Will you be developing some machines based on the new theory? It would be interesting to compare a machine based on the new theory, with an example machine based on the existing aerodynamic theories...
Some machines do quite well actually.
Have a look at www.enercon.de and look at the data sheet for their E70 model.
At 9 m/s and a swept area of 3,959 square meters, their output is 892 kw.
In standard numbers, 20.1 mph, 42,614.3 square feet.
So...
Comments?
Ted.
The 1740.65 kw would be the total energy in the wind with a maximum of 1032.2 kw obtainable due to Betz 892 /1032= 86% efficient. Very good indeed.
Victor[ Parent ]
Typing faster than thinking!
Makes their number look even more impressive.
It would be neat if we could find ways to make the small machines closer to this kind of efficiency. On the one hand a lot of people I talk to have the attitude that since the power input (wind) is free what does it matter...
But it does matter - if you can get closer to this kind of efficiency then the cost for each watt collected should go down, provided the price of the efficiency isn't too high.
Let's see:
On a 10' machine, also at 20 mph...
20^3 x 78.5 x .00503 x .59 = 1,863
1,863 x .86 = 1,602
Wouldn't THAT be nice!
Ted.[ Parent ]
((9/13.41)^3 x 3959) / 1.14 = 1049.6 kw. and 892 / 1049.6 = about the same 85%.
This, though, is applicable to "near-perfect conditions". Anything less or more than 9 meters/second and it falls off. Remember that I said "at rated power". On the ridges here in Tehachapi the winds go from nothing to 20 meters/second in no time at all and in remembering all of this, take a look at perhaps an older (possibly out-of-date) production curve of the 1.5 MW sl from the GE website (with my own notations including the Betz energy curve added): Meanwhile one BTU - the heat equivalent of burning one match stick - is 778 foot pounds or raising 778 pounds off the floor one foot. One pound of lignite (low BTU) coal has about 7000 BTUs in it. One pound. Thermodynamic efficiencies are only about 30% for burning coal as such but even the air in just a cubic yard of volume has a mass weight of two pounds.
It is in the big picture where efficiency differences become important. Back in the Minnesota farm country where land goes by square mile sections, visualizing the wind at 30 mph entering one side of such an area up to an elevation of 1000 feet results in a Betz-adjusted total energy potential of 429.9 MWs. Remember that the air enclosed in a square mile of surface area up to this elevation has a mass of over one million tons, about the same as the displacement weight of all ten of the U.S. Navy's mighty nuclear powered aircraft carriers (one more is being built). One square mile.
Even just this 100% - 85% = 15% energy inefficiency deficit applied to 429.9 MWs is 64.5 MWs. How many 1.5 MW turbines is this again on just one square mile? I am using the optimum performance criterion established above for the Enercon.
The other part of the problem is where does the energy in this energy deficit of 15% go? Likely most of it currently goes into the parasitic drag of the blades and creating the "whoosh" sound from them. What isn't no doubt escapes downwind due to a missing blade or two that would be there if it weren't for the parasitic drag thereby added.
It is easy to go on like this and I am sure not very welcome, even a little off-topic. At this time of the close of the year before the start of the next, it might be appropriate to reflect on these thoughts. Wind energy has embraced many euphemisms about how well it is doing - the number of homes serviced, etc. - but knuckling down to some of the hard facts of the details of blade performance over hard won land areas available to it also needs to be considered.
Anthony "Knuckling down Knucks" Chessick Integener-W Tehachapi, CA www.integener.com[ Parent ]
There is always the 30 page booklet on the Lift Principle mentioned on my website, offered specially right here and right now for free upon sending an e-mail message with an address for the mailing of it, even outside the States. (The address information is deleted from our files upon completion of the shipment.) It is a good start in seeing the Newtonian Principle as described in some detail and really quite worth while. No need to click on the PayPal button but send off your message soon.
See comments made elsewhere on this thread and also on the recent "How to avoid stalling" thread for more detail. It is not so difficult to understand that it is airflow deflection and only airflow deflection that creates a driving force on a blade moving faster than the wind and made amenable to calculation with straightforward equations such as the Bent Air Law (as is described in some detail in the booklet mentioned above).
Does anyone need to see how I clamp the aluminum sheet metal pieces from the 4 inch (100 mm.) wide rolls of roof flashing in the hardware store to a counter edge corner and back it with a 5/16" diameter wooden dowel in order to start the bending of the leading edge? It isn't fair (and often quite persnickety) to tell me that I am doing something wrong when what I am doing works so well!
Thin blades for lift-based rotors rule!
Anthony C. IntegEner-W www.integener.com [ Parent ]
I do like the look of those.
However;
I made some PVC blades that spun like crazy in the slightest breeze, very fast and smooth. Right up until you attempted to extract any power.
I see you only have these on a "bearing". Have you tried pulling any power from them yet?
Cheers.
TomW
Without fools, you could not look intelligent. There is no knowledge without questions.
[ Parent ]
Within the context of 3 foot diameter blades near ground level the above horizontals rotor certainly outperforms the well known 22" diameter decorative old time farm windmill rotors we often see here in the yards of homes with their 12 blades. I think all this speaks for itself, something that satisfies small needs for power that people find easy and inexpensive to buy.
Anthony C. IntegEner-W www.integener.com[ Parent ]
