Measurement of hydrodynamic coefficient of underwater robotic arm based on vortex-induced vibration

In this paper the vortex-induced vibration of an underwater robotic arm was simulated using ANSYS-Fluent fluid simulation platform. The effects of water flow direction and the rotational speed of the robotic arm on vortex-excited vibration are discussed. The results indicated that the drag coefficient of the underwater robotic arm in the countercurrent state has a larger range of values and numerical variations compared to the downstream state. The maximum difference in numerical value is 4.84 times. The numerical fluctuation of the lift coefficient of the underwater robotic arm in the downstream state is more significant than that in the upstream state. And when the upstream angle of the underwater robotic arm is 45° there was a significant fluctuation in the lift coefficient. By fitting the change curves of the lift coefficient and drag coefficient, the correlation functions of the lift coefficient and drag coefficient with the displacement of the center of mass were obtained. It also provided a basis for the vortex-excited vibration of the ocean engineering equipment.