Velocity Augmentation Model for an Empty Concentrator-Diffuser-Augmented Wind Turbine and Optimisation of Geometrical Parameters Using Surface Response Methodology

Abstract

Wind energy, renowned for cost-effectiveness and eco-friendliness, addresses global energy needs amid fossil fuel scarcity and environmental concerns. In low-wind speed regions, optimising wind turbine performance becomes vital and achievable by augmenting wind velocity at the turbine rotor using augmentation systems such as concentrators and diffusers. This study focuses on developing a velocity augmentation model that correctly predicts the throat velocity in an empty concentrator-diffuser-augmented wind turbine (CDaugWT) design and determines optimal geometrical parameters. Utilising response surface methodology (RSM) in Design Expert 13 and computational fluid dynamics (CFD) in ANSYS Fluent, 86 runs were analysed, optimising parameters such as diffuser and concentrator angles and lengths, throat length, and flange height. The ANOVA analysis confirmed the model’s significance (p < 0.05). Notably, the interaction between the concentrator’s length and the diffuser’s length had the highest impact on the throat velocity. The model showed a strong correlation (R2 = 0.9581) and adequate precision (ratio value of 49.655). A low coefficient of variation (C.V.% = 0.1149) highlighted the model’s reliability. The findings revealed a 1.953-fold increase in inlet wind speed at the throat position. Optimal geometrical parameters for the CDaugWT included a diffuser angle of 10°, concentrator angle of 20°, concentrator length of 375 mm (0.62Rth), diffuser length of 975 mm (1.61Rth), throat length of 70 mm (0.12Rth), and flange height of 100 mm (0.17Rth) where Rth is the throat radius. A desirability value of 0.9, close to 1, showed a successful optimisation. CFD simulations and RSM reduced calculation cost and time when determining optimal geometrical parameters for the CDaugWT design.

Optimization Based on Computational Fluid Dynamics and Machine Learning for the Performance of Diffuser-Augmented Wind Turbines with Inlet Shrouds

“…In addition, this study indicated that the adding duct might break the vortices behind the turbine, reducing the noise level generated by the rotor. Shambira et al [52] utilized RSM and a two-dimensional CFD model to develop and optimize the design of a DAWT equipped with a concentrator at the inlet without considering the rotor. The objective function was the throat velocity, and six geometrical parameters, including diffuser and concentrator angles and lengths, throat length, and flange height were considered in this research.…”

“…According to the literature reviewed in this study, Nikolić et al [41], who employed the ML algorithm (ANFIS) to estimate the rotor performance of DAWT, did not conduct further optimization research and suggested trying other algorithms to examine the same topic. Optimization studies of DAWTs [47][48][49][50][51][52] all have their own compromised simplifications, mainly due to the high computational cost of CFD simulation. Therefore, for the sake of optimization, partial simplification is necessary.…”