Abstract:

This study investigates the influence of immersion depth on the performance and stability of horizontal-axis hydrokinetic turbines operating near the free surface. Tests were carried out in the IPT’s Towing Tank at depths of 1D, 2D, 4D, 6D, and 8D, where D is the rotor diameter. Torque and rotational speed measurements were used to construct power coefficient (Cp) curves as a function of tip speed ratio (TSR). Each condition was tested in 10 repeated runs; statistical uncertainty was assessed via the standard error of the mean (SEM) and significance evaluated through Student’s t-test with Welch correction. The shallowest configuration (1D) consistently yielded the highest Cp, up to 13% above that obtained at 8D. In contrast, depths away from the extremes ( 4D and 6D) exhibited lower mean performance; for the intermediate cases (4D and 6D), reductions reached up to 14% relative to the deep reference (8D). The 2D case also showed elevated variability, consistent with stronger free-surface interactions. These findings demonstrate that installation depth affects both mean power extraction and operational stability, reinforcing its role as a critical design parameter for turbines in shallow or confined environments.

Referência:

BERTOLINA, Ramiro M.; MENDES, Rafael Castilho Faria; BRASIL JUNIOR, Antonio C.P.; OLIVEIRA, Taygoara F.; CASTRO, Felipe Santos de; KOGISHI, André Mitsuo; DONALD, Ramsay Mac; SIRIANNI, Corrado. Experimental evaluation of the performance of hydrokinetic turbines in a towing tank: influence of depth relative to the free surface. In: INTERNATIONAL CONGRESS OF MECHANICAL ENGINEERING, COBEM, 28., 2025, Curitiba. Proceedings… 6p.

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https://escriba.ipt.br/pdf_restrito/180048.pdf