Vertical-axis wind turbine experiments at full dynamic similarity

Abstract

Laboratory experiments were performed on a geometrically scaled vertical-axis wind turbine model over an unprecedented range of Reynolds numbers, including and exceeding those of the full-scale turbine. The study was performed in the high-pressure environment of the Princeton High Reynolds number Test Facility (HRTF). Utilizing highly compressed air as the working fluid enabled extremely high Reynolds numbers while still maintaining dynamic similarity by matching the tip speed ratio (defined as the ratio of tip velocity to free stream, $\unicode[STIX]{x1D706}=\unicode[STIX]{x1D714}R/U$) and Mach number (defined at the turbine tip, $Ma=\unicode[STIX]{x1D714}R/a$). Preliminary comparisons are made with measurements from the full-scale field turbine. Peak power for both the field data and experiments resides around $\unicode[STIX]{x1D706}=1$. In addition, a systematic investigation of trends with Reynolds number was performed in the laboratory, which revealed details about the asymptotic behaviour. It was shown that the parameter that characterizes invariance in the power coefficient was the Reynolds number based on blade chord conditions ($Re_{c}$). The power coefficient reaches its asymptotic value when $Re_{c}>1.5\times 10^{6}$, which is higher than what the field turbine experiences. The asymptotic power curve is found, which is invariant to further increases in Reynolds number.

A double-multiple streamtube model for vertical axis wind turbines of arbitrary rotor loading

“…The rotor was designed to be similar to the one used in the Field Laboratory for Optimized Wind Energy (FLOWE) (Dabiri, 2011). More details related to the experimental campaign can be found in Miller et al (2018).…”

A Double Multiple Streamtube model for Vertical Axis Wind Turbines of arbitrary rotor loading

“…In order to compare the effect of the two momentum theories in the DMST, an experimental campaign of VAWT performace was carried out at Princeton's High Reynolds number Test Facility (HRTF). More details related to this campaign can be found in Duvvuri et al (2018) and Miller et al (2018).…”

Implications of biofouling on cross-flow turbine performance

“…The Reynolds number for these experiments is defined in terms of the blade chord length, c, as where ν is the kinematic viscosity of water. For all experiments, Re c was 2.7 × 10 4 , which is likely in a transitional regime [21,22].…”

“…It was also found that turbine power output was enhanced by the roughened blade surface below a critical Reynolds number, but degraded above that value. This is indicative of the general sensitivity of cross-flow turbine performance to Reynolds number [21,22]. Here, we evaluate the changes in turbine power output and structural loads as barnacle fouling progresses from initial colonization to maturity.…”