bylerfamily16 years ago

Yeah but don't crimp the ends shut unless you want an explosion.

lasermaster353116 years ago

not all the way, just enough to make it a really tiny hole.

bylerfamily16 years ago

Yeah.More like a pin sized hole or something.

LetsBuildOne(author)16 years ago

Yes, your both right, the smaller you make your nossles the more pressure build up and the higher velocity of the exit vapours/gases. As Ke=(1/2*M)*V^{2 the Kinetic energy of the steam and hence its reactive force on the vessel on expulsion increases with the square of the exit velocity.}

Put Simply- Decrease Nossle Size->Increase steam exit velocity->Increase rotation speed (rpm).

Also you could add a small amount of acetone to the water before you boil it, being careful to make sure it is mixed well. By a small amount i mean less than 10% although i cannot find the exact water acetone ratio right now. When you mix water and acetone together they form an "azeotrope" this is usefull because as the acetone boils/evaporates it takes molecules of water with it effectually lowering the boiling point of water from 100*C (pure water at 1bar atmospheric pressure) down to around 70-80*C (acetone-water azeotrope at 1bar atmospheric pressure). This means it will boil faster and produce more steam at 100*C than the pure water would.

More steam=more pressure=higher exit velocty vapours=more mass out per second. Going back to Ke=(1/2*M)*V^{2 if you increase the mass (flow rate ie mass out per unit time) the Kinetic Energy increases and since the same equation applies to the vessel and the mass is constantly decreasing as the azeotrope evaporates the velocity must increase.}

The only other thing you could do would be to make the vessel lighter, more aerodynamic and reduce the rotational friction from the bearing. You could experiment with pipe lengths but lengthening increases torque action but decreases rpm, shortening increases rpm but decreases torque. (Torque is the rotational force applied to the vessel by the steam, too little torque and it wont have enough force to spin although this is unlikely).

In conclusion:
@ Smallest Possible Holes/nossles.
@ Add Less than 10% acetone to the water to lower the boiling point.
@ experiment

Hope this has helped,

LBO

11225191911216 years ago

WHY YOU TORTURE USS WITH BIG WORDS!?!!?!?!?!?!!?! AHHHHHHHHHHH!

threecheersfornick16 years ago

Ow, my ears!

Arbitror16 years ago

Calm down...

The nerdling14 years ago

extraterestrial yay i used a big word i'm smart yay!!

LetsBuildOne(author)14 years ago

Call that big? If the length of the the words you use is a measure of your intellect try this on for size: Antidisestablishmentarianism, I'm not a fan of medical terms so that's as long as I will go.

Joking aside, am I actually using particularly long words? I'm aware can be rather verbose at times but that's because I want to be clear. I use a few technical terms to be accurate but my intention isn't to bamboozle you. I don't think theres anything in there that the average person won't understand. Azeotrope may need a quick Google but I explained what it meant for those people who didn't know, I explained everything in case people didn't know the science, I even explained what torque was.

I'm an engineer, maybe I have a different perspective on what a big word or what simple is. I may do a "Building a... for dummies" series where the instructions are simplified. I could do it as a comedy series and write it in hill billy? Could be fun... Especially if it's to build something particularly precise, scientific and complex. I do enjoy irony.

The nerdling14 years ago

yeah wel kjxkjnxkjwehwejfjdm,fowe,djwqlrmwqdjkefbjwqejhdkjjakwejwqkdmnkjeq.
i wrote it so that is a word

Brekenridge14 years ago

Pneumonoultramicroscopicsilicovolcaniosis. Just saying.

Back on topic
Would you get more power with more pipes attached? I wouldn't think so, since that would decrease the pressure inside because there would be more openings. More stability maybe?

If you want the smallest opening possible, could you make a hero's engine with only one pipe/arm/thingy? It would have to be balanced perfectly because of stability issues but I think it might be a bit more effective.

LetsBuildOne(author)14 years ago

Ah, I see you have no problems with mediacal terms. Well done, that's one hell of a word and an interesting meaning.

Back on topic
If you want more power then boil something with a lower boiling point. adding more exhausts wouldn't help because what you gain in mass flow rate out of the engine, you lose in exit velocity. Increasing your torque but decreasing your pressure and top speed as the engine can only be propelled as fast as it's exhaust travels. One pipe may make it faster but it would probably require a solid shaft to spin on over a piece of string because of the stability issues you mentioned.

You would get the same effect by using smaller tubes. remember that it is the cross sectional area of the exhaust nozzle that effects the exit velocity so halfing the diameter doesn't half the area as the area is equal to pi multiplied by the square of the nozzle radius.

wiggins847214 years ago

Thanks for this. I think the "azeotrope" concept is useful for several of the steam designs on this site.

LetsBuildOne(author)14 years ago

Your welcome, It was a real epiphany for me too!