Answer B 

Q4-The fuel in diesel engine is normally injected at pressure of

A 5-10 kg/cm2 

B 20-25 kg/cm2 

C 60-80 kg/cm2 

D 90-130 kg/cm2

 Answer D 

Q5-Compression loss in I.C. engines occurs due to 

A Leaking piston rings 

B Clogged air-inlet slots 

C Increase in clearance volume caused by bearing-bushing wear 

D All of the above 

Answer D

Q6-In direct combustion chambers, the swirl generated is ___________ 

A Weak 

B Strong 

C Can’t say 

D Swirl is not generated

 Answer A 

Q7-The output of a diesel engine can be increased without increasing the engine revolution or size in following way

 A Scavenging 

B Increasing flywheel size

 C Supercharging. 

D Feeding more fuel

 Answer C

Q8-Which of the following medium is compressed in a diesel engine cylinder 

A Air alone 

B Air and lube oil 

C Fuel alone 

D Air and fuel

 Answer A 

Q9-In a typical medium speed, 4-stroke cycle diesel engine 

A Fuel injection starts at 10° before top dead center and ends at 20° after top dead center 

B Fuel injection starts at top dead center and ends at 20° after top dead center 

C Fuel injection starts at just before top dead center and ends just after top dead center 

D May start and end anywhere 

Answer A

Q10-Diesel fuel, compared to petrol is 

A Less difficult to ignite 

B Just about the same difficult to ignite 

C More difficult to ignite 

D Highly ignitable 

Answer C 

Q11-The rating of a diesel engine is given by 

A Octane number 

B Diesel index 

C Cetane number 

D Either B or C 

Answer D 

Q12-Starting of the diesel engine is difficult because of 

A Low wall temperature 

B Less cranking speed 

C Leakage past the piston ring 

D All of the above 

Answer D

Q12-In diesel engine, the compression ratio in comparison to expansion ratio is 

A Same 

B Less 

C More 

D Variable 

Answer C

Q13-In a typical medium speed, 4 stroke cycle diesel engine 

A Exhaust valve opens at 35° before bottom dead center and closes at 20° after top dead center 

B Exhaust valve opens at bottom dead center and closes at top dead center 

C Exhaust valve opens just after bottom dead center and closes just before top dead 

D May open and close anywhere 

Answer A 

Q14-Scavenging is usually done to increase 

A Thermal efficiency 

B Speed 

C Power output 

D Fuel consumption 

Answer C

Q15-The knock in diesel engine occurs due to 

A Instantaneous and rapid burning of the first part of the charge

B Instantaneous auto ignition of last part of charge 

C Delayed burning of the first part of the charge 

D Reduction of delay period 

Answer A

Q16-Volatility of diesel fuel oil is 

A Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame

 B Temperature at which it solidifies or congeals 

C It catches fire without external aid 

D Indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off 

Answer D 

Q17-In a naturally aspirated diesel engine, the air is supplied by A 

A supercharger 

B A centrifugal blower 

C An injection tube 

D None of the above 

Answer D

Q18-CI engine was developed by 

A Otto 

B Carnot 

C Diesel 

D Faraday 

Answer C 

Q19-Thermal efficiency of CI engine is .............to/than SI engine

 A Equal 

B Higher 

C Lower 

 D Equal or lower 

Answer B 

Q20-The diesel knock can be controlled by reducing delay period.the delay is reduced by the following 

A High charge temperature 

B High fuel temperature 

C A fuel with short induction period 

D All above 

Answer D

Q21-The most important property of fuel which affect delay period is 

A Volatility 

B Self ignition temperature

C Density 

D None of above

 Answer B 

Q22-Fuel is injected in to combustion chamber after ..........stroke 

A Suction 

B Compression 

C Power 

D Exhaust 

Answer B

Q23-In a diesel engine, the fuel is ignited by 

A Spark 

B Injected fuel 

C Heat resulting from compressing air that is supplied for combustion 

D Ignitor 

Answer C

Q24-Diesel cycle consists of following processes 

A Isentropic process 

B Constant pressure process 

C Both A & B D None of these 

Answer C

Q25-In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the 

A Beginning of suction stroke 

B End of suction stroke 

C Beginning of exhaust stroke 

D End of exhaust stroke 

Answer A 

Q26-The brake power of a diesel engine, keeping other parameters constant, can be increased by 

A Decreasing the density of intake air 

B Increasing the temperature of intake air 

C Increasing the pressure of intake air 

D Decreasing the pressure of intake air 

Answer C 

Q27-In diesel engines, the fuel is injected in the form of very fine spray, into the engine cylinder, which gets ignited due to high temperature of the compressed air. 

A Agree 

B Disagree 

C Data incomplete 

D Undefined 

Answer A

Q28-Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to 

A Cylinder walls being too hot 

B Overheated spark plug points 

C Red hot carbon deposits on cylinder walls 

D Any one of these 

Answer D

Q29-In open combustion chamber in diesel engines, the shape and layout of the piston crown, the inlet port and the valve produce the turbulent effect of fuel mixture.

A Yes 

B No 

C Data insufficient 

D None of these 

Answer A

Q30-In a diesel engine, the duration between the time of injection and ignition, is known as 

A Pre-ignition period 

B Delay period 

C Period of ignition 

D Burning period 

Answer B