Experimental Flash Steam and others

[a41capt]

The Harley Davidson KR engine (45 cubic inch racing engine from 1959 to 1969) was of a side valve configuration with only a 6:1 compression ratio. However, it was very competitive until the overhead valved British motorcycles hit the racing scene, causing the AMA to limit the total displacement of the British bikes.

I raced both a KR and a BSA Lightning 650 on the dirt track in the late 60s early 1970, and I felt the overhead valve higher compression engine (9:1) outperformed the side valve flatheads hands down, even with the 100cc difference.

John W

 

[Richard Hed]

https://www.homemodelenginemachinist.com/threads/diy-tesla-impulse-turbine.35214/page-10

I wanted to add a bit to the above discussion, but wasn't sure it was appropriate so thot I would metntion it here where anything is allowed.

What I have always wondered about the Tesla Turbine was how the input gasses are very compressed but when they exhaust they have expanded mightily HOwever, on the exhaust side, That is, that very strange way of exhausting thru holes in the disks themselves near the center. Also the gasses at the input push the disks at a radial speed much higher than near the center. This seems to be just the opposite oif what is needed.

The expanded/cooled gas should be moving at high velocity but actually must be creating a drag on the disks by the time it gets exhausted. From this perspective the gass should be input near the center and exhausted out at the edges of the disks.

 

[Toymaker]

https://www.homemodelenginemachinist.com/threads/diy-tesla-impulse-turbine.35214/page-10

I wanted to add a bit to the above discussion, but wasn't sure it was appropriate so thot I would metntion it here where anything is allowed.

What I have always wondered about the Tesla Turbine was how the input gasses are very compressed but when they exhaust they have expanded mightily HOwever, on the exhaust side, That is, that very strange way of exhausting thru holes in the disks themselves near the center. Also the gasses at the input push the disks at a radial speed much higher than near the center. This seems to be just the opposite oif what is needed.

The expanded/cooled gas should be moving at high velocity but actually must be creating a drag on the disks by the time it gets exhausted. From this perspective the gass should be input near the center and exhausted out at the edges of the disks.

Check out the Ljungstrom turbine.

 

[Richard Hed]

Check out the Ljungstrom turbine.

How ever did you find that? I wonder what speeds the rotors got up to?

 

[Toymaker]

How ever did you find that? I wonder what speeds the rotors got up to?

Lots more info on the Ljungstrom Turbine (LT) under the inventor's name: Fedrik Ljungstrom.

One of the interesting aspects of the LT is that both disks spin in opposite directions, which has the effect of cutting the rpm in half. Seems many LTs of Fedrik's time rotated at 10,000.

 

[Nerd1000]

https://www.homemodelenginemachinist.com/threads/diy-tesla-impulse-turbine.35214/page-10

I wanted to add a bit to the above discussion, but wasn't sure it was appropriate so thot I would metntion it here where anything is allowed.

What I have always wondered about the Tesla Turbine was how the input gasses are very compressed but when they exhaust they have expanded mightily HOwever, on the exhaust side, That is, that very strange way of exhausting thru holes in the disks themselves near the center. Also the gasses at the input push the disks at a radial speed much higher than near the center. This seems to be just the opposite oif what is needed.

The expanded/cooled gas should be moving at high velocity but actually must be creating a drag on the disks by the time it gets exhausted. From this perspective the gass should be input near the center and exhausted out at the edges of the disks.

The gas is introduced tangentially at high velocity, so it ends up.spinning in the casing. Ever spun on an office chair and noticed that if you pull your legs in you start spinning faster? That's conservation of angular momentum. The same applies to gas flows, the net effect is that the flow through the discs is trying to accelerate to higher and higher RPM as it spirals inwards. The drag from the discs holds it back and results in work being done on the turbine. Ideally it will exit the disc rotating at the same speed as the inner disc edges.

Unfortunately the lack of exducer vanes means that the Tesla turbine has no choice but to leave a little bit of momentum on the table, so to speak. In an ideal turbine the exiting gas would not be rotating at all, having transfered all of its angular momentum to the rotor. Might be interesting to try adding an exducer to one.

 

[Peter Twissell]

Another factor is the expansion of the gas as it loses pressure.
As the gas moves from the outside to the inside of the discs, it's pressure falls. As it's pressure falls, the gas expands and must travel at greater velocity so that the same mass of gas can pass through the space between the discs, which decreases towards their centre.

 

[Richard Hed]

Another factor is the expansion of the gas as it loses pressure.
As the gas moves from the outside to the inside of the discs, it's pressure falls. As it's pressure falls, the gas expands and must travel at greater velocity so that the same mass of gas can pass through the space between the discs, which decreases towards their centre.

Yes, Precisely, this is what I attempted to express but could not wrap my words around it. You have expressed precisely what I meant to say.

