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

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electrodacus:

--- Quote from: dunkemhigh on July 08, 2022, 11:25:11 pm ---In other words, it can't be done.

--- End quote ---

1. I see what you mean the screw has elasticity as any real screw will have but you apply the force in the direction the screw will move where with the vehicle the applied direction is opposite to vehicle moving direction.

3. It is not possible without energy storage. The main point I make is that pressure differential energy storage is what powers the direct down wind blackbird above wind speed. If you calculate the amount of stored energy based on volume of air at different pressure on each side of the propeller you will understand that there is exactly enough energy stored there to allow blackbird to get to accelerate up to the speed shown in the record test.

Here is the diagram showing the difference in pressure on each side of an axial fan



So yes it can be done and if the Blackbird will have continued for another minute or so you will have seen that it slows down as all stored energy was used.
The treadmill model is the same is just that treadmill is way to short to show how vehicle slows down to zero and starts to move backwards once the stored energy is used up.
But since treadmill is in a much more controlled environment with less variable you can just take a video from the side and see how acceleration rate drops.
Easy to calculate acceleration rate from the side video.

Naej:

--- Quote from: electrodacus on July 08, 2022, 11:32:25 pm ---
--- Quote from: Naej on July 08, 2022, 11:03:45 pm ---You provided zero argument for this claim. You won't be surprise to learn that it is wrong.
What is providing the 3MW to a wind turbine?

I don't understand your example. Here is mine: imagine you have a giant gear above your hear, which is turning at constant speed. How fast can a vehicle go?

--- End quote ---

I guess you do not quite get what air is.  The analogy is not "giant gear above your head witch is turning at constant speed" but a large ball at constant speed hitting the vehicle or propeller blade or anything else in the path.

So a sail vehicle direct downwind or Blackbird can only have access to same amount of wind power as interaction between wind (moving air particles) and vehicle is by air particles hitting the vehicle and so exchanging kinetic energy.

When direct downwind vehicle (no matter the design) gest to wind speed those balls speed the balls can no longer hit the vehicle so no energy can be transferred to vehicle from wind.
And when vehicle exceeds wind speed it will encounter drag as now the vehicle will hit the balls and not the other way around.

--- End quote ---
I know what air is, I just offered a mechanical analogue to help you.

You argument that a wind turbine cannot work in still air is correct. However it's a propeller. Propeller can work in still air, and even when the 'craft is moving.
Why don't you get this simple thing?

And you didn't explain who is providing 3 MW to the wind turbine so that it can stay at the same place. So, who? A Diesel engine hidden in it?

electrodacus:

--- Quote from: Naej on July 09, 2022, 12:09:50 am ---I know what air is, I just offered a mechanical analogue to help you.

You argument that a wind turbine cannot work in still air is correct. However it's a propeller. Propeller can work in still air, and even when the 'craft is moving.
Why don't you get this simple thing?

--- End quote ---

I do not think you understand what air is based on your analogy.

Of course a propeller can work in still air but what powers the propeller if there is no longer any wind power available when vehicle is at wind speed and above.
And please do not say that propeller is powered by the wheels. That is a very silly thing to say but I heard that so many times.

If you ignore the energy stored in pressure differential (pressure differential on each side of the propeller) that pulls and pushes the vehicle then you will never be able to explain how vehicle accelerates once vehicle speed equals wind speed.

And if you think there is no pressure differential then check this  https://en.wikipedia.org/wiki/Axial_fan_design  and how do you think that energy was stored there ? It was stored when vehicle was well below wind speed and starts to discharge way before vehicle gets to wind speed.


P1 is much lower than atmospheric pressure and P2 is much larger. This is what allows the treadmill model to run against the treadmill surface direction for some limited amount of time.

Naej:

--- Quote from: electrodacus on July 09, 2022, 12:25:20 am ---
--- Quote from: Naej on July 09, 2022, 12:09:50 am ---I know what air is, I just offered a mechanical analogue to help you.

