Can Hydraulic Pressure Convert into Kinetic Energy?

[RonL]

A short video of a button toy I'm sure most have played with at some point of their life



In my mind I have carried it to a different level, a drawing made many years ago, that I will never follow through on. It is a conceptual rendering only and not intended to be operationally correct, other than the mass of structure to hopefully fit the energy that will be working.
Lacking the engineering skills needed to calculate things, I'm making this thread for anyone that might be interested.
I'm not looking for confirmation that it will work, (I know it will) using the start point as a 100kg flywheel and the tension provided with hydraulic pressure between the pistons. Looking at the cable section, as I see, the length and diameter of attachment, will determine the energy and speed induced into the flywheel.
There will be a critical timing of pressure involved and taking energy away from the flywheel as it reaches the end of twisting the cables.

I would love to see some thoughts from anyone in relation to converting pressure into kinetic energy.
Thanks
RonL

 

[jedishrfu]

It would help if you explained the real world purpose of using this toy as a machine.

Right now it reminds me of this song from Peter, Paul and Mary:

 

[RonL]

Typical me, not being satisfied with a button or cardboard, stepped up to a 2" and about 2 or 3 oz steel washer, the fishing line that I used broke at just the right time because I did not chamfer the holes I had drilled in the steel, poor workmanship in that case saved the tips of my fingers.
In the operation of the video the toy version is energized by pulling the twisted string causing the disc to spin as the string unwinds, the tension in a persons arms add and absorb the flywheel energy in each cycle.

My drawing, In the shortest words, it's a generator.
In the drawing the flywheel cycles each direction but the energy to slow the flywheel is transferred into one side of the generator and then the other. The generator halves are using clutch bearings, which allows them to continue spinning one direction while the flywheel turns opposite.

It will be a high pressure small volume force between the pistons.
If a combustion chamber is the design choice, it might be that the short stroke and slow distribution of power will allow an almost 100% efficient burn of fuel.
I had hoped the drawing might help prevent me trying to explain so much (my biggest downfall, explaining what's in my head)

 

[jedishrfu]

What are you trying to do? what is this machine for?

 

[RonL]

What are you trying to do? what is this machine for?

In my mind I see a very low maintenance, slow steady action generating machine. The actions throughout the machine have very little sliding friction wear points. The pressure applied from the pistons all through the twisted cables transforms into spin of the flywheel and generating halves, those bearings would need lubrication once or twice and replacement would be several years. IMHO bearing life is one of the most predictable things in mechanical engineering.

 

[jedishrfu]

Wouldnt you have stress / strain on the cables? Wouldnt they fail sooner than bearings?

 

[RonL]

Wouldnt you have stress / strain on the cables? Wouldnt they fail sooner than bearings?

Yes, but the twist involves very little linear motion. The cable set, depending on diameter of attachment, would extend and shorten as indicated by the rectangular shaft with spring tension shown in the drawing.
That is one thing I'm not sure is needed and if it serves a good function, just how much movement or tension will help or hinder the energy to the generating and flywheel portion.
I don't think anything would wear out before the bearings.

 

[RonL]

I'm not sure, but this might be the slowest cycle generator ever invented.

 

[OmCheeto]

What are you trying to do? what is this machine for?

it looks like a novel design for a gas powered generator to me.

RonL's question appears to be:

I would love to see some thoughts from anyone in relation to converting pressure into kinetic energy.

Which seems like a legitimate question to me.
I interpret it as "What are the energy losses associated with Whirlygig toy, and do those losses scale up?"

I'm afraid I'm not willing to build a 100 kg (220 lb !) version to find out, empirically, those losses, as my physical therapists limited me to lifting only 20 lbs.

But I just went out and weighed one of my 4 very useless spare tires, and it weighs 17.37 kg. I wouldn't have done that normally, but I'm in the midst of my own invention, which requires me to know that number.

I'm not sure, but this might be the slowest cycle generator ever invented.

