An Experimental Investigation of Wake Characteristics and Power Generation Efficiency of a Small Wind Turbine under Different Tip Speed Ratios

Yu-Ting Wu, Chang-Yu Lin and Che-Ming Hsu
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Yu-Ting Wu: Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan
Chang-Yu Lin: Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan
Che-Ming Hsu: Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan

Energies, 2020, vol. 13, issue 8, 1-19

Abstract: We carried out a wind tunnel experiment to examine the power generation efficiency of a stand-alone miniature wind turbine and its wake characteristics at different tip speed ratios (TSRs) under the same mean inflow velocity. Resistors in the electrical circuit were adjusted to control the TSRs to 0.9, 1.5, 3.0, 4.1, 5.2, and 5.9. The currents were measured to estimate the turbine power outputs versus the TSRs and then establish the actual power generation coefficient C p distribution. To calculate the mechanical power coefficient, a new estimation method of the mechanical torque constant is proposed. A reverse calibration on the blade rotation speed was performed with given electrical voltages and currents that are used to estimate the mechanical power coefficient C p, mech . In the experiment, the maximum C p,mech was approximately 0.358 (corresponding to the maximum C p of 0.212) at the TSR of 4.1. Significant findings indicate that the turbine at the TSR of 5.2 produces a smaller torque but a larger power output compared with that at the TSR of 3.0. This comparison further displays that the turbine at the TSR of 5.2, even with larger power output, still produces a turbine wake that has smaller velocity deficits and smaller turbulence intensity than that at the TSR of 3.0. This behavior demonstrates the significance of the blade-rotation control (i.e., pitch regulation) system to the turbine operation in a large wind farm for raising the overall farm power productivity.

Keywords: Cobra probe; power coefficient; power output; tip speed ratio; wake measurement; wind tunnel experiment (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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