The maximum propulsive efficiency of a turbojet engine is at a speed of
1000 km/h
2000 km/h
2400 km/h
3000 km/h
Correct Answer :
C. 2400 km/h
Related Questions
The cetane number of diesel oil, generally available, is
20 to 25
25 to 30
30 to 40
40 to 55
As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
Increase maximum pressure and maximum temperature
Reduce maximum pressure and maximum temperature
Increase maximum pressure and decrease maximum temperature
Decrease maximum pressure and increase maximum temperature
For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of
9 : 1
12 : 1
15 : 1
18 : 1
Theoretically, a four stroke cycle engine should develop _________ power as that of a two stroke cycle engine.
Half
Same
Double
Four times
The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is
Same
More
Less
Less or more depending on operating conditions
Which of the following is false statement? Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following
Piston ring and cylinder wear
Formation of hard coating on piston skirts
Oil sludge in the engine crank case
Detonation
The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of
Morse test
Prony brake test
Motoring test
Heat balance test
The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will
Increase
Decrease
Be independent
May increase or decrease depending on other factors
The combustion in compression ignition engines is
Homogeneous
Heterogeneous
Both (A) and (B)
None of these
The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in metres, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Dia. of brake drum in metres, and d = Dia. of rope in metres)
B.P = (Wl × 2πN)/60 watts
B.P = [(W - S) πDN]/60 watts
B.P = [(W - S) π (D + d) N]/60 watts
All of these
Which of the following statement is correct?
Compression ratio for petrol engines varies from 6 to 10
Higher compression ratio in diesel engines results in higher pressures
Petrol engines work on Otto cycle
All of the above
The firing order in an I.C. engine depends upon
Arrangement of the cylinders
Design of crankshaft
Number of cylinders
All of these
The specific fuel consumption per B.P. hour for a petrol engine is about
0.2 kg
0.25 kg
0.3 kg
0.35 kg
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
The specific fuel consumption per BHP hour for diesel engine is approximately
0.15 kg
0.2 kg
0.25 kg
0.3 kg
Gaseous fuel guarantees are based on
Calorific value of oil
Low heat value of oil
High heat value of oil
Mean heat value of oil
The output of a diesel engine can be increased without increasing the engine revolution or size in following way
Feeding more fuel
Heating incoming air
Scavenging
Supercharging
For the same compression ratio
Otto cycle is more efficient than the Diesel
Diesel cycle is more efficient than Otto
Both Otto and Diesel cycles are, equally efficient
Compression ratio has nothing to do with efficiency
Morse test can be conducted for
Petrol engines
Diesel engines
Multi cylinder engines
All of these
Which of the following statement is wrong?
In compression ignition engines, detonation occurs near the beginning of combustion.
Since the fuel, in compression ignition engines, is injected at the end of compression stroke, therefore, there will be no pre-ignition.
To eliminate knock in compression ignition engines, we want to achieve auto-ignition not early and desire a long delay period.
In compression ignition engines, because of heterogeneous mixture, the rate of pressure rise is comparatively lower.
The knocking tendency in compression ignition engines for a given fuel will be
Enhanced by decreasing compression ratio
Enhanced by increasing compression ratio
Dependent on other factors
None of the above
The mechanical efficiency (ηm) of the engine is given by
ηm = B.P/I.P
ηm = I.P/B.P
ηm = (B.P × I.P)/100
None of these
Diesel as compared to petrol is
Highly ignitable
More difficult to ignite
Less difficult to ignite
None of these
Compression ratio of I.C. Engines is
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
If petrol is used in a diesel engine, then
Low power will be produced
Efficiency will be low
Higher knocking will occur
Black smoke will be produced
Pour point of fuel oil is the
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
Temperature at which it solidifies or congeals
It catches fire without external aid
Indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off
In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the
Beginning of suction stroke
End of suction stroke
Beginning of exhaust stroke
End of exhaust stroke
In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will _________ the knocking tendency.
Not effected
Decrease
Increase
None of these
A diesel engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle