regenerative ramjet engine

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larry cottrill
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Re: regenerative ramjet engine

Post by larry cottrill » Tue Jul 29, 2008 2:08 pm

Viv wrote:I would question the ability of the recirculated exhaust gas to usefully add pressure or volume to the intake by entrainment
Pressure no, but volume is no problem -- that's what every ejector does. The resultant gas mix is slower than the driving jet stream, but MUCH denser and cooler. This should work well if you get it into the front end of a properly designed diffuser.
... any energy taken from the exhaust is lost to propulsion
Like, for instance, the energy taken up by a turbine? ;-)
... the losses will add up and negate the gains.
What makes this a given? What if the losses somewhat, but not quite, negate the gains? If you have that, the rest is just tuning.

The first "successful" gas turbine was the 1905 Armengaud-Lamale turbine, which was big enough to take months to build and weighed many tons. When they fired this baby up, they were able to get a whopping ONE PERCENT of the total combustion energy delivered to the shaft! If you were an investor, and these guys told you, "You know, this really proves that is IS practical -- the design just needs some more work to make it really good," what would you have said to that?
I would recommend Foa's book on propulsion as it covers these types of engine and other interesting types as well.
Yes, it is probably just my own ignorance that makes this look so great. NASA certainly didn't buy into my attempt at it:
http://www.cottrillcyclodyne.com/Cyclod ... ction.html

L Cottrill

Viv
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Re: regenerative ramjet engine

Post by Viv » Tue Jul 29, 2008 8:43 pm

Hi Larry

All good points but I just don't think the maths add up in the right direction, mind you having said that there are a few around here who are convinced that if you can build one and get some noise out of it it obviously works and damn the detractors in shouting from the wings ;-)

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

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Monsieur le commentaire

Ghrey
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Re: regenerative ramjet engine

Post by Ghrey » Mon Sep 01, 2008 9:33 am

I do not think it would work as drawn, It just seems like you would have to take to much from the back end to feed the front end.


But a very hot fuel or NO2 or both.

There is allot of may be here.

Will it maintain? Will it start to pulse? ( would that be bad ? )

Can it be built in a more aircraft friendly form?

It may just have to be built to know.
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.

sockmonkey
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Re: regenerative ramjet engine

Post by sockmonkey » Tue Mar 10, 2009 2:51 pm

What if there were a set of vanes in the intake that caused the looped around exhaust to spin as it entered rather like a toilet flush?

Ghrey
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Re: regenerative ramjet engine

Post by Ghrey » Tue May 26, 2009 6:44 am

sockmonkey; I am thinking drag. But ...
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.

larry cottrill
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Re: regenerative ramjet engine

Post by larry cottrill » Tue Jun 02, 2009 7:38 pm

Ghrey wrote:I do not think it would work as drawn, It just seems like you would have to take to much from the back end to feed the front end.
What makes everybody think you have to take it from the back end?

Hint ... hint ...

See "Cyclodyne Revealed", coming up shortly.

L Cottrill

Viv
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Re: regenerative ramjet engine

Post by Viv » Tue Jun 02, 2009 8:19 pm

larry cottrill wrote:
What makes everybody think you have to take it from the back end?

L Cottrill
Like a lot of other people here we are all dying to see how this gets answered ;-)

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

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Ghrey
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Re: regenerative ramjet engine

Post by Ghrey » Wed Jun 03, 2009 6:25 am

Just referring to the device in question, I long ago came up with a different geometry my self. Weight...

My current build uses head pressure to suck gas out the tail to increase blow.

Cheers
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.

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