No matter. It's novel, and may have oceanic wave energy extraction potential. As I pointed out the other day, options shouldn't be discounted, until science shows that it doesn't work out.

Not sure if you checked out the rest of my scientific idea failures the other day. Here's another one:

The second good bad idea eliminated was the storage of energy in springs.
This was a bit problematic to calculate as the college text equation for a springs stored energy, 1/2*k*x^2, does not correspond to the real world. By that I mean that "k", or the spring constant, is not a value assigned to springs you buy at the store. The springs you buy at the automotive store will always have a "weight" rating, which may or may not correspond to "k" in some way.
But science demanded that I solve the problem.
Basically, I measured the height of the vehicle's wheel well from the ground, before and after I sat on the car, above said wheel well.
Quite unscientific, but I hoped it would get me a ballpark figure.
Originally I thought the value I came up with must have been wildly incorrect, as the number of car springs to store the energy my car has at 20 mph, is 4200. I believe that many springs would probably weigh about 10,000 lbs. Although using wiki as a reference for energy density, I came up with 590 pounds of springs to store the same energy(80,000 joules). Still an unacceptable number.

ps. Just looking at this "whirlygig" thread sparked something in my brain this morning, and I solved one of many technical problems. Thanks!

 

[jedishrfu]

Om, i couldn't find the humorous punchline.

 

[RonL]

@Om, thanks for the comments,
I think I understand how you made the leap to ocean wave energy, but there is room also for the thought "boat anchor"
If I helped you solve something, then my life can't be a complete waste
Also I didn't find your secret web site, I'll look again.

 

[OmCheeto]

Om, i couldn't find the humorous punchline.

After a lifetime of having an overactive imagination, science, sooner or later, killed the humor.

@Om, thanks for the comments,
I think I understand how you made the leap to ocean wave energy, but there is room also for the thought "boat anchor"
If I helped you solve something, then my life can't be a complete waste
Also I didn't find your secret web site, I'll look again.

Wow. I just checked, and that website was put up less than a year after I joined this forum.
It's hard to believe I've been here 8 years, and this place destroyed all of my fantasies, in only 9 months.

I don't think I've ever shared the URL, as I badmouthed PF the day I wrote it up; "I decided to bring my ideas home, as the science forums I usually post at tend to dilute any hard science with opinions, disinformation, and general hysteria. I'm sure you've heard people saying they wouldn't drive one of those "death traps", or it's "bad economics" to be energy efficient."

That looks kind of mean. But that was 8 years ago, and my opinion of this place has changed a tad since then, so: Investigations into Poly-Hybridization of Prime Movers of Human Mobility Devices.

ps. I just noticed that there were no updates after 2008. So "my idea" seems to have popped up around that time.

pps. Sorry, that I seem to be in a hurry, but my friend just showed up, and I have to go to the river now. Ciao!

ppps. Oh. And I decided somewhere along the line, that god is an accountant. Hence my later "Energy is like my bank account" statement. Ciao! Ciao!

 

[RonL]

Wouldnt you have stress / strain on the cables? Wouldnt they fail sooner than bearings?

If the cable ends have a design ball and the point of attachment is a socket slot, the angle will very slightly move to a more appropriate alignment with the applied force of starting or stopping the motion of the flywheel. The strain eliminated will justify the very slight friction movement.
Little things like this can involve so many variations and complexities to the finished product, is why I realize it is a bigger project than my flat wallet can handle.

 

[berkeman]

@RonL -- This thread has been reported as a Perpetual Motion Machine (PMM) thread or exploring an over-unity mechanism. I don't see that from a quick read, but how do you respond? What are you trying go achieve here? What are the thermodynamics of the improved fuel-->work mechanism that you propose please? Thanks.

