The Aircraft Engine Cooling System and Its Types

When operating an aircraft engine, an immense amount of internal heat is generated, sometimes even reaching temperatures around 2,000 degrees Celsius in certain engines. This is due to the process of fuel combustion that many engines utilize for producing propulsion. With such fuel ignition and heat generation, engines and their surrounding components can heat up very quickly, leading to damage if left unchecked. To mitigate this heat and cool down the engine to acceptable temperature limits, various aircraft cooling systems are in place. In this blog, we will discuss the various aircraft cooling systems that benefit different aircraft, and how they provide for temperature reduction.

In general, the cooling system is implemented to ensure that the engine cylinder barrels and head are regulated in temperature. This is because these sections hold the combustion chamber and valves. While other parts such as aircraft bearings and pistons heat up as well, there is often recirculating oil in place that ensures heat is mitigated in such areas. Reducing temperature in an operating engine is critical to the longevity of parts and to general safety as unchecked heat would quickly lead to detonation and internal damage. This could also cause oil to begin to boil, causing it to become less effective, thus also leading to inevitable engine failure. A majority of heat is vented from the aircraft as exhaust across engine types, but there is still a great amount that must be dissipated by other means. Across aircraft, the two most common types of engine cooling are air cooling and liquid cooling, each of which bring their own advantages and disadvantages.

Radial engines, which are primarily used on smaller piston aircraft, cool their engines with the use of airflow. To do this, the cylinders are exposed to airflow with an even temperature distribution. Inline engines also follow this method, entirely using air for reducing heat. While this method may cause drag, it does not add weight such as liquid cooling systems do, thus making up for the drag. When cool air enters the system, the warm air needs to be exhausted. To remove such air, venting is typically done through the lower cowling which may be controlled by cowl flaps. This operation may be conducted by the pilot during high power and low speed operations, though they will increase parasite drag while open.

Liquid cooling is another method of decreasing engine temperature, utilizing fluids that run through the engine to regulate heat. While liquid cooling has the disadvantage of increasing weight, all cylinders may be cooled more evenly and will not be shock cooled during high speed and low power descents. The liquid coolant may also be thermostatically controlled, meaning that the engine can be quickly warmed up and then remain at a steady temperature during the entire flight operation. Because of these various advantages, liquid cooling allows many aircraft to operate with a lower fuel consumption, longer engine life, and with more reliability.

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1. dany geller
2. Posted on July 8, 2020
aviation

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