Engine Cooling

Question 1

WHAT EFFECT DOES EXCESSIVE HEAT HAVE ON RECIPROCATING ENGINES?

Answer 1

1) Shortens engine parts life
2) Changes behavior of combustion
3) Impairs lubrication

Question 2

WHAT IS THE PURPOSE OF COOLING FINS

Answer 2

Provide cooling surface area for removing heat from cylinder heads of air-cooled recip engines. Transfers 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

Cowling streamlines the engine to reduce drag and is used together with the baffles and cowl air seals to direct airflow around the cylinders for cooling

Question 4

WHAT IS THE PURPOSE OF COWL FLAPS AND HOW ARE THEY OPERATED

Answer 4

Control the amount of airflow through the cowling. Operated mechanically, electrically or hydraulically

Question 5

HOW DOES AN AUGMENTER COOLING SYSTEM WORK?

Answer 5

Outer tube placed over the exhaust creates a venturi effect that draws more airflow over the engine. Providing cooling

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 COWL FLAPS?

Answer 7

Manual, hydraulic, or electrical

Question 8

WHAT SHOULD BE DONE WHEN COOLING FIN DAMAGE IS DISCOVERED?

Answer 8

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

Question 9

WHAT HAPPENS TO WASTE GATE ENGINE HEAT AFTER IT IS TRANSFERRED TO CYLINDER COOLING FINS?

Answer 9

Transferred from engine cylinders to the air

Question 10

WHAT IS THE PRINCIPLE FUNCTION OF ENGINE COWLING AND BAFFLES?

Answer 10

To direct airflow over the cylinders for cooling

Question 11

WHAT INFORMATION MUST BE CONSULTED PRIOR TO RE-PROFILING A COOLING FIN?

Answer 11

The manufacturer’s service or overhaul publications

Question 12

WHY IS COWL FLAP ADJUSTMENT IMPORTANT?

Answer 12

Because the movement must be within tolerances to keep cylinder head temperatures within allowable limits

Question 13

HOW ARE TURBINE ENGINES COOLED?

Answer 13

Air passing through the engine. About 25% for combustion. About 75% for cooling air. The air is used to cool the combustion
chamber and turbine

Question 14

IN A TURBINE ENGINE, WHERE DOES BLEED AIR COME FROM THAT IS USED TO COOL BEARINGS AND OTHER PARTS?

Answer 14

The engine compressor

Question 15

WHAT IS THE RELATIONSHIP BETWEEN TURBINE ENGINE UPPER TEMPERATURE LIMITS AND POWER PRODUCED?

Answer 15

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

Question 16

WHAT IS THE APPROXIMATE PERCENTAGE OF AIR PASSING THROUGH ENGINE THAT IS USED FOR COOLING RATHER THAN COMBUSTION?

Answer 16

Approximately 75%

Question 17

WHAT CAN BE DONE TO EFFECTIVELY ALLOW HIGHER GAS TEMPERATURES IN THE TURBINE SECTION OF SOME ENGINES?

Answer 17

Bleed air ducted through hollow sections in the turbine IGV’s and first stage rotor blades can lower temperatures enough to prevent heat damage

Question 18

WHERE MUST MOST COOLING AIR FLOW TO COOL A TURBINE ENGINE?

Answer 18

Through the inside of the engine