Posted by on Oct 25, 2014 in INNOVATIONS | Comments Off on WIND TURBINE INNOVATION

WIND TURBINE INNOVATION
© The Waters Trust, 2014, All Rights Reserved

Wind Lesson

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Current mainstream wind turbine designs are based on incorrect aerodynamic calculations. This is not a small mistake. It is a massive error and obvious once understood. A global industry employing thousands of physicists, aerodynamicists, engineers and chemists has misunderstood the most fundamental principle involved in capturing energy from wind.The error is in using the same aerodynamics as an aircraft.

In aviation, drag must be minimized to increase performance. The faster an aircraft goes, the more drag is created and the more fuel is used. An aircraft has to penetrate air efficiently. This is why long thin wings are used by sailplanes. They are designed to maximize efficient penetration of air without an engine.

Drag increases by the square with velocity. D = Mv2
Aircraft must reduce drag to increase efficiency.


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In wind power, the goal is to convert wind force into useable energy. The faster the wind blows, the more energy is available. A wind turbine is anchored in a stream of air. Air can be deflected around an obstacle with no penalty. This can significantly increase the amount of energy available despite creating drag.Force available increases by the cube with velocity. F = Mv3*
Wind turbines can use drag to increase efficiency.

These concepts are diametrically opposed so the error could not be more incorrect. This is a disturbing and baffling discovery. How could something so blatantly obvious be missed by the entire global wind industry?

This question has far greater ramifications

To maximize true wind force efficiency, kinetic energy must logically be extracted from as many molecules passing through a given area as possible. Currently, only the outer 30% of a typical wind turbine blade produces any meaningful torque and involves less than 5% of the total disk area. Aerodynamic efficiency is utilized but no attempt is made to divert or accelerate the air at all. In other words, the drag side of the equation is completely ignored.

Ironically, a mountain ridge is a good example of converting drag to energy. Wind is forced to go over the ridge, thereby compressing and accelerating the air. If the ridge is considered to be part of the design, by placing a wind turbine near the top of a ridge, it becomes obvious that a fixed obstacle (drag) can efficiently increase the amount of energy available. Just doubling wind speed amplifies available energy by 8 times.

When considered from this perspective, the difference between aircraft and wind turbines becomes obvious. The idea of using a few long thin blades to maximize aerodynamic efficiency is ridiculous. Why try to efficiently penetrate the air when you are anchored to the ground?

The primary goal of a wind turbine is to convert the kinetic energy
of air molecules into electrical energy.

An “efficient” wind turbine produces energy by first maximizing and then
extracting energy differential between the air and the ground.


PictureCopyright The Waters Trust, 2014 All Rights Reserved

So what is an efficient design? Once the basic principle is understood, there are few optimal ones. In simplest terms, the goal is to accelerate every available molecule and direct it to the region of greatest leverage at maximum velocity like the outside ring of a rotating turbine in my example to the left.Even though this design is not fully optimized, torque is considerably higher, cut in speed far lower and wind direction can vary significantly with little efficiency loss. This is despite the fact that the blades appear to point directly into the wind.

Remember that available energy increases by the cube with velocity. Small changes in wind velocity therefore have a large impact on available energy. In this example, the flat plate obstacle is the “ridge”, forcing air to divert and accelerate before passing through the energy extraction blades at the perimeter – the area of maximum leverage. The more that the air is accelerated and focused, the more energy is available. Additionally, by creating a low pressure void behind the obstacle, or by vortexing etc, air can be accelerated even more. Yet again, the only penalty for doing so is drag, which is compensated for by anchoring to the ground.

Extracting energy from rivers and tides
This primary knowledge becomes even more effective when applied to extracting energy from river and tidal forces. Air can compress. Water cannot. This means that any constriction in water flow is translated directly into increased velocity. Constrict a wide slow river into a narrow channel and you have “rapids”. Triple the speed and you have nine times the force. Focus all of that force towards a point of maximum leverage and the results are predictable. Density of water is approximately 770 times greater than air.

Conclusion

  1. Far more energy can be extracted from both wind and water sources at far lower cost and effort if we use both lift and drag to achieve useful force.
  2. It is possible for thousands of PhD’s in a broad range of disciplines to make diametrically incorrect assumptions at a fundamental level.

http://en.wikipedia.org/wiki/Drag_equation
http://en.wikipedia.org/wiki/Drag_(physics)

Initially, and in my lecture, I state that force increases by the square. It would normally be argued that force increases by the cube but the wind turbine error relate to the drag side of the equation. Using the same squared function as drag makes the comparison more conservative. Practical ability to use force is somewhere in between. I changed this page to reflect that force increases by the cube since it is more widely accepted by the wind turbine industry. In reality the term “force” is misused, Power available increases by the cube.

Third party and direct comparison test
There have been three separate third party tests, including computer flow analysis. My own direct comparative tests against a conventional high performance wind turbine in a broad range of conditions confirms theory. We ran direct comparisons in real world conditions for days because 3rd party results seemed too high. They had reported between 30 and 122 times more efficient.

Comparing my 4′ design against a stock 5′ three blade, under the same load, the conventional product starts at 8 mph and produces very little torque or rpm at that speed. My turbine, under the same load starts at under 1 mph. If the square rule is used that is 49 times more force required to turn a conventional design. If the cube rule is used the difference is 343 times. In terms of watts available the cube rule is used by most turbine charts.

The conventional design was a molded precision product with an accurate airfoil. Mine was far from optimized, using no airfoils. Also in direct comparison, under extreme shaft load, the conventional turbine would not turn, even at 28 mph with assistance. My design in the same conditions self starts at 10 mph.

Test equipiment involved a prony brake, rpm meter and wind meter. Accuracy of both wind and rpm meters was within 5%. Prony brake measurements were comparative and direct, utilizing the same shaft, load and conditions for both designs.

Here is another example that shows that the so called Betz limit is not a universal limit. http://machinedesign.com/blog/wind-turbines-low-wind-speeds-defy-betz-limit-efficiency?NL=ED-03&Issue=ED-03_20140625_ED-03_843&YM_RID=displaygraphics@gmail.com&YM_MID=1473391&sfvc4enews=42&cl=article_2