Study on the design method for axial flow runner that combines design of experiments, response surface method, and optimization method to one-dimensional design method

Abstract

In this study, we created an optimization design method for axial flow runner by combining one-dimensional design method with a design of experiments, a response surface method, and an optimization method. This design method was applied to the runner of a palm-sized ultra-small axial flow hydraulic turbine, which can be applied to existing pipelines and low head of an open channel. We investigated the mechanism of performance improvement by examining turbine performance and internal flow of the obtained runner with numerical analysis and experiments and by surveying vortex structure and loss. As a result, the optimized runner designed with the design method in this study presented about 9.1% of significant improvement in the experimental value of turbine efficiency compared to the original runner designed only with the one-dimensional design method. This was because the optimized runner experienced less loss by tip leakage vortex and vortex near the hub of the runner outlet on the runner, especially less loss of vortex by swirling flow downstream from the runner. The results showed the effectiveness of the design method in this study.