Here's a post from jibbguy I just read:
Seems CWATs are not so 'secretized' after all, if we can trust Wikipedia:
Compact Wind Acceleration Turbines
CWATs are a class of wind turbine that uses structures to accelerate wind before it enters the wind-generating element.[1] The concept of these structures has been around for decades [2] but has not gained wide acceptance in the marketplace. In 2008, two companies targeting the mid-wind (100 kW-1 MW) marketplace have received funding from venture capital. The first company to receive funding is Optiwind, which received its series A funding in April 2008, and the second company is FloDesign Wind Turbine Corp, which also received its series A funding in April 2008. Optiwind [3] is funded through Charles River Ventures and FloDesign is funded through Kleiner Perkins.[4] Other CWATs under development include the WindTamer from AristaPower, WindCube, Innowind (conceptual offshore application) and Enflo turbines.
CWATs are a new acronym that encompasses the class of machines formerly known as DAWTs (diffuser augmented wind turbines). The technologies mentioned above all use diffuser augmentation that is substantially similar to previous designs as the primary means of acceleration. DAWTs were heavily researched by K. Foreman and Oman of Grumman Aerospace in the 1970s and 1980s and Igra in Israel in the 1970s. At the end of a decade of wind tunnel research and design funded by Grumman, NASA, and the DOE, it was determined that the DAWT system's economics were not sufficient to justify commercialization. In the 1990s the Grumman technology was licensed to a New Zealand company, Vortec Wind. The attempt to commercialize the Vortec 7 in New Zealand from 1998 to 2002 proved it to be economically untenable when compared to the dominant HAWT (horizontal axis wind turbine) technology.
Ultimately, any wind turbine design must be measured against economic realities. It must positively answer the question, "is the cost to install and operate the system lower than the cost of other alternatives, including the local electric grid?" Historically, CWAT/DAWT designs have failed to overcome this hurdle as compared to more conventional HAWT designs, however, there is reason to believe that this equation may be shifting towards these new designs. The two primary drivers of this equation have been the amount of augmentation and the structural implications of these additional design elements.
For the highest claimed velocity increase in a DAWT of 1.6 x freestream
Power ratio DAWT to HAWT = (1/2.75)(16ms/10ms)3 = 1.48 increase
Not significant enough to offset the associated costs. The problem with optiwind is even more severe since the system only covers a fraction of the swept area available to a HAWT of the stack height.
The challenge has always been, and remains, installing, operating, and maintaining these structures for a cost that is less than the incremental value gained by their presence. Recent developments in material science, installation methodology and overall system integration have led to the far more realistic view that we are very close to this advent and the dawn of a new, highly sustainable class of wind turbine if the issues elucidated above can be dealt with which still remains highly questionable for the DAWT geometry.
Among the recent DAWT designs that appear to have a definitive positive power, if not cost, comparison to HAWTs is the Enflo turbine. Based on its rotor:exit ratio and the published power performance this turbine appears to have a confirmed 2 times increase in power output over a HAWT of the diameter of the exit area. It is still unlikely that this machine can scale to larger ratings but based on published data the Enflo appears to be the best performing DAWT/CWAT yet built.
BTW: One thing jibbguy didn't mention on that Suppression Document and YouTube post was that FloDesign, itself, and by it's own admission is... get this! ...a world-renowned expert in suppression technology
...mixer/ejector suppression, that is: Suppression « FloDesign – Innovative Business Incubator
Originally posted by jibbguy
View Post
Seems CWATs are not so 'secretized' after all, if we can trust Wikipedia:
Compact Wind Acceleration Turbines
CWATs are a class of wind turbine that uses structures to accelerate wind before it enters the wind-generating element.[1] The concept of these structures has been around for decades [2] but has not gained wide acceptance in the marketplace. In 2008, two companies targeting the mid-wind (100 kW-1 MW) marketplace have received funding from venture capital. The first company to receive funding is Optiwind, which received its series A funding in April 2008, and the second company is FloDesign Wind Turbine Corp, which also received its series A funding in April 2008. Optiwind [3] is funded through Charles River Ventures and FloDesign is funded through Kleiner Perkins.[4] Other CWATs under development include the WindTamer from AristaPower, WindCube, Innowind (conceptual offshore application) and Enflo turbines.
CWATs are a new acronym that encompasses the class of machines formerly known as DAWTs (diffuser augmented wind turbines). The technologies mentioned above all use diffuser augmentation that is substantially similar to previous designs as the primary means of acceleration. DAWTs were heavily researched by K. Foreman and Oman of Grumman Aerospace in the 1970s and 1980s and Igra in Israel in the 1970s. At the end of a decade of wind tunnel research and design funded by Grumman, NASA, and the DOE, it was determined that the DAWT system's economics were not sufficient to justify commercialization. In the 1990s the Grumman technology was licensed to a New Zealand company, Vortec Wind. The attempt to commercialize the Vortec 7 in New Zealand from 1998 to 2002 proved it to be economically untenable when compared to the dominant HAWT (horizontal axis wind turbine) technology.
Ultimately, any wind turbine design must be measured against economic realities. It must positively answer the question, "is the cost to install and operate the system lower than the cost of other alternatives, including the local electric grid?" Historically, CWAT/DAWT designs have failed to overcome this hurdle as compared to more conventional HAWT designs, however, there is reason to believe that this equation may be shifting towards these new designs. The two primary drivers of this equation have been the amount of augmentation and the structural implications of these additional design elements.
For the highest claimed velocity increase in a DAWT of 1.6 x freestream
Power ratio DAWT to HAWT = (1/2.75)(16ms/10ms)3 = 1.48 increase
Not significant enough to offset the associated costs. The problem with optiwind is even more severe since the system only covers a fraction of the swept area available to a HAWT of the stack height.
The challenge has always been, and remains, installing, operating, and maintaining these structures for a cost that is less than the incremental value gained by their presence. Recent developments in material science, installation methodology and overall system integration have led to the far more realistic view that we are very close to this advent and the dawn of a new, highly sustainable class of wind turbine if the issues elucidated above can be dealt with which still remains highly questionable for the DAWT geometry.
Among the recent DAWT designs that appear to have a definitive positive power, if not cost, comparison to HAWTs is the Enflo turbine. Based on its rotor:exit ratio and the published power performance this turbine appears to have a confirmed 2 times increase in power output over a HAWT of the diameter of the exit area. It is still unlikely that this machine can scale to larger ratings but based on published data the Enflo appears to be the best performing DAWT/CWAT yet built.
BTW: One thing jibbguy didn't mention on that Suppression Document and YouTube post was that FloDesign, itself, and by it's own admission is... get this! ...a world-renowned expert in suppression technology
...mixer/ejector suppression, that is: Suppression « FloDesign – Innovative Business Incubator
Comment