Aircraft Engine Induction and Exhaust Systems | Aircraft Systems

Aircraft Engine Induction and Exhaust Systems

The primary purpose of an induction system in a reciprocating engine is to provide a sufficient quantity of air to support normal combustion. Reciprocating engine induction systems are broadly classified as normally aspirated, supercharged, and turbocharged.

Turbine engine induction systems are substantially different from the induction systems on reciprocating engines. Turbine engines consume much more air than reciprocating engines, generally operate at faster airspeeds, and the distance from the inlet to a turbine engine is extremely short. Typically, the air inlet duct on a turbine engine is considered an airframe component. However, because the supply of air is essential to the operation of a turbine engine, it is important to discuss this topic in the context of engine operation.

A byproduct of combustion in a reciprocating engine is high-temperature, noxious gases. Due to the corrosive nature of exhaust gases and the wide range of temperatures that the system experiences, modern exhaust system components are typically made of nickel-chromium steel or other corrosion and heat-resistant alloys.

The exhaust system of a turbine engine must withstand very high temperatures, and it is usually manufactured from nickel or titanium. The engine heat must not be permitted to transfer to nearby airframe components or structures. The airframe structures are protected by routing ventilating air around the exhaust pipe and by covering the exhaust pipe with an insulating blanket. An insulating blanket has an inner layer of insulating material under a stainless steel skin, which is dimpled to increase its strength. This assembly prevents the heat from leaving the engine anywhere except for the exhaust.