The APU is usually located at the rear of the aircraft, in the tail, so the intake is generally somewhere on the side of this location. Aircraft place the inlet in different places though, and some even put the APU somewhere different. For some examples: 737 intake, the small NACA inlet at the bottom

Feb 19, 2023 · The APU will only be operational with the inlet deactivated OPEN (for a maximum of 10 days). The air inlet actuator is equipped with a manual drive. In case of failure the manual drive may be used to move the inlet to the required position prior to deactivation.

Feb 14, 2018 · A P U Air Inlet The APU air inlet provides the compressor inlet air and cooling air to the APU engine. The air inlet consists of the air diffuser duct, compressors air inlet duct, accessory cooling air duct, and the air inlet door (Fig. 1).

Oct 7, 2016 · During an airplane operation, the air inlet scoop supplies forced outside air through the empty space between the APU insulation panels and the bulkhead for ventilation and for the removal of flammable or unwanted fluids.

The engine inlet of a turbine engine is designed to provide a relatively distortion-free flow of air, in the required quantity, to the inlet of the compressor. [Figure 1] Many engines use inlet guide vanes (IGV) to help straighten the airflow and direct it into the first stages of the compressor.

Aug 3, 2018 · An air inlet system for an auxiliary power unit (APU) has an intake duct having a wall defining an inlet plenum and forming an inlet opening configured to direct air into the inlet plenum.

Mar 25, 2008 · There is an inlet door that controls the speed of the air entering the APU in flight to prevent surging. If the door is not working the cruise speed is limited to 300 mph. I would assume its similar for other aircraft.

Nov 5, 2001 · The design of the inlet for the APU was particularly complicated, being constrained by the inlet location, available space, inlet aerodynamic loss, acoustics, manufacturability and maintainability requirements.

Jan 6, 2003 · Results indicate that an optimum NACA submerged-inlet design should employ a width-to-depth ratio of from 3 to 5, curved diverging ramp walls, and a 5 to 7 deg ramp angle.

Jan 6, 2003 · A methodology for the design of air inlets used in Auxiliary Power Units (APU) of regional commercial aircraft is described. Starting from the general requirements for the aircraft and the APU system the methodology is divided in steps of increasing complexity.