ACTIVE CONTROL OF VORTEX-INDUCED VIBRATION OF CYLINDR BASED ON VELOCITY AND DISPLACEMENT FEEDBACK

Taking a single degree of freedom two-dimensional cylinder as the research object, the velocity feedback and displacement feedback are added to the vortex-induced vibration theory model, and the control laws of velocity feedback and displacement feedback are explored. At the same time, intelligent algorithm is introduced, neural network is used to map the flow field information to the feedback gain, and genetic algorithm is used to optimize the neural network parameters, so as to obtain the optimal combination of velocity feedback and displacement feedback under different reduced flow rates ( U_r = 3.5 ~ 8). Therefore, the cylindrical vortex-induced vibration enhancement strategy is proposed, and then the active control of cylindrical vortex-induced vibration under different flow rates is realized. The results show that the velocity feedback and displacement feedback provides an energy source for the vortex-excited vibration system, and stimulates the vibration of the cylinder and the vortex shedding, so that the onset time of the vortex-excited vibration under controlled is earlier than the uncontrolled state, and the vibration frequency under controlled is higher than the uncontrolled state, beside that, the vorticity frequency of a cylinder is no longer dominated by the natural frequency of the cylinder, and the vibration amplitude ratio of the cylinder is maintained at target amplitude ratio (0.6 ~ 0.8) in the range of referred flow rate U_r = 3.5 ~ 8 in the end. These consequences indicates that the external excitation control can increase the vibration speed and start-up time of the structure. At the same time, the feedback gain constraint is introduced into the intelligent control algorithm model, and the original calculation model is further optimized, so that the average energy consumption J is reduced by 33.08% compared with the unconstrained condition. The feedback gain constraint greatly reduces the energy consumption of the active control process. This study can realize active control of vorticity vibration enhancement of blunt body, it will be beneficial to capture wind vibration energy.