Systematic study on propulsive performance of tandem hydrofoils for a wave glider

摘要

This paper presents the propulsive performance optimization of tandem hydrofoils equipped in a wave glider in head sea conditions with the aid of computational fluid dynamic (CFD) method by using a commercial CFD code, STAR-CCM +.Firstly, this work performs a systematic study on a single 2D hydrofoil to study the effect of varying the pivot position and the torsional spring stiffness to seek for the optimum propulsive performance within a range of velocity. Secondly, parametric studies on the propulsive performance of 2D and 3D six tandem hydrofoils are conducted by varying the oscillation amplitude and the torsional spring stiffness.The result reports: The results show that the torsional springs play a critical role in propulsive performance, comparing to the pivot position. The propulsive performance of the middle hydrofoil is greater than the others in the fore and after positions. When 2D and 3D six tandem hydrofoils achieve the optimum propulsive performance, the frequency ratio is chosen to be around 25 (torsional spring stiffness (k(S) = 0.8N.m/rad)) and 17 (torsional spring stiffness (k(S) = 11.8N.m/rad)), respectively. Comparing to previous study, the propulsive performance of each hydrofoil in six tandem hydrofoil configuration is greatly improved and none of hydrofoil produce negative thrust.