Yaw operation of a shrouded horizontal axis hydrokinetic turbine

A 19.8 cm diameter horizontal axis hydrokinetic turbine and two shrouds are designed, manufactured and tested in a water tunnel. Effect of yaw angle on performance of the shrouded and unshrouded turbine is investigated experimentally. Consistent power coefficients for the shrouded and unshrouded turbine are obtained for the entire range of tip speed ratio. Output power of the unshrouded turbine is observed to decrease in off-axis flows. Reduction is negligible up to 10° yaw angle but increases as yaw angle increases. The turbine with the convergent-divergent shroud model experiences negligible performance loss in yaw operation compared to the unshrouded turbine. Maximum reduction in performance of the turbine with the shroud in yawed flows is 6% at three Reynolds numbers investigated. This is 17% less than the power reduction of the unshrouded turbine.