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The jet propulsion with closed combustion type


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looks like the inside of a pulsating shower head. alot like a rodial engine.   purty neat engines here http://www.keveney.com

Dear DFINITLYDISTRUBD:   I suggest firstly you fixed the engine with a shelf. after adjust it ,it can work normally, You let it drive your cart.

dear all:   I always think whether the new jet can work under various conditions. to adopt some cases if it must be adjusted.   In some cases we hope the jet provides less push force than common. I a

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"As to the noise, I agree there are big noise occur while the gas run from the chamber to the branch pipes.I have a new idea how to reduce the bad effect.If the gas' speed at the outlet over sonic speed. the noice isn't easy to spread from inside from the outlet."

should be corrected as" the noise can be absorbed by the gas when the gas's speed is more than sonic speed''

The explanation will be more proper.

 

I also hope that the noise canbe weaken a lot after branch pipes though some transformations. Gas converge;be resisted and sorted by turbine;expand as cushion effect,and so on.

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DFINITLYDISTRUBD:

 

If you adopt the rotary valve, you would notice the new issues though I am not familiar your rotary valve.

1. can the valve bear the high temperature?

2. Does the valve's gate have enough strength to bear the pressure of gas/

Further question;

Does the rotary valve only serve a chamber? I deigned couples of chambers.If you only use one chamber, the stability became a little worse.

How to drive the rotary valve, In my design that it is driven by the turbine directly.If you do so,I suggest that the energy for turbine can be adjusted to a extent,thus the rotary valve's speed can be changable.You may need to adjust the current of gas through the turbine a little.

 

In responce to your questions:

 

1. Absolutely!!:xx:

2. They will serve only one combustion chamber one turbine. (one valve exhaust one valve for intake side) And yes as I mentioned before they will be driven by the turbine directly (driveshaft?). They are of a multiple gate design meaning that as the valve rotates openings in the valve will line up with openings in the valve body allowing fuel and air in and exhaust out at regular intervals while also sealing the combustion chamber completely between these intervals several times per rotation.

 

I described this in an earlier post but decided against it at the time as it seemed too expensive to be feasable for me to build. I"VE CHANGED MY MIND!!!!!!!!! If I ever try to use reed valves for this type of application somebody had better slap me!!!!!!!!!!!!!!!!:)

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DFINITLYDISTRUBD :

 

"They are of a multiple gate design meaning that as the valve rotates openings in the valve will line up with openings in the valve body allowing fuel and air in and exhaust out at regular intervals while also sealing the combustion chamber completely between these intervals several times per rotation"

I don't know why it is "these intervals several times per rotation". i think it is one interval per rotation because there is only one chamber and you use same shaft for chamber and turbine,unless you use transmision gear for them.

in any case, as long as you can confirm ,OK.

 

the difficult things are;

1. the proper time after exhaust gate opens, the intake gate open. If the intake gate open too early,the gas will come back from chamber from intake gate. If too late, it will influence the frequnce speed and so on. I suggest that you choose late than early first. once it can work orderly, It can work at rather wide range if design correctly.the time also depends on rotation speed of valve. You can adjust the ralative position of the gates of intake and exhaust valve.

2. the proper time after intake gate open, the exhaust close. I suggest that you choose early than later at first . once it can work orderly, It can work at rather wide range if design correctly.the time also depends on rotation speed of valve. You can adjust the ralative position of the gates of intake and exhaust valve.

3. the proper time after exhaust close, the intake gate. It is rathe easy compare with upper two. I suggest that you choose the intake gate close early than later at first.You can adjust the ralative position of the gates.

 

beside you adjust the gates' ralative position,you also can adjust the pipes' size and the size of chamber.

do you feel very troublesome about these?

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DFINITLYDISTRUBD:

 

I have some remind you, very important.

 

besides the questions, I mentioned before, you also should consider if the rotary valve match the turbine(turbo-changer). What is the individual rotation speed of them (valve and turbine).as well as their sizes.In this small machine, you can use transmission gear between them.

In my design I use coupls of chamber. by my experience, the essicial diameter of valve must more than turbine. If it has different size of chamber,different interval times per rotation , you should recalculate the proportion of their size by this principle.

If the diameter of turbine is too small,the chamber can't get enough gas .If it is too big, the turbine's efficiency is bad ,maybe the turbine can't work appropriate ( not in common condition),thus worse .

 

You should use branch pipes for the chamber if you use over one couple of chambers.

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Dear seeking_aeolus:

 

As to the noise, I agree there are big noise occur while the gas run from the chamber to the branch pipes.I have a new idea how to reduce the bad effect.If the gas' speed at the outlet over sonic speed. the noice isn't easy to spread from inside from the outlet.

generally the noise from the outlet is the main sourse.I also can use other method to isolate the noise.

The solution you proposed is a good idea. I amn't sure that it is easy to realize.

 

response your last post,If at last I think a new jet is better than the current jet, I would acquire it better at main aspects; efficiency,weight,life reliablity.At least not worse than the current one at certain aspect.In the whole it is better than the current one obviously. otherwise nobody wants it.

There are some course/detail that I am not clear that how to analyse sciencally or realize reliable though i have thought the m a long time. maybe depend on experiment.

