Flow dynamics inside the rotor of a three straight bladed cross-flow turbine

• Published in: Applied ocean research Vol. 69; pp. 138 - 147
• Main Authors: Somoano, M., Huera-Huarte, F.J.
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01-12-2017; Elsevier BV
• Subjects: Cross-flow turbines; Darrieus rotors; Dynamics; Flow; Fluid dynamics; H-rotors; Interactions; Profiles; Reynolds number; Rotation; Straight-bladed turbines; Studies; Turbine engines; Turbines; Vertical axis wind turbines; Cross-flow turbines; Straight-bladed turbines; Vertical axis wind turbines; H-rotors; Darrieus rotors
• ISSN: 0141-1187; 1879-1549
• DOI: 10.1016/j.apor.2017.10.007

•We describe a set-up especially designed for optical measurements inside the rotor.•The vortex dynamics inside the rotor of a CFT is crucial for the analysis of its performance.•For low TSRs, there is a strong interaction between upstream and downstream generated vorticity.•For intermediate TSRs, wakes show how blade velocity vectors have larger tangential components.•For high TSRs, wakes are dominated by the rotation of the turbine.
In this work we study experimentally the flow dynamics inside the rotor of a three straight-bladed Cross-Flow Turbine (CFT). The CFT model used in the experiments is based on symmetric NACA-0015 profiles, with a chord to rotor diameter ratio of 0.16. The turbine model was designed in order to quantify the flow inside and around the rotor using planar Digital Particle Image Velocimetry (DPIV). Tests were made by forcing the rotation of the turbine with a DC motor, which provided precise control of the Tip Speed Ratio (TSR), while being towed in a still-water tank at a constant turbine diameter Reynolds number of 6.1×104. The range of TSRs covered in the experiments went from 0.7 to 2.3.
The focus is given to the analysis of the blade-wake interactions inside the rotor. The investigation has allowed us to relate the interactions with the performance differences in this type of turbines, as a function of the operational tip speed ratio.