 

[RonL]

@RonL -- This thread has been reported as a Perpetual Motion Machine (PMM) thread or exploring an over-unity mechanism. I don't see that from a quick read, but how do you respond? What are you trying go achieve here? What are the thermodynamics of the improved fuel-->work mechanism that you propose please? Thanks.

I'll respond in a couple of hours or early tomorrow morning.

 

[berkeman]

Thanks Ron. I'm the Mentor assigned to your thread at this point.

 

[jack action]

I would love to see some thoughts from anyone in relation to converting pressure into kinetic energy.

Energy (in joules) is equal to the average pressure (in pascals) acting on the pistons times the volume (in cubic meters) displaced, or $E = p\Delta V$.

Power wise, it becomes: power (in watts) equals the average pressure times the volumetric flow (in cubic meter per second), or $P = p\dot{V}$.

That is what will come out of your generator (minus some minor losses).

The speed of the generator will depend on the load it has. If there is no load, then all the energy will be stored in the flywheel and/or the springs and, at any moment, $E =$ $\frac{1}{2}I\omega^2$ + $\frac{1}{2}kx^2$.

 

[RonL]

Thanks Ron. I'm the Mentor assigned to your thread at this point.

I guess the comment about combustion in the piston chamber being dissipated very slowly as pressure through to the flywheel, might allow fuel burn to be almost 100% complete, would give someone that doesn't understand mechanics very well a feeling that I'm talking nonsense.
Other than that, I have tried to mimic the video in every respect, the piston chamber I show, mimics the arm energy of a human.

The transfer of spin from the flywheel to generator halves should not strain the mind of anyone that has any understanding of rotational mechanics.
As for me I can see and understand mechanical things that I can in no way evaluate, hence my thread.

I hope the thread doesn't get out of hand and become locked, I feel the power transfer through so little slide friction should produce good efficiency.
Thanks
RonL

 

[RonL]

Energy (in joules) is equal to the average pressure (in pascals) acting on the pistons times the volume (in cubic meters) displaced, or $E = p\Delta V$.

Power wise, it becomes: power (in watts) equals the average pressure times the volumetric flow (in cubic meter per second), or $P = p\dot{V}$.

That is what will come out of your generator (minus some minor losses).

The speed of the generator will depend on the load it has. If there is no load, then all the energy will be stored in the flywheel and/or the springs and, at any moment, $E =$ $\frac{1}{2}I\omega^2$ + $\frac{1}{2}kx^2$.

Thank you for your input,

 

[256bits]

I feel the power transfer through so little slide friction should produce good efficiency.

The spring will have some internal heat buildup during the flex cycle, you some loss there.

As a kid we used to thread a string through the holes of a large button and whirl around.
I imagine the force from our hands was nearly constant during the power cycle; and during the relax cycle less force kept the string from twisting up on itself.

Your industrial sized version MIGHT have those forces varying in strength correctly as just a feature built right into it. Not sure though. I would expect some tinkering would be necessary to get it to operate at max mode of energy extraction.

Interesting scale up.

 

[RonL]

The spring will have some internal heat buildup during the flex cycle, you some loss there.

As a kid we used to thread a string through the holes of a large button and whirl around.
I imagine the force from our hands was nearly constant during the power cycle; and during the relax cycle less force kept the string from twisting up on itself.

Your industrial sized version MIGHT have those forces varying in strength correctly as just a feature built right into it. Not sure though. I would expect some tinkering would be necessary to get it to operate at max mode of energy extraction.

Interesting scale up.

Thanks,
As I stated at the start, the timing of power added and extracted will be very delicate. The length of the cables and the diameter of their attachment should determine how fast the spin and how much torque is applied to the flywheel.
Good engineers should be able to eliminate a lot of trials and errors with their calculators or computer software programs.
Thanks again

 

[256bits]

Thanks,
As I stated at the start, the timing of power added and extracted will be very delicate. The length of the cables and the diameter of their attachment should determine how fast the spin and how much torque is applied to the flywheel.
Good engineers should be able to eliminate a lot of trials and errors with their calculators or computer software programs.
Thanks again

This would really be a good engineering project for 2nd, 3rd year engineers .
Competitions even.
Who can make the most energy efficient version.
Lots of practice for material science, strength of materials, kinematics, combustion or whatever energy source, electronics, generators, etc.
Put their knowledge to the test.

