08. The Diesel Engine Flashcards
Diesel engine
Diesel engines produce heat through what means and which stroke
COMPRESSION
Heat generated during compressiong stroke
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Diesel engine
Another name given to Diesel engines based on them creating heat during compression is what
COMPRESSION IGNITION ENGINES
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Diesel engine
As ignition occurs spontaneously, which 3 components are not needed in a diesel engine
- Spark Plugs
- Distributors
- Magnetos
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Diesel engine
Why is there no need for a mixture control on a diesel engine
DIRECT FUEL INJECTION
Diesel engines use direct fuel injection into the cylinder
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Diesel engine
What method do diesel engines use to get fuel into the cylinder
DIRECT FUEL INJECTION
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Diesel engine
Operating at a higher compression ratio ensures a sufficiently high enough what
TEMPERATURE
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Diesel engine
The typical compression ratio is from ____ : ____ to ____ : ____
14:1 < > 28:1
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The maximum compression ratio of a petrol engine compared to a diesel engine is what
9:1
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Diesel engine
What is increased as a result of a higher compression ratio of the charge
POWER OUTPUT
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Diesel engine
As power output is improved given a higher compression ratio of the charge, what benefit does this have to the engine in terms of temperature
THERMAL EFFICIENCY
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Diesel engine
What fuel is used in a diesel engine
JET A1
(Kerosene)
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Diesel engine
Why can’t gasoline be used in a diesel engine
DETONATES UNCONTROLLABLY
Detonates uncontrollably at such high compression ratios
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Diesel engine
What is the specific gravity range for Jet A1
0.8 - 0.9
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Diesel engine
Jet A1 compared to AVGAS is;
1. MORE or LESS viscous
2. More or LESS volatile
3. HIGHER or LOWER flash point
- MORE
- LESS
- HIGHER
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Diesel engine
As Jet A1 is more viscious, the main disadvantage is what
POOR LUBRICANT
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Diesel engine
Since Jet A1 is more viscious and makes a poor lubricant, which component needs to be specifically designed for a diesel engine
FUEL PUMP
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How are Kerosene fuels sometimes categorised
CETANE NUMBER
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Diesel engine
What is a cetane number
KEROSENE CATEGORISATION
HIGHER the cetane number, SHORTER the ignition period
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Diesel engine
A high cetane number means a LONGER or SHORTER ignition time
SHORTED
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Diesel engine
Select which of the following are advantages of a diesel engine
1. Fuel Efficient [ ]
2. Light Weight [ ]
3. Robust [ ]
4. Ideal for Supercharging [ ]
5. Ideal for Turbocharging [ ]
6. Cheaper to run than AVGAS engine [ ]
7. Larger engine size than petrol engine gives more power [ ]
8. Lower power to weight ratio [ ]
9. More reliable than petrol engine [ ]
- FUEL EFFICIENT
- ROBUST
- TURBO
- RELIABLE
- CHEAPER
- POWER RATIO
1, 3, 5, 6, 8, 9
- More fuel efficient
- Heavier build makes them more robust and ideal for turbocharging
- No ignition system, makes them simplier and more reliable
- Jet A1 is cheaper than AVGAS
- Compared to similar size AVGAS engine, power to weight ratio is better
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Diesel engine
What are the 4 strokes of a diesel engine
- Induction
- Compression
- Power Exhaust
Suck, squeeze, bang, blow
Similar operation to a petrol engine
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Diesel engine
During the induction stroke, what is drawn into the cylinder, and how does this differ to a petrol engine
- Air
- Petrol engine draws in mixture i.e. air AND fuel
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Diesel engine
What position and in during which stroke is the piston in when fuel is introduced into the cylinder
- TDC
- Very end of compression stroke
Compression ratio is so high, flash point would be reached very quickly during compression strok.
Fuel is subsequently injected at the very last moment
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Diesel engine
What is the force exerted in a power stroke so much greater than a petrol engine
VOLUME
Compression is so much greater, volume is compressed greatly
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