Effect of aspect ratio on cross-flow turbine performance
Aidan Hunt, Carl Stringer, Brian Polagye
备注：
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Hunt et al, J. Renewable Sustainable Energy 12, 054501 (2020) and may be found at https://doi.org/10.1063/5.0016753. Supplementary material can be found in the UW ResearchWorks archive at http://hdl.handle.net/1773/45618
Cross-flow turbines convert kinetic power in wind or water currents to mechanical power. Unlike axial-flow turbines, the influence of geometric parameters on turbine performance is not well-understood, in part because there are neither generalized analytical formulations nor inexpensive, accurate numerical models that describe their fluid dynamics. Here, we experimentally investigate the effect of aspect ratio - the ratio of the blade span to rotor diameter - on the performance of a straight-bladed cross-flow turbine in a water channel. To isolate the effect of aspect ratio, all other non-dimensional parameters are held constant, including the relative confinement, Froude number, and Reynolds number. The coefficient of performance is found to be invariant for the range of aspect ratios tested (0.95 - 1.63), which we ascribe to minimal blade-support interactions for this turbine design. Finally, a subset of experiments is repeated without controlling for the Froude number and the coefficient of performance is found to increase, a consequence of Froude number variation that could mistakenly be ascribed to aspect ratio. This highlights the importance of rigorous experimental design when exploring the effect of geometric parameters on cross-flow turbine performance.
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