WorksheetsIC ENGINES
Total questions: 15
Worksheet time: 15mins
1. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft
1/2
1
2
4
8
1. In a diesel engine, the fuel is ignited by
spark
injected fuel
heat resulting from compressing air that is supplied for combustion
ignition
combustion chamber.
Scavenging air in diesel engine means
(a) air used for combustion sent under pres-sure
air used for combustion sent under pres-sure
forced air for cooling cylinder
burnt air containing products of combustion
air used for forcing burnt gases out of engine’s cylinder during the exhaust period
air fuel mixture.
1. Supercharging is the process of
supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere
providing forced cooling air
injecting excess fuel for raising more load
supplying compressed air to remove combustion products fully
raising exhaust pressure.
1. Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged ?
yes
no
to some extent
unpredictable
depends on other factors.
1. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
net efficiency
efficiency ratio
relative efficiency
overall efficiency
cycle efficiency.
1. Compression ratio of LC. engines is
(a)
(b)
(c)
(d)
(e)
the ratio of volumes of air in cylinder before compression stroke and after compression stroke
volume displaced by piston per stroke and clearance volume in cylinder
ratio of pressure after compression and before compression
swept volume/cylinder volume
cylinder volume/swept volume.
1. The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is
same
less
more
more or less depending on power rating
unpredictable.
The calorific value of gaseous fuels is expressed in terms of
kcal
kcal/kg
kcal/m2
kcal/n2
all of the above
1. If the intake air temperature of I.C. engine increases, its efficiency will
increase
decrease
remain same
unpredictable
depend on other factors.
. An engine indicator is used to determine the following
speed
temperature
volume of cylinder
m.e.p. and I.H.P.
BHP.
Fuel oil consumption guarantees for I .C. engine are usually based on
low heat value of oil
high heat value of oil
net calorific value of oil
calorific value of fuel
all of the above.
12. In case of gas turbines, the gaseous fuel consumption guarantees are based on
high heat value
low heat value
net calorific value
middle heat value
calorific value.
In a typical medium speed 4-stroke cycle diesel engine the inlet valve
opens at 20° before top dead center and closes at 35° after the bottom dead center
opens at top dead center and closes at bottom dead center
opens at 10° after top dead center and closes 20° before the bottom dead center
may open or close anywhere
remains open for 200°.
The pressure and temperature at the end of compression stroke in a petrol engine are of the order of
4 – 6 kg/cm2 and 200 – 250°C
6 – 12 kg/cm2 and 250 – 350°C
12 – 20 kg/cm2 and 350 – 450°C
20 – 30 kg/cm2 and 450 – 500°C
30 – 40 kg/cm2 and 500 – 700°C
