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Title:: CFD Simulation of Fixed and Variable Pitch Vertical Axis Tidal Turbine

Author(s):: Qihu Sheng; Syed Shah Khalid; Zhimin Xiong; Ghazala Sahib and Liang Zhang

Abstract:: In this paper, hydrodynamic analysis of vertical axis tidal turbine (both fixed pitch & variable pitch) is numerically analyzed. Two-dimensional numerical modeling & simulation of the unsteady flow through the blades of the turbine is performed using ANSYS CFX, hereafter CFX, which is based on a Reynolds-Averaged Navier-Stokes (RANS) model. A transient simulation is done for fixed pitch and variable pitch vertical axis tidal turbine using a Shear Stress Transport turbulence (SST) scheme. Main hydrodynamic parameters like torque T, combined moment CM, coefficients of performance CP and coefficient of torque CT, etc. are investigated. The modeling and meshing of turbine rotor is performed in ICEM-CFD. Moreover, the difference in meshing schemes between fixed pitch and variable pitch is also mentioned. Mesh motion option is employed for variable pitch turbine. This article is one part of the ongoing research on turbine design and developments. The numerical simulation results are validated with well reputed analytical results performed by Edinburgh Design Ltd. The article concludes with a parametric study of turbine performance, comparison between fixed and variable pitch operation for a four-bladed turbine. It is found that for variable pitch we get maximum CP and peak power at smaller revolution per minute N and tip sped ratio λ.

Memo:: This research is financially supported by National “863” Program (Grant No.2007AA05Z450, No. 200805040), National S&T Program (No.2008BAA15B04), 2010 National Ocean Special Funds (No.ZJME2010GC01, No. ZJME2010CY01, No.GHME2010GC02). And it is supported by the Fundamental Research Funds of the Universities (No.HEUCF130105). And it is also supported by “111 project” foundation (No. B07019) from State Administration of Foreign Experts Affairs of China and Ministry of Education of China.