CFD Simulation of a Hybrid Vertical Axis Wind Turbine

Challenge

Lift-type vertical-axis rotors are efficient at speed but struggle to self-start, while drag-type rotors start easily but limit efficiency. A hybrid rotor combines both, but the two elements disturb each other’s flow, and blade incidence changes continuously through each revolution. As a result, performance cannot be predicted by treating either rotor on its own.

Approach

Transient sliding-mesh CFD resolved the rotating hybrid rotor over multiple revolutions. Instantaneous blade loading, torque variation with azimuth angle and wake evolution were analysed to identify how each rotor element contributes to, or detracts from, overall performance.

Key Findings

• The drag-type element supplied most of the torque at low rotational speed, improving self-starting, while the lift-type blades dominated power production at higher speeds.
• Blade loading peaked in the upwind half of the revolution. Downwind blades operated in the wake of the rotor and contributed noticeably less torque.
• The combination of azimuthal loading variation and element interaction produced periodic torque ripple, a key input for drivetrain and structural design.

Deliverables

Transient flow animations, torque and loading variation with azimuth, wake analysis and aerodynamic recommendations for hybrid vertical-axis wind-turbine development.