( If they would only get off trying to make the "car" that gets the most mpg per gallon, and do something practical )

 

[jack action]

You could also replace your piston assembly by a crankshaft and connect the motor of your choice to it. Much easier to deal with. But at that point, I guess connecting the motor directly to the alternator is also even much easier!

 

[RonL]

This would really be a good engineering project for 2nd, 3rd year engineers .
Competitions even.
Who can make the most energy efficient version.
Lots of practice for material science, strength of materials, kinematics, combustion or whatever energy source, electronics, generators, etc.
Put their knowledge to the test.

( If they would only get off trying to make the "car" that gets the most mpg per gallon, and do something practical )

I think what I learned with my 2 or 3 oz steel disc, was the feel of energy at the point the load on the fishing line might have injured my fingers, was pretty strong. That was the point at which I knew anything of serious weight, would have to be held in complete control, the idea evolved quickly and the drawing took less than an hour.
All these years I have felt it is a good idea, I have just been drawn to more things that I have a little more understanding of.
My original thoughts did involve the compression and expansion of air in piston chamber, but I never believed it didn't need an additional input of some kind. I do, very much, think it will have a very high efficiency.

 

[RonL]

I feel that 256bits captured the full essence of why I started this thread, my drawing should be a reflection of how serious I think the machine should be, but I kinda get lost when I think about how to approach the analytical process...is there a single thing that will become the control factor, that determines the size and strength of everything else, or would the supply of power (example...can a pair of electric solenoids be strong enough to push the pistons ?) electric would be very precise for how much and when to apply pressure.
I'm not sure a thread like this can stay on track, but I'm sure I'll learn a lot.

 

[berkeman]

I feel that 256bits captured the full essence of why I started this thread, my drawing should be a reflection of how serious I think the machine should be, but I kinda get lost when I think about how to approach the analytical process...is there a single thing that will become the control factor, that determines the size and strength of everything else, or would the supply of power (example...can a pair of electric solenoids be strong enough to push the pistons ?) electric would be very precise for how much and when to apply pressure.
I'm not sure a thread like this can stay on track, but I'm sure I'll learn a lot.

Why would you use electric solenoids to put the pistons to turn the generator to make electricity? I though you were using combustion of a fuel to drive the generator...

 

[RonL]

Why would you use electric solenoids to put the pistons to turn the generator to make electricity? I though you were using combustion of a fuel to drive the generator...

It was just a thought as I was typing, fuel of some sort will give the most energy to harvest from, but my very first thoughts (as the drawing shows) were centered around compression and expansion of air and a possible heat difference, that might show a very slight advantage.

 

[berkeman]

Just don't be trying to use electric power from the generator to drive the solenoids that are the power input to the mechanism. You know what would happen if you tried to do that...

 

[RonL]

In respect to berkeman and his hard task of watching this thread, I will request that all comments revolve around combustion of a fuel and the efficiency of the flywheel operation.
Thanks
RonL

 

[jack action]

Your cylinder could be pneumatic or hydraulic, for which control of pressure can be easier than controlled combustion. Open a valve, the pressure drops; open another valve, you're connected to the compressor outlet.

