EP-4737708-A2 - A ROTOR BLADE, NOISE REDUCTION MEANS FOR A ROTOR BLADE, AND METHOD FOR REDUCING NOISE FOR A ROTOR BLADE

EP4737708A2EP 4737708 A2EP4737708 A2EP 4737708A2EP-4737708-A2

Abstract

The present invention relates to a wind turbine rotor blade comprising a leading-edge section having a leading-edge; a trailing-edge section having a trailing-edge; a pressure-side surface and a suction-side surface extending from the leading-edge section and meeting at the trailing-edge section; and an aerodynamic structure, for reducing noise, provided at the trailing-edge section, wherein the aerodynamic structure comprises a plurality of pressure communication channels between the suction-side surface and the pressure-side surface; a camber line connecting the leading-edge section and the trailing-edge section and lying halfway between the pressure-side surface and the suction-side surface, wherein the camber line of the aerodynamic structure is tilted toward the suction-side surface with respect to a camber line of the rest of the wind turbine rotor blade.

Inventors

VAN CAMPENHOUT, Olaf Wilhelmus Gerardus
VAN NESSELROOIJ, Michiel
HARTOG, Friso Hans
Ragni, Daniele
AVALLONE, Francesco

Assignees

Mutech B.V.

Dates

Publication Date: 20260506
Application Date: 20240216

Claims (15)

A wind turbine rotor blade, wherein the wind turbine rotor blade comprises: - a leading-edge section having a leading-edge; - a trailing-edge section having a trailing-edge; - a pressure-side surface and a suction-side surface extending from the leading-edge section and meeting at the trailing-edge section; and - an aerodynamic structure, for reducing noise, provided at the trailing-edge section, wherein the aerodynamic structure comprises a plurality of pressure communication channels between the suction-side surface and the pressure-side surface; - a camber line connecting the leading-edge section and the trailing-edge section and lying half-way between the pressure-side surface and the suction-side surface, wherein the camber line of the aerodynamic structure is tilted toward the suction-side surface with respect to a camber line of the rest of the wind turbine rotor blade.
The wind turbine rotor blade of any preceding claim, wherein the camber line of the aerodynamic structure is tilted toward the suction-side surface with an angle of at least 1°, preferably between 1.5-10°.
The wind turbine rotor blade of claim 1, wherein the camber line of the aerodynamic structure is tilted toward the suction-side surface with an angle between 2-5°.
The wind turbine rotor blade of any of previous claims, wherein the plurality of pressure communication channels each have a generally continuous inner surface connected to the pressure side surface and/or the suction-side surface.
The wind turbine rotor blade of any of previous claim, wherein the plurality of pressure communication channels define a pressure communication channel number density that is increasing in the direction from the leading-edge section to the trailing-edge section.
The wind turbine rotor blade of any of the preceding claims, wherein the plurality of pressure communication channels has a first pressure communication channel and a second pressure communication channel, wherein the first pressure communication channel has an hourglass channel configuration (HGCC) and the second pressure communication channel has the HGCC, wherein the HGCC is formed by: - a first surface area formed on the suction-side surface and having a first size, - a second surface area formed on the pressure-side surface and having a second size, and - a third minimal surface area having a third size formed within the pressure communication channel and located between the first surface are and the second surface area, wherein the third size is smaller than the first size and than the second size.
The wind turbine rotor blade of claim 6, wherein the first and second size are in size of surface areas, preferably formed by a circle having a diameter between 0.5 - 2.0 mm; and/or wherein a surface area ratio between the third size and the first size is between 1:1 and 1:2; and/or wherein a surface area ratio between the third size and the second size is between 1:1 and 1:2.
The wind turbine rotor blade of any preceding claim, wherein the plurality of pressure communication channels comprises at least three different sizes of surface areas on the pressure-side surface and/or on the suction-side surface.
The wind turbine rotor blade of any preceding claim, wherein the plurality of pressure communication channels comprises at least one airflow blocking means configured between the suction-side surface and the pressure-side surface, wherein the at least one airflow blocking means is acoustically permeable, preferably the blocking means is located at the third minimal surface area.
The wind turbine rotor blade of any preceding claim, wherein the aerodynamic structure is an add-on attached to the trailing-edge section of the wind turbine rotor blade, or wherein the aerodynamic structure is integrally formed as the trailing-edge section of the wind turbine rotor blade.
The wind turbine rotor blade of any preceding claim, wherein the aerodynamic structure is forming the trailing-edge section and connected to rest of the wind turbine rotor blade using any or any combination of following means: (i) a butt joint, (ii) a socket at the suction-side surface, (iii) a socket at the pressure-side surface, (iv) a hinge, (v) a flexible connecting member, or (vi) flexible connecting sheet elements.
The wind turbine rotor blade of any preceding claim, wherein the plurality of pressure communication channels is irregularly distributed with at least three different spacings, preferably with at least four different spacings, more preferably with at least five different spacings, even more preferably with at least six different spacings.
The wind turbine rotor blade of any preceding claim, wherein the aerodynamic structure further comprises a serration at the trailing-edge.
A method of producing the wind turbine rotor blade of any preceding claim for noise reduction.
A wind turbine comprising: - a wind turbine tower having a top and a bottom; - a nacelle arranged at the top of the wind turbine tower; - a rotor hub rotatably mounted to the nacelle; - one or more wind turbine blades of claim 1 mounted to the rotor hub, wherein the wind turbine blades define a rotor plane; - a shaft coupled to the rotor hub; and - a generator coupled to the shaft, wherein the generator configured to transform a torque of the shaft into electrical power.

