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Part 1 > Systemmmmssss exam > Flashcards

Systemmmmssss exam Flashcards

1
Q

A piston engine has _____ parts. _______ internal combustion and converts _____ energy to ______ energy.

A

Reciprocating, intermittent, heat, mechanical

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2
Q

A Jet engine has _____ parts. _______ internal combustion and uses _______ to provide _____.

A

Rotating, continuous, action/reaction, thrust.

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3
Q

A cycle is:

A

A series of events which are repeated in a regular sequence and constitute the principle of operation (Otto cycle)

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4
Q

A stroke is:

A

The distance which a piston travels up or down in a cylinder

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5
Q

TDC is the position ____ to the crankshaft.

A

Furthest

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6
Q

BDC is the position ____ to the crankshaft.

A

Closest

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7
Q

Swept volume is:

A

The volume in the cylinder that is swept by the piston between TDC and BDC

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8
Q

Clearance volume is:

A

The volume in the cylinder above the piston at TDC

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9
Q

Compression ratio formula

A

swept + clearance / clearance

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10
Q

The bore is:

A

Internal diameter of the cylinder

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11
Q

Firing interval is:

A

The interval measured in crank shaft rotation between and two cylinders in the ignition sequence. eg. Four stroke takes two revs of CS, (720/4), firing interval of 180 degrees.

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12
Q

Firing order

A

Numerical order in which the cylinders fire eg. 1,3,2,4

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13
Q

Manifold is:

A

Pipes/ducts that lead the charge from carb to cylinders and cylinders to main outlet

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14
Q

Manifold pressure is:

A

The pressure of charge existing at any one time in the induction manifold

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15
Q

Crank angle is:

A

Same as the crank rotation from a datum

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16
Q

Ideal gas law

A

pV = nRT

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17
Q

Boyles law

A

pV = C

for a given mass, at a constant temp, the pressure x volume = constant

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18
Q

Charles law

A

V = CT

for a given mass, at a constant pressure, the volume is directly proportional to the temperature

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19
Q

1-2 Otto cycle

A

Induction

Piston starts at TDC, moves to BDC, total mass of charge inside the cylinder increases throughout the stoke, pressure is constant

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20
Q

2-3 Otto cycle

A

Compression

Piston moves from BDC to TDC, compressing the constant mass of gas isentropically. At the top of this stroke, combustion takes place.

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21
Q

3-4 Otto cycle

A

Combustion

Combustion takes place rapidly before the piston has moved any notable distance, hence we take it as a process of constant volume. Since energy is released, temperature increases significantly. Because V is constant, pressure increases (pV = nRT)

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22
Q

4-5-6 Otto cycle

A

Power

The high pressure exerted on the face of the piston during combustion generates a strong force which drives the piston downwards. The gas expands isentropically to a lower pressure. At the bottom of this stroke, the exhaust valve opens. The pressure inside the cylinder adjusts to the exhaust manifold pressure.

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23
Q

5-6 Otto cycle

A

Exhaust

Piston pushes the burnt gases out of the cylinder to return to the conditions at p1.

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24
Q

The inlet valve _____ by _____ degrees.

A

Lags, 60

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25
Q

The exhaust valve ____ by _____ degrees.

A

Leads, 55

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26
Q

Advantages of valve overlap

A

Cooling of upper cylinder
Better waste scavenging
Increased charged induced

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27
Q

Why does the valve lag?

A

Charge has mass and therefore inertia, change in velocity takes take. Restricted by inlet valve and friction from walls of inlet pipe.

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28
Q

Why does the valve lead?

A

Improves expulsion burnt gases.

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29
Q

The piston travels faster in the ____ 90 degrees than it does in the ____.

A

First, second

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30
Q

Piston travels a ____ distance for a given crank rotation at the _____ of the stroke

A

greater, middle

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31
Q

Con rod thrust will be most effective when the angle between the ______ and the _____ is at ___ degrees

A

Con rod, crank web, 90

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32
Q

Usually the crank angle for max con rod thrust is:

A

67 degrees

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33
Q

How many seconds does the combustion process take?

