Combustion Section Flashcards

1
Q

2 layers of the combustion section and purpose

A

Air casing - cool and dilute the air in the flame tube

Flame tube - burns fuel supplied by the compressor - must be done with min loss of pressure and max release of heat

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2
Q

Hottest part of the combustion section

A

Primary zone - were combustion takes place

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3
Q

Multiple can combustion system

A

Cans are arranged around the turbine shaft

Multiple flame tubes with interconnecting tubes

Each can is surrounded by an outer casing

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4
Q

Mutliple can system adv and disadv

A

Makes for easier servicing

Does not prevent gas stream to all areas of the turbine

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5
Q

Tubo annular system

A

Cans arranged closer together

Whole assembly surrounded with an inner and outer air casing

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6
Q

Adv and disadv of a tubo annular system

A

Servicing is more difficult

Presents the gas stream to a greater area of the turbine

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7
Q

Annular chamber system

A

One single annular flame tube with inner and outer air casing

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8
Q

Adv and disadv of annular system

A

Shorter combustion section

Easier flame propagation

Presents the gas stream to all areas of the turbine

Shaping of the flame is more difficult

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9
Q

Combuster chamber flow break up

A

20% into primary zone

80% is used for cooling and dilution where 20% goes into the primary cooling, 40% into the cooling of the dilution zone and 20% dilution in the dilution zone

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10
Q

Purpose of the diffuser

A

AVTUR is less volatile - if you allow air straight from the compressor - it will blow it away

Diffuser is a divergent duct - slows the air down

Air from the compressor = 500ft/sec AVTUR = 2-3fps

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11
Q

Purpose of swirl vanes and perforated flare

A

Induce a vortex to mix the fuel and air

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12
Q

% pressure drop in the combustion section

A

5%

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13
Q

Air to fuel ratio in the combustion section

A

15:1

However due to the remaining 60% going into the dilution zone the overall air fuel ratio can be as high as 60:1

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14
Q

Purpose of a pressuring valve

A

Allows you to maintain pressure with a little amount of fuel

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15
Q

Purpose of fuel drains

A

Spring loaded valve - drain unburned fuel in the combustion section

Held closed by the pressure of combustion - anything over 0.5psi will close the valves

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16
Q

When to use continuous ignition

A

When there is a danger of flame extinction

Icing, t/o, l/d in heavy rain, slush, snow etc

Operated manually or automatically - auto when anti ice is on

Operates at low energy - 6-7 joules