Determination of optimal geometric parameters for empty concentrator–diffuser augmented wind turbines using the whale optimization algorithm

Abstract

Expanding electricity access in off-grid regions, alongside increasing global energy demand, requires sustainable alternatives to fossil fuels, which are major drivers of greenhouse gas emissions. Wind energy provides a clean option but often suffers from intermittency and insufficient speeds in many locations, limiting turbine performance. This research focuses on improving energy capture in low-wind-speed areas, through an empty concentrator–diffuser augmented wind turbine (CDaugWT). A mathematical relationship linking throat velocity amplification to six geometric variables was developed, and these parameters were refined using the whale optimization algorithm (WOA), an artificial intelligence-based search technique. The final configuration achieved a maximum throat wind speed increase of 1.978 times. WOA outputs were in close agreement with those from response surface optimization, differing by just 1.3%. The optimum design included a diffuser angle of 10.5°, concentrator angle of 20.5°, concentrator length of 397.9 mm (0.66 Rth), diffuser length of 997.9 mm (1.65 Rth), throat length of 74.6 mm (0.12 Rth), and flange height of 104.6 mm (0.17 Rth), with Rth denoting the throat radius. Computational fluid dynamics validation showed only a 1.66 % deviation, confirming the robustness of the optimized design for enhancing wind turbine operation in resource-constrained environments.