Understanding the Aircraft Engine Cooling System

Both reciprocating and turbine aircraft engines operate on the basic principle of igniting fuel and air mixtures. While combustion can provide sufficient propulsive force and mechanical energy for aircraft to fly, it also causes a large amount of heat generation that must be mitigated for the integrity of engine components and surrounding structures. The cooling system of an aircraft may vary depending on the type of engine and its design, often relying on methods such as liquid cooling and air cooling to protect assemblies.

Reciprocating engines are those that often power propeller aircraft, and they rely on a system of pistons in order to convert chemical energy into a rotational motion. As combustion is a rapidly recurring process throughout a standard flight operation, it is important that pistons are cooled so that engine failure is avoided. Generally, overheating can affect the performance of combustion, may damage or weaken engine components, and may impair lubrication.

With excess heat, combustion may even occur before the intended time due to the preheating of fuel and air mixtures. When early combustion occurs, it can result in detonation, knocking, and other detrimental effects. While there are a number of ways to track engine heat for monitoring health, two common methods involve taking readings from the oil temperature gauge or cylinder-head temperature gauge.

For numerous engines, excess heat may be removed through expulsion or absorption. When the engine absorbs heat, the oil system serves to transfer heat from engine parts to the airstream with the use of an oil cooler. Cooling can also be increased with airflow from the surrounding atmosphere, but components such as cylinders can often be too large to make placing everything in the airstream feasible.

Instead, cooling fins, cowling, and baffle components are implemented in order to direct air around cylinders to combat hot spots as air enters the engine from inlets located behind the propeller hub. When relying on air cooling, it is important to be aware that it can actually be over effective in winter months. In such conditions, it is important to use a winterization kit in order to limit incoming airflow so that the oil system and surrounding components do not freeze.

Beyond air cooling, liquid cooling is an option that many aircraft may be able to take advantage of. While liquid cooling increases the total weight of an aircraft due to the added fluids and equipment, it is capable of providing more even temperatures for the benefit of cylinders. Liquid cooling systems also avoid the risk of shock cooling as coolant is thermostatically controlled. With the advantages that liquid cooling offers, aircraft can achieve more reliable engine operations and lower fuel consumption at the price of added weight.

As reciprocating engines ignite fuel on every fourth stroke of their combustion cycle, they can be fairly easy to cool. With turbine engines, on the other hand, combustion is continuous. As such, air cooling must be conducted internally and excess air brought into the engine for the combustion process may be used. Due to the design of the engine and the implementation of tubing, cooling air is directed to various areas in order to reduce heat and increase the efficiency of the combustion process.

With the use of various air inlets across the exterior of the engine, air can enter the system to cool the turbine nozzle, case, and bearings. As many sections of the turbine engine are closed off with fireproof bulkheads, calibrated airflow is used to maintain optimal temperatures throughout the engine. Similar to the reciprocating engine, turbine engines may also take advantage of insulation blankets to reduce heat.

Whether relying on air flow or liquid cooling, reducing the heat of an aircraft engine is paramount to its health and integrity. At Aerospace Exchange, we are a leading supplier of cooling system components and other aircraft parts that have all been sourced from top global manufacturers. With our quality assurance standards and practices, we proudly operate with AS9120B, ISO 9001:2015, and FAA AC 0056B certification and accreditation. Begin the purchasing process today and receive a personalized quote for your comparisons in 15 minutes or less upon the submission of an RFQ form!