Ducted Turbines Research References
When it comes to physics of the ducted turbines, researchers and scientists around the globe have concluded since the early 1900’s that ducting turbines increases energy output.
Below is a short list of work by researchers, professors, and business community.
Kenneth Visser (Professor, Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, NY, November 2009), “Wind Tamer Turbine Performance Report”.
Quote 1: “In general, it was observed from the numerical estimations that the WindTamer turbine can produce approximately twice the annual energy output for a given swept rotor area than a conventional open rotor design.”
Quote 2: “These data above indicate that the WindTamer is capable of Cp values in the 0.6 to 0.8 range, well above that of small wind turbines on the market today by almost a factor of 2, and as has been shown, above the Betz level for an open rotor. As will be shown in the next section, these values are quite close to those predicted by the design code, mRotor used at Clarkson.”
Quote 3: “The 52 inch rotor WindTamer is estimated to generate about 3,030 kWh per year, roughly 2.5 times more energy than a comparable open rotor of the same diameter, which yields 1220 kWh per year.”
C J Lawn (Professor, Department of Engineering, Queen Mary, University of London, London, UK, IMechE 2003), “Optimization of the power output from ducted turbines”.
Quote 1: “An enhancement in the power coefficient of more than 30 per cent over the optimum for an unshrouded turbine can be gained, provided the turbine resistance is reduced appropriately by choosing a more lightly loaded design.”
Quote 2: “Such an enhancement is associated with a 15 per cent increase in velocity through the turbine over the freestream value.”
Jifeng Wang, Janusz Piechna, Norbert Muller (Researcher at Turbomachinery Laboratory, Michigan State University, East Lansing, MI, USA, and Institute of Aeronautics and Applied Mechanics, Warsaw University of Technology, Warsaw, Poland, 2003), “ Computational Fluid Dynamics Investigation of a Novel Multiblade Wind Turbine in a Duct”.
Quote 1: “Through the comparison of power coefficient variation with thrust coefficient, it was found that a ducted turbine can be 2-3 times that of the power extracted by a bare turbine.”
Chandan D. Chaudhari , Sainath A. Waghmare, and AshishP. Kotwal (Dept. of Mech. Engg., Datta Meghe College of Eng, Airoli, Navi Mumbai, and Institute of Aeronautics, and Dept. of Mech. Eng, Lokmanya Tilak College of Eng, Koparkhairane, Navi Mumbai, 2013), “Numerical Analysis of Venturi Ducted Horizontal Axis Wind Turbine for Efficient Power Generation”.
Quote 1: “The increased velocity of wind resulted in significant improvement in the kinetic energy hence power output of turbine.”
I.H. Al-Bahadly and A.F.T. Petersen (Massey University, New Zealand, 2013), “A Ducted Horizontal Wind Turbine for Efficient Generation.”
Quote 1: “Power calculations were provided for the ducted turbine and the conventional turbine. These provided a direct comparison that was referred to as condition 1 and condition 2. This showed a theoretical power rating difference of a factor of 17, it must be shown here that the theoretical power shows the amount of power that is available in the wind flow.”
Ducted Turbines International (DTI), “Ducted Turbines Technology”, 2016
Quote 1: “A duct surrounding the rotor captures more of the oncoming wind, directing it through the rotor to increase the amount of wind energy the rotor sees.”
Quote 2: “While a proper duct design is key a performance increase, the additional cost is even more important in evaluating the cost/kWh of the turbine.”
Belloni and R.H.J. Willden (Department of Engineering Science, University of Oxford, Oxford, UK), “A computational study of a bi-directional ducted tidal turbine”, 2010
Quote 1: “Compared to the bare disc a clear increase in both thrust and power coefficient is visible for the ducted disc.”
Quote 2: “Simulation results show that the turbine’s power coefficient, defined based on the rotor swept area, can be modestly increased through the use of the duct. The increase in power coefficient is accompanied by an increase in the overall thrust acting on the device.”