A

0.003 - 0.004

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34
Q

At 2000 rpm the crank turns ____ degrees every ____ seconds.

A

15, 0.001

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35
Q

Factors affecting combustion time

A

Fuel/air ratio
Temperature of charge/cylinder
Grade of fuel
CR and manifold pressure
No of ignition points
Gas turbulence (swirl)

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36
Q

In order for peak pressure to develop before 90 the ignition must be ______ between _______ degrees _____ TDC.

A

Advanced ,15-40, before

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37
Q

Most engines spark advance is ______ degrees

A

25

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38
Q

Diesel engines are ______ ignited

A

Compression

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39
Q

CCM

A

1:15 complete combustion of fuel/air

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40
Q

Rich

A

more fuel that ccm eg 1:10

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41
Q

Lean

A

less fuel than ccm eg 1:18

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42
Q

Workable ignition limits for fuel/air ratio

A

1:9 - 1:18

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43
Q

Max power

A

1:12

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44
Q

Best Econ

A

1:16

45
Q

Why is the charge atomised?

A

Makes it less vicious and therefore readily available to respond to rapid power increases.

46
Q

Accelerating system is for:

A

Supplying extra fuel during increases in power. Because fuel has inertia it can’t respond immediately to rapid throttle demands. Without it the engine would lean cut.

47
Q

Idling system

A

At low rpm and low velocity through Venturi the pressure difference between the float chamber and Venturi is not enough to ensure sufficient fuel flow.

48
Q

What rpm does the filing system kick in?

A

1000 and below

49
Q

Power enrichment

A

Utilizes second metering jet when the throttle is near fully open to ensure a sufficiently rich mixture. Without it there is risk of overheating and detonation. Can be mechanically operated or automatically at high MP.

50
Q

Why is the mixture idle c/o used to stop the engine?

A

Cuts fuel off at the carb, ensures no fuel is left in the cylinders and the carb is full of fuel for next start.

51
Q

Over rich leads to

A

Rough running, loss of power, spark plug fouling, lead deposits on valves and piston head.

52
Q

Over lean leads to

A

Overheating, excessive CHT, detonation, engine damage

53
Q

Disadvantages of carburation

A

Fuel flow upset by manoeuvres that upset float Susceptible to ice

54
Q

Float carburettor failures

A

Fuel nozzle breaking off
Becoming waterlogged
Fuel contamination blocking jets

55
Q

Advantages of pressure injection carburettor

A

Less icing due to throttle position
No effect from inertia/gravity
More accurate fuel metering at all engine speeds, throttle settings, atmospheric conditions
Better atomisation/mixing
Some protection against vapour lock

56
Q

Four functions of the oil system

A

Lubrication
Cooling
Cleaning
Sealing

57
Q

Lubrication

A

Reduces friction between moving parts. Cushioning for highly loaded parts.

58
Q

Cooling

A

Assists with removing hear from vulnerable parts, oil pumped around, sprayed onto parts and then passes through a cooler and re-circulates

59
Q

Cleaning

A

Removes contaminants which could cause abrasive wear on engine, circulating oil then passed through filter.

60
Q

Sealing

A

Helps seal piston rings in sealing crankcase from combustion gases/pressures

61
Q

Disadvantages of fuel injection

A

Vapour lock
Susceptible to contamination as lines are fine
Carbon build up on intake as no fuel flow to remove it

62
Q

Advantages of fuel injection

A

Free from refrigeration ice
Uniform delivery of charge
Fewer maintenance issues
Better throttle response
Increase efficiency

63
Q

Direct injection components

A

FCU
Injection pump
Injection nozzle

64
Q

FCU

A

Delivers correct amount of fuel to injection pump depending on amount of air flow through throttle

65
Q

Injection pump

A

Divides fuel equally for the cylinders and timed to force fuel at high pressure through discharge nozzle

66
Q

Injection pump

A

Spring loaded to open only when fuel under pressure is applied

67
Q

Continuous flow components

A

Injection pump
FCU
Manifold valve
Injector nozzles

68
Q

Injection pump

A

Engine driven, maintains positive pressure on fuel being delivered to metering unit

69
Q

FCU

A

Filters fuel and passes it through mixture control valve to metering valve. Throttle metering valve is directly linked to mixture control and butterfly, at full throttle all fuel is passed through.

