3-D Computational Study of a Diffuser Augmented Micro Wind Turbine

Abstract

The present study focuses on the design optimization of a 3D DAMWT (Diffuser Augmented Micro Wind Turbine geometry). DAMWTS are compact devices with a swept area of only few square meters and energy production capacity of a few kilowatts. Their small size makes it convenient for domestic power generation. The box-shaped shroud makes it possible to stack multiple DAMWTS in an array configuration, thereby multiplying power output. 3-D CFD simulations were carried out using the k-ω SST turbulence model to compare the performance characteristics of different turbine geometries with a square inlet. With a constant shroud diffuser angle of 12 degrees as obtained in a previous study, the shroud nozzle angle and curvature were varied to obtain the maximum velocity factor and minimize flow stagnation at the inlet. Best performance was obtained with a nozzle angle of approximately 27 degrees and semi-concave curvature, with a velocity factor of 1.2. Further increase in nozzle angle resulted in a decline in performance and an increased flow stagnation. To analyze the influence of stacking on flow characteristics, a computational study of two DAMWTS placed horizontally next to each other was carried out. An investigation of the effectiveness of Vortex Generators in inhibiting flow stagnation at the inlet was also conducted.