Achieving travelling wave drag reduction by micro piezoelectric actuator

Abstract

In order to improve the endurance mileage and the sailing speed of micro underwater vehicles, it is critical to reduce the drag of underwater devices. However, the existing underwater drag reducers are not suitable for micro underwater device due to its large size and complex structure. Inspired by the adaptive deformation of fish to achieve traveling wave drag reduction when the flow field changes, a micro piezo-actuated traveling wave drag reducer (PTWDR, the size of 30 mm × 28 mm × 0.75 mm), which can be embedded into the wall of the micro vehicle and hardly increasing the volume and weight of the vehicle, is proposed in this work to realize active drag reduction. The mechanism of active disturbing the turbulent boundary layer by piezoelectric micro-amplitude traveling waves to achieve drag reduction has been revealed. The drag reduction performance control method, which can meet different drag reduction requirements, is given. The experimental results of frictional drag and total drag indicate that the designed micro PTWDR is feasible to reduce the drag. The maximum local drag reduction rate of 47 % can be achieved at resonance frequency, which can improve the maneuverability of micro vehicles. While when the low frequency is applied, it cannot only obtain a certain drag reduction rate in a large drag reduction area, but also realize net energy saving. This work provides a novel and effective theoretical and technical reference for realizing active drag reduction and net energy saving, which can be applied for micro underwater vehicles.