Air Intake Duct Types Questions: Answers & Info

[kach22i]

Questions:

1. Passive air intake (no fan) body moving under 100 mph, which air intake is most efficient?

2. Active powered fan situation, body moving under 100 mph, which air intake system is most efficient?

3. Please direct me to an on-line source of information which explains when, where and why.

http://i184.photobucket.com/albums/x295/kach22i/Intake-Duct-Types-2.jpg

 

[kach22i]

Not exactly right out of my sketch book (and wall of clay models), but similar. I can see some of the Joint Strike Fighter layout being doubled here and scaled down.

http://www.rutherford-research.ca/rrx/aerospace/aerospaceDesign.php

One factor, for some specialized UAVs, may be the ability to hover, land vertically, or possibly dock with some form of airborn platform.

Nuclear UAV's? :blink:

 

[kach22i]

I found this today...on waterjets.

http://marinejettech.com/IntelliJET Development History.htm

Why It All Works Together

Bigger jets are desirable because they create higher thrust. But the bigger the jet, the more power that is lost in the ordinary inlet duct. This power loss has to be made up by the motor and the pump.

The adjustable inlet duct reduces this power loss. And, as the inlet duct becomes more efficient, it increases pressure on the nozzle, which results in higher flow through the system.

But, higher flow through the system results in reduced pump efficiency. Hence the need for the variable nozzle to regulate the system flow for pump efficiency.

Summary: Using the combination of these three innovations means a high volume of water, an efficient inlet duct and an efficient pump operation under all operating conditions.

 

[kach22i]

Just adding to the collection, comments anyone?

http://www.aiaa.org/tc/vstol/unbuilt/breguet/index_a.html

 

[kach22i]

Another way to skin a cat....

http://www.marinetalk.com/articles-marine-companies/art/Hydro-Air-Drive-DKG00123645TU.html
The Hydro Air Drive is highly efficient at high speeds because the inlet water does not have to bend upward and has less wetted area friction compared to the inlet water flowing into the fully submerged standard water-jet rotor.

 

[kach22i]

Every now and then I pick up a little more information, however this one is difficult to absorb (for me).

S-Duct Inlet
http://www.grc.nasa.gov/WWW/wind/valid/sduct/sduct.html

S-Duct Inlet: Study #1
http://www.grc.nasa.gov/WWW/wind/valid/sduct/sduct01/sduct01.html


http://engineers.ihs.com/news/newsletters/esdu/esdu-issue11-05.htm

Subsonic drag and pressure recovery of rectangular planform flush auxiliary inlets with ducts at angles up to 90 degrees.

A flush auxiliary inlet is designed to supply air to various aircraft systems or components via a duct. Space restrictions often require ducts to be set at large angles to the onset flow direction and it is important to know the effect on the inlet drag and pressure recovery of turning the flow through large angles.

 

[FredGarvin]

The operative words in what you quoted is pressure recovery. For a duct design that is the one of top hitters in terms of importance. Distortion is probably the most important.

 

[kach22i]

The operative words in what you quoted is pressure recovery. For a duct design that is the one of top hitters in terms of importance. Distortion is probably the most important.

Thanks, I'll do some Googling of those terms.

Maybe I should just purchase a textbook on the topic, I'm a block from U of M, go Wolverines!

 

[Danger]

For any of the conditions set forth in the first post, I would think that the gooseneck would be best. A couple of hundred thousand car racers can't be wrong, and almost all automotive scoops are of that basic configuration. (I'm not sure how velocity stacks compare, though.)

 

[kach22i]

For any of the conditions set forth in the first post, I would think that the gooseneck would be best. A couple of hundred thousand car racers can't be wrong, and almost all automotive scoops are of that basic configuration. (I'm not sure how velocity stacks compare, though.)

P-51 Mustang, F-16 Fighting Falcon...fancier words and functions than Goose-Neck and I'm sure they are the most efficient at relative speeds.

I'm truly interested in the louvered vents (bottom image), the likes of which we have not seen since the Porsche 550 Spyder (James Dean's car) of the 1950's and early jet fighters.

The vents we see today which are to let pressure out of wheel wells or the heat out of engine bays are in opposite direction and use than I'm interested in.

 

[kach22i]

The hunt is on......pressure recovery.

NACA Ducts
http://members.aon.at/wrathall/rotary/72_Engine/72-47 NACA ducts.htm

As summarized by the NACA engineers themselves, the submerged duct "...does not have desirable pressure recovery characteristics for use in supplying air to oil coolers, radiators, or carburators...".

There you have it from the guys with the research grants, time and wind tunnel access to test this stuff.