Oscillating Hydrofoil, Turbine, Propulsive System and Method for Transmitting Energy

Abstract

System and method for converting kinetic energy from a fluid flow into mechanical energy, the method comprising the steps of: a) providing a turbine including first and second hydrofoils, each of the hydrofoils being able to move lin-early in a heaving motion, and being able to oscillate about a spanwise axis in a pitching motion, said heaving and pitching motions being quasi-si-nusoidal, b) coupling the heaving motions of the first and second hydrofoils to the pitching motions of the second and first hydrofoils respectively, with the pitch-heave motion phase being substantially equal to the inter-hydrofoil phase, the heaving motion of one of the hydrofoils thereby driving the pitching motion of the other hydrofoil; and c) transforming the heaving motions of the hydrofoils into a rotational movement of a rotatable shaft, with linear-to-rotary transmission means.

1 . A turbine for converting kinetic energy from a fluid flow into mechanical energy by driving a rotatable shaft, the turbine comprising:
 a support structure;   first and second hydrofoils extending from said support structure, each hydrofoil being slidably and rotatably connected to said structure, for allowing each of the hydrofoils to move linearly in a heaving motion, and to oscillate about a spanwise axis in a pitching motion; said heaving and pitching motions being quasi-sinusoidal, wherein:
 for a given one of said hydrofoils, the heaving and pitching motions are out of phase by a pitch-heave motion phase, and 
 the respective heaving motions of the first and second hydrofoils are out of phase by an inter-hydrofoil phase; and 
   a heaving-to-pitching assembly, for coupling the heaving motions of the first and second hydrofoils to the pitching motions of the second and first hydrofoils respectively, the pitch-heave motion phase being substantially equal to the inter-hydrofoil phase, the heaving motion of one of the hydrofoils thereby driving the pitching motion of the other hydrofoil; and   a linear-to-rotary transmission system operatively connected to the first and second hydrofoils and to the rotatable shaft, the heaving motions of the first and second hydrofoils thereby driving a rotational motion of the shaft.   
     
     
         2 . The turbine according to  claim 1 , wherein the coupling-to-heaving assembly comprises:
 a pair of first and second linear actuators, said first linear actuator being connected to said first hydrofoil, and said second linear actuator being connected to said second hydrofoil, each of the first and second linear actuators being driven by the heaving motion of the corresponding hydrofoil;   a pair of first and second rotary actuators, said first rotary actuator being connected to said first hydrofoil, and said second rotary actuator being connected to said second hydrofoil, each of the first and second rotary actuators driving the corresponding hydrofoil in the pitching motion; and   a heaving-to-pitching coupling system for coupling the first linear actuator to the second rotary actuator, and for coupling the second linear actuator to the first rotary actuator.   
     
     
         3 . The turbine according to  claim 1  or  2 , wherein the support structure comprises one post, the first and second hydrofoils extending on opposite sides of the post. 
     
     
         4 . The turbine according to  claim 1  or  2 , wherein the support structure comprises two spaced-apart posts, the first and second hydrofoils extending between said posts. 
     
     
         5 . The turbine according to any one of  claims 1  to  4 , wherein each of the hydrofoils has an elongated and substantially planar body. 
     
     
         6 . The turbine according to any one of  claims 1  to  5 , wherein each of the hydrofoils has an extending curved profile. 
     
     
         7 . The turbine according to  claim 6 , wherein each of said hydrofoils has a symmetrical transversal cross-section. 
     
     
         8 . The turbine according to any one of  claims 1  to  7 , wherein the first and second hydrofoils each comprises a pair of foils extending in parallel. 
     
     
         9 . The turbine according to  claim 8 , wherein for each of the hydrofoils, said pair of foils are rigidly connected via rigid links. 
     
     
         10 . The turbine according to any one of  claims 2  to  9 , wherein said first and second linear actuators are hydraulic cylinders. 
     
     
         11 . The turbine according to  claim 10 , wherein said hydraulic cylinders, and said first and second rotary actuators are housed within said base structure. 
     
