This isn't exactly speaker related (but it is) but if you start reading this thread linked below (starting with the post I linked to on page 10, you will find it very very interesting, trust me!
(Mods: This thread is about applied enclosure design)
(Mods: This thread is about applied enclosure design)
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Basically they built a solid stainless steel pool buttressed by more steel for olympic trials. They ended up making the dimensions exact multiples of eachother. All the wave reduction technology out there only deals with the part of the wave on the surface. Everyone is baffled as to why everybody times were slower than their seed times (much more so than any other olympic trials ever)
I know you never want to make a standard sealed or ported enclosure that has dimensions that are exact multiples, and that is exactly what they did with this pool. I can't prove it but im sure someone here can.
Also, whoever adapts existing home theatre sound control device/ method (room treatments) patients to competition pool wave reduction could make alot of money.
Note: waves in a pool slow swimmers down.
I know you never want to make a standard sealed or ported enclosure that has dimensions that are exact multiples, and that is exactly what they did with this pool. I can't prove it but im sure someone here can.
Also, whoever adapts existing home theatre sound control device/ method (room treatments) patients to competition pool wave reduction could make alot of money.
Note: waves in a pool slow swimmers down.
Doesn't seem that your idea is well received. Maybe they think it doesn't - you know - hold water.
I guess you could measure it. What is used to measure waves under water?
I guess you could measure it. What is used to measure waves under water?
I don't know about pools...but I'd think damping wave motion would steal energy from the swimmers.
But the "acoustic" theory learned modelling speakers has been one part of my success porting motorcycle heads and designing motorcycle airboxes and exhausts (though I'm no 2-stroke guru, which is where a lot of this theory came from as they pretty much run on dynamic intake and exhaust tuning). They may have a flow component but modern tuning is moslty about a dynamic pulse component rather than old-school constant-flow theory. The pulse component is modelled much like our bass-reflex ports, as an inductor, they transfer pulses efficiently within a narrow bandwidth. The way the airbox volume is tuned is like a big capacitor, just like we model our cabinets. The result is being able to pack more air/fuel mix into the cylinder just before the intake valve closes (most efficiently at a particular RPM). Of course there's a lot of old-school constant-flow and boundary-layer consderations etc. and the old-school theory of big straight ports avoiding the resistance problems as the intake approaches the speed of sound. Lots of applications in muffler design too, and intake noise mufflers. But the difference between old-school hot-rodding and modern tech is like going from DC theory to AC. I see a LOT of bad advice on how to port on the internet, but luckily the art has advanced significantly. Now I've started working on an old Pontiac, and I'm amazed at the theoretically terrible porting services available, yet they remain viable in the marketplace because even a bad job is an improvement over small block chevy intake before Vortec.
I know Danley is into Ducati twins; probably has "tapped" intakes and exhausts (or is that just 'scavenging'??). There are weird engine designs which use combustion on both sides of the piston instead of just one, with potential for excellent power/weight...something he'd probably appreciate.
But the "acoustic" theory learned modelling speakers has been one part of my success porting motorcycle heads and designing motorcycle airboxes and exhausts (though I'm no 2-stroke guru, which is where a lot of this theory came from as they pretty much run on dynamic intake and exhaust tuning). They may have a flow component but modern tuning is moslty about a dynamic pulse component rather than old-school constant-flow theory. The pulse component is modelled much like our bass-reflex ports, as an inductor, they transfer pulses efficiently within a narrow bandwidth. The way the airbox volume is tuned is like a big capacitor, just like we model our cabinets. The result is being able to pack more air/fuel mix into the cylinder just before the intake valve closes (most efficiently at a particular RPM). Of course there's a lot of old-school constant-flow and boundary-layer consderations etc. and the old-school theory of big straight ports avoiding the resistance problems as the intake approaches the speed of sound. Lots of applications in muffler design too, and intake noise mufflers. But the difference between old-school hot-rodding and modern tech is like going from DC theory to AC. I see a LOT of bad advice on how to port on the internet, but luckily the art has advanced significantly. Now I've started working on an old Pontiac, and I'm amazed at the theoretically terrible porting services available, yet they remain viable in the marketplace because even a bad job is an improvement over small block chevy intake before Vortec.
I know Danley is into Ducati twins; probably has "tapped" intakes and exhausts (or is that just 'scavenging'??). There are weird engine designs which use combustion on both sides of the piston instead of just one, with potential for excellent power/weight...something he'd probably appreciate.
Hi
Boy water is a 3d problem and you’re talking about surface waves, not sound waves.
Also, a reflection depends on having a sharp discontinuity in the “impedance” such that little energy is transferred and so reflected back.
The weird thing about water is it’s density is a lot closer to solid materials than air would be with sound.
It would be my bet that if it were actually different (as the swimmers seem to think) it would be more like one of the posters suggested, that the construction makes it more damped than normal.
Cyclecamper (Greg?) is right, there is something about the L twin Ducati’s that appeals to me.
They are pretty normal engines except for the valve gear.
Cyclecamper mentions another type of engine that is pretty cool, the compound engine, it has combustion on both sides of the piston and usually they also have more than one piston. They were pretty popular once but at the time in a large scale execution like everything else then haha.
I love big old engines, there is something indescribable standing next to them running, you can feel them.
Here is a large one a friend of my Dad’s was running;
Rollag Minnesota 600HP SNOW Gas Engine - YouTube
Best,
Tom Danley
Boy water is a 3d problem and you’re talking about surface waves, not sound waves.
Also, a reflection depends on having a sharp discontinuity in the “impedance” such that little energy is transferred and so reflected back.
The weird thing about water is it’s density is a lot closer to solid materials than air would be with sound.
It would be my bet that if it were actually different (as the swimmers seem to think) it would be more like one of the posters suggested, that the construction makes it more damped than normal.
Cyclecamper (Greg?) is right, there is something about the L twin Ducati’s that appeals to me.
They are pretty normal engines except for the valve gear.
Cyclecamper mentions another type of engine that is pretty cool, the compound engine, it has combustion on both sides of the piston and usually they also have more than one piston. They were pretty popular once but at the time in a large scale execution like everything else then haha.
I love big old engines, there is something indescribable standing next to them running, you can feel them.
Here is a large one a friend of my Dad’s was running;
Rollag Minnesota 600HP SNOW Gas Engine - YouTube
Best,
Tom Danley
With valves being driven directly, cams having the right shape and springs having the resonances driven out, there's no reason to need the desmo system anymore. Still, it's hard to argue with all their wins.
Go Casey
Hey Guys,
seem to remember the Sydney 2000 games had a fast pool
What made the Sydney Olympic pool so fast?
maybe the existing pool could have some of these features incorporated
ps Ducati 999 is my favourite 😎
seem to remember the Sydney 2000 games had a fast pool
What made the Sydney Olympic pool so fast?
maybe the existing pool could have some of these features incorporated
ps Ducati 999 is my favourite 😎
An externally hosted image should be here but it was not working when we last tested it.
It looks like the dimensions are standardized. Therefore, if there's a problem with standing waves, it would affect all 50x25meter olympic pools equally, assuming the lane spacing is identical.
Also, the standing waves would depend on which lane you are in. Generally the center of the pool would suffer the most from standing waves, since all the dimensions are a multiple of 25 meters. But at the same time the size of the waves at the center of the pool would be reduced by the distance that the waves have to travel. You'd have to know how much the waves decay to make a real guess at this.
Ideally you'd want to model this on a computer 🙂
ah good point about the gutters. That would make a huge difference, as it would absorb the reflected waves
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