Active Drag Reduction for the Wall of Microunderwater Vehicles by Piezoelectric Actuated Drag Reducer

The driving performance and endurance mileage of microunderwater vehicle can be improved by reducing the wall friction drag. The existing underwater drag reducers can achieve good drag reduction performance, but they are not suitable for microunderwater vehicle due to the large structure size and the high energy consumption. An active drag reducer, which is driven by piezoelectric actuator and can be embedded into the outer wall of microunderwater vehicle hardly changing the streamline structure and structural strength of the wall, is proposed. The active drag reduction on demand and effective energy saving can be realized by combining with the motion monitoring system of the underwater vehicle. The drag reduction mechanism of the proposed drag reducer driven by piezoelectric actuator is discussed. The influences of single parameter and comprehensive effect of parameters on the characteristics of the near-wall turbulent boundary layer are obtained, and the control methods of drag reduction performance for meeting different requirements are proposed. The simulation and experimental results show that the proposed microdrag reducer can effectively reduce the frictional and total drag, and can achieve positive energy saving. The drag reduction rate of 37.82% can be achieved with the excitation amplitude of 150 V and the operating frequency of 1500 Hz. This article can provide an important reference for the research of active drag reduction of microunderwater vehicle.