Pulse Jet Valve Material

Sorry, but until you define the material requirements, I'm with Doorman.

"large amount of pressure and exponintal amounts of heat." aren't qualities that can be used to specify materials.

Diamonds are non metal and can withstand, "large amount of pressure and exponintal amounts of heat." So, you are welcome. There's your material selection. You didn't mention price, so I assume that this material will be acceptable.

Yeah, and this reads a little like a homework question anyway...

OP has developed a ramjet/scramjet/pulsejet improved feed technique (or something, I guess, I dunno), but cannot figure out how to wire up a radio in his car?

And developing an improvement for a pulsejet? Why improve something nobody wants to use?

Nathan, if I misread you, please forgive me. If I didn't misread you, please come clean.

Doorman,

I don't think it's homework. The requirements would have been more clearly defined.

I think Nathan's just a dreamer. I think he needs a new vehicle, too.

I clued him in to the fuse block for his stereo.

Cheers.

"Why improve something nobody wants to use?"

well you know some guys like to reenact historical battles... and who has a V1 in their garage these days?

i want to use it. i like doing things like this ... making unusual cool things. (or at least cool to me)

and it just happens to be that this car is great ... it is a tank and its just the fact that i can not find the ingnition wire .... but for future referance there is no problem with the fuse box! or any of the fuses for that matter.

I concede that diamonds may not be the perfect choice. (Just the most expensive)

I expect there are ceramics which may be better suited. Isn't there a "nano-something" that would work? I see a switchable maze to throttle the air in-flow.

I think it's time for a response from Nathan Kimzey.

the valve (to which i am asking the first question to) does not have any mechanical moving parts. i just need it to act as a kind of flap, but it needs to be able to be air resistant ... so it moves when the air is sucked in but when the pressure on the inside becomes greater than the outside then it will close, by that pressure, and wont let air escape.

with those requirements, go all the way and make it invisble too.

I love bench racing hypotheticals..

Can you provide more information (such as what your existing theoretical design is). No use trying to improve some theoretical design that doesn't work, unless you want theoretical answers.

If a theoretical answer is all you are after however, then a semi-rigid mesh weave composed of carbon fibre nanotubes and ceramics should meet most of your requirements (additional strength can be obtained from titanium bracing to create a flexible one-way valve). This is easier to manufacturer than the above alternatives (and cheaper), but I seriously doubt it or any solution here to meet your stated requirements will be economically practical.

Please provide more information.

My partners in British Columbia (West Coast Canada) make pulse-jet-based thermal reactors. Pretty much any kind of solid fuel with up to 70% moisture in it can be gasified, and the syngas gets burnt in the pulse jet. Result: 2,300 F hot hot heat.

E-mail me and I'll give you their coordinates: stratos@spp-consultants.com

They're straight-up fellows who won't screw you, but don't take my word for it. And who knows? You and my partners could perhaps help each other out.

Looking forward to an e-mail from you. Cheers! DZ

There are some pulse jet style boilers out there you could look at them.

The test for a real or fake diamond is to set fire to it the real diamond burns and then you know it was a real one, all you are left with is CO2.

From the design of the V1 bombs, they had an interesting way of reducing the losses on the valves. They were bent so that the valve was trying to curl downwards onto the seat. When the valve opened the holes was a better shape. Read this in an old German weapons of WW2 book (by Allied forces). It was very interesting, covered their use of wire guided and TV guided bombs. Things that weren't put into use by otehr forces until much later. The recent bunker busting bombs (TV guided) were not so clever.

