Data from: An experimental evaluation of the interplay between geometry and scale on cross-flow turbine performance

Cross-flow turbines harness kinetic energy in wind or moving water. Due to
their unsteady fluid dynamics, it can be difficult to predict the
interplay between aspects of rotor geometry and turbine performance. This
study considers the effects of three geometric parameters: the number of
blades, the preset pitch angle, and the chord-to-radius ratio. The
relevant fluid dynamics of cross-flow turbines are reviewed, as are prior
experimental studies that have investigated these parameters in a more
limited manner. Here, 223 unique experiments are conducted across an order
of magnitude of diameter-based Reynolds numbers (≈8×104–8×105) in which
the performance implications of these three geometric parameters are
evaluated. In agreement with prior work, maximum performance is generally
observed to increase with Reynolds number and decrease with blade count.
The broader experimental space clarifies parametric interdependencies; for
example, the optimal preset pitch angle is increasingly negative as the
chord-to-radius ratio increases. As these experiments vary both the
chord-to-radius ratio and blade count, the performance of different rotor
geometries with the same solidity (the ratio of total blade chord to rotor
circumference) can also be evaluated. Results demonstrate that while
solidity can be a poor predictor of maximum performance, across all scales
and tested geometries it is an excellent predictor of the tip-speed ratio
corresponding to maximum performance. Overall, these results present a
uniquely holistic view of relevant geometric considerations for cross-flow
turbine rotor design and provide a rich dataset for validation of
numerical simulations and reduced-order models.