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Computational Optimization of Adaptive Hybrid Darrieus Turbine: Part 1

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Centre for Nanofibers and Nanotechnology, Department of Mechanical Engineering, National University of Singapore, Engineering Drive 3, Singapore 117587, Singapore
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Energy Research Institute, Nanyang Technological University, Innovation Centre, 71 Nanyang Drive, Singapore 638075, Singapore
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NTUitive, Nanyang Technological University, Innovation Centre, 71 Nanyang Drive, Singapore 638075, Singapore
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School of Science and Technology, Singapore University of Social Sciences, 463 Clementi Rd, Singapore 59949, Singapore
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Singapore Institute of Manufacturing Technology, Surface Technology group, A*STAR, Fusionopolis way 2, Innovis, Singapore 138634, Singapore
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Author to whom correspondence should be addressed.
Fluids 2019, 4(2), 90; https://doi.org/10.3390/fluids4020090
Received: 17 April 2019 / Revised: 10 May 2019 / Accepted: 16 May 2019 / Published: 17 May 2019
(This article belongs to the Special Issue Flow-Based Optimization of Products or Devices)
Darrieus-type Vertical Axis Wind Turbines (VAWT) are promising for small scale decentralized power generation because of their unique advantages such as simple design, insensitive to wind direction, reliability, and ease of maintenance. Despite these positive aspects, poor self-starting capability and low efficiency in weak and unsteady winds deteriorate further development. Adaptive Hybrid Darrieus Turbine (AHDT) was proposed by the author in the past study as a potential solution to enhance low wind speed characteristics. The objective of the current research is to optimize the parameters of AHDT. AHDT integrates a dynamically varying Savonius rotor with a Darrieus rotor. A fully detailed 2D numerical study employing Reynold-Averaged Navier Stokes (RANS) is carried out to investigate the impact of the Darrieus rotor diameter (DR) on the Savonius rotor (DT) with regard to hybrid turbine performance. The power coefficient of the Darrieus rotor is evaluated when the Savonius rotor is in the closed condition (cylinder) of various diameters. The influence of Reynolds number (Re) on the torque coefficient is examined. Power loss of 58.3% and 25% is reported for DR/DT ratio of 1.5 and 2 respectively for AHDT with solidity 0.5 at 9 m/s. The flow interaction between the Savonius rotor in closed configuration reveals the formation of von Karman vortices that interact with Darrieus blades resulting in flow detachment. An optimum diametrical ratio (DR/DT) of 3 is found to yield the maximum power coefficient of the Darrieus rotor. View Full-Text
Keywords: wind turbine; Savonius; Darrieus; power coefficient; torque coefficient; wake wind turbine; Savonius; Darrieus; power coefficient; torque coefficient; wake
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Mohan Kumar, P.; Surya, M.R.; Sivalingam, K.; Lim, T.-C.; Ramakrishna, S.; Wei, H. Computational Optimization of Adaptive Hybrid Darrieus Turbine: Part 1. Fluids 2019, 4, 90.

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