I don't think you need fancy materials, just thin spring steel. It gets cooled by every inlet flow.

spring steel is what is generaly used. I think he is looking for somthing else.

oilcan13

we would like to introduce our selves as manufacturers of venturis in Single Piece for pulsejet bag filters we are in to metal spinning and deep drawing and we can develop as per your requirement and we can work on ms,cr,almiunium,brass,304steel,copper and any other metal that can be spun from thickness from .3mm to 3mm thick. Dia 50 mm to 700mm
Thanking you
For Kohinoor Enterprises
Aftab Ahmed
prop

Kohinoor Enterprises
no 11 1st a cross
J C road Bangalore 27
India
mob;9243106223
PH 0091 80 41142001
Telefax 0091 80 41142001
E-mail : kohinoorenterprises@yahoo.com

www.kohinoorenterprise.com

This has become a joke. Good Bye.

Pulsejets are good, but a ram jet is better once you get going (three to four times the speed of sound seems about right for ram jets, a lot slower for pulsejets). Fewer moving parts. I heard that somebody put ram jets on the ends of helicopter wings once. Seems a little unlikely since chopper wings are pretty complicated things and installing jets on the tips just tips the complexity into the realm of OMG, but I can imagine something similar being used somewhere.

Mind you, once you get going, the pulse jet becomes a ram jet because the incoming divergent ducting keeps the valves open against the plenum pressure (translation, the pulses disappear once you get up to speed and the ram effect becomes important).

My furnace uses a pulse jet to heat my house. It's kind of neat, buzzes in operation. What's wrong with using existing furnace-based pulse jet valves?

tip jets have been around a long time.

http://en.wikipedia.org/wiki/Tip_jet

one of the products of using propaine as the fuel im going to use is CO2 and water vapor and on other home made pulse jets, the people have made a point that thier metal reed valves rust rather quickly. so i rather not have to deal with it ... if i still had auto-CAD then i would try to show you the design but then i think that other people would take it as their own. i dont want that exactly right now.

thank you i will look into what you have said ... i only know so much i am only 17 years old and i still hacelearning to do and this is what i am trying to do here.

i have the right kind of mind for these things but my knowledge only goes so far so that is why i look here for help

A good rule of thumb you should keep in mind is look at existing applications that are similar (such as jet engines and rockets, which pulse jets are a hybrid of the two) and look at what is used there. Those materials weren't plucked out of someone's arse just because they like the name, they were chosen for valid reasons. There is a reason why non-metals aren't used in these parts. Non-metals have very poor fracture toughness and poor flexibility (Young's Modulus) (thier yeild and UTS are virtually the same number and the stress strain curve is ruler straight to failure). Those are very important features for a material in this application. They also require good hot strength, which is a measure of how much of the room temperature strength a material retains at high temperature. Steels lose a large percentage of their strength at (relatively speaking) moderately low temperatures (which is why the WTC towers collapsed, not because the steel "melted", it simply lost too much strength to support the load above it.). there are some duplex stainlesses that start out at about 85KSI yeild at room temp, but by the time they get to about 150C they are down to about 60KSI and the strength loss accellerates at higher temps. for the most part it comes back as the material cools back down (as long at the temp doesn't get high enough to change the material's crystalline structure).

and finally you need to look at the high temp oxidation resistance (a form of corrosion) of the material. Iron and carbon both rapidly oxidize at high temperatures and iron and carbon are the two fundamental components of steel. Chromium combines with Carbon to form Chromium carbide at temperatures as low as 800 degrees F. Chromium Carbide is very hard but brittle. Nickel and Cobalt alloys do not have this problem until they reach much higher temps, especially alloys with large amounts of Niobium in them.

The problem you have is you don't know what you don't know. You need to do more research to find out what it is you don't know in order that you can try to find out.

maybe some time when i am able to make computer images of my disign i could show you them and we could talk about what i would be the proper item to use and other stuff like that..

could i have your email?

but thank you that is very good advice

just click on my username and you'll find a link to send me a message.

Steels used in relatively high temp applications generally have large amounts of Chrome (for strength), Moly (for oxidation resisitance), and vanadium (for impact resistance and hot strength), but they can only go so far, Nickel and Cobalt Alloys blow these materials out of the water in high temp applications.