 

pls advise

 

I think experimenting at more of a trial & error approach rather than actually gathering the known information would be a considerable waste of time and money. As average poeple, we are limited on resources, especially time and money, because there will always be someone else out there with same idea, more resources, more knowledge, and before you know it, what was your idea gets implemented and marketed by someone else! There are resources out there that can help you at least find a starting point, I am currently in the same boat you are in, I think.

 

I am currently taking classes at college in order to fulfil my dream, and make it a career. Some of my future course load deals directly with what we are discussing. I am right now designing a jet engine, however mine is based on fundamentals, nothing more. This isnt as complex as everyone wants to make it.

 

gotta go, be right back....I'll post more later.

 

~seeking_aeolus

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Q-man

 

Ok, I'm back. Meatloaf! mmmm...

 

As far as experimenting is concerned, I would find a good starting point and work from there. I am using Law of Conservation of Momentum. Basically, I am building a testing device, to measure propulsive force. From using The known mass of the test engine, I will measure distance vs. time, and from that I can get anything I need, because all of the other info is based off of mass, distance, and time! I already have the pipe fittings I need, (this is what my design is based on anyway), next I must build a platform, and a rail-system, (probably out of unistrut) to create as frictionless of a ride as possible. This way I can make friction negligabe from the rail, but I will not be able to make air friction negligable. But it is a good starting point I think. At best, whatever you design, theoretically, in real life it prolly wont give you bust 85% of what was calculated on paper. So give yourself an extra 15% (engineers call this a F*** FACTOR). And sometimes, what's on paper is either too expensive, too impractical, too complicated, or simply "It just won't work". But don't give up on it, if that ever happens.

 

It may be that you can use me if you have any questions (I prolly wont help much....) but I can help find some answers, and who knows maybe you can provide me with some answers if I get in a bind.

 

I have been using this guy Mike Davis' web-page for some hands-on ideas, and it makes a lot of good sense. Great pictures by the way. He has given me some great ideas. Here is the website:

 

http://www.junkyardjet.com/index.html

 

Also, check out NASA's web-page, just type it in google. They have some very cool information about jet engines.

 

And finally, there is a book out by Rolls-Royce, The Jet Engine that you should look into buying, I have heard it gives a lot of information. I don't have it, but I want to buy it badly!

 

I have been neglecting one aspect of this whole jet engine idea, and that is lifetime. I havent considered prolongued wear-and-tear on my design. But I have a great idea for a glide-bearing!cIt would seal unlike anyother, yet provide a stout, virtually frictionless support mount for the drive shaft.

 

write back

 

~Seeking_Aeolus

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seeking_aeolus:

 

thank you provide those information, i will read the web carefully that you recommend. Though the jets inside are different from my design,i also can a lot from these web pages.

 

DFINITLYDISTRUBD, I hope you study these web pages before you start to build the engine. i think it is very helpful for you.

 

the book" The Jet Engine" out by Rolls-Royce,i have read the book carefully in library ten years ago. It is real good book. unfortunately I can't lend now.But i have remembered most of them. That is a good book.

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DFINITLYDISTRUBD:

 

I only a little surprised that you use only one chamber, and the engine can spout several times per rotation. Maybe you seperate the chamber.What is constrution of the rotation valve?

 

not only the spouting gas you should consider, but also the sweeping the waste gas. Do you use the branch pipes as i drew? You should ensure it work smoothly and in high frequency. That is important.

 

Are the valve able to work smoothly under high pressure?

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In recent years, in the world the fuel is always in short supply. the price has been risen a lot and continue to rise afterwards. So to study the efficiency is important.Meanwhile the ability on manufacture and development new material rise a lot than before. It is more feasible to realize the new jet than before.

Before I wrote sth about the theoretic efficiency and the possible actual efficiency. I think I should study further.

As to the new jet: efficiency=1-k*[u^(1/k)-1]/(u-1)/{w^[(k-1)/k]}

as the current jet: efficiency=1-1/{W^[(k-1)/k]}

u: the rise rate of gas pressure in combustion.

w: the rise rate of gas pressure in compressor or blower

you can find the explanation in post #59.

 

All can see we can change two parameters "u" & "w" in the new jet to get a efficiency. In the current jet you only can change one parameter "w". so the new jet is more flexible for us. it is more convenient for us at this point.

 

I study the work done by gas. the amount depends on the pressure of the gas.The higher pressure, the more work it can do if other aspects are same. The gas pressure depends on "u" and 'w" two parameters. the final pressure rise rate =u*w. I study it roughly(because the detailed research is very complicated). As to a certain pressure, There is proper proportion between 'u" and "w", the new jet has a minimum weight in the whole.That is because ,when the "w' reduce, the volume of the chambers will increase. it is not economical.To some extent when "w" rise, the volume of the chamber will reduce a lot.

That is one of reasons I select the blower ,not throw it away.

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pls see post #86 (page 9) about "the possible actual efficiency".

 

noy only the weight should be consider, but also the actual efficiency should be considered. The acual efficiency is also hard to analyze. It is related with blower and turbine's actual efficiency.

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to change "W", there are two ways:

1. change the proportion of fuel to air, it can change a little

2. change the proportion on valume of fresh gas to waste gas in each input to the chamber

 

Dear everbody:

 

I made a mistake, "W" in the post should be "U"

I am sorry.

 

qumf

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