PIV measurements of flows around the wind turbines with a flanged-diffuser shroud

Abstract

The wind turbines with a flanged-diffuser shroud -so called "wind lens turbine"-are developed as one of high performance wind turbines by Ohya et al. In order to investigate the flow characteristics and flow acceleration, the paper presents the flow velocity measurements of a long-type and a compact-type wind turbines with a flanged-diffuser shroud by particle image velocimetry. In the case of the long type wind turbine, the velocity vectors of the inner flow field of the diffuser for turbine blades rotating and no blades rotating are presented at Reynolds number, 0.9×105. Furthermore the flow fields between with and without rotating are compared. Through the PIV measurement results, one can realize that the turbine blades rotating affects as suppress the disturbance and the flow separation near the inner wall of the diffuser. The time average velocity vectors are made on the average of the instantaneous velocity data. There are two large vortices in downstream region of the diffuser. One vortex behind the flange acts as suck in wind to the diffuser and raise the inlet flow velocity. Another large vortex appears in downstream. It might be act as blockage vortex of main flow. The large blockage vortex is not clear in the instantaneous velocity vectors, however it exists clearly in the time average flow field. The flow field around the wind turbine with a compact-type flanged-diffuser shroud is also investigated. The flow pattern behind the flange of the compact-type turbine is the same as the long-type one. It means that the effect of flow acceleration is caused by the unsteady vortices behind the flange. The comparison with CFD and PIV results of meridional time-average streamlines after the compact-type diffuser is also presented.

Effect of shroud on the performance of horizontal axis hydrokinetic turbines

“…The authors published several other papers on the numerical and experimental studies they did on the flanged diffuser (Abe and Ohya, 2004;Abe et al, 2006;Ohya and Karasudani, 2010;Ohya et al, 2008;Toshimitsu et al, 2008). Widnall (2009) following the method of Lewis (1991), developed an incompressible potential flow vortex method to study the flow field in a ducted wind turbine.…”

Study on an Axial Flow Hydraulic Turbine with Collection Device

“…Open and shallow water channels are constrained in the height direction. Accordingly, the type described here 2 International Journal of Rotating Machinery differs from conventional wind turbines [7][8][9][10][11] and hydraulic turbines [12][13][14][15] in which the diffuser section of the collection device is constant vertically and varies horizontally. Thus, the outer diameter of the runner is almost as large as the water depth.…”

Study on Performance Improvement of an Axial Flow Hydraulic Turbine with a Collection Device

“…Open channels with shallow water depth are constrained in the height direction. Accordingly, the hydraulic turbine described here differs from conventional wind turbines [8,[12][13][14] and hydraulic turbines [15][16][17][18] in which the diffuser section of the collection device is constant vertically and varies horizontally. The brim was attached to the left and right sides of the outlet of the collection device.…”