System for a turbine with a gaseous or liquideous working medium

Abstract

This invention relates to a system for a turbine with a gaseous or liquideous working medium, in particular a wind turbine for a wind turbine generator. The turbine comprises a shaft ( 3 ), which is rotatable at a certain angular frequency, a hub ( 2 ), on which at least one turbine blade ( 1 ) is attached, and a hinge member ( 12, 13 ) disposed between said shaft ( 3 ) and hub ( 2 ). The hinge member comprises a bearing ( 12 ) and spring elements ( 13 ), together forming a rigidity (k) against movements in the hinge member ( 12, 13 ). The turbine blade ( 1 ) has a mass inertia factor relatively to the hinge member ( 12, 13 ) and is adapted to move through said gaseous or liquideous flow, which has a flow direction essentially perpendicular to the rotational plane of said turbine blade ( 1 ), and has a varying flow velocity in said direction such that the system is exposed to disturbance forces. An essential component of the disturbance forces has a disturbance frequency (Ω disturbance ) which is composed of said angular frequency (Ω rotation ) and the rigidity (k) of said hinge member ( 12, 13 ), the mass inertia factor (J turbine ) of said turbine blade ( 1 ) and the angular frequency (Ω rotation ) of said shaft ( 3 ) in the system has been selected such that the system is supercritical or subcritical. The invention also related to a wind turbine generator with such a system.

1 . A turbine adapted for a gaseous or liquideous working medium, in particular a wind turbine for a wind turbine generator, comprising 
 a shaft ( 3 ), which is rotatable at a certain angular frequency (ω rotation ),    a hub ( 2 ), on which at least one turbine blade ( 1 ) is attached, and    a hinge member ( 12 ,  13 ) disposed between said shaft ( 3 ) and said hub ( 2 ) and comprising a bearing ( 12 ) and spring elements ( 13 ), together forming a rigidity (k) against movements in the hinge member ( 12 ,  13 ),    said turbine blade ( 1 ) having a mass inertia factor (J turbine ) relatively to the hinge member ( 12 ,  13 ) and being adapted to move through said gaseous or liquideous flow, which has a flow direction essentially perpendicular to the rotational plane of said turbine blade ( 1 ), and has a varying flow velocity in this direction, such that the turbine is exposed to disturbance forces whose essential component has a disturbance frequency (ω disturbance ) which is composed of said angular frequency (ω rotation ), and    that said hinge member ( 12 ,  13 ) forms a teeter hinge having an eigenfrequency (ω resonance ), that is calculated at ω resonance ={square root}{square root over (k i Jturbin)},    characterised in that 
 the rigidity (k) of said hinge member ( 12 ,  13 ),  
 the mass inertia factor (J turbine ) of said turbine blade ( 1 ) and  
 the angular frequency (ω rotation )  
 have been selected such that the condition ω rotation ≠{square root}{square root over (k/Jturbin)} is fulfilled.  
   
     
     
         2 . A turbine according to  claim 1 , characterised in that the ratio of the angular frequency (ω rotation ) to the eigenfrequency of the teeter hinge (ω resonance ) is 0.9 at most.  
     
     
         3 . A turbine according to  claim 2 , characterised in that the ratio of the angular frequency (ω rotation ) to the eigenfrequency of the teeter hinge (ω resonance ) is at least 0.1.  
     
     
         4 . A turbine according to  claim 3 , characterised in that the ratio of the angular frequency (ω rotation ) to the eigenfrequency of the teeter hinge (ω resonance ) is at least 1.1.  
     
     
         5 . A turbine according to  claim 4 , characterised in that the ratio of the angular frequency (ω rotation ) to the eigenfrequency of the teeter hinge (ω resonance ) is 10.0 at most.  
     
     
         6 . A turbine according to any one of the preceding claims, characterised in that said hinge member ( 12 ,  13 ) includes dampers.  
     
     
         7 . A turbine according to any one of the preceding claims, characterised in that said spring elements ( 13 ) are progressive.  
     
     
         8 . A turbine according to any one of the preceding claims, characterised in that said spring elements ( 13 ) are pre-stressed.  
     
     
         9 . A wind turbine generator with a turbine according to any one of the preceding claims.  
     
     
         10 . A method to design a turbine adapted for a gaseous or liquideous working medium, in particular a wind turbine for a wind turbine generator, said turbine comprising a shaft ( 3 ), which is rotatable at a certain angular frequency (ω rotation ), a hub ( 2 ), on which at least one turbine blade ( 1 ) is attached, and a hinge member ( 12 ,  13 ) disposed between said shaft ( 3 ) and said hub ( 2 ) and comprising a bearing ( 12 ) and spring elements ( 13 ), together forming a rigidity (k) against movements in the hinge member ( 12 ,  13 ), said turbine blade ( 1 ) having a mass inertia factor (J turbine ) relatively to the hinge member ( 12 ,  13 ) and being adapted to move through said gaseous or liquideous flow, which has a flow direction essentially perpendicular to the rotational plane of said turbine blade ( 1 ) and has a varying flow velocity in this direction, such that the turbine is exposed to disturbance forces whose essential component has a disturbance frequency (ω disturbance ) which is composed of said angular frequency (ω rotation ), and that said hinge member ( 12 ,  13 ) forms a teeter hinge having an eigenfrequency (ω resonance ) , that is calculated at ω resonance ={square root}{square root over (k/Jturbin)}, 
 characterised in that the rigidity (k) of said hinge member ( 12 ,  13 ), 
 the mass inertia factor (J turbine ) of said turbine blade ( 1 ), and  
 the angular frequency (ω rotation ) are selected such that the condition ω rotation ≠{square root}{square root over (k/Jturbin)} is fulfilled.  
 
 
     
     
         11 . A method according to  claim 10 , characterised in that the rigidity (k) of said hinge ( 12 ,  13 ) is selected such that the condition ω rotation ≠{square root}{square root over (k/Jturbin)} is fulfilled at normal angular frequency (ω rotation ).