70
Q

Manifold valve

A

Evenly distributes fuel to all nozzles

71
Q

Injector nozzles

A

Injects fuel into inlet ports of each cylinder.

72
Q

The amount of fuel reaching the cylinder depends on:

A

Engine RPM, mixture, and throttle settings

73
Q

What type of gyro does a TI use?

A

Rate

74
Q

In a slipping turn the CFF is ____ than weight

A

Less

75
Q

In a skidding turn the CFF is ____ than weight

A

More

76
Q

Disadvantage of gravity fed systems

A

Relies on gravity
Vapour lock

77
Q

What is the most common type of engine pump

A

Vane type

78
Q

Functions of aux pump

A

Purging lines
Fuel for starting
Primary FI engines
Back up incase eng driven pump failures

79
Q

Mogas is:

A

Less quality control
More volatile
Low power output
Fouling and detonation

80
Q

Higher fuel grade

A

Plug fouling
Corrosion of seals and valves

81
Q

Lower fuel grade

A

Prohibited
Detonation

82
Q

Oil pressure gauge measures

A

Pressure being delivered to engine by pump

83
Q

Oil temperature gauge measures

A

Temp after oil has circulated through cooler

84
Q

Ashless dispersant oil

A

Reduced oxidation/sludge
No ash deposits

85
Q

Detergent oils

A

Reduced oxidation
Form metallic ash

86
Q

Mineral oil

A

Gummy residues/carbon deposits
Prone to oxidation

87
Q

Viscosity index number

A

how much an oils viscosity changes with temperate

88
Q

Is a high or low viscosity index number good?

A

High

89
Q

Pour point

A

Lowest temp oil pours satisfactorily

90
Q

Flash point

A

Lowest temp oil gives off vapours than can ignite

91
Q

SAE measures what kind of viscosity?

A

Kinematic, takes into account density

92
Q

Viscosity index improvers

A

MG
Polymer additives

93
Q

Chemical oil changes

A

Oxidation
Water absorption

94
Q

Oil pressure should rise within _____ seconds

A

15

95
Q

Low oil pressure

A

Insufficient oil
Lack of oil due to failure in system
Leak in oil tank/lines
Oil pump failure
Engine problem
PRV stuck open

96
Q

High oil temp

A

Insufficient oil
Prolonged operation at high CHT

97
Q

Excessive engine temps

A

Reduces life of engine parts
Impairs lubrication
Detonation

98
Q

Eng temp managed by

A

Cooling oil
Expulsion exhaust gases
Air cooling system

99
Q

The magento system is ____ of the electrical systems

A

Independant

100
Q

Magneto uses ____ to generate ____ and convert it into ____

A

EMI, low voltage current, high voltage current

101
Q

Breaker points

A

Used to interrupt primary circuit

102
Q

Capacitor

A

Aids in collapse of primary circuit
Helps prevent arcing across breaker points when open

103
Q

Rotating cam

A

Attached to mag drive shaft
Set so points open each time spark required

104
Q

Rotor

A

Attached to secondary coil
Rotates half crankshaft
Directs HT current to cylinder

105
Q

Distributor

A

Directs spark to cylinder at correct time

106
Q

Ignition harness

A

carry HT current from magneto to spark plug via distributor

107
Q

Shuttle type

A

Fixed magnet
Rotating coil

108
Q

Polar induction

A

Fixed magnet and coil
Soft iron rotor

109
Q
A

Part 1 (6 decks)

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