



Andrew

Tim.Wright wrote:Fluids is not my strong point, but I suspect that the above equations are for a freestream condition at a nominal air pressure. What happens when you increase the air speed with the aerofoils is that the pressure drops. The total power (pressure x flow_rate) stays the same.
It appears this is not accounted for in your equations. Or is it included in the coefficient?
In effect its acting like an aerdynamic gearbox, possibly putting the airflow at a better operating point (pressure and flow_rate) for the turbine to give max power or max efficiency.
You could argue that a more conventional (reverse) diffusor would do the same thing.
I didn't understand any of that...Feliks wrote: Well, this is the rather delicate matter .. Upload wearing the NASA simulator , and you'll see that the reduction in pressure is relatively small, and can increase speed of three times. the graph can be seen also from the lift ( Lift ) has the value three times greater than the resistance. (Drag ) . You can ask a question where you're cur is three times greater lift force , in relation to the resistance. Lift is 212 N and 77 N Drag . So where you're taking this growth ? Therefore, it is greater because MASS air, which is above the wing is relatively large , because its size is related to the length of the profile, which must have adequate long dimension. And then the whole mass is involved in LIFT . It is about increasing our speed because at high speed , our windmill has a high efficiency , and we get to tzreciej might of the increase in power on the shaft of the windmill ... drop in pressure at the top of the profile is a minimum order of a few percent, and increase the speed up to 5 times the beginning of the profile. .. Well, it has nothing to do with the diffuser .. We are concerned about the speed .. Then more energy ( air ) is moving through the windmill .. Three times more .. and it can efficiently collect .. And no thermodynamics is not mentioned here .. For where some thermo ..??
If the windmill works better at high speed then ok, it somewhat makes sense. However, a bit of reading about Betz' Law suggests that you should be slowing the air speed down in order to maximise energy recovered.Feliks wrote:I think the fundamental thing is that you understand what causes the air at the beginning of the profile is 50 km / h, and not, as the incoming 10 km / h .. Sure pressure at this point, is not it is five times smaller .. Pressure drops us a little, and the speed increases very much .. Ask yourself this question, and the rest will be a piece of cake ..