Induction And Engine Cooling

Question 1

What effect does excessive heat have on reciprocating engines?

Answer 1

It shortens the life of the engine parts, changes the behavior of combustion and impairs lubrication.

Question 2

What is the purpose of cooling fins?

Answer 2

They provide a larger cooling surface area for removing heat from cylinder
heads of air-cooled reciprocating engines. Airflow around the cooling fins transfers the heat from the cylinder heads to the air.

Question 3

What are the reasons for using engine cowlings, baffles and cowl air seals?

Answer 3

It streamlines the engine area to reduce drag, and direct airflow over the cylinders for cooling.

Question 4

What is the purpose of cowl flaps and how are they operated?

Answer 4

They are used to control the amount of airflow through the cowling. They are either mechanically, electrically or hydraulically operated.

Question 5

What is used to control the amount of airflow through the cooling area of a reciprocating engine?

Answer 5

Cowl Flaps

Question 6

Where should cowl flaps be positioned for ground operations?

Answer 6

Fully Open

Question 7

What type of power is used to operate cowflaps?

Answer 7

Manual(mechanical), hydraulic or electrical.

Question 8

What should be done when cooling fin damage is discovered?

Answer 8

Depending on the scope of damage some cooling fins may be repaired subject to the manufacturer’s overhaul and repair limitations. If an excessive amount of the cooling fin is broken off, the cylinder should be replaced.

Question 9

Why is cowl flap adjustment important?

Answer 9

The movement must be within tolerances to keep cylinder head temperatures within allowable limits.

Question 10

How are turbine engines cooled?

Answer 10

They are cooled by air passing through the engine. About 75% of the air passing through the engine is used for cooling which leaves only 25% for combustion. This air is used to cool the combustion chamber and turbine.

Question 11

In a turbine engine where does bleed air come from that is used to cool bearings and other parts?

Answer 11

The engine compressor.

Question 12

What is the relationship between turbine engine upper temperature limits and power produced?

Answer 12

The higher combustion temperatures that an engine can withstand without damage, the more power it is capable of producing.

(Higher the temp higher the power)

Question 13

What is the approximate percentage of air passing through a turbine engine that is used for cooling rather than combustion?

Answer 13

75%

Question 14

What can be done to effectively allow higher gas temperatures in the turbine section of some engines?

Answer 14

Compressor bleed air ducted through hollow sections in the turbine inlet guide vanes (IGV) and first stage rotor blades
can lower temperatures enough to prevent heat damage.

Question 15

What happens to waste engine heat after it is transferred to cylinder cooling fins?

Answer 15

It is further transferred from the engine cylinders to the air.

Question 16

What are the functions of engine cowling?

Answer 16

It streamlines the engine area to reduce drag and it forms an envelope around the engine to aid in controlling cooling airflow.

Question 17

What is the purpose of cowl air seals?

Answer 17

They force air to circulate around and through the baffle system.

Question 18

How does an augmenter cooling system work?

Answer 18

An outer tube placed over the existing exhaust gas creates a venturi effect that draws more airflow over the engine thus providing additional cooling.

Question 19

What information must be consulted prior to re-profiling cooling fin?

Answer 19

The manufacturer’s service or overhaul publications.

Question 20

Where must cooling air flow to cool a turbine engine?

Answer 20

Through the inside of the engine.

Question 21

What areas of a turbine engine are cooled by air passing through the engine?

Answer 21

The combustion chamber and turbine.