 

[OmCheeto]

In respect to berkeman and his hard task of watching this thread, I will request that all comments revolve around combustion of a fuel and the efficiency of the flywheel operation.
Thanks
RonL

And ignore how the wirligig works?
Strange little contraptions. I spent half an hour trying to find the "physics" behind their operation, and couldn't find anything.
So I built one out of an old AOL CD and some string.
Now the internet says a CD weighs about 0.02 kg, and I had to apply an equivalent force of 2 kg to keep the CD cycling. (I'm using a fish scale to measure the forces)
That's a factor of 100.
Scaling that up to your 100 kg flywheel gives me an equivalent force of 10,000 kg. (98,000 Newtons)
One place on the internet says that a 4" diameter gasoline driven piston applies the equivalent of 2860 kg (6300 lbs) of force near the top of its stroke, [ref]
So that's equivalent to 3.5 small block pistons.
Seems like a lot.
Although I was willing to build and test a CD version, I'm not willing to upscale to another model, as I'm not seeing any advantage in adding complexity to what appears to be a gas driven generator.

ps. Might make a fun chest muscle exercise machine.
pps. I'm still not sure how a wirligig works. Although, obviously there's torque involved. I'm assuming because of the 100:1 ratio of flywheel mass to equivalent force required, it's a function of the diameter of the string.

 

[RonL]

Your cylinder could be pneumatic or hydraulic, for which control of pressure can be easier than controlled combustion. Open a valve, the pressure drops; open another valve, you're connected to the compressor outlet.

In my mind I tend to see a 5 to 10 second cycle, not a lot of linear take up by the cables, so a short stroke.
Power will be determined basically by piston diameter, I think keeping the pressure steady (or increasing) as the cables unwind until that last twist, at which point a full release and the flywheel transfers energy to one generator half, save what is needed to twist the unloaded cable set in the other direction. This action would exhaust the chamber and have the pistons close together and ready for the next power stroke.

 

[RonL]

@ Om, I'm always amazed at how you test things, I hope your simple test was representing 50% of what was going on and that the CD disc was wasting the other half. If you had pulled harder would that have resulted in much more wasted energy ? I'm delighted you took time to test my idea in any detail.
Thank you
ps. Flywheel operation is the wirligig, at least in my mind

 

[OmCheeto]

@ Om, I'm always amazed at how you test things,

Sometimes it's easier to test things, rather than analyze them theoretically. This is especially true if you don't know how something works.

I hope your simple test was representing 50% of what was going on

I don't fully understand what is going on, so I have no idea.

and that the CD disc was wasting the other half.

Odd. I didn't include that part of my experiment. How did you know that?
From Jack Action's equation in post #17: $E =$ $\frac{1}{2}I\omega^2$ + $\frac{1}{2}kx^2$
I came up with that the energy imparted to the disk was 0.64 joules.
But I had supplied 1.2 joules. (work = force * distance)
I assumed that I was either missing something, or the test device was so poorly designed: Just me, the whirligig, and the fish scale
that there was no way I was going to get any meaningful values.
I did throw out Jack's "spring" part of the equation, as, well, there was no spring.
It's possible that "I" was the spring, but being a very poor spring, all springy energy from me was lost.

If you had pulled harder would that have resulted in much more wasted energy ?

Still not seeing where you are getting that there was wasted energy, from my post #31.

I'm delighted you took time to test my idea in any detail.

A real detailed analysis would require a VERY fancy rig.
Try operating your whirligig with you eyes shut. Without visual cues as to when to apply and release forces, I can't do it.
It would probably be much easier to figure out the math.
And I have no idea how to do twisted rope torque maths.
And given that Google says; "No results found for "twisted rope torque equation"."
I'm guessing it's not a well researched subject.

Thank you
ps. Flywheel operation is the wirligig, at least in my mind

This is starting to remind me of "Nobody knows how bicycles work!"
Yes, your flywheel is a whirligig, but I can't analyze this problem until I know how a whirligig works.

 

[RonL]

@Om, I don't have but just a moment, wanted to say I looked at your reference and liked it, I might have missed something, but when the 6300 pounds of force on the crankshaft was mentioned, the increased pressure of the combustion explosion was not mentioned.
His numbers in general helped me to think about where to start, in the evaluation of my machine.
Waiting for berkeman to give me some guidance