Bay cooling in aircraft, Other Engineering

Bay cooling in Aircraft:

There are two methods of bay cooling, they are:

• Ram air cooling
• Fan air cooling

RAM AIR COOLING

For ram air cooling, the aircraft has to be moving forward at sufficient speed to enable the cooling air to be picked up by the air scoops in the external skin. This cold air is ducted into the APU bay and passed onto various hot zones to provide a cooling medium. The air is then vented overboard through exhaust ducts.

FAN AIR COOLING

Cooling fans are fitted to the APU gearbox to provide a supply of cooling air to the APU when it is running. The cooling air is pumped into the APU compartment and then vented overboard. The air from the fan is also used to cool the generator drive oil and the exhaust duct on some APU installations.

1557_bay cooling.png 
The main components are the:-

• cooling air fan.
• cooling air shut-off valve.

Air is drawn from the normal intake plenum or an external intake and is directed along the cooling air ducts to the cooling fan shut-off valve (when fitted). The shut-off valve closes on APU shutdown to prevent air from entering the compartment to support combustion in the event of an APU fire.

The cooling fan is linked to the APU gearbox and as long as the APU is running, the fan is turning. Air is also used to cool the oil within the APU lubricating system (on some APU's), however, such air is usually ducted overboard and not into the APU compartment. Upstream of the oil cooler the cooling air is ducted into the APU bay an/or the exhaust insulating ducting to provide general cooling.

Cooling Fan Shut-Off Valve

The cooling valve figure 18.33. is a spring-loaded closed butterfly valve with a pneumatic actuator. When the APU is started, the compressor discharge pressure is ported to the top of the diaphragm. The piston moves down with increasing air pressure and opens the valve against the spring pressure. The cooling air then flows to the compartment. On APU shutdown the air pressure is reduced and spring pressure closes the valve.

517_bay cooling1.png

Cooling Fan Arrangement

The cooling fan is attached to the APU gearbox, (figure 18.34) and is designed to run at extremely high speeds, the fan boosts the air from the intake plenum (or ambient) into the APU compartment or the coolers etc.

574_bay cooling2.png

Overboard Venting

Figure represents a typical APU bay overboard vent arrangement. The cooling air is directed into the compartment and also to the oil cooler, this air is then vented overboard along a separate duct. Compartment cooling air is vented overboard, through a louvered door at the rear of the compartment.

623_bay cooling3.png

Posted Date: 9/12/2012 7:29:57 AM | Location : United States







Related Discussions:- Bay cooling in aircraft, Assignment Help, Ask Question on Bay cooling in aircraft, Get Answer, Expert's Help, Bay cooling in aircraft Discussions

Write discussion on Bay cooling in aircraft
Your posts are moderated
Related Questions
What is the difference between real money & nominal money?  Moderate cash is relevant to the evaluate of keeping track of. nominal figure is what is published on the expenses. w

Essentially, the strategy of CFD is to replace the continuous problem domain with a discrete domain using a grid domain with a discrete domain using a grid. In a continuous doma

CO 2  Molds (Carbon dioxide Moulding) is the process of hardening the moulds and cores by using carbon dioxide and sodium silicate liquid base binder is one of the most widely u

analysis the wien bridge oscillator practical?

Q.   Differentiate crystalline and amorphous materials? (a)Crystalline solids:  Those solids in which the, ions atoms or molecules in a definite regular repeated

Sulphuric acid can be made with concentration of 99%. However for different industrial process different concentrations are used. For a specific industrial requirement, 62% H2SO4

I would like to ask in detail. How can I attach the files?

Illustrate the importance of communication in a retail business organisation?25 marks

Non-discounted cash flow method, Payback period method In this method, time value of money is not considered. It takes into account the number of years required to recover the in

Procedures for starting and ground running: Before starting and ground running any gas turbine powered aircraft, several considerations must be taken into account. The first an