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Electroboom: How Right IS Veritasium?! Don't Electrons Push Each Other??
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Naej:

--- Quote from: SiliconWizard on July 06, 2022, 08:02:46 pm ---Getting off-topic here, but yes, "interestingly", what we commonly call "wind turbines" these days, in the common green vocabulary, are not really turbines.

--- End quote ---
"Turbine: a machine for producing continuous power in which a wheel or rotor, typically fitted with vanes, is made to revolve by a fast-moving flow of water, steam, gas, air, or other fluid."
Is it too slow for you???
aetherist:

--- Quote from: Alex Eisenhut on July 06, 2022, 11:02:42 pm ---What if there's lightning inside a tornado? Will the electons move faster if the lightning is going in the same direction as the tornado?
--- End quote ---
Tornados are indeed electric machines.
But i doubt that the electricity in a tornado has much to do with my electons.
It involves electrons not my electons. The electrons are the usual kinds – free solitary electrons -- & ions (negative & positive).
My electons liv on conductors, eg wires.
electrodacus:

--- Quote from: gnuarm on July 06, 2022, 10:49:25 pm ---
Lol!  It is YOU who has failed.  You have mis-attributed the quotes of your words to me!

I don't care about convincing you of anything.  Your failure is self-sustaining and you will live a rich, full life believing you are right.  So, enjoy.   

--- End quote ---

All evidence points to the fact that energy travels through wires.
There are no invisible hard to measure effects to prove that.
Inside a charged capacitor (potential energy storage device) you have a constant electric field.
If you were to measure that field (invisible but can be measured or calculated) you will see that as capacitor gets discharged (electrons traveling through a conductor from the negatively charged plate to the negatively charged one) the field strength decreases and you see electromagnetic energy being radiated out of the conductor not the other way around. Also the electromagnetic energy release will happen delayed due to the thermal storage capacity of the condutor.
All this is fact and can be measured.
Naej:

--- Quote from: electrodacus on July 06, 2022, 10:07:38 pm ---
--- Quote from: Naej on July 06, 2022, 07:54:09 pm ---It's not a wind turbine, it's a propeller.
You'd use a wind turbine into the wind, not dead wind.

So the question you should ask is what's the force propelling the car for a given energy consumption.
With a mass flow of Q, and efficiency of 1, the energy consumption is 1/2*Q*Delta V^2; the momentum given to the car is Q*Delta V.
If Q is large (a big propeller), you obtain a high ratio between the 2, and a good efficiency overall.
Power is of course taken from the wheels.

--- End quote ---

Yes it is not a wind turbine but the propeller can only be powered by the wind and stored energy (with is actually the case and was ignored).
You need to ask what is the power available to propel the vehicle. Asking what the force alone is may get you to wrong conclusions.

You can not take power from the wheels.  What you call power from the wheels can only be from wind power or from stored energy like from pressure differential or vehicle kinetic energy or a combination or wind power and power from stored energy.

I think pressure differential energy storage is difficult for people to understand so here is an alternative model.
A sail vehicle that has an electrical generator at the back wheels and say a capacitor or rechargeable battery and motor on the front wheels (propeller replacement).

So initially when starting you have say an ideal sail (they are very close anyway for direct down wind).
So wind power available is 0.5 * air density * sail area * (wind speed - vehicle speed)3
Say wind power is 130W initially
If you do not take any energy from the generator all 130W will be available to accelerate the vehicle (increase vehicle kinetic energy).
If you take 50W at the generator wheels then only difference of 80W is available to accelerate the vehicle.
If you have no energy storage device just put this 50W at 100% efficiency in to front motor wheels then you are back to 130W for acceleration and it will not make sense to do that.
But if you have a supercapacitor or rechargeable battery you can put say 10W in to motor and 40W in to battery.
This way vehicle will spend more time at lower speed as it accelerates slower with just 90W (80+10) but as vehicle gets up to speed there is less and less wind power available so the only thing that still accelerates the vehicle are those 10W coming from the battery and powering the motor.

Hope you understand that no vehicle powered only by wind can exceed wind speed unless it has an energy storage device where it stores energy than is then later used to accelerate the vehicle for a limited amount of time above wind speed.
Any vehicle that is wind powered driving directly downwind without an energy storage device can not exceed wind speed as that will violate the energy  conservation law.

