Since I've got a stuffed head and runny nose passed on from the kids, I've been wandering around in my recent bookmarks trying to cleanup things; and spent some time learning the fundamentals of aircraft gas turbines. The US Army has opened sourced all its learning materials, and a number of web sites have put the material up online. My favorite right now is Free-Ed which is trying out GoogleAds as a way to generate revenue.
While I'm familiar with the basics of how jet engines work, its good to review things like the brayton cycle and I still find Bernoulli's principle counter intuitive in some cases, and am still scratching my head about why when you constrict a flow, the pressure and temperature drop instead of increasting.
Besides the mechanics of the engine itself, the training manual was talking about gerotor pumps for the oil. Now I know about gear pumps, but hadn't heard about gerotors before so I had to go dig up pictures on them. A gerotor is neater than a normal gear pump, because it takes up less space (one gear is inside of the other), and the teeth only mesh with each other at 1/N times the shaft rotation rate, so there's less wear.
There's a couple good pages on how these work (just forget wikipedia as they have no clue), and if you want to design you're own, you can even download a design program that will let you create 10 designs free before having to pay $250 for the program. This would be a great program to get if I had a 3d prototyping machine and could mill these out of brass, or cut roughs out of steel with the CNC plasma table and then machine them down to final tollerances.
Whoever thought up the geometry for the gerotor was thinking outside the box. Maybe they had been staring at the wankel engine too long. All these dynamic geometry inter-meshing engines are remarkable engineering achievements (especially considering most of them were originally designed in the 1800s--long before computer modelling).
Or maybe someone was just tired of making crop circles.
