6 ms·

-I've seen a small-ish one disintegrate under test. (Some 480kg of mass in a ~600mm diameter configuration, at some 8-9000rpm maximum if memory serves) It ama

by lb1lf 8y ago

-I've seen a small-ish one disintegrate under test. (Some 480kg of mass in a ~600mm diameter configuration, at some 8-9000rpm maximum if memory serves) It amazes me how hard it is to contain that kind of energy if it wants to get out. They're really terrifying devices. Particularly when left in the hands of engineers who do not fully appreciate that any sufficiently rapid release of stored energy is indistinguishable from an explosion.

rurban 8y ago
The ones in Formula 1 cars had 140.000 rpm, but not much mass. It's terrifying indeed, so much that Kubica refused to sit in such a thing.
- King-Aaron 8y ago
  Having seen a flywheel + clutch assembly disintegrate on a drag car in the lane next to me (10,000rpm - bits of flywheel came through the bodywork of his car), I can understand why you'd be hesitant to sit on top of something spinning at 140,000rpm.
  - bigiain 8y ago
    Isn't that fairly typical turbocharger turbine speed though? I saw a Mazda RX3 Sport Sedan (a circuit racing class here in Australia ~25-30 years back) spectacularly blow a flywheel/clutch at the end of the main straight (at Oran Park) a long time back - it pretty much perforated all the bodywork in the plane of the flywheel - bonnet and both guards - as though it was a tearoff line on a set of stamps. We could hear bits landing 10+ seconds later hundreds of meters behind us in the parking lot. Depending on what port job he had, that could have been up around 12k rpm (if my vague 30 year old car modifying memory serves...)
    - King-Aaron 8y ago
      > Isn't that fairly typical turbocharger turbine speed though? I believe so, but compressor/turbine wheels don't have a lot of mass to them, so fragments don't usually escape very far if they blow up. I've seen a few compressor housings split, and the main damage is done to the engine itself really. I guess if your turbo was sitting high up and exposed, it might be a danger. Flywheels however just seem to fail more regularly from my experience. (Also, yeah anything rotary powered deals with scary rpm's, haha!) For anyone interested, here's some in-car footage of what we're describing here: https://www.youtube.com/watch?v=qOHUwL0zeXc https://www.youtube.com/watch?v=qOHUwL0zeXc and an image of what the result can look like: http://images.thetruthaboutcars.com/2011/04/LNJ11-BlowedUpParts-08.jpg http://images.thetruthaboutcars.com/2011/04/LNJ11-BlowedUpPa...
  - rurban 8y ago
    He wasn't sitting on top of it, it was rather behind his ass. He either felt the vibrations or the hizzing sound, and that made him very uncomfortable.
    - King-Aaron 8y ago
      Figure of speech, apologies.
RobertRoberts 8y ago
I was thinking about this the other day, why not use a liquid as the mass? Say water? If the spinning disk is treated like the tanks in a liquid tractor trailer, with slots to divide the mass up evenly. When the disk starts spinning all the liquid turns into essentially a solid, if there is a massive failure, simple venting could easily disperse the liquid 360 degrees or away from people, etc... (ie, a giant massive mist explosion) I've worked with power washers that are dangerous when focused, but when the water is dispersed, it's practically harmless. Is there some obvious thing I am missing here?
- cjalmeida 8y ago
  Density, cost, complexity.
  - RobertRoberts 8y ago
    That's too bad. But that sort of describes every technology at one point in time...
- Scaevolus 8y ago
  Fluid flywheels are used for hydraulic couplings in automobile transmissions. They're not good for long-term energy storage, since the fluid loses energy to friction and turbulence much faster than a solid-- think about how long a swirling vortex lasts in a cup versus how long spinning top can continue.
  - RobertRoberts 8y ago
    Ya, I was thinking that the water wouldn't be sloshing around, only being inside a sectioned donut wheel. The water could be hermetically sealed (with some kind of preasure relief for temp changes) in chambers, no sloshing or friction issues. Externally it would look exactly like any other fly wheel. The thought being that since it's a safe medium to explode out, you could spin it faster than other mediums. The steel would just be a shell to hold the water, and therefore the containment vessel wouldn't have to be as robust, as the amount of steel that would fail would not be as much, and as soon as the water exploded out , the remaining steel would dramatically loose kinetic energy and possibly not even flyout. Another comment said that 20k rpm would hold 4x the energy as 10k rpms. That implies that if you truly aren't afraid of the spinning medium hurting anyone, it would seem that water/steel hybrid would be better than solid steel, because you could spin it faster more safely.
woodandsteel 8y ago
Aha, a whole new meaning for RUD.
maxehnert 8y ago
When I used to work on turbo generators, the kind you find at power plants I saw carnage of what happens when those blow up. The retaining rings on the ends, typically a few thousand pounds were prone to breaking on older generators because of the alloy used. When that would happen it would send the projectiles through steel and concrete walls. The balance bunker for load testing and balancing these at the shop I worked in was a pit 40 feet underground with 50 ton caps placed over top.
bachbach 8y ago
Velkess (bill gray) solved that problem before they went bankrupt. The answer is to make the flywheel from a flexible kinetic lasso such that when it blows up, the forces tangle the parts in a manner that it is safely destroyed.

by lb1lf 8y ago

rurban 8y ago

The ones in Formula 1 cars had 140.000 rpm, but not much mass. It's terrifying indeed, so much that Kubica refused to sit in such a thing.