--- End quote ---
The power is taken from the wheel in the sense that there is a significant friction on the tires, and this is the key for understanding how the car accelerates.
At the same time there is larger force forward given by the propeller (when you accelerate).
As I said before, it's a propeller not a turbine.
If wind speed+1m/s=vehicle speed, you can take 130 W from the wheel and get a large thrust from the propeller.
For example, if the propeller gets 10 kg/s of air, it can accelerate it to 2.7 m/s and get a thrust of 27 N.
If the vehicle speed is more than 5 m/s this is more than tire friction and your vehicle accelerate.
You get a large torque, which is why the vehicle is shaped like this.

Energy conservation is correct in a closed system. If you don't define the system, you can easily say wrong things, like here. And if you don't define the reference frame, ditto.
Bottom line is: both the atmosphere and the Earth are big, so there's a huge amount of energy in wind and if you neglect the annoying drag, you can go as fast as you want.

There are plenty of things going faster than the wind.
For example:
- a glider, here at 880 km/h in 104 km/h wind  8)
- all wind turbines.

It works in the same way as sailing boats which go faster than the wind, you just need to change direction regularly (tacking), and a rotor does this in an almost perfect way.
PlainName:

--- Quote from: electrodacus on July 06, 2022, 10:32:37 pm ---
--- Quote from: dunkemhigh on July 06, 2022, 09:23:44 pm ---I gave you exactly what you asked for. The propeller power is taken from the wheels and reduces the power available from the wind, but in turn it provides thrust.

The propeller does not take power from the wind nor provide drive to the wheels. If you think it does then that explains your inability to understand what's going on. Or inability to understand equations, but similar conclusion.

--- End quote ---

The thrust that propeller provides can only be smaller than the one wind will have provided if you did not take that energy from the wheels.

The only (and I mean only) energy source is the wind as this is a wind powered vehicle.  There is no such thing as ground power or power from the wheels.


--- End quote ---

OK, I'll allow that the way I wrote that could be misinterpreted. Obviously, the only source of power is the wind, and what I meant was that the wind is not driving the wheels via the propeller - the wind is pushing the vehicle which turns the wheels that drive the propeller.

Nevertheless, you asked what power from the wind was available to push the vehicle, and that formula tells you - it is the wind power acting on the surface MINUS the power necessary to turn the propeller. I am still surprised that you can't grasp that that power to turn the prop is taken from the power available to push, reducing the apparent pushing power.


--- Quote ---The only (and I mean only) energy source is the wind as this is a wind powered vehicle.  There is no such thing as ground power or power from the wheels.
--- End quote ---

I have no idea why you think this equation shows any power source other than the wind. I have explicitly and at length told you that the wind is the only source, and said that several times.


--- Quote ---Your equation includes "wash speed" can you let me know what that is in an example ?
--- End quote ---

It is the thrust from the propeller. I can't believe that now we have to explain to you how an airplane manages to fly. Do you really need to be told what 'thrust from a propeller' means? Really?


--- Quote ---How do you calculate that ?
--- End quote ---

It will depend on the gearing to the prop, the pitch, the speed of the vehicle, etc. However, that is not important or relevant - you asked for a formula showing the available power and that is what you got. If you want the know the maximum speed possible then we would then need to work out the details of the prop and do some calculations, but that isn't what you asked so it's not what you got.


--- Quote ---Subtracting the propeller power (more correctly power you take at the wheel to provide the propeller if propeller is not 100% efficient) will just show the power available for accelerating the vehicle and not wind power available to vehicle.
--- End quote ---

Well, at this point one has to ask "What the  hell is the question you're asking!?!?" Clearly, the total power available is the wind acting on the surface, which is the equation you provided. There is no other power, so it is that which provides for the acceleration and everything else.

Also, I think you've failed to remember that the test vehicle had the prop blades feathered until it reached close to wind speed, at which point they were manually adjusted to provide appropriate thrust. I think you should consider that a significant clue.

However, what is very clear is that even when you get precisely what you ask for, you don't live up to your promise. There is no point or use in discussing anything with you because you are blind and immune to anything except whatever your mind has made up.
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