Benchmark experiments for simulations of a vertical axis wind turbine

Driven by the need to verify a CFD model of a novel vertical axis wind turbine (VAWT) device, a 1.6m diameter prototype was designed, built to a high specification and tolerance and then tested in the industry standard MIRA wind tunnel over the full wind range that might be expected in an urban environment. Although the original intention was simply to provide data to verify a CFD model of the specific device – documented separately – it was realised that given (a) the repeatability and quality of the experimental data, and (b) its utility for the authors in verifying their CFD simulations, the data itself might well form the basis for a requirement for a reliable benchmark for the wind engineering community in assessing CFD simulation technology against a specific VAWT device design with the complexity of a housing. The experiments cover a full range of operational conditions for a specific design including the variation of wind speed, wind direction, tip speed ratio and blade pitch angle, recorded in the experiments as well as the torque output and the pressure levels at a range of specific locations. Over 60 tests were carried out in such a way as to assess the repeatability of the measurements; the results showed an overall remarkable degree of consistency.