How Tiny Bumps on Wind Turbine Blades Reduce Noise

This patent describes how small, specially shaped bumps or grooves on a wind turbine blade's underside can reduce noise by controlling airflow and preventing turbulence.

What it covers

This patent covers a wind turbine blade assembly that includes small features called "micro boundary layer energizers" on its pressure side. These energizers, which can be vanes, grooves, dents, or dimples (Claim 1), are placed in a specific "outboard area" of the blade, between 0% and 50% of the blade's length from the tip (Claim 1). Their job is to create small swirls of air, called "longitudinal vortices," that mix the air near the blade's surface (Claim 1, Claim 2). This mixing helps the airflow stick to the blade longer, delaying "separation of a boundary layer" at low angles of attack (Claim 1). By doing this, the energizers reduce unwanted noise generated by the blade. For example, a wind turbine blade might have a series of 1-15mm high wedge-shaped bumps (Claim 6, Claim 10) positioned 20-55% of the way back from the leading edge (Claim 1) to smooth the airflow.

What it doesn't cover

• —It does not cover micro boundary layer energizers placed on the suction side of the rotor blade.
• —It does not cover energizers positioned in the inboard portion of the blade, only the outboard area between 0%-50% from the blade tip (Claim 1).
• —It does not cover energizers placed downstream from the start of a "separation bubble" (Claim 1).
• —It does not cover energizers that are not specifically shaped and positioned to delay boundary layer separation at a low angle of attack (Claim 1).
• —It does not cover energizers with x/c ratios outside the 20-55% range (Claim 1).

The clever bit

The novelty lies in precisely shaping and positioning these tiny "micro boundary layer energizers" on the *pressure side* of the blade to specifically generate longitudinal vortices. This targeted approach delays airflow separation at low angles of attack, which directly reduces aerodynamic noise without significantly impacting performance.

Why it matters

Wind turbines are a key part of renewable energy, but noise can be a significant issue for nearby communities. This patent offers a way to make wind turbines quieter by improving how air flows over the blades. Reducing noise allows wind farms to be located closer to populated areas or to operate more efficiently without causing disturbances, potentially increasing the adoption of wind power.

Real-world examples

• 1.Modern large-scale wind turbine blades
• 2.GE Renewable Energy wind turbines
• 3.Aerodynamic noise reduction features on aircraft wings