Flow-driven rotor simulation of vertical axis tidal turbines: A comparison of helical and straight blades

• Published in: International journal of naval architecture and ocean engineering Vol. 6; no. 2; pp. 257 - 268
• Main Authors: Le, Tuyen Quang, Lee, Kwang-Soo, Park, Jin-Soon, Ko, Jin Hwan
• Format: Journal Article
• Language: Korean
• Published: 2014
• Subjects: Helical-bladed; Self-starting capability; Tidal steam generation; Flow-driven rotor simulation; Darrieus turbine; Torque fluctuation
• ISSN: 2092-6782; 2092-6790

In this study, flow-driven rotor simulations with a given load are conducted to analyze the operational characteristics of a vertical-axis Darrieus turbine, specifically its self-starting capability and fluctuations in its torque as well as the RPM. These characteristics are typically observed in experiments, though they cannot be acquired in simulations with a given tip speed ratio (TSR). First, it is shown that a flow-driven rotor simulation with a two-dimensional (2D) turbine model obtains power coefficients with curves similar to those obtained in a simulation with a given TSR. 3D flow-driven rotor simulations with an optimal geometry then show that a helical-bladed turbine has the following prominent advantages over a straight-bladed turbine of the same size: an improvement of its self-starting capabilities and reduced fluctuations in its torque and RPM curves as well as an increase in its power coefficient from 33% to 42%. Therefore, it is clear that a flow-driven rotor simulation provides more information for the design of a Darrieus turbine than a simulation with a given TSR before experiments.