Description

TECHNICAL FIELD The present invention relates generally to a rotor blade, noise reduction means for a rotor blade, a wind turbine having rotor blades and methods for reducing noise for rotor blades. The invention specifically relates to reducing noise while having low drag at a trailing-edge portion of a wind turbine rotor blade by introducing pressure communication channels such as through-holes to the trailing-edge portion. The pressure communication channels can be provided to rotor blades, trailing-edge inserts, add-ons, or in any other forms that can reduce the noise of a rotor blade. BACKGROUND A wind turbine is a device that is designed to capture the energy of the wind and convert it into a form that can be used to generate electricity. The wind turbine includes a rotor that is mounted on a tower. The wind turbine includes a hub and one or more rotor blades that are mounted on the hub and are configured to generate lift when the wind blows over them. The lift generated by the rotor blades causes the rotor to rotate about an axis of the hub, and this rotational energy is then transmitted to a generator via a drivetrain. The generator converts the rotational energy into electrical energy, which is then transmitted to a power grid or stored in a battery system for later use. The wind turbine may also include various sensors and control systems that are used to optimize its performance and ensure that it is operating safely and efficiently. A wind turbine rotor blade has a leading edge, a trailing edge, and opposed suction side (upper) and pressure side (lower) side surfaces each beginning at the leading edge and terminating at the trailing edge. The wind turbine rotor blades create noise when they are operating. The rotor blades are moving through the air at a high speed, and this movement can create turbulence and vortices that produce noise. The materials used to make the rotor blades may also play a role in the amount of noise they generate, as some materials may be more prone to vibrating or producing other types of noise than others. Noise reduction is particularly important for on-shore wind turbines because they are built on land, as opposed to off-shore wind turbines which are built in bodies of water which are typically more remote from residential areas. For on-shore industry scale wind turbines, the noise problem is more problematic due to their high speed and physical scale. The acoustic power of the noise produced by a trailing-edge of a wind turbine blade scales exponentially to free-stream flow speed. It is hence important to have a proper noise reduction technology for installing large wind turbines with reasonable noise level at a location close to homes. Due to the potential health hazard and its societal impact, governing bodies are establishing regulations and guidelines on noise requirements for wind turbines. For example, in 2018, the World Health Organization has issued guidelines for wind turbine noise, recommending the day-evening-night-weighted Sound Pressure Level (SPL) to be below 45 dB. The level of noise hence determines the region where the wind turbines can be installed, or correspondingly the manner in which the wind turbine can be operated in order to comply with noise requirements in the surroundings. Turbulent boundary-layer trailing-edge noise (TBL-TE noise) is a dominant noise source of a wind turbine, and is caused by the interaction between the turbulent boundary layer of air that flows from the blade's leading-edge to its trailing-edge, which is the back edge of the blade where the air flows off of it. One way in which TBL-TE noise can be generated is through the formation of vortices at the trailing-edge of the blade. These vortices can create a fluctuating pressure field that radiates noise into the surrounding air. There are several factors that can influence the level of TBL-TE noise that is generated by a wind turbine rotor blade. These include the shape and size of the blade, the speed at which the blade is moving through the air, material of the blade, surface structure and property of the trailing-edge, and the properties of the air flow over the blade. A promising approach for reducing TBL-TE noise is using through-holes near the trailing-edges. The through-holes can be formed integrally in a wind turbine rotor blade or can be attached as an add-on to a trailing-edge of a wind turbine rotor blade. This through-hole approach uses a series of small through-holes, openings, or through-holes in or near a trailing-edge portion of a blade. The through-holes allow air pressure communication between the suction-side and the pressure-side surfaces. As a result, the pressure differences between the suction-side and pressure-side merge more smoothly at the trailing-edge compared to a blade without trailing-edge through-holes, which can help to reduce the level of turbulence and noise generated by the blade as it moves through the air. One advantage of trailing-edg