Aerodynamic loads simulation of a new concept 250 kW floating vertical-axis wind turbine: An experimental study in wind tunnel

This study addressed the critical challenge of Reynolds number scale effects inherent in wind tunnel model test of a novel 250 kW floating vertical-axis wind turbine (VAWT). Traditional geometric scaling reduces model Reynolds numbers by orders of magnitude, diminishing aerodynamic loads and power output compared to full-scale conditions. To resolve this discrepancy, a high Reynolds number extrapolation method integrating experimental and numerical approaches was proposed. A 1:20 scaled model, fabricated with carbon fiber and Q235 steel, underwent systematic model test in Northwestern Polytechnical University’s NF-3 low-speed wind tunnel. Aerodynamic loads were measured under operational conditions and extreme shutdown scenarios. By amplifying experimental wind speeds while maintaining TSR similarity, empirical correlations between thrust coefficients and Reynolds numbers were established, enabling extrapolation to full-scale Re ( 1 0 6 ). Experimental results revealed a linear relationship between thrust coefficients and log (Re), validating the extrapolation framework. Simultaneously, a vortex-based numerical model was validated against experimental data, identifying significant wind tunnel blockage effects at high rotor speeds ( > 500 rpm) that reduce thrust by 30%. During shutdown, maximum thrust occurred at 80 deg azimuth angle due to minimal tower shadowing, while 0 deg and 60 deg azimuth angles minimized loads. This methodology provides critical datasets for full-scale VAWT performance assessment and floating foundation design. • This study addressed the Reynolds number scale effect in VAWT wind tunnel model test. • 1:20 scaled model with carbon fiber-Q235 steel hybrid ensured test integrity. • High-Re extrapolation resolved scale effects via linear Cx vs log(Re). • Blockage effect reduced thrust in wind tunnel tests (experimentally quantified). • Max shutdown thrust at 80 °azimuth; minima at 0°/60° due to tower shadowing.