 

[Steamchick]

Aha! There is a Twist in this tale (Please excuse the Pun?). As the gas travels around the first "coil of the helix, it loses some energy. - Actually, a bit of momentum exchange occurs at the boundary layer between the moving gas and stationery gas at the disc surface. The drop in velocity (transferred 1/2 M.Vsq energy) means the mass- flow must reduce slightly. And with this loss of kinetic energy comes a slight drop of internal pressure and temperature - (I think???). So the gas stream is pushed inwards by faster moving gas radially outwards, and lower speed gas inside its radius. in ideal conditions (Tesla "tuned speed" = the "Tesla effect" - ?) the gas stream forms an ideal helix in the slot where each turn of the gas stream is just above the speed of discs either side of the gas stream. As well as mechanically preventing expansion sideways, the streams outside and inside at any point so the only expansion (acceleration of gas molecules) can be "forwards" along the helix. But then the extra Vsq component is equally extracted by momentum exchange plus a little more, so the helix naturally drops to a smaller radius where it is not slower than the discs. It is the slowing down of the gas stream that causes it to spiral inwards, the dropping speed caused by kinetic energy removal from the gas stream. The "longitudinally" expanding gas stream doesn't happen as it naturally finds equilibrium throughout the gas flow in the natural helix. The Genius of Tesla was working out what happens, then making a machine to use the effect - even though impractical in some cases.
Hard to explain, very complex, and I don't really understand it, so if this is wrong or meaningless, it's my fault, not Nature or Tesla!
Cheers,
K2

 

[Richard Hed]

Anybody who might be within driving distance of Detroit, might be interested in this bearing auction:

https://www.bidspotter.com/en-us/au...40627&utm-content=bscmayn10259-viewauctioncta

As for myself, I would very much like to bid on some of this stuff, however, I know about the shipping and packing costs which makes the stuff out of reasonable cost

 

[Richard Hed]

I tird third that.
We used Lubriplate (moly grease) of various thicknesses for turbine starter generator splines, and driveshafts/power trains of various Bell helis. The stuff is pretty gnarly though (as in, thick black and doesn't come off your clothes).

Par-al-ketone is top dog extreme for anything exposed. That's for if your garage is sprayed daily with saltwater (Your area is nice and dry though).

We had this amazing (cleaner) grease for critical areas that I no longer remember the name of, but SuperLube is very similar. The FDA says you can eat it, even though it's packed with Teflon.
https://www.sherline.com/product/7550-super-lube-multi-purpose-synthetic-grease/
I slather this stuff all over the exposed surfaces on the Sherlines after every machining run on the kitchen island. I can go straight to dinner without warshing my hands!

Hey Zeb,
where the heck are you? Usually love to heer your cheer.

 

[Lloyd-ss]

The Harley Davidson KR engine (45 cubic inch racing engine from 1959 to 1969) was of a side valve configuration with only a 6:1 compression ratio. However, it was very competitive until the overhead valved British motorcycles hit the racing scene, causing the AMA to limit the total displacement of the British bikes.

I raced both a KR and a BSA Lightning 650 on the dirt track in the late 60s early 1970, and I felt the overhead valve higher compression engine (9:1) outperformed the side valve flatheads hands down, even with the 100cc difference.

John W

HARLEY DIRT FLAT TRACK BIKES Fact or fiction???

I know this particular post (#361) is over 6 months old, but I feel like I am dumpster diving in a big industrial park area and finding all sorts of cool and useless/useful stuff. Is it "bin diving" in the UK?
And speaking of vintage Harley dirt-flat track bikes, I have heard that one of the many reasons the Harleys gave the British bikes such a run for their money is that some of the engine builders shifted the firing timing of one of the cylinders by 360 degrees. That made the firing sequence change from the standard 45 degree offset (degrees of crank rotation) which was 360 degrees apart minus the 45 offset, were at 0-315- 720-1035 -0 degrees. Those standard firing pulses were spaced apart thusly: zero degrees, then 315 degrees later, then 405 degrees later, and finally 315 degrees later. That also gives the distinctive Harley exhaust sound.
But by shifting the firing of one cylinder by 360 degrees (cam change needed too), the firing sequence became 0-45-720-765-0. That made the firing pulses be almost in pairs instead of evenly spaced almost 360 degrees apart. So the firing pulses were at zero degrees (0), then 45 degrees later, then 675 degrees later, then 45 degrees later.
Supposedly, pairing the firing pulses like that made the power at the rear wheel feel, to the rider, like 2 big pulses spaced almost 720 degrees apart (like a big single) instead of 4 almost evenly space pulses about 360 degrees apart. Some riders found the altered firing sequence and heavy pulses more controllable for breaking the rear tire loose for sliding the tail out thru the turns.

Is there any truth to that or is that just an engineer's overworked imagination? Truth or not, that is an ingenious alteration to change how the power is applied to the track.

Thanks, Lloyd

 

[Tug40]

I do remember reading an article in a M/C magazine in early 60’s about the HD KR putting power to the dirt track better than the 500 singles that they raced against.
I don’t remember that BSA 650’s were allowed to race against KR’s, per AMA rules, only 500cc ohv bikes like the BSA Gold Star.
Can’t remember, been a long time.