Free-air performance tests of a 5-metre-diameter Darrieus turbine

A five-meter-diameter vertical-axis wind turbine has been tested at the Sandia Laboratories Wind Turbine Site. The results of these tests and some of the problems associated with free-air testing of wind turbines are presented. The performance data obtained follow the general trend of data obtained in extensive wind tunnel tests of a 2-meter-diameter turbine. However, the power coefficient data are slightly lower than anticipated. The reasons for this discrepancy are explored along with comparisons between experimental data and a computerized aerodynamic prediction model