     
         12 . The turbine according to  claim 2 , wherein:
 the base structure comprises two spaced-apart posts, the first and second hydrofoils extending between said posts;   the pair of first and second linear actuators is a first pair of linear actuators, the pair of first and second rotary actuators is a first pair of rotary actuators, and the heaving-to-pitching coupling system is a first heaving-to-pitching coupling system, wherein said first pair of linear actuators, said first pair of rotary actuators and said first heaving-to-pitching system are housed in the first post;   
       the turbine further comprising:
 a second pair of first and second linear actuators, wherein for said second pair, the first linear actuator is connected to said first hydrofoil, and the second linear actuator is connected to said second hydrofoil; 
 a second pair of first and second rotary actuators, wherein for said second pair, the first rotary actuator is connected to the first hydrofoil, and the second rotary actuator is connected to the second hydrofoil; and 
 a second heaving-to-pitching coupling system, wherein for said second pairs of linear and rotary actuators, the first linear actuator is coupled to the second rotary actuator, and the second linear actuator is coupled the first rotary actuator; and 
 
       wherein said second pair of linear actuators, said second pair of rotary actuators, and said second heaving-to-pitching coupling system are housed in the second post. 
     
     
         13 . The turbine according to any one of  claims 2  to  12 , wherein each of the rotary actuators is a single vane actuator. 
     
     
         14 . The turbine according to any one of  claims 2  to  12 , wherein each of the rotary actuators includes a drum and cable mechanism. 
     
     
         15 . The turbine according to  claims 1  to  14 , wherein the heaving-to-pitching assembly comprises a pitch-controlling mechanism for controlling a pitching amplitude of the corresponding hydrofoil. 
     
     
         16 . The turbine according to  claim 15 , wherein said pitch-controlling mechanism comprises relief valves in combination with stoppers or a controllable volumetric pump. 
     
     
         17 . The turbine according to any one of  claims 1  to  16 , wherein said pitch-heave motion phase, and said inter-hydrofoil phase are approximately 90 degrees. 
     
     
         18 . The turbine according to  claim 10 , wherein each hydraulic cylinder is a coaxial hydraulic cylinder, thereby facilitating alignment of the first and second linear actuators. 
     
     
         19 . The turbine according to any one of  claims 1  to  18 , wherein the linear-to-rotary transmission system comprises:
 at least two transmission actuators, each operatively connected to a corresponding one of the hydrofoils; and 
 linear-to-rotary transmission links, for transforming a linear motion of the transmission actuators into the rotational motion of the shaft. 
 
     
     
         20 . The turbine according to  claim 10 , wherein the linear-to-rotary transmission system comprises:
 linear-to-rotary transmission links connected to the shaft;   at least two transmission cylinders, each connected to the linear-to-rotary transmission links; and   
       wherein:
 each hydraulic cylinder comprises a rod and two pistons located at both ends of the rod, each piston delimiting first and second chambers on both sides of the cylinder, 
 each rod is connected to a corresponding one of the hydrofoils, said first chamber is connected to one of the rotary actuators via the heaving-to-pitching coupling means, and said second chamber is connected to one of said at least two transmission cylinders; 
 
       each hydraulic cylinder thereby being part of the linear-to-rotary transmission system. 
     
     
         21 . The turbine according to  claim 20 , wherein for each of the hydraulic cylinders, the rod is articulated. 
     
     
         22 . The turbine according to any one of  claims 1  to  21 , wherein the fluid flow is a flow of water and the turbine is a hydrokinetic turbine. 
     
     
         23 . The turbine according to any one of  claims 1  to  21 , where the fluid flow is a flow of air and the turbine is a wind turbine. 
     
