A Study on a Casing Consisting of Three Flow Deflectors for Performance Improvement of Cross-Flow Wind Turbine

Abstract

We investigated the effective use of cross-flow wind turbines for small-scale wind power generation to increase the output power by using a casing, which is a kind of wind-collecting device, composed of three flow deflector plates having the shape of a circular-arc airfoil. Drag-type vertical-axis wind turbines have an undesirable part of about half of the swept area where the inflow of wind results in low output performance. To solve this problem, we devised a casing consisting of three flow deflector plates, two of which were to block the unwanted inflow of wind and the remaining flow deflector plate having an angle of attack with respect to the wind direction to increase the flow toward the rotor. In this study, output performance experiments using a wind tunnel and numerical fluid analysis were conducted on a cross-flow wind turbine with three flow deflector plates to evaluate the effectiveness of the casing on output performance improvement. As a result, it was confirmed that the casing could improve the output performance of the cross-flow wind turbine by approximately 60% at the maximum performance point and could also maintain the output performance about 50% higher compared to the bare cross-flow wind turbine without the casing within a deviation angle of ±10 degrees, even when the casing direction was inclined against the wind direction due to changes in wind direction.

Investigation of a cross-flow wind turbine with frontal deflector

“…The maximum value of Cp is around 0.19, which almost matches with that of the examined in this paper arc-shaped deflector (Figure 6.1(a) red curve). The calculated power coefficient of a bare turbine with a 2D k-ω turbulence model (w/o TFD (EFD) the straight dashed line on Figure 6.1(b)[26]) predicts quite well the value of Cp at the peak point of the examined in this paper bare turbine (Figure6.1(c) orange curve). The maximum deviation of Cp max is around 0.005.…”

“…Comparing the data with different sources from the reviewed literature: power coefficient as a function of the development angle of the arc-shaped deflector (a) ; power coefficient as a function of the inclination angle of the vanes of a frontal deflector, composed of three vanes -CFD and physical experiment (EFT) (b)[26] ; power and torque coefficients as a function of the TSR of the examined frontal deflectors (c) ; power and torque coefficients as a function of the TSR for different inclination angles of a frontal deflector[27] (d).…”