King-Aaron 8y ago
Having seen a flywheel + clutch assembly disintegrate on a drag car in the lane next to me (10,000rpm - bits of flywheel came through the bodywork of his car), I can understand why you'd be hesitant to sit on top of something spinning at 140,000rpm.
- bigiain 8y ago
  Isn't that fairly typical turbocharger turbine speed though? I saw a Mazda RX3 Sport Sedan (a circuit racing class here in Australia ~25-30 years back) spectacularly blow a flywheel/clutch at the end of the main straight (at Oran Park) a long time back - it pretty much perforated all the bodywork in the plane of the flywheel - bonnet and both guards - as though it was a tearoff line on a set of stamps. We could hear bits landing 10+ seconds later hundreds of meters behind us in the parking lot. Depending on what port job he had, that could have been up around 12k rpm (if my vague 30 year old car modifying memory serves...)
  - King-Aaron 8y ago
    > Isn't that fairly typical turbocharger turbine speed though? I believe so, but compressor/turbine wheels don't have a lot of mass to them, so fragments don't usually escape very far if they blow up. I've seen a few compressor housings split, and the main damage is done to the engine itself really. I guess if your turbo was sitting high up and exposed, it might be a danger. Flywheels however just seem to fail more regularly from my experience. (Also, yeah anything rotary powered deals with scary rpm's, haha!) For anyone interested, here's some in-car footage of what we're describing here: https://www.youtube.com/watch?v=qOHUwL0zeXc https://www.youtube.com/watch?v=qOHUwL0zeXc and an image of what the result can look like: http://images.thetruthaboutcars.com/2011/04/LNJ11-BlowedUpParts-08.jpg http://images.thetruthaboutcars.com/2011/04/LNJ11-BlowedUpPa...
- rurban 8y ago
  He wasn't sitting on top of it, it was rather behind his ass. He either felt the vibrations or the hizzing sound, and that made him very uncomfortable.
  - King-Aaron 8y ago
    Figure of speech, apologies.

RobertRoberts 8y ago

I was thinking about this the other day, why not use a liquid as the mass? Say water? If the spinning disk is treated like the tanks in a liquid tractor trailer, with slots to divide the mass up evenly. When the disk starts spinning all the liquid turns into essentially a solid, if there is a massive failure, simple venting could easily disperse the liquid 360 degrees or away from people, etc... (ie, a giant massive mist explosion) I've worked with power washers that are dangerous when focused, but when the water is dispersed, it's practically harmless. Is there some obvious thing I am missing here?

cjalmeida 8y ago
Density, cost, complexity.
- RobertRoberts 8y ago
  That's too bad. But that sort of describes every technology at one point in time...
Scaevolus 8y ago
Fluid flywheels are used for hydraulic couplings in automobile transmissions. They're not good for long-term energy storage, since the fluid loses energy to friction and turbulence much faster than a solid-- think about how long a swirling vortex lasts in a cup versus how long spinning top can continue.
- RobertRoberts 8y ago
  Ya, I was thinking that the water wouldn't be sloshing around, only being inside a sectioned donut wheel. The water could be hermetically sealed (with some kind of preasure relief for temp changes) in chambers, no sloshing or friction issues. Externally it would look exactly like any other fly wheel. The thought being that since it's a safe medium to explode out, you could spin it faster than other mediums. The steel would just be a shell to hold the water, and therefore the containment vessel wouldn't have to be as robust, as the amount of steel that would fail would not be as much, and as soon as the water exploded out , the remaining steel would dramatically loose kinetic energy and possibly not even flyout. Another comment said that 20k rpm would hold 4x the energy as 10k rpms. That implies that if you truly aren't afraid of the spinning medium hurting anyone, it would seem that water/steel hybrid would be better than solid steel, because you could spin it faster more safely.

woodandsteel 8y ago

Aha, a whole new meaning for RUD.

maxehnert 8y ago

When I used to work on turbo generators, the kind you find at power plants I saw carnage of what happens when those blow up. The retaining rings on the ends, typically a few thousand pounds were prone to breaking on older generators because of the alloy used. When that would happen it would send the projectiles through steel and concrete walls. The balance bunker for load testing and balancing these at the shop I worked in was a pit 40 feet underground with 50 ton caps placed over top.

bachbach 8y ago

Velkess (bill gray) solved that problem before they went bankrupt. The answer is to make the flywheel from a flexible kinetic lasso such that when it blows up, the forces tangle the parts in a manner that it is safely destroyed.