Innovations like the Leading Edge Tubercle on wind turbine blades improve efficiency and performance. These tubercles have little rounded edges at their leading edge, inspired by humpback whale flippers. The biomimetic design reduces turbulence and stall, allowing the blade to function in a broader wind speed range. Tubercles interrupt flow separation and reduce drag, resulting in more uniform lift distribution along the blade, boosting the capture of energy and turbine efficiency.

Given the reference paper entitled “ Leading edge tubercle on wind turbine blade to mitigate problems of stall, hysteresis, and laminar separation bubble [1] “, CFD simulation is carried out to model the leading-edge tubercle effect on turbine blades.

• Reference [1]: Joseph, Jeena, and A. Sathyabhama. “Leading edge tubercle on wind turbine blade to mitigate problems of stall, hysteresis, and laminar separation bubble.” Energy Conversion and Management255 (2022): 115337.

Figure 1: . Schematic of baseline blade (BB) and tubercle blade [1]

Simulation Process

The wavy shape of the leading edge is designed utilizing Spaceclaim software. In the second step, Fluent Meshing software takes the lead and generates 4031516 cells over the domain. The extended domain around the blade is necessary to capture the wakes formed behind the blade. The K-omega SST turbulence model is employed because it brings benefits of K-epsilon features near the wall regions and K-omega features far behind the blade. Further, air enters with a positive angle of attack toward the blade.

Post-Processing

Biomimetic design is supported by the CFD study of the Leading Edge Tubercle wind turbine blade, which shows interesting aerodynamic behavior. The velocity lines show a complicated flow pattern, with speeds ranging from 0 to 14.013 m/s and clear wake features farther downstream of the blade. Most importantly, the tubercles organize vortical structures that successfully separate flows, which is very similar to how a humpback whale’s flippers work. The blue color of the wake area shows lower speeds of about 2 to 4 m/s, which suggests that the tubercles effectively prevent flow detachment and reduce turbulent energy losses compared to other blade designs.

Figure 2: Velocity & pressure field around Leading Edge blade

The pressure distribution visualization, which shows pressures from -125.662 Pa to 7.83 Pa, supports the usefulness of the tubercles even more. The changing pressure zones along the leading edge, which can be seen most clearly in the red and yellow parts of the pressure curve, show that counter-rotating vortices are forming between the tubercle peaks. The K-omega SST turbulence model’s predictions across 4,031,516 mesh cells, along with this pressure pattern, show how the biomimetic changes form a series of parallel streamwise vortices that energize the boundary layer. This kind of flow behavior explains why the blade has better stall resistance and a wider operational envelope. These are important benefits for wind turbines that need to work the same way in all kinds of wind situations.