Twin marine hydrokinetic cross-flow turbines in counter rotating configurations: A laboratory-scaled apparatus for power measurement

Minh N. Doan, Yuriko Kai, Shinnosuke Obi

Research output: Contribution to journalArticlepeer-review

Abstract

This article proposes an experimental apparatus design to measure the power of a cross-flow marine hydrokinetic turbine system operating in a laboratory water tunnel. Data, from one Hall sensor output signal, was processed to capture the three types of torque exerted on the turbines: mechanical loss, brake, and hydrodynamic torque. The method was then applied to compare the power of a twin turbine system in different counter-rotating configurations. Controlled by a hysteresis brake, the tip-speed-ratio was varied in a constant freestream velocity of 0.316 m/s. While the braking torque was independent of the speed, the mechanical loss was found to depend on the system rotational speed and the amount of mass mounted on the mechanical support. In a counter-rotating configuration, the turbines were synchronized through a pair of spur gears and timing pulleys. Operating at the average chord based Reynolds number of 8000, each turbine had three NACA0012 blades mounted at 15 pitch angle. The power coefficient results of 8 turbine configurations showed the tendency of power enhancement of counter-rotating configurations due to blade interaction and increase in blockage ratio. Comparison of the results suggested direct application in a river flow scenario and manipulation of the blade interaction for optimal power production.

Original languageEnglish
Article number918
Pages (from-to)1-16
Number of pages16
JournalJournal of Marine Science and Engineering
Volume8
Issue number11
DOIs
Publication statusPublished - 2020 Nov

Keywords

  • Counter-rotating
  • Cross-flow turbine
  • Marine hydrokinetic
  • Power measurement
  • Vertical-axis
  • Water tunnel

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Water Science and Technology
  • Ocean Engineering

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