Inconel X750, MP35N (nickel based) and Elgiloy(cobalt based) are three relatively common materials available in strip that would work quite well in this application. Others will be much more expensive and generally only available in round barstock or as castings/forgings.

the thing to remember in engineering is that there is no such thing as a "perfect" material. Everything has negatives as well as positives, one of the biggest negatives you can deal with is cost. That is why academics are often very bad engineers, they don't have to meet a budget or a price-point. the best engineer is the one that pick the material that is just good enough but cheap enough that the product can be built and sold at a profit.

Hi,

"flexible but not too flexible" is designed by geometry - so not a material property.

Exotic flexure materials: quartz, quartz-glass, other high-temp glasses, sapphire, titania, spinels, the many different garnets, pyrolytic carbon, mixtures of metals with oxides, nitrides and borides...

RHABE

There are types of aerogels that fit your bill, some are flexable with high heat tollerances, there is a new nonsilica base that is supposed to be the next big thing, but I dont know its qualities, NASA had a recent paper on it. the presure requirment when using aerogel can be overcome with design.

well i think that some kind of carbon fiber would work ... but im not sure ... for lynlynch i need it to be thin nearly a half of a millimeter in thickness it needs to be able to flex back in forth and it needs to stand very high tempetures.

Carbon fiber in a resin matrix generally wont stand up to the heat, its strong under preasure and flexable, but when mixed with a material to handle the heat you loose flexability.

try aerogel in a duckbil configuration

Nope carbon-carbon composite MIGHT work, but I suspect it will eventually burn up.

thank you for your imput ... this is why i ask these questions here.. a ton of people that can i can look to for some help ... it seems like a nice thing but i also like reading other things on this site ...

but i dont want bussness deals...i dont want any smartass remarks line "unobtainium" or any other thing of that nature. just say you need more information and i would be glad to give it to you ... but some of the comments above are unacceptable and i will give no attention to.

well i have made other comments and they have more details than the original question

Well, O.K. No more smartass comments (probably).

Would you please tell us a few things:

Reaction time of valve; how fast does this flap have to open and close. Is that a steady rate, or does the rate change somehow? How does it change? Does it close by mechanical transfer, gravity, internal pressure increase (combustion?), a spring...? Open by mechanical transfer, gravity, internal pressure reduction (intake?), a spring...?

This valve... is it metering fuel, or air, or a combination? What chemicals will the valve need to resist?

You tell us "...material that will resist a large amount of pressure..." I would assume positive pressure? 4 bar? 160 bar? Something else?

You also tell us "...and exponintal amounts of heat." An exponent of what? I guess you are telling us it will get pretty hot. 1,000⁰ F? 1,000⁰ C? 1,000 K? Something else?

You see, without some quantative information, I believe unobtanium, nonobtanium, administratium, or some similar material is the correct answer to your question. If you believe otherwise, please tell us what we should base any constructive comments on.

internal pressure increase

it is metering air, it needs to keep the air and the fuel from getting out

i dont know how much pressure

and it can get over 1,200 F. i would aim for something that could withstand that

Hi Nathan, good for you young man. I am 60 an just about where you are with your question.

I am also new to and happy to find this link. Stumbled upon it.

For years I have been thinking porcelain products with mechanical linkage.

But I have to agree with the ram jet fellow.

Where my interest is to develop a jet forced steam that will work for cleaning and fighting fire. I have seen one patent but not much development.

My thanks to all of you for helping Nathan and also me.

I have seen pulse jets on one man helicopters and wind machines used for crop frost protection.

Hi Stephens 1949,

there was an interesting application of MIG fighter engines firefighting the oil-wells in Kuwait that Saddam Hussein let set afire after his defeat in the first Iraq war.

This was a pair of engines mounted on top a military tank with a lot of water and some foam agent introduced into the exhaust.

A Czech company came up with this.

This was so effective that the estimated time that was thought necessary was cut by a factor of 30 or so and the major time needed was for transportation of this equipment.

So I am convinced that your idea is suitable on a smaller scale too.

Have success!

RHABE