Inlet duct arrangement in aircraft engine, Other Engineering

Inlet duct arrangement in Aircraft Engine:

Wherever the APU is located, ducting will be required to bring air to the APU inlet. In figure 18.9. we can see that the inlet duct connecting the inlet door to the APU plenum chamber is divided into three parts. The plenum chamber has the APU inlet duct bolted to its structure, thus reducing a complicated duct joint arrangement. These ducts can be manufactured from various materials, but the most common are aluminium, titanium, steel or composite (fibre glass/carbon). Figure 18.8. shows a light alloy side mounted intake duct without an intake door.

When the duct length is short, steel or titanium ducts may be used. When ducts cover a large distance an unacceptable weight problem may result. Ducts of this length are therefore manufactured from light alloy or composite materials.
One of the main problems of APU's is the ingestion of foreign objects this can be eliminated by fitting wire mesh grills either in the ducting, or around the APU air inlet.

The length of the inlet ducts will depend upon the location of the APU and its distance from the inlet. Some APU inlets are fitted with a door, these are usually forward facing or top mounted inlets. The door will open before the APU starts and close after a time delay on APU shut down The duct may be short or fairly long as shown in the figure.
691_inlet duct arrangement.png 
Operation of the door opening and closing is achieved by using an electrical actuator, which receives its signal from a command from the flight deck APU switch.

138_inlet duct arrangement1.png

In the event of an electrical failure to an actuator, there is normally incorporated into the actuator a means of disengaging the clutch drive mechanism. This enables the actuator to be manually turned to open or close the inlet door.
A proximity switch ensures that the door is fully open before the APU start sequence is initiated.

APU inlet doors serve three functions:

• They seal off the inlet duct from harmful weather conditions and foreign objects when the APU is not in use.
• They open to allow air into the APU when the start sequence is initiated.
• They can be used to adjust the intake area when on ground in flight.

2203_inlet duct arrangement2.png

The variable intake door figure 18.11. is used to reduce the ram air entering the APU intake ducting. This could effect the APU fuel system if intake pressure is not taken into the calculation of engine fuel scheduling which is the case with most APU's .

Posted Date: 9/12/2012 6:46:51 AM | Location : United States







Related Discussions:- Inlet duct arrangement in aircraft engine, Assignment Help, Ask Question on Inlet duct arrangement in aircraft engine, Get Answer, Expert's Help, Inlet duct arrangement in aircraft engine Discussions

Write discussion on Inlet duct arrangement in aircraft engine
Your posts are moderated
Related Questions
give me basic programming of vhdl

how can i operate cisco switches without packet tracer?

3. Design and draw a circuit using the cascade system to operate two cylinders (A and B) which, on the operation of a start valve, produces the sequence A – B + B – A+. The cylinde

Design a dc-coupled one op amp circuit that will amplify the 100uV EOG to have the maximal gain possible without exceeding the ttypical guarenteed linear outpt range.

Working of bi- CMOS invertor in vlsi

Write a program to calculate from the infinite series: Print a table showing the value of approximated by one term, two terms, three terms, four terms, and so on from th

Fire alarm systems: Fire alarm systems can be very complex and it is usually not possible for an enforcing officer to check all the cabling, the components, the software and t

Wave function is a complex quantity, which itself has no physical significance. But square of its magnitude gives the probability of finding a particle in a given volume of space a

offer an explanation for why cracking might have occurred. Give at least three suggestion on how to prevent this type of corrosion. You may supple with appropriate figures

how to work ever moll models