You argument that a wind turbine cannot work in still air is correct. However it's a propeller. Propeller can work in still air, and even when the 'craft is moving.
Why don't you get this simple thing?

--- End quote ---

I do not think you understand what air is based on your analogy.

Of course a propeller can work in still air but what powers the propeller if there is no longer any wind power available when vehicle is at wind speed and above.
And please do not say that propeller is powered by the wheels. That is a very silly thing to say but I heard that so many times.

--- End quote ---
Yes the propeller is powered by the wheels. Yes it is silly. Many things in physics are silly yet correct.

--- Quote from: electrodacus on July 09, 2022, 12:25:20 am ---If you ignore the energy stored in pressure differential (pressure differential on each side of the propeller) that pulls and pushes the vehicle then you will never be able to explain how vehicle accelerates once vehicle speed equals wind speed.

--- End quote ---
Yes air applies a force on the car, which pushes it. Amazing, no?

By the way, you didn't tell what was the engine providing 3MW to a wind turbine so that it can stay at the same place.  :-X

electrodacus:

--- Quote from: Naej on July 09, 2022, 09:49:22 am ---Yes the propeller is powered by the wheels. Yes it is silly. Many things in physics are silly yet correct.

Yes air applies a force on the car, which pushes it. Amazing, no?

By the way, you didn't tell what was the engine providing 3MW to a wind turbine so that it can stay at the same place.  :-X

--- End quote ---

Wheels are not a power source (they are not radioactive and not being burned to extract energy from them). Wheels are an intermediary but power to any part of the (wind powered vehicle) can only be provided by air particles hitting the vehicle body (any part of the body including the propeller blades).
When air particles hit the direct downwind vehicle from the back (wind speed higher than vehicle speed) the wind power is available to vehicle to accelerate in the desired direction and or store that.
When vehicle speed equal wind speed there is zero available wind power to vehicle and when vehicle exceeds wind speed the vehicle will now hit the air particles so wind power available to vehicle will be negative meaning will slow down the vehicle unless as it is the case here vehicle also has access to earlier stored pressure differential that will be used to cover vehicle friction losses including air drag. 

The stored high pressure and low pressure created by the propeller is called pressure differential energy storage.
That pressure differential was created by the propeller using wind energy while vehicle speed was well below speed then after that this stored energy is what powers the vehicle for the next few minutes (how many minutes or seconds depending on how high you set the acceleration rate).

The 3MW wind turbine is anchored to the ground so what is being accelerated is the entire earth and obviously a 3MW wind turbine will not make any measurable difference to such a large mass but it can be calculated as we know the mass and speed of air particles the equivalent area of the wind turbine and the mass of the earth.

You can imagine this 3MW wind turbine installed on a 4 wheel platform with say a weight of 1000kg including the wind turbine weight and then you can imagine this 4 wheel platform on a 200000kg 4 wheel platform that sits on the ground.
Wheels are ideal with no friction.

The 3MW for 1ms will provide at least 3000Ws (this is absolute minimum not to violate energy conservation) to the 1000kg 4 wheel platform
So starting from zero kinetic energy the platform will end up with 3000Ws
3000Ws = 0.5 * 1000kg * v2
So after this 1ms the platform speed relative to the large platform will be
sqrt(3000Ws/(0.5*1000kg)) = 2.45m/s  relative to both the large platform and ground.

Now if the small wheel platform is anchored to the large 4 wheel platform (say brakes are enabled).
Then that same energy will be transferred to the large platform
Now the weight is 201000kg
3000Ws = 0.5 * 201000kg * v2
so speed of the large platform after 1ms
sqrt(3000Ws/(0.5*201000kg)) = 0.17m/s relative to ground
Now if you apply the brakes to large platform also the energy will be transferred to planet earth and if you know the mass you can calculate the speed increase of the planet after 1ms.

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