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ATPL - [Mod 2] AGK - Engines > 08. The Diesel Engine > Flashcards

08. The Diesel Engine Flashcards

1
Q

Diesel engine

Diesel engines produce heat through what means and which stroke

A

COMPRESSION

Heat generated during compressiong stroke

Pg 184

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2
Q

Diesel engine

Another name given to Diesel engines based on them creating heat during compression is what

A

COMPRESSION IGNITION ENGINES

Pg 184

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3
Q

Diesel engine

As ignition occurs spontaneously, which 3 components are not needed in a diesel engine

A
  1. Spark Plugs
  2. Distributors
  3. Magnetos

Pg 184

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4
Q

Diesel engine

Why is there no need for a mixture control on a diesel engine

A

DIRECT FUEL INJECTION

Diesel engines use direct fuel injection into the cylinder

Pg 184

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5
Q

Diesel engine

What method do diesel engines use to get fuel into the cylinder

A

DIRECT FUEL INJECTION

Pg 184

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6
Q

Diesel engine

Operating at a higher compression ratio ensures a sufficiently high enough what

A

TEMPERATURE

Pg 185

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7
Q

Diesel engine

The typical compression ratio is from ____ : ____ to ____ : ____

A

14:1 < > 28:1

Pg 185

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8
Q

The maximum compression ratio of a petrol engine compared to a diesel engine is what

A

9:1

Pg 185

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9
Q

Diesel engine

What is increased as a result of a higher compression ratio of the charge

A

POWER OUTPUT

Pg 185

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10
Q

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

A

THERMAL EFFICIENCY

Pg 185

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11
Q

Diesel engine

What fuel is used in a diesel engine

A

JET A1
(Kerosene)

Pg 185

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12
Q

Diesel engine

Why can’t gasoline be used in a diesel engine

A

DETONATES UNCONTROLLABLY

Detonates uncontrollably at such high compression ratios

Pg 185

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13
Q

Diesel engine

What is the specific gravity range for Jet A1

A

0.8 - 0.9

Pg 185

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14
Q

Diesel engine

Jet A1 compared to AVGAS is;
1. MORE or LESS viscous
2. More or LESS volatile
3. HIGHER or LOWER flash point

A
  1. MORE
  2. LESS
  3. HIGHER

Pg 185

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15
Q

Diesel engine

As Jet A1 is more viscious, the main disadvantage is what

A

POOR LUBRICANT

Pg 185

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16
Q

Diesel engine

Since Jet A1 is more viscious and makes a poor lubricant, which component needs to be specifically designed for a diesel engine

A

FUEL PUMP

Pg 185

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17
Q

How are Kerosene fuels sometimes categorised

A

CETANE NUMBER

Pg 185

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18
Q

Diesel engine

What is a cetane number

A

KEROSENE CATEGORISATION

HIGHER the cetane number, SHORTER the ignition period

Pg 185

19
Q

Diesel engine

A high cetane number means a LONGER or SHORTER ignition time

A

SHORTED

Pg 185

20
Q

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 [ ]

A
  • 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

Pg 186

21
Q

Diesel engine

What are the 4 strokes of a diesel engine

A
  1. Induction
  2. Compression
  3. Power Exhaust

Suck, squeeze, bang, blow

Similar operation to a petrol engine

Pg 187

22
Q

Diesel engine

During the induction stroke, what is drawn into the cylinder, and how does this differ to a petrol engine

A
  1. Air
  2. Petrol engine draws in mixture i.e. air AND fuel

Pg 187

23
Q

Diesel engine

What position and in during which stroke is the piston in when fuel is introduced into the cylinder

A
  1. TDC
  2. 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

Pg 187

24
Q

Diesel engine

What is the force exerted in a power stroke so much greater than a petrol engine

A

VOLUME

Compression is so much greater, volume is compressed greatly

Pg 187

25
Q

Diesel engine

Given that there is no risk of detonation, what benefit does this have regarding the stoichiometric ratio of the fuel

A

MUCH LEANER

Pg 187

26
Q

Diesel engine

How is power output controlled

A

CONTROL AMOUNT OF FUEL INJECTED

Control the amount of fuel injected into the cylinder.
This differs to a petrol engine where the amount of mixture is controlled that is introduced to the cylinder

Pg 817

27
Q

Diesel engine

What pressure (in bar and PSI) must a direct fuel injection system cope with

A

1600 BAR
24,000 PSI

Pg 188

28
Q

Diesel engine

What 2 types of injection system are used in an aero diesel engine

A
  1. Direct Injection
  2. Common Rail
29
Q

Diesel engine

What is the difference in terms of fuel delivery to the cylinder between a direct injection system and a common rail system

A

DIRECT INJECTION - High pressure fuel pumped directly into each cylinder
COMMON RAIL - Pressure pump suppliers a common rail where fuel is distributed to the cylinders evenly

Pg 188

30
Q

Diesel engine

Most common diesel engines use a DIRECT INJECTION or COMMON RAIL system

A

COMMON RAIL

Pg 188

31
Q

Diesel engine

What 4 things must the pump of a direct fuel injection system be able to do in order to deliver an exact meterd amount of high pressure fuel to the injector

A
  1. RPM
  2. DENSITY
  3. TIMING
  4. PULSES

  • Sense the engine RPM
  • Sense air density
  • Advancing and retarding the timing of fule pulses
  • Generate fuel pulses of sufficient pressure

Pg 190

32
Q

Diesel engine

How does the fuel injector port open when the pressure is correct

A

SPRING LOADED POPPET

Spring loaded poppet opens momentarily when the fuel line pressure exeeds the opposing force

Pg 191

33
Q

What are the 4 key components that make up a common rail injection system

A
  1. PRESSURE PUMP
  2. COMMON RAIL
  3. INJECTORS
  4. ECU - Engine Control unit

  1. High pressure pump - also with a pressure regulator and metering valve
  2. Common rail acts as an accumulator of high pressure fuel
  3. Injectors - electro-magnetically operated
  4. Engine Control Unit - monitors engine conditions and controls pressure in common rail, and timing of injectors opening and closing

Pg 192

34
Q

When can diesel engines be difficult to start

A

COLD DAY

Pg 194

35
Q

Why are diesel engines difficult to start on a cold day

A

FLASHPOINT TEMPERATURE NOT REACHED

Compression stroke may not be enough to raise temp above flash point

Pg 194

36
Q

To overcome the issues of flash point of fuel not being reached by the compression stroke on a cold day, what is fitted into diesel engines to increase the temperature

A

GLOW PLUGS

Pg 194

37
Q

What is the purpose of a glow plug

A

INCREASE TEMPERATURE in COMBUSTION CHAMBER

Pg 194

38
Q

What are the 2 types of glow plug

A
  1. Sheathed
  2. Ceramic

Pg 194

39
Q

A sheathed glow plug contains an ____.
A ceramic glow plug contains a ____.

A
  1. Electrically heated coil
  2. Heating element

Pg 194

40
Q

Where do glow plugs obtain their power

A

BATTERY

Pg 195

41
Q

Compared to an equivilant petrol engine, in regards to temperature, what does a diesel engine require more of

A

COOLING

Pg 196

42
Q

What is the most common method of cooling a diesel engine

A

LIQUID

Pg 196

43
Q

What is the cooling liquid in a diesel engine comprised of typically

A

WATER & ANTIFREEZE

Pg 196

44
Q

What component located in the intake of the cooling system helps disperse heat absorbed by liquid coolant

A

AIR COOLED HEAT EXCHANGER

Pg 196

ATPL - [Mod 2] AGK - Engines (23 decks)

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