Engine cooling systems Flashcards
(21 cards)
What effect does excessive heat have on reciprocating engines?
Shortens the life of the engine parts
Changes the behavior of combustion
Impairs lubrication
What is the purpose of cooling fins?
They provide a larger cooling surface area for removing heat from cylinder. Heads of air cooled engines most airflow around the cooling fins. Transfers, more heat from the cylinder heads to the air.
What are the reasons for using engine cowlings, baffles and cowling air seals?
Cowlings streamline the engine area to reduce drag and work with the baffles and cowl air seals to direct and maximize airflow over the cylinders for cooling
What is the purpose of Cowl flaps and how are they operated?
They are used to control the amount of airflow through the cowling they can be mechanically, electrically, or hydraulically operated
What is used to control the amount of airflow through the cooling area of a reciprocating engine?
Cowl flaps
Where should cowl flaps be positioned for ground operations?
Fully open
What type of power is used to operate cowl flaps?
Manual
Hydraulic
Electrical
What should be done when cooling fin damage is discovered?
It depends on the scope of the damage. Some cooling fins can be repaired based on the manufacturers overhaul and repair limitations. If too much of the cooling fin is broken off the cylinder should be replaced.
Why is cowl flap adjustment important?
Cowl flap movements must be within tolerances to keep cylinder head temperatures within allowable limits
How are turbine engines cooled?
By the air passing through the engine, most (75%) of the air passing through the engine is used for cooling. The rest is used for the combustion process
In a turbine engine, where does the bleed air come from that is used to cool bearings and other parts?
The engine compressor
What is the relationship between turbine engine upper temperature limits and power produced?
The higher the combustion temperatures that an engine can withstand without damage, the more power that is capable of producing
What is the approximate percentage of air passing through a turbine engine that is used for cooling rather than combustion?
75%
What can be done to effectively allow higher gas temperatures in the turbine section of some engines?
Compressor bleed air can be ducted through hollow sections in the turbine inlet guide vanes, and first stage rotor blades. This can lower temperatures enough to prevent heat damage.
Happens to waste engine heat after it is transferred to cylinder cooling fins?
It is transferred from the cooling fins to the air
What are the functions of engine cowling?
Streamline the engine area to reduce drag into form and envelope around the engine to aid and controlling cooling airflow
What is the purpose of cowl air seals?
They force air to circulate around and through the baffle system
How does an augmenter cooling system work?
An outer tube placed over the existing exhaust gas creates a Venturi effect that draws more airflow over the engine, thus providing additional cooling
What information must be consulted prior to re-profiling cooling fin?
The manufacturers service or overhaul publications
Where must cooling airflow through to cool a turbine engine?
The inside of the engine
What areas of a turbine engine are cooled by air passing through the engine?
Combustion chamber and turbine
