I think that even one session, and we'll be in full accord
dedeleco a écrit :This is not very clear ?
and the maximum possible power of the wind for all designs.
The maximum power inside the wind is defined as ;
This power is the maximum of Kinetic energy that can be extracted by stopping all the air arriving in one second.
without considering how it is made or even if it is possible easily !!
If extremely very clever, it is possible to extract all the energy inside the wind so that at the end, the wind is no more moving !!! For example stopping bullets, like the air, gives all their energy in heating and accelerating the stopping material.
The difficulty is what to make with the air immobile unable to go out of the turbine at zero speed !!
For example several turbine with increasing diameter consequently are possible, so that the speed of the wind is quite smaller.
For example 1/5 with 5 times diameter for out, allows to extract the same quantity of air as at the entrance, and gives (1/5)^2=1/25 of power in the wind lost in the outside ( 4% ) and the 96% inside the turbines !!
!!
There is commercialy several turbines one after the other !!
I agree that if the turbines or the sails are not moving, the real power obtained is zero !!
but it is not a good design.
The design is free and the maximum possible power of the wind, (or the necessary power to move the wind), is given by this formual as V^3.
This power is the maximum of Kinetic energy that can be extracted by stopping all the air arriving in one second.
The answer to this question: Why in one second ?
And not, for example, at time 0, 5 seconds or 3 seconds?
I you a hint: because it's such a whim, in order to "simplify " the calculations were...
Because one second looks nice..
And you can completely skip the discussion of
mass energy, which gives the energies....
And why do you consider a complete stop the wind, as in the venturi nozzle is repeated acceleration of the wind ??
For example stopping bullets, like the air, gives all their energy in heating and accelerating the stopping material.
We are not a good example.
After the first round has its own strictly defined
mass.
Wind staying on a fixed obstacle, rather, it is not heated, and vice versa - cooled.
More interesting is an example of how the ball takes on this energy, for example, pneumatic weapons.
In short, a pneumatic gun, the ball is rather low energies, while in the air rifle with a long barrel, energy and range of a projectile are much larger.
Because the length L is of crucial importance here.
Regards Andrew
