APU (Auxiliary Power Unit), or auxiliary power unit, is an important system on the aircraft. It is mainly used to provide electricity and compressed air when the main engine stops, ensuring the normal operation of the aircraft and the comfort of the passengers. The basic functions and functions of APU
1. Provide power: When the main engine stops, the APU can independently supply power to ensure the normal operation of various electrical systems of the aircraft, such as lighting, communication equipment, etc.
2. Provide compressed air: APU generates high-temperature compressed air through its small gas turbine engine to supply the cabin air conditioning system to ensure the comfortable temperature and pressure of the cabin.
3. Emergency start: During the flight, if the main engine fails, the APU can be used as an emergency power source to help restart the main engine and ensure flight safety.
4. Reduce ground dependence: When operating on the ground, APU can reduce dependence on ground power supply facilities, especially when starting the main engine in cold weather.
Historical background and technical details of APU
The APU is usually installed at the rear of the aircraft and uses a small gas turbine engine with an independent gas and power system. It can suck in air through the air intake, discharge high-temperature and high-pressure gas through turbine compression, and drive the generator to generate electricity at the same time. APU has an independent starting motor, battery, lubrication system, cooling system and fire protection device to ensure its safe operation 12.
The future development trend and application prospects of APU
With the progress of aviation technology, APU is also constantly improving. Modern APU is more efficient and reliable, and can better adapt to various flight conditions. In the end, with the increasing application of sustainable aviation fuel (SAF), APU will play a greater role in reducing carbon emissions and improving flight efficiency. For example, China Eastern Airlines has used mixed fuel mixed with SAF on some flights, which has further promoted the development and application of APU technology.
2025/6/27