Comprehensive evaluation of velocity distribution inside flanged straight converging-diverging diffuser models for small wind turbines
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Abstract
Performance of small wind turbines can be improved by adding an enclosure (diffuser) through velocity enhancement. Diffuser Augmented Wind Turbine uses different diffuser shapes to improve the performance. The flanged straight converging-diverging diffusers are still preferred by many researchers because of their various advantages. The major research works about these are based on parametric analysis in terms of global velocity values. However, it is important to study the detailed velocity distribution. This research paper presents the detailed velocity evaluation of nine straight converging-diverging diffusers in addition to parametric study. Computational Fluid Dynamics analysis is performed for all model (S1-S9) designed using Design of Experiments. Four variables - inlet diameter, converging section, diverging section lengths and exit diameter are considered at three levels. The throat diameter and flange height are kept as constant for all models. Flow simulations are carried out at an inlet wind velocity of 7 m/s using turbulence model using ANSYS 2022 R1. Velocity path lines, local velocity ratios, average radial velocities and radial velocity variations are evaluated. Among these nine models, model S3 is observed with better average radial velocity and less radial velocity variation. Models S7, S8 and S9 are observed with poor performance.
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