Hybrid vertical/horizontal axis wind turbine for deep-water offshore installations

A method of designing a wind-driven power generating system comprising a hybrid wind turbine having a turbine rotor including a shaft rotatable about an axis, at least two rotor blades, and at least two struts, with each of the rotor blades being mounted to the shaft by at least one of the struts so that at least a portion of each of the rotor blades along the length of said rotor blade is spaced radially from the shaft, and a floating platform for supporting the hybrid wind turbine on a body of water for permitting the turbine axis to freely assume an operating heel angle β relative to vertical in the presence of a prevailing wind, the method comprising:

• setting a target velocity of the prevailing wind;
• designing the portion of each of the rotor blades spaced radially from the shaft to have a predetermined configuration and aerodynamic characteristics for producing on the rotor blades a lift force having a component in the direction of rotor blade rotation at a designated non-zero value of β in the presence of the prevailing wind at the target velocity;
• and
• designing each of the struts with at least a portion to have a predetermined configuration and aerodynamic characteristics for producing on each of the struts a lift force having a component in a direction traveled by said struts as the rotor blades rotate around the shaft axis at the designated non-zero value of β in the presence of the prevailing wind at the target velocity;
• determining a quantitative relationship between the geometry of the system and the value of β;
• and
• using the quantitative relationship between the geometry of the system and the value of β to configure the system so that the turbine shaft heels at the designated non-zero value of β in the presence of the prevailing wind at the target velocity.

A method of generating electrical power using a wind-driven power generating system comprising a hybrid wind turbine having a turbine rotor including a shaft rotatable about an axis, at least two rotor blades, and at least two struts, with each of the rotor blades being mounted to the shaft by at least one of the struts so that at least a portion of each of the rotor blades along the length of said rotor blade is spaced radially from the shaft, wherein:

• the hybrid wind turbine is mounted on a floating platform supporting the hybrid wind turbine at a predetermined location on a body of water for permitting the turbine axis to freely assume an operating heel angle β relative to vertical in the presence of a prevailing wind,
• the portion of each of the rotor blades spaced radially from the shaft has a predetermined configuration and aerodynamic characteristics producing a lift force on the rotor blades having a component in the direction of rotor blade rotation at a designated non-zero value of β in the presence of the prevailing wind,
• each of the struts with at least a portion has a predetermined configuration and aerodynamic characteristics for producing on each of the struts a lift force having a component in a direction traveled by said struts as the rotor blades rotate around the shaft axis at the designated non-zero value of β in the presence of the prevailing wind, and
• the system is configured by determining a quantitative relationship between the geometry of the system and the value of β so that the turbine shaft will heel at the designated non-zero value of β in the presence of the prevailing wind at a target velocity,
• the method comprising:
• determining the target velocity of the prevailing wind based on historical environmental data at the predetermined location;
• and
• deploying the system on the body of water at the predetermined location.