Effects of support structure on the performance of a diffuser-augmented hydrokinetic turbine

A diffuser-augmented hydrodynamic turbine (DAHT) is composed of three main components: a diffuser, a rotor, and a support structure. The design of the support structure plays a crucial role in the performance of the DAHT. It has a significant influence on both the rotor and diffuser performance. However, research on this specific topic is currently limited. In this study, the influence of various parameters such as support distance, the number of columns comprising the support structure and the aspect ratio of support section on the performance of the DAHT is analyzed using blade-resolved Computational Fluid Dynamics (CFD) numerical simulations. Reynolds-Averaged Navier-Stokes (RANS) equations are performed and the k-ω SST turbulence model is utilized to predict the performance of the DAHT. The accuracy of the CFD model is verified by experiments. The results indicate that support structures may significantly reduce the acceleration ratio and power coefficient of the DAHT. With a column number of 3, a support distance of 0.1 and an aspect ratio of 1, the acceleration ratio decreases by approximately 22% and the power coefficient decreases by approximately 26%. It is recommended to choose a front support with a larger aspect ratio and maintain an appropriate support distance.