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Figure 1
A turbine is the most efficient way to extract mechanical energy from a moving fluid – much more efficient than a narrow Bernoulli blade such as those used in conventional, three-bladed windmills. (In the engineering world, a fluid can be either a liquid or a gas). As an example, a conventional, three-bladed windmill does not begin to rotate unless the wind has a speed of at least 2 meters per second. A turbine with large area vanes, such as described here, begins to produce power in winds of less that 0.5 meters per second (1 mile per hour).
A turbine is the most efficient way to extract mechanical energy from a moving fluid – much more efficient than a narrow Bernoulli blade such as those used in conventional, three-bladed windmills. (In the engineering world, a fluid can be either a liquid or a gas). As an example, a conventional, three-bladed windmill does not begin to rotate unless the wind has a speed of at least 2 meters per second. A turbine with large area vanes, such as described here, begins to produce power in winds of less that 0.5 meters per second (1 mile per hour).
The large, typically three bladed devices mistakenly called wind turbines are very different from those of an actual turbine. The cross-section of a conventional windmill blade has the same basic shape as the cross-section of an airplane wing. The three blades of a typical windmill use Bernoulli’s principle to extract energy from moving air (wind) and transfer it to the three blades. They use Bernoulli’s principle and not Exchange of Momentum and, therefore, are not turbines. A better name for them is windmill. It seems that windmill is not high-techy enough and sounds a bit old-fashioned, and, hence, the industry improperly glommed onto the word turbine. A more modern sounding name for three-bladed windmills is aerogenerator.
The large, typically three bladed devices mistakenly called wind turbines are very different from those of an actual turbine. The cross-section of a conventional windmill blade has the same basic shape as the cross-section of an airplane wing. The three blades of a typical windmill use Bernoulli’s principle to extract energy from moving air (wind) and transfer it to the three blades. They use Bernoulli’s principle and not Exchange of Momentum and, therefore, are not turbines. A better name for them is windmill. It seems that windmill is not high-techy enough and sounds a bit old-fashioned, and, hence, the industry improperly glommed onto the word turbine. A more modern sounding name for three-bladed windmills is aerogenerator.
Today, almost everything that is called a wind turbine is not a turbine. A reasonably good description of what a turbine is can be found at www.engineering-dictionary.com: “a rotary device that is actuated by the impact of a moving fluid against blades or vanes.” The engineering term for “actuated by the impact of a moving fluid” against a movable surface is Exchange of Momentum.
Today, almost everything that is called a wind turbine is not a turbine. A reasonably good description of what a turbine is can be found at www.engineering-dictionary.com: “a rotary device that is actuated by the impact of a moving fluid against blades or vanes.” The engineering term for “actuated by the impact of a moving fluid” against a movable surface is Exchange of Momentum.
Air that is moving has momentum. When moving air impacts a turbine vane, the air is slowed and loses some of its momentum to the turbine vane - momentum is exchanged from the moving air to the turbine.
Air that is moving has momentum. When moving air impacts a turbine vane, the air is slowed and loses some of its momentum to the turbine vane - momentum is exchanged from the moving air to the turbine.
Turbines and aerogenerators are physically different devices that operate on different principles. From this point forward wind turbines which operate on the principle of exchange of momentum will be called “wind turbines” or turbines. Devices operating on Bernoulli’s principle will be called windmills or aerogenerators.
Turbines and aerogenerators are physically different devices that operate on different principles. From this point forward wind turbines which operate on the principle of exchange of momentum will be called “wind turbines” or turbines. Devices operating on Bernoulli’s principle will be called windmills or aerogenerators.
Functioning differently and using different principles of operation means that turbines and aerogenerators have significantly different physical characteristics and perform differently. Turbines convert a much higher percentage of the kinetic energy in wind passing through their swept area into mechanical energy than aerogenerators. Aerogenerators tend to operate at a higher speed meaning rotate at a higher speed than wind turbines in a given wind speed. The significantly greater amount of power which a wide-blade wind turbine can produce compared with the narrow blades of an aerogenerator should be intuitively obvious and easy to grasp. Its other features and advantages will be described infra.
Functioning differently and using different principles of operation means that turbines and aerogenerators have significantly different physical characteristics and perform differently. Turbines convert a much higher percentage of the kinetic energy in wind passing through their swept area into mechanical energy than aerogenerators. Aerogenerators tend to operate at a higher speed meaning rotate at a higher speed than wind turbines in a given wind speed. The significantly greater amount of power which a wide-blade wind turbine can produce compared with the narrow blades of an aerogenerator should be intuitively obvious and easy to grasp. Its other features and advantages will be described infra.
