Multi-disciplinary design optimization of a horizontal micro Kaplan hydro turbine

This study investigates a performance-based design optimization for a Kaplan hydro turbine at a maximum water head of 2.6 m (8.5 ft), micro-sized horizontal Kaplan turbine with 7.6 cm (3.0 in) diameter that is featured fixed blades to attain the optimum performance for such type and size of hydro turbines. Optimization process includes solving design problems and enhance design development by applying a multidisciplinary design optimization (MDO) technique. Varying the geometrical parameters of the turbine, i.e., dimensions, number of blades, blade wrap angles, and different rotational speeds (500 – 3000 RPM) are the relevant proposed disciplines of this study. An in-house code is used for optimizing the geometrical parameters of the turbine. A numerical solution that utilizes computational fluid dynamics (CFD) for a 3D, turbulent, transient unsteady and swirl flow is developed using STAR-CCM+ software in conjunction with an experimental setup of a lab-sized closed-loop water system for validation. The performance of the turbine is predicted by evaluating the power output (in watts), mesh independency analysis is also presented for CFD results validation. Two multi-simulation matrices were solved by using the high-performance computing (HPC) cluster of the University of Wisconsin-Milwaukee. First matrix includes different number of the blades (3, 4, 5, 6, and 7 blades) over six different rotational speeds (500, 1000, 1500, 2000, 2500, and 3000), while the second matrix includes 121 possible combinations of blade wrap angles starting at 60°-60° (hub-shroud) angle to 110°-110° angle with 5° increment alternated at both sides, the hub and the shroud.