Peace-Maker Masukume, Golden Makaka, and David Tinarwo [Department of Physics, University of Fort Hare & University of Venda, South Africa], “Technoeconomic Analysis of Ducted Wind Turbines and Their Slow Acceptance on the Market,” 2014
Quote 1: “A ducted wind turbine produces more power than an unducted wind turbine of the same parameters.”
Quote 2: “Failure to penetrate the market is due to negative publicity as a result of the erroneous evaluation undertaken and lack of appropriate engineering techniques to protect ducted wind energy systems in extreme wind conditions.rs.”
Quote 3: “The encasing of wind turbines in a duct or “shroud” in order to enhance their performance dates back to the 1950s, when it was recognized that a shroud augmented wind turbine can produce up to twice the power of unshrouded turbine of the same diameter.”
Quote 4: “The study has illustrated that the average LUCE of the ducted wind turbine is US 0.26/kWh compared to US 0.30/kWh of the bare wind turbine. The calculation did not take into account savings in CO2, wastes associated with conventional power production and their related external effects, and saved amount of water. Taking these factors into account would make ducted wind turbines even more favorable.”
Sheng-Huan Wang and Shih-Hsiung Chen [Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan City, Taiwan], “Blade number effect for a ducted wind turbine”, 2008
Quote 1: “It was found that the blade geometry, stagger angle, and number of blades have different duct blockage effects, and do affect the turbine performance (specifically the power coefficient and torque coefficient, etc.). The fewer number of blades has higher through flow speed, while the larger number of blades provides larger torque. The best power coefficient lies in between the two extremes. The appropriate number of blades is important to match the generator performance curve for optimal overall performance and efficiency”.
Quote 2: “The number of blade effect on a ducted wind turbine was studied with the use of CFD technique. On the whole, the increasing number of blades effectively creates the higher starting torque, reduces cut-in speed and provides the sufficient blade areas to transfer wind energy.”
Ducted turbine companies under development:
Ogin Energy at http://www.Oginenergy.com
Quote 1: “The Ogin Turbine is different. Its unique shroud design takes advantage of the latest advances in the aerospace industry to change physical airflow patterns through and around the turbine. Annual energy output per kW of rated capacity is increased by 50%, while peak energy output from the ultra-compact rotor is increased by up to three times per unit of swept area.”
V2 Wind at http://www.vsquaredwind.com
Quote 1: “Phase 1 Testing focused on the acceleration capabilities of the module designs in the field. Testing demonstrated that V 2 nozzles achieve close to theoretical acceleration with no power extraction, nearly twice the performance of previous accelerators. Results were reviewed and confirmed by Cermark Peterka Peterson (CPP), a world known wind engineering consulting firm.”
Quote 2: “Phase 2 Testing focused on the power extraction of arrays and physical aspects of the machine that drive costs. MIT wind tunnel research was performed with a 3 x 5 scale array of modules pictured below.”
Quote 3: “Phase 2 Research validated the expected power extraction of the technology when deployed in arrays, confirmed the low drag forces the arrays will experience and showed that the arrays can be expected to passively self-orient to wind direction.”
Quote 4: “Testing, performed under US Army contract, focused on full-scale module power extraction and the energy intensity of arrays in the field. The module was tested at a site in Littleton, MA over several weeks. Measurements were taken by three different systems. Results closely matched those of the MIT array tests confirming the power extraction and energy intensity of the technology in field conditions. Measured energy intensity indicates DE deployments of the technology could have ~1.5-3 times the intensity of a modern coal plant, 1/3 – 1/2 the intensity of a modern Natural Gas plant, and roughly ~50 times the intensity of other clean generation technologies.”
Wind Lens by professor Yuji Ohya at Kyushu University, Japan
Quote 1: “Forget about traditional tri-blade wind turbines — the ultra-efficient turbine of the future might look completely different if Kyushu University professor Yuji Ohya has anything to say about it. Ohya and his team recently unveiled the Wind Lens, a honeycomb-like structure that purportedly triples the amount of wind energy that can be produced by offshore turbines.”
Quote 2: “Two-threefold increase in output power as compared to conventional (bare) wind turbines due to the concentration of wind energy.”
Quote 3: “The further significant features of the WindLens technology include, improved safety, reduction of acoustic noise and Doppler radar interference.”