Numerical study on hydrodynamic characteristics of deep sea microfluidic eel energy capture device

Ocean current energy is a stable, reliable, and highly predictable renewable energy source. The effective development of ocean current energy conversion technology is beneficial in addressing the issue of power shortage. However, the majority of current velocities worldwide are below 1.5 m/s, limiting the feasibility of using conventional current energy capture devices. This paper presents a vortex induced vibration based deep sea microfluidic eel energy capture device (VIV-EEL) designed to efficiently harness energy in low-speed current environments. The system employs Computational Fluid Dynamics (CFD) to develop a series of computational models that couple underwater multibody fluid-solid interactions. These models are subsequently validated through experiments. The study analyzed the flow field of VIV-EEL under different working conditions and discussed the impact of several dimensional parameters of the elastically supported cylinders, structural parameters of raft plates, and flow velocity on the hydrodynamic performance. The results demonstrate that the energy capture efficiency of VIV-EEL is enhanced by the vorticity vibration effect. It is evident that there exists an optimal radius size for the elastic support column to achieve the most favorable resonance effect in the flow field of VIV-EEL. The energy capture characteristics of the raft plate show a linear relationship with its structural parameters, enabling quantitative design according to the requirements of the power take-off system (PTO). Moreover, VIV-EEL exhibits a lower start-up flow velocity compared to traditional current energy capture devices, enabling it to initiate and capture energy at a flow rate of 0.3 m/s. This innovative solution offers technical support for efficient low-speed current energy capture.