     
         24 . A method for converting kinetic energy from a fluid flow into mechanical energy, the method comprising the steps of:
 a) providing a turbine including first and second hydrofoils, each of the hydrofoils being able to move linearly in a heaving motion, and being able to oscillate about a spanwise axis in a pitching motion, said heaving and pitching motions being quasi-sinusoidal, wherein:
 for a given one of said hydrofoils, the heaving and pitching motions are out of phase by a pitch-heave motion phase, and 
 the respective heaving motions of the first and second hydrofoils are out of phase by an inter-hydrofoil phase; 
   b) coupling the heaving motions of the first and second hydrofoils to the pitching motions of the second and first hydrofoils respectively, with the pitch-heave motion phase being substantially equal to the inter-hydrofoil phase, the heaving motion of one of the hydrofoils thereby driving the pitching motion of the other hydrofoil; and   c) transforming the heaving motions of the hydrofoils into a rotational movement of a rotatable shaft, with linear-to-rotary transmission means.   
     
     
         25 . The method according to  claim 24 , wherein step b), comprises the sub-steps of:
 i) providing a pair of first and second linear actuators, a pair of first and second rotary actuators and a heaving-to-pitching coupling system;   ii) connecting said first linear actuator to said first hydrofoil, and said second linear actuator to said second hydrofoil, each of the first and second linear actuators being driven by the heaving motion of the corresponding hydrofoil;   iii) connecting said first rotary actuator to said first hydrofoil, and said second actuator to said second hydrofoil, each of the first and second rotary actuators driving the corresponding hydrofoil in the pitching motion; and   iv) coupling the first linear actuator to the second rotary actuator, and the second linear actuator to the first rotary actuator with the heaving-to-pitching coupling system.   
     
     
         26 . The method according to  claim 24  or  25 , wherein step a) comprises a sub-step of providing two spaced-apart posts, the first and second hydrofoils extending between said posts. 
     
     
         27 . The method according to any one of  claims 24  to  26 , wherein step a) the first and second hydrofoils each comprises a pair of foils extending in parallel. 
     
     
         28 . The method according to any one of  claims 24  to  27 , wherein in step b), said pitch-heave motion phase, and said inter-hydrofoil phase are approximately 90 degrees. 
     
     
         29 . The method according to any one of  claims 24  to  28 , further comprising a step of controlling respective pitching amplitudes of the first and second hydrofoils. 
     
     
         30 . A propulsive system for transmitting mechanical energy from a rotatable driving shaft, the system comprising:
 a support structure;   first and second hydrofoils extending from said support structure, each hydrofoil being slidably and rotatably connected to said structure, for allowing each of the hydrofoils to move linearly in a heaving motion, and to oscillate about a spanwise axis in a pitching motion; said heaving and pitching motions being quasi-sinusoidal, wherein:
 for a given one of said hydrofoils, the heaving and pitching motions are out of phase by a pitch-heave motion phase, and 
 the respective heaving motions of the first and second hydrofoils are out of phase by an inter-hydrofoil phase; and 
   a heaving-to-pitching assembly, for coupling the heaving motions of the first and second hydrofoils to the pitching motions of the second and first hydrofoils respectively, the pitch-heave motion phase being substantially equal to the inter-hydrofoil phase, the heaving motion of one of the hydrofoils thereby driving the pitching motion of the other hydrofoil; and   a rotary-to-linear transmission system operatively connected to the rotatable shaft and to the first and second hydrofoils, the rotational motion of the driving shaft thereby driving the heaving and pitching motions of the hydrofoil.   
     
     
         31 . A hydrofoil comprising a pair of foils extending in parallel, said foils being connected via rigid links. 
     
     
         32 . The hydrofoil according to  claim 31 , wherein each of said foils has an elongated and substantially planar body. 
     
     
         33 . The hydrofoil according to  claim 31  or  32 , wherein each of said foils has an extending curved profile. 
     
     
         34 . The hydrofoil according to any one of  claims 31  to  33 , wherein each of said foils has a symmetrical transversal cross-section. 
     
     
         35 . The hydrofoil according to any one of  claims 31  to  34 , wherein the rigid links comprise reinforcing plates distributed spanwise along the hydrofoil, for providing added foil rigidity.