There is another very significant difference between turbines and aerogenerators. For both aerogenerators and turbines, the pitch of the blade must continually decrease with distance from the axis of rotation in order to allow the blade to operate by receiving energy from the wind and not operate as a fan by imparting energy to the air at the blade's extremities. This is because the greater the blade’s length, the greater the speed of the end of the blade for any given rotational speed. Thus, at some point along the length of the blade, the pitch will become so small and the driving force the wind can impart to the blade will be so small that the drag forces will exceed the driving force imparted by the wind.
There is another very significant difference between turbines and aerogenerators. For both aerogenerators and turbines, the pitch of the blade must continually decrease with distance from the axis of rotation in order to allow the blade to operate by receiving energy from the wind and not operate as a fan by imparting energy to the air at the blade's extremities. This is because the greater the blade’s length, the greater the speed of the end of the blade for any given rotational speed. Thus, at some point along the length of the blade, the pitch will become so small and the driving force the wind can impart to the blade will be so small that the drag forces will exceed the driving force imparted by the wind.
At a point along the length of the blade, the driving force at that point less the drag force will reach zero. At any greater distance from the axis of rotation, the wind will extract energy from the blade rather than impart energy. Stated another way, the inner part of the blade will be a turbine, and the outer part will be a fan. The significance of this is that turbines have a maximum practical size whereas aerogenerators seem to have no limit.
At a point along the length of the blade, the driving force at that point less the drag force will reach zero. At any greater distance from the axis of rotation, the wind will extract energy from the blade rather than impart energy. Stated another way, the inner part of the blade will be a turbine, and the outer part will be a fan. The significance of this is that turbines have a maximum practical size whereas aerogenerators seem to have no limit.
One Blade Aerogenerator
Figure 2
Aerogenerators - 3-bladed wind devices operating on Bernoulli’s Principle - in addition to being not very efficient are quite bizarre in their operation and apparently not well understood. According to the work of Dr. Ken Youssefi at San Jose State University, an aerogenerator with two blades will produce only 6% more power than an aerogenerator with just one blade such as the one in the adjacent picture. An aerogenerator having three blades will produce just 3% more power than one with two blades. I have been unable to find an explanation of this unexpected result nor have I been able to devise one of my own. See https://engineering.sjsu.edu/e10/wp-content/uploads/Wind_Power_S13.pdf at page 15.
Aerogenerators - 3-bladed wind devices operating on Bernoulli’s Principle - in addition to being not very efficient are quite bizarre in their operation and apparently not well understood. According to the work of Dr. Ken Youssefi at San Jose State University, an aerogenerator with two blades will produce only 6% more power than an aerogenerator with just one blade such as the one in the adjacent picture. An aerogenerator having three blades will produce just 3% more power than one with two blades. I have been unable to find an explanation of this unexpected result nor have I been able to devise one of my own. See https://engineering.sjsu.edu/e10/wp-content/uploads/Wind_Power_S13.pdf at page 15.
A wind turbine, in contrast, produces power roughly proportional to the blade area for a properly designed device. This means one can use basic intuition in thinking about the device. Thus, a wind turbine with four blades will produce roughly twice as much power as a turbine with two similar sized blades.
A wind turbine, in contrast, produces power roughly proportional to the blade area for a properly designed device. This means one can use basic intuition in thinking about the device. Thus, a wind turbine with four blades will produce roughly twice as much power as a turbine with two similar sized blades.
One significant difference between wind turbines and aerogenerators is the relationship between power and swept-area diameter. Aerogenerators seem to have almost no limit on size. The longer the length of a Bernoulli blade, the more power it produces. In contrast, after a certain size, increasing the size of a wind turbine produces very little additional power. My work has an indication that a practical size limitation of a wind turbine is approximately 30 to 40 feet in swept area diameter. The world’s largest aerogenerator is about 730 feet in swept area diameter.
One significant difference between wind turbines and aerogenerators is the relationship between power and swept-area diameter. Aerogenerators seem to have almost no limit on size. The longer the length of a Bernoulli blade, the more power it produces. In contrast, after a certain size, increasing the size of a wind turbine produces very little additional power. My work has an indication that a practical size limitation of a wind turbine is approximately 30 to 40 feet in swept area diameter. The world’s largest aerogenerator is about 730 feet in swept area diameter.
Wind Turbine Innovation
Wind Turbine Innovation
In the past relatively large area blades have been impractical for use in wind turbines. The immense forces created by high speed winds in storms will always lead to their destruction without some means of decreasing the blade area exposed to the wind. In average winds the large blade area allows the harvest of substantial power. In storm conditions, however, it poses an existential threat to wind turbines. In contrast, aerogenerators have relatively narrow blades which are able to withstand high speed winds. If necessary, the blade circle can be oriented parallel to the wind to further reduce wind forces. None of these defenses are easy to implement with a wind turbine.
