I have been checking up on what is actually needed to build a basic
ramjet and what design parameters have values that can looked up.
You need an inlet, diffuser, flame holder, combustion chamber and exhaust nozzle.
For anything operating below Mach1 the inlet actually needs to be nothing more than the front opening of the diffuser. A Bellmouth fitting from a
HVAC supplier can be optionally used as a Mach0 inlet.
The diffuser included angle can range from 10 to 15 degrees, this is necessary to prevent the flow from separating from the wall.
The region of maximum static pressure begins at the exit of the diffuser.
This is one place to position the flame holder. Alternatively you can
build a can-type combustor, designed like those used in a turbojet and inject the fuel at the top end.
Bill Lubarsky
New ramjet experiments
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re: New ramjet experiments
Rats!
No picture. Maybe this time?
WEL
No picture. Maybe this time?
WEL
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re: New ramjet experiments
Here is a neat picture of a few different styles of ramjet
http://www.erkenntnishorizont.de/images ... ramjet.jpg
top appears to be subsonic, middle supersonic and bottom hypersonic (scramjet). But I'm not sure about that.
http://www.erkenntnishorizont.de/images ... ramjet.jpg
top appears to be subsonic, middle supersonic and bottom hypersonic (scramjet). But I'm not sure about that.
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re: New ramjet experiments
Yup.
Though even the subsonic design shown would be working at a much higher free stream velocity than anything you can test with a garden or workshop blower. The included angles for the diffuser given are for an essentially
Mach0 design. With enough ram-compression you can build something
with lorger include angles and gain far higher values of pressure recovery.
So many people seem wedded to designs using hard to make conical
components. A ramjet will work quite well with a rectangular cross-section
and simple tapered boxes and wedges. Adding hinges, the inlet and exhaust
can be adjusted during operation.
WEL
Though even the subsonic design shown would be working at a much higher free stream velocity than anything you can test with a garden or workshop blower. The included angles for the diffuser given are for an essentially
Mach0 design. With enough ram-compression you can build something
with lorger include angles and gain far higher values of pressure recovery.
So many people seem wedded to designs using hard to make conical
components. A ramjet will work quite well with a rectangular cross-section
and simple tapered boxes and wedges. Adding hinges, the inlet and exhaust
can be adjusted during operation.
WEL
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re: New ramjet experiments
I always wanted to see if a "semicircle" ramjet would work. Like a ramjet cut down the middle from front to back then welded to a flat plate.
Next project is for sure a square jet, rolling cones is a pain!
Next project is for sure a square jet, rolling cones is a pain!
Sailing Student- How do I know if my life jacket is tight enough?
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Me- Then its too loose!
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re: New ramjet experiments
I have scanned a couple of ramjet diagrams from old NACA
reports. The quality isn't good buy it illustrated some points.
WEL
reports. The quality isn't good buy it illustrated some points.
WEL
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re: New ramjet experiments
Thanks, Bill. Those were keepers.
Mike Often wrong, never unsure.
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re: New ramjet experiments
Very cool, I wish more views were drawn in though...
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!