A Model Study Of Piezoelectric Generator Based On The Flow Around A Blunt Body

The marine environmental monitoring is the basis means to develop, utilize and protect the marine environment condition for human beings. The development of modern marine environment monitoring technology is closely related to the development of wireless sensor network. The wireless sensor network is a new kind type of network technology which has been widely used in environmental monitoring and protection, medical treatment and nursing, military, industrial and other fields. The network needs no base station and has a low cost, in addition, monitoring multiple nodes at the same time can be realized through the dense deployment of sensors. Therefore, the wireless sensor network has a unique advantage for marine environmental monitoring.For the work surrounding of wireless sensor network used in marine environmental monitoring, this paper proposes a piezoelectric generation technology based on the flow around a blunt body to supply power for the node of sensor network. The piezoelectric generator is placed in the ocean current, and it uses the shedding vortex in wake stream of the blunt body as the excitation source of entire device, it can collect the kinetic energy from media flow and convert it into electrical energy directly, so as to realize the self-powered of wireless sensor network nodes.Firstly, this paper has designed a piezoelectric power generation system that can be used for energy harvest of the ocean current based on the flow around a blunt body. The system consists of three parts, such as a blunt body, a piezoelectric flexible plate and peripheral circuit. The design is focused on the study of exciting force of the piezoelectric generator. The paper selects a cylinder as the blunt object and analyzes the typical phenomenon——flow around a cylinder as well as the vortex field it has created. The thesis has also studied the correlation theory of piezoelectric transducer.Secondly, the paper has analyzed and solved the fluid-structure coupling and electromechanical coupling respectively according to the fluid-structure interaction dynamics, the related theory of piezoelectric materials and the basic knowledge of circuit, and has established the mathematical model of the piezoelectric generator based on the flow around a blunt body.At the same time, the paper has used the ANSYS software to simulate the piezoelectric generator based on the flow around a blunt body. The Fluent unit and the Mechanical APDL unit are selected and used to solve the fluid-solid coupling and electromechanical coupling. Finally we have gained the open circuit voltage of the piezoelectric generator, as well as the output power with a pure resistance load. In addition, we have studied how the factors such as flow velocity, cylinder size effects on the output power of piezoelectric generator.Finally, the paper has set up a small experiment platform. It uses water pump as the power source and products a water tank with constant flow velocity. We fix the cylinder together with a piezoelectric film in the sink and obtain the output voltage waveform under the condition of different velocity and cylinder diameter. Moreover, the output power has also been gained with external load.