In the past relatively large area blades have been impractical for use in wind turbines. The immense forces created by high speed winds in storms will always lead to their destruction without some means of decreasing the blade area exposed to the wind. In average winds the large blade area allows the harvest of substantial power. In storm conditions, however, it poses an existential threat to wind turbines. In contrast, aerogenerators have relatively narrow blades which are able to withstand high speed winds. If necessary, the blade circle can be oriented parallel to the wind to further reduce wind forces. None of these defenses are easy to implement with a wind turbine.
The innovation described in U. S. Patent 9,181,924 provides a solution to this problem. The innovation is a resiliently buckleable wind turbine vane. Below is a short video showing the turbine in operation in low speed wind. In this case the wind speed is 2 - 3 meters per second. This new device allows for very large area vanes which will buckle in winds of a predetermined speed, and, then, resiliently unbuckle at a lower speed. This allows the vanes to buckle and drape around the spar upon which they are mounted when the wind reaches a high speed which could damage the turbine or tower upon which it is mounted. Then, in lower speed winds, the vanes will spontaneously unbuckle and return to their original shape when the wind speed decreases to a lesser, safe speed. The higher force required to cause buckling paired with the significantly lower force required to maintain the buckled state of the vane minimizes unhelpful cycling of vane buckling and unbuckling. The buckling and unbuckling of vanes will be shown below.
The innovation described in U. S. Patent 9,181,924 provides a solution to this problem. The innovation is a resiliently buckleable wind turbine vane. Below is a short video showing the turbine in operation in low speed wind. In this case the wind speed is 2 - 3 meters per second. This new device allows for very large area vanes which will buckle in winds of a predetermined speed, and, then, resiliently unbuckle at a lower speed. This allows the vanes to buckle and drape around the spar upon which they are mounted when the wind reaches a high speed which could damage the turbine or tower upon which it is mounted. Then, in lower speed winds, the vanes will spontaneously unbuckle and return to their original shape when the wind speed decreases to a lesser, safe speed. The higher force required to cause buckling paired with the significantly lower force required to maintain the buckled state of the vane minimizes unhelpful cycling of vane buckling and unbuckling. The buckling and unbuckling of vanes will be shown below.
Animotica_30_9_17_51_52.mp4Resiliently Buckleable Wind Turbine in 2 - 3 meter/second wind.
Figure 3
Below is a short video demonstrating the buckling and unbuckling of a turbine with vanes constructed according to the new technology. The vanes shown are designed to buckle in extremely low speed wind for this demonstration. Here, the unit is operating in wind of approximately 0.5 - 1.5 m/s. It has a swept-area diameter of approximately 3 m. The turbine comprises two spars each approximately 1.4 meters long. The two spars each have 2 vanes (or vanelettes). The video shows the vanes spontaneously buckling and later unbuckling.
Below is a short video demonstrating the buckling and unbuckling of a turbine with vanes constructed according to the new technology. The vanes shown are designed to buckle in extremely low speed wind for this demonstration. Here, the unit is operating in wind of approximately 0.5 - 1.5 m/s. It has a swept-area diameter of approximately 3 m. The turbine comprises two spars each approximately 1.4 meters long. The two spars each have 2 vanes (or vanelettes). The video shows the vanes spontaneously buckling and later unbuckling.
Copy of AnimoticaSLOW_1_10_12_5_9.mp4Resiliently Buckleable Turbine Demonstrating Ability to Buckle and Unbuckle
Figure 4
Resiliently Buckleable Wind Turbine Vane
Resiliently Buckleable Wind Turbine Vane
One of the unique features of the design is the incorporation of differential buckling and unbuckling forces. The blade has the ability to only buckle in high speed wind and only unbuckles in much lower speed wind. This allows the blade to greatly reduce the occurrence of continuous buckling and unbuckling in day to day operation. As can be seen in all the pictures and videos, the normal condition of the vanes is complete rigidity. However, if a sufficiently large force is applied to the vanes, they will spontaneously buckle. The specific wind speed which causes buckling can be varied according to the design of the blade.
One of the unique features of the design is the incorporation of differential buckling and unbuckling forces. The blade has the ability to only buckle in high speed wind and only unbuckles in much lower speed wind. This allows the blade to greatly reduce the occurrence of continuous buckling and unbuckling in day to day operation. As can be seen in all the pictures and videos, the normal condition of the vanes is complete rigidity. However, if a sufficiently large force is applied to the vanes, they will spontaneously buckle. The specific wind speed which causes buckling can be varied according to the design of the blade.
