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Windstar Turbines
Wind Harvest International’s Windstar turbines operate in the same basic manner as all blade-type vertical axis wind turbines (VAWTs). Wind moving over the blades creates lift and torque similar to the blades of horizontal axis wind turbines (HAWTs). VAWTs have more drag than HAWTs because the blades revolve back into the wind. Because of this, VAWTs aren’t generally as efficient at extracting energy out of the wind as HAWTs. WHI has solved this classic VAWT problem in two ways.
1. Our older Windstar models have “stators”, which are aerodynamically shaped columns at the points of a star. These stators change the character of the airflow and funnel a larger swept area of wind into the rotors. The older model’s swept area is relatively small (the largest being the Windstar 1066 with 1066 square feet of swept area and a 50kW generator). They are more costly to fabricate and install, and the stators require larger foundations.
2. The “coupled vortex” effect (Patent 6784566) occurs when two VAWTs are placed close together. The neighboring rotors create additional lift and torque on each other with rotors in the middle of two other rotors receiving the largest effect. WHI proved the vortex effect with the Windstar 530Gs. By returning from guyed wires to an external support structure, the best features of all past models could be combined into a new set of turbine models known as Linear Array Vortex Turbine Systems (LAVTS). Windstar LAVTS are systems because they can be built in different lengths, combinations of generator sizes and other customizations that help maximize the returns for a specific wind farm.
Windstar rotors have straight, aerodynamically shaped blades (a NACA 0018 airfoil) that are extruded from strong aircraft aluminum. Horizontal arms support the blades on each end and attach to the central shaft. The length of the blade arms determines the diameter of the rotor, and diameter and rotor height determines the swept area, the parameter that gives Windstar turbines their model numbers. The shaft sits on a bottom bearing that is mounted to a relatively small, freestanding frame on a concrete pad. The housing encloses the bearing, brake, gearbox, belt drive and generator.
Windstar turbines have a dual braking system. A set of brake shoes clamps down on a flange welded to the steel shaft when the power goes out on the turbine or the controls direct the turbine to be shut down. The second brake is unique among VAWTs in that the lower blades of Windstar turbines flare out in an emergency-braking event. This is similar to how modern HAWTs work.
Windstar turbine generators, gearboxes, bearings and most other parts are “off-the-shelf” products made by companies such as Marathon, Emerson, and Sealmaster. Blades are mass manufactured in a simple aluminum extrusion and tempering process. Induction generators are widely available, have been used for decades in wind turbine applications. and eliminate the need for costly inverters and controls.
The belt drive significantly reduces the startup impacts and wear and tear on the transmission system. Gear belt losses though are standard and combined gearbox generator systems offer an area for significant improvements in Windstar output efficiencies.
Increasing the blade length and cord diameter while reducing blade arms and blade end drag offer another area where Windstar turbines can significantly improve their cost benefit.
1. Our older Windstar models have “stators”, which are aerodynamically shaped columns at the points of a star. These stators change the character of the airflow and funnel a larger swept area of wind into the rotors. The older model’s swept area is relatively small (the largest being the Windstar 1066 with 1066 square feet of swept area and a 50kW generator). They are more costly to fabricate and install, and the stators require larger foundations.
2. The “coupled vortex” effect (Patent 6784566) occurs when two VAWTs are placed close together. The neighboring rotors create additional lift and torque on each other with rotors in the middle of two other rotors receiving the largest effect. WHI proved the vortex effect with the Windstar 530Gs. By returning from guyed wires to an external support structure, the best features of all past models could be combined into a new set of turbine models known as Linear Array Vortex Turbine Systems (LAVTS). Windstar LAVTS are systems because they can be built in different lengths, combinations of generator sizes and other customizations that help maximize the returns for a specific wind farm.
Windstar rotors have straight, aerodynamically shaped blades (a NACA 0018 airfoil) that are extruded from strong aircraft aluminum. Horizontal arms support the blades on each end and attach to the central shaft. The length of the blade arms determines the diameter of the rotor, and diameter and rotor height determines the swept area, the parameter that gives Windstar turbines their model numbers. The shaft sits on a bottom bearing that is mounted to a relatively small, freestanding frame on a concrete pad. The housing encloses the bearing, brake, gearbox, belt drive and generator.
Windstar turbines have a dual braking system. A set of brake shoes clamps down on a flange welded to the steel shaft when the power goes out on the turbine or the controls direct the turbine to be shut down. The second brake is unique among VAWTs in that the lower blades of Windstar turbines flare out in an emergency-braking event. This is similar to how modern HAWTs work.
Windstar turbine generators, gearboxes, bearings and most other parts are “off-the-shelf” products made by companies such as Marathon, Emerson, and Sealmaster. Blades are mass manufactured in a simple aluminum extrusion and tempering process. Induction generators are widely available, have been used for decades in wind turbine applications. and eliminate the need for costly inverters and controls.
The belt drive significantly reduces the startup impacts and wear and tear on the transmission system. Gear belt losses though are standard and combined gearbox generator systems offer an area for significant improvements in Windstar output efficiencies.
Increasing the blade length and cord diameter while reducing blade arms and blade end drag offer another area where Windstar turbines can significantly improve their cost benefit.
