초록 ▼

The invention discloses versions of a horizontal axis wind turbine and methodologies for the design of wind turbines, which are capable of extracting both kinetic and thermal energy from the wind. The wind turbines disclosed use a large diameter forward inlet fairing to accelerate the airflow to the

The invention discloses versions of a horizontal axis wind turbine and methodologies for the design of wind turbines, which are capable of extracting both kinetic and thermal energy from the wind. The wind turbines disclosed use a large diameter forward inlet fairing to accelerate the airflow to the more effective outer radii of the turbine rotor where the airflow is constrained by an airfoil-shaped flow control ring. This serves to prevent rotor tip losses, to inhibit wake expansion, and to accelerate the airflow through the turbine. A similarly large diameter aft pressure recovery fairing promotes rotation and contraction of the wake downstream of the turbine. Further methodologies for optimization and an algorithm for detail design are disclosed.

대표청구항 ▼

1. A horizontal axis wind turbine comprising: a forward central portion including a streamlined inlet fairing attached to a tower but free to rotate about the vertical axis of said tower allowing for alignment of said wind turbine with the wind, the purpose of said inlet fairing is for reducing the

1. A horizontal axis wind turbine comprising: a forward central portion including a streamlined inlet fairing attached to a tower but free to rotate about the vertical axis of said tower allowing for alignment of said wind turbine with the wind, the purpose of said inlet fairing is for reducing the flow area thereby causing an acceleration of the airflow velocity and furthermore redirecting the airflow to the more effective outer radii of the wind turbine;an aft central portion including an aft streamlined fairing of a diameter approximately equal to said forward inlet fairing, the purpose of which is to provide for a smooth aerodynamic pressure recovery of the airflow aft of the wind turbine;a plurality of conventional airfoil-shaped rotor blades attached to and extending radially out from said aft streamlined fairing all of which are free to rotate about the horizontal axis of the wind turbine; andan outer airfoil-shaped flow control ring with the lower pressure (suction) side of the airfoil oriented to the outside of the ring and the higher (positive) pressure side of the airfoil forming the inner surface of the ring which is attached to the tips of and rotating with said rotor blades;whereby the airflow entering the wind turbine is accelerated and therefore of higher dynamic pressure to react with said rotor blades and furthermore the airflow is constrained at the more effective outer radii of the wind turbine and accelerated into the aft slipstream causing an increase in the slipstream rotation thereby increasing the overall efficiency and power extraction of the wind turbine;wherein the power coefficient of the wind turbine is maximized based on the following equality: CP=ηTsasai[2(1−ai1.5)−CD],whereCp is the power coefficient defined as CP=W.outqV1⁢A2,where{dot over (W)}out is the power extracted by the wind turbine,ρ is the density of the air,V1 is the free stream velocity of the airflow,A is the area swept by the wind turbine,V2 is the minimum velocity of the airflow as it approaches the wind turbine,ai is the inflow velocity ratio equal to V2/V1, which is evaluated by the equality ai=[1−0.5(CT+CD)]2/3,whereCT is the thrust coefficient equal to Fn/(qA),CD is the drag coefficient equal to (DC+DO+DI)/(qA)Fn is the total normal force acting on said rotor blades,DC is the combined drag force of said forward inlet and said aft streamlined fairings,DO is the drag force of said outer flow control ring,DI is the accumulated intersection drag of said rotor blades,q is the dynamic pressure of the airflow equal to ρV12/2,ηTs is the efficiency at a given annular element of said rotor blades, which is evaluated by the equality ηTs=LD-λrai⁢asLD+ai⁢asλr,whereL/D is equal to the local lift to drag ratio at a given annular element of said rotor blades,λr is equal to the local speed ratio at a given annular element of said rotor blades which is defined as λr=Ωr/V1,r is the local radius of the given annular element of said rotor blades,Ω is the angular velocity of said rotor blades,as is the flow acceleration factor evaluated by the equality as=11-(rsR)2,wherers is the outer radius of said streamlined inlet fairing, andR is the inner radius of said outer flow control ring. 2. A horizontal axis wind turbine according to claim 1, wherein said rotor blades are furthermore configured to produce a thrust coefficient, CT equal to 1.20+/−10%, in order to achieve an optimum inflow velocity ratio, ai equal to 0.54+/−10%. 3. A horizontal axis wind turbine comprising: a forward central portion including a streamlined inlet fairing for the purpose of reducing the flow area thereby causing an acceleration of the airflow velocity while furthermore redirecting the airflow to the more effective outer radii of the wind turbine;a plurality of conventional airfoil-shaped rotor blades attached to and extending radially out from said forward inlet fairing all of which are free to rotate about the horizontal axis of the wind turbine;an aft central portion including an aft streamlined fairing of a diameter approximately equal to said forward inlet fairing and which is attached to a tower but free to rotate about the vertical axis of said tower allowing for alignment of the wind turbine with the wind, the purpose of said aft streamlined fairing is to provide for a smooth aerodynamic pressure recovery of the airflow aft of the wind turbine; andan outer airfoil-shaped flow control ring with the lower pressure (suction) side of the airfoil oriented to the outside of the ring and the higher (positive) pressure side of the airfoil forming the inner surface of the ring which is attached to the tips of and rotating with said rotor blades;whereby the airflow entering the wind turbine is accelerated and therefore of higher dynamic pressure to react with said rotor blades and furthermore the airflow is constrained at the more effective outer radii of the wind turbine and accelerated into the aft slipstream causing an increase in the slipstream rotation thereby increasing the overall efficiency and power extraction of the wind turbine; wherein the power coefficient of the wind turbine is maximized based on the following equality: CP=ηTsasai[2(1−ai1.5)−CD],whereCP is the power coefficient defined as CP=W.outq⁢⁢V1⁢A2,where{dot over (W)}out is the power extracted by the wind turbine,ρ is the density of the air,V1 is the free stream velocity of the airflow,A is the area swept by the wind turbine,V2 is the minimum velocity of the airflow as it approaches the wind turbine,ai is the inflow velocity ratio equal to V2/V1, which is evaluated by the equality ai=[1−0.5(CT+CD)]2/3,whereCT is the thrust coefficient equal to Fn/(qA),CD is the drag coefficient equal to (DC+DO+DI)/(qA)Fn is the total normal force acting on said rotor blades,DC is the combined drag force of said forward inlet and said aft streamlined fairings,DO is the drag force of said outer flow control ring,DI is the accumulated intersection drag of said rotor blades,q is the dynamic pressure of the airflow equal to ρV12/2,ηTs is the efficiency at a given annular element of said rotor blades, which is evaluated by the equality ηTs=LD-λrai⁢asLD+ai⁢asλr,whereL/D is equal to the local lift to drag ratio at a given annular element of said rotor blades,λr is equal to the local speed ratio at a given annular element of said rotor blades which is defined as λr=Ωr/V1,r is the local radius of the given annular element of said rotor blades,Ω is the angular velocity of said rotor blades,as is the flow acceleration factor evaluated by the equality as=11-(rsR)2,wherers is the outer radius of said streamlined inlet fairing, andR is the inner radius of said outer flow control ring. 4. A horizontal axis wind turbine according to claim 3, wherein said rotor blades are furthermore configured to produce a thrust coefficient, CT equal to 1.20+/−10%, in order to achieve an optimum inflow velocity ratio, ai equal to 0.54+/−10%.