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Ducted Turbine Technology

Ducted wind turbines are not a new idea.  The basic premise is illustrated in the sketch below. 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’.  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.    Many attempts have been made to build a viable unit and all have failed commercially.


DTI has licensed two patent pending technologies from Clarkson University that enable an economically viable turbine, setting a new standard in small turbine output.

DTI Key Technology #1: Rotor Design **

The presence of the duct influences the velocity field that the turbine rotor sees. If this is not accounted for, as is the case with earlier commercial failures, the turbine will actually perform less efficiently than an open rotor. Our rotor design takes this into consideration and creates the proper twist of the blade.

DTI Key Technology #2: Rotor Location **

Ducted turbines have traditionally placed the rotor at the throat of the duct, the location of highest velocity. DTI has discovered that if the rotor is moved farther into the duct, the power output increases dramatically.

Our experimental data has been conducted on a 2.5 m diameter rotor, the same as that found on a Bergey Excel 1.  The wind tunnel data from our experimental test rig, acquired at the University of Waterloo in Canada this past November, has indicated that our duct will more than double the power output of a commercial open rotor turbine of the same diameter. Test photos can be clicked on below.

The measured data is shown in the plot below. The solid circles represent experimental data taken on the 2.5 m diameter rotor test rig. The data ends at 9 m/s because the 1.8 kW test rig was producing in excess of 1900 W at that speed and we did not want to ruin the generator. The x symbols represent the published power curve of the 2.5 m rotor Bergey Excel 1. The open symbols represent projected power curve behavior with respective generators utilizing the same rotor diameter of 2.5 m.

The Annual Energy Outputs (AEO) for the turbines illustrated in the plot are listed below, based on a 5 m/s Rayleigh wind distribution. The DTI 1.2, DTI 2.0, and DTI 3.5 would utilize generators limited to their respective outputs.

Utilizing a generator of the same size as the Excel 1 would more than double the AEO.

Turbine AEO (5 m/s)
Bergey Excel 1.0 1923 kWh
DTI 1.2 kW 3931 kWh
DTI 2.0 kW 4783 kWh
DTI 3.5 kW 5261 kWh

Design Overview and Explanation of Wind Tunnel Data acquired at the University of Waterloo in Canada in November 2016.

The focus of DTI’s product development is to reduce the cost per annual kWh of wind energy.  And that’s without incentives, since those won’t last forever. Our target is 1/2 the $/kWh of products on the market today.  In other words, we would produce twice the energy for the same cost. Energy is what’s important, not the power rating of a turbine at 11 m/s.  We are currently focusing on developing a commercial prototype in the ~7000 kWh/year and ~10,000 kWh/year ranges, based on an average Rayleigh distribution wind speed of 5 m/s.


Configuration: 3-5 bladed downwind
Cut-In wind speed: < 2 m/s
Cut-Out wind speed: TBD
Braking: Mechanical/Electrical
Blades Composite / Aluminum
Generator 3.5 kW

3 Meter (9.8 ft) Rotor

Duct Diameter 3.7 m (12 ft.)
Rated Power (11 m/s): 3500 W
AEO (est. for 5 m/s annual average): ~6500 kWh
Nominal Rotation: 250 RPM
Nacelle Weight: 100 kg (220 lb)

4 Meter (13.1 ft) Rotor

Duct Diameter 4.7 m (15.4 ft.)
Rated Power (11 m/s): 3500 W
AEO (est. for 5 m/s annual average): ~ 10000 kWh
Nominal Rotation: 250 RPM
Nacelle Weight: 120 kg (264 lb)


Below is a list of recent presentations and publications on the current ducted wind turbine technology licensed from Clarkson University:

Kanya, B. and Visser, K. D.: Experimental Validation of a Ducted Wind Turbine Design Strategy, Wind Energ. Sci.,,, (accepted for publication)

Bagheri-Sadeghi, N., Helenbrook, B. T., and Visser, K. D.: Ducted wind turbine optimization and sensitivity to rotor position, Wind Energ. Sci., 3, 221-229,, 2018.

Venters R, Helenbrook BT, Visser KD. Ducted Wind Turbine Optimization. ASME. J. Sol. Energy Eng. 2017;140(1):011005-011005-8. doi:10.1115/1.4037741

Kanya, B., and Visser, K.D., “Experimental Validation of a Ducted Wind Turbine Rotor Design Strategy”, Wind Energy Sciences Conference, DTU, Copenhagen, Denmark, June 27, 2017

Bagheri-Sadeghia, N., B.T. Helenbrook, and Visser, K.D.,“Design and Performance Parameters of a Ducted Wind Turbine”, Wind Energy Sciences Conference, DTU, Copenhagen, Denmark, June 27, 2017.

Venters, R., Helenbrook, B., and Visser, K.D., “Ducted Wind Turbine Optimization,” AIAA 2016-372, AIAA Aviation, 13-17 June 2016, Washington, D.C., 34th AIAA Applied Aerodynamics Conference

Visser, K.D., “Small Wind: It Can Be a Game Changer!,” Thousand Islands Energy Research Forum, Alexandria Bay, NY, Oct. 30 – Nov 1, 2015.

Helenbrook, B., Visser, K.D., and Wilson, S., “Ducted Wind Turbines: More Efficient Than Open Rotors?”, The 2nd International Conference on Future Technologies in Wind Energy (WindTech2015), October 19-21, 2015 – London, Ontario, Canada

Visser, K.D., “Towards a Viable Ducted Wind Turbine,” Thousand Islands Energy Research Forum, University of Ottawa, Ottawa Canada, October 23-25, 2014.




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