Force required to buckle a vane depends primarily on the shape (second moment of area) of the vane and secondarily upon the thickness of the polycarbonate sheet comprising the vane. Once buckled, the force tending to restore the vane to its original shape is only the internal stress produced by the vane's change of shape after buckling. After buckling, the shape of the blade is essentially a bent rectangle wrapped around its supporting spare having a width as long as the flattened width of the blade and a height the thickness of the blade as shown in Figure 6 below.
Force required to buckle a vane depends primarily on the shape (second moment of area) of the vane and secondarily upon the thickness of the polycarbonate sheet comprising the vane. Once buckled, the force tending to restore the vane to its original shape is only the internal stress produced by the vane's change of shape after buckling. After buckling, the shape of the blade is essentially a bent rectangle wrapped around its supporting spare having a width as long as the flattened width of the blade and a height the thickness of the blade as shown in Figure 6 below.
The force required to buckle a vane is the sum of the relatively tiny force required to bend the polycarbonate sheet around the spar and the much greater force required to buckle the shape taken by the polycarbonate sheet. Figure 5, below, shows a possible shape with two stiffening sides which could be produced by thermoforming to manufacture a satisfactory vane. If a stiffer vane were desired, one or more corrugations could be made in the vane parallel to the length of the vane. In wind strong enough to buckle the vane, it would take a shape similar to that shown in Figure 6.
The force required to buckle a vane is the sum of the relatively tiny force required to bend the polycarbonate sheet around the spar and the much greater force required to buckle the shape taken by the polycarbonate sheet. Figure 5, below, shows a possible shape with two stiffening sides which could be produced by thermoforming to manufacture a satisfactory vane. If a stiffer vane were desired, one or more corrugations could be made in the vane parallel to the length of the vane. In wind strong enough to buckle the vane, it would take a shape similar to that shown in Figure 6.
Flexible Plastic Vanelette Made Rigid by Two Thermoformed Winglettes or VanelettesFigure 5
Plastic Vanelette Made Flexible After Buckling Under High Speed WindFigure 6
In areas where facilities for thermoforming are not easily available, there is the method for producing vanes which I used, specifically "Poor Man's Thermoforming" or PMT. PMT involves physically forcing polycarbonate sheet into an appropriate shape to produce the buckling and unbuckling characteristics desired. One of the easier and least expensive ways to achieve PMT is with the use wire and a spring as shown in Figure 7 below.
In areas where facilities for thermoforming are not easily available, there is the method for producing vanes which I used, specifically "Poor Man's Thermoforming" or PMT. PMT involves physically forcing polycarbonate sheet into an appropriate shape to produce the buckling and unbuckling characteristics desired. One of the easier and least expensive ways to achieve PMT is with the use wire and a spring as shown in Figure 7 below.
Vanelette Produced using PMTFigure 7
Example Appearance of Buckled Spring Formed VaneletteFigure 8
Care should be taken in designing for PMT to avoid sharp angles as that is likely to cause stresses above the proportional limit of the polycarbonate which will damage the vanelette. Another way to achieve PMT for higher speed wind would be to put two pairs of holes spaced a reasonable distance - one adjacent pair on each long side; place a loop of wire between each adjacent hole; and, finally connect the loops with a spring. Variations on the method should lead to a satisfactory arrangement. With just a little experimentation, how to do this should become immediately obvious to those skilled in the art of whatever art this is.
Care should be taken in designing for PMT to avoid sharp angles as that is likely to cause stresses above the proportional limit of the polycarbonate which will damage the vanelette. Another way to achieve PMT for higher speed wind would be to put two pairs of holes spaced a reasonable distance - one adjacent pair on each long side; place a loop of wire between each adjacent hole; and, finally connect the loops with a spring. Variations on the method should lead to a satisfactory arrangement. With just a little experimentation, how to do this should become immediately obvious to those skilled in the art of whatever art this is.
Performance
Performance
No other wind turbine nor aerogenerator nor windmill can approach the efficiency and performance of the device presented herein. Below is a graph produced by data logged using the turbine shown above.
No other wind turbine nor aerogenerator nor windmill can approach the efficiency and performance of the device presented herein. Below is a graph produced by data logged using the turbine shown above.
Power (W) vs Wind Speed (m/s)Figure 9
A picture of the tower for the turbine and the tower for the anemometer can be seen here. The location was able to provide relatively stead wind at mostly lower speeds. Since one of the objectives of the turbine and the tests was to demonstrate the significantly greater efficiency of the design, the site was beneficial to the purpose.
A picture of the tower for the turbine and the tower for the anemometer can be seen here. The location was able to provide relatively stead wind at mostly lower speeds. Since one of the objectives of the turbine and the tests was to demonstrate the significantly greater efficiency of the design, the site was beneficial to the purpose.
email: ecarecar1111@gmail.comWebsite URL: https://sites.google.com/view/plasticturbine
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