Kyrasis6

Geeze you guys are making my engineering education look like chicken ****, I like it lol.

Ok, to understand this think of a cooling system. You want it to stay liquid right, that is the reason to pressurize the system and one reason for anti-freeze. If the coolant boils you get steam pockets and the engine overheats. This is because gasses don't transfer heat as efficiently as fluids.

Now, if you expose a fluid to a surface with a temperature that is substantially higher than its boiling point what happens is the fluid in direct contact with the surface flash vaporizes and insulates the fluid on top of it. So for a few milliseconds heat transfer is very fast then it slows down dramatically.

To visuallize this take an old pan and put it on the range on medium. After it warms up a few minutes take an eye dropper and drop one drop of water. It will boil and evaporate very quickly. Now turn the range all the way up on high and let it get all the way hot. Let another drop fall and see what happens... The second the water hits the pan it flash vaporizes so fast that it will bounce off the pan and look almost solid, it will continue bouncing around until it is vaporized or hits a cooler spot.

Even though the pan is much hotter it will take longer for the water to vaporize because the fluid does not remain in contact with the hot surface.

0.0 I need a girlfriend, lol.

RandomHero

iTrader: (2)

Ahh, i see. Maybe that engineering education just made it easier for you to relate certain ideas to somewhat well-read individuals. LOL. But that does make sense when you think about it. A little while ago someone from the forum told me not to try so hard to relate pistons and rotaries, and now i understand why. Although obviously many of the principals need to be the same, they are indeed very different animals. Still, whenever i read Auto Math, I cant help but try to translate to rotary. Someone would do pretty well if he/she would write a new book about rotary engines in design, theory, and practice.....

Kyrasis6

Thanks, good to know I still have the touch, lol.

Auto Math is a good book for beginners but once you got all the basic concepts its really pretty much useless as there are more accurate and useful formulas out there.

For example in a book called Internal Combustion in Theory and Practice they give a really good example of Petroff's Equation. They give an example of an 8 cylinder piston engine with a 4 inch bore, 3.5 inch stroke operating at 4,000 rpm, they also provide the bearing dimensions, clearance, and oil viscosity. Given that information they come to the conclusion that the power lost in that engine just in the main and rod bearings is about 66 hp just due to the shearing of the oil used.

They also use a similar formula to calculate the power lost due to the piston rings. After doing a few conversions you could do the same to calculate how much power a rotary is loosing due to all the seals and how far they travel around the rotor housing. Of course this neglects the RA finish of the housings and cylinders and the material of the seals but it still would give you an effective comparison between the frictional losses of rotary and piston engines.

RandomHero

iTrader: (2)

Yup, i have that one. But i need a bit more knoweledge under my belt before i can read the whole thing. I flipped through it a bit when i got it along with a couple other books. The author is some kind of professor and i find it hard to understand all of the terminology he uses. Lately ive thought about taking some classes on physics and engineering.

Kyrasis6

lol, well you better milk the professor for everything you can because even with the engineering classes I took I still have a hard time really understanding it. I usually end up reading a chapter over and over 3 or 4 times and end up saying to myself "ok, they're saying larger parts take longer to dissipate heat, and smaller parts are more efficient but can't handle as much stress so you must compromise"

Both volumes of the book are really geared towards designing an engine from scratch before building a prototype. Since you already have an engine really you just need to understand the concepts, then you can learn to look at a part and know what you want it to do, what you need to do it, and what the consequenses of the modification will have.