so yeah, for my final year uni project ive gotta design a vacuum seal on a shaft that will be spinning at a max speed of 68000rpm
and also design a gearbox that has a 17:1 ratio, going from a max of 4000rpm to 68000rpm

as i currently know pretty much nothing about gear and seal design at the moment im wondering if anyone on here has any experience with anything even removelty like this

right now im just trying to figure out the basics of both these topics but searching the internet for seal information is proving rather hard. As im not finding a whole heap of info on seals for rotating shafts

so basically i need to find out

-the type of seal to cope with the high speed
-the material to make said seal out of
-type of gears to use
-material to make the gears from
-arrangement of the geartrain

so yeah once again, anyone with any kind of experience with anything remotely like this it would be great to hear from you

I'm just thinking about the seal first, you want to consider what the rotational forces are doing to the seal and shape it for that then apply vacume, I was thinking of some sort of tapered shaped jobby. Can the shaft design be modified to suit the seal? otherwise a recess in the shaft to prevent the seal inner from moving. The recess one seems like the better idea now cos the taper shape inner will probly just expand under that vacume.

can design anything how ever i want

shaft will connect to a small flywheel about 20cm diameter 20cm long...it will be spinning in the vacuum

only types of seals i know about really are your run of the mill rubber type seal. which i would imagine would want to melt when the shaft is spinning at 68000rpm

and the other type ive seen lots of info on is megnetic fluid seals, but all the available ones ive found so far are limitted to under 20000rpm and only handle a couple of Nm of torque

after a bit of reading today im feeling less confident about the seal, Flybrid Systems have a kinetic energy recovery system with a flywheel spinning at 64000RPM in a vacuum. they claim that the seal that they developed for it is the highest speed vacuum seal in the world

yay

lol ... may wanna look into mechanical seals with ceramic on one side and ?carbon? on the other ... i was using them in a vacuum pump i rebuilt a couple months ago at work. dunno if they'd go that fast though

looks like its going to be a magnetic fluid seal. pretty sure its what flybrid are using and seems to be about the only way of going about it

they are the sort of seal that is used on the shaft of a hard disc drive

sounds like a turbo/gas turbine to me
1200 deg F
100000 rpm
couple of bar of pressure difference on each side
get an old turbo, seal one half in a box, suck out the air and check for leaks. this will prove/disprove the concept
centrifugal blowers are geared up heaps
chesterton do seals for this kind of thing for industry
your going to need to balance this flywheel at a MIN to turbo specs. an engine balancer wont cut it.
as shaft dia increases surface speed will increase too

graphite?
http://www.roccarbon.com/cgcompressor ... Iz9iJiVip0CFR0SagodlhGX_w