A fluid-solid coupling modal analysis of piezoelectrically actuated microjet and the frequency design of nozzles layout

A 3D model of a piezoelectrically actuated microjet was built to characterize acoustic wave propagation in liquid produced by the vibration of a piezoelectric transducer. The model considered the coupling between the piezoelectric transducer, the liquid and the nozzle film. Modal analysis was carried out based on numerical simulation to study the field of pressure wave. The contours of amplitude of pressure wave on the liquid-solid interface at the nozzles inlet were obtained under different resonant frequency. The results demonstrated that the transducer dominated vibration mode with an axis-symmetric distribution is more efficient for the device operation than others. The results also indicated that pressure distribution in the liquid chamber is related to driven frequencies in a different way from that of displacement of structure. The impedance analyzer was used to measure the resonant frequencies of the microjet system and validate the simulation results experimentally. The experimental results agreed well with the predicted. The microjet we developed has the optimum frequency of about 36.5KHz, which corresponds to the first axis-symmetric vibration mode dominated by the transducer, as is predicted well by the simulation result. According to comparison of pressure wave field with nozzle layout of present design under different resonant frequencies, the phenomena that the microjet behaves differently under different orders of resonant vibration are explained, and a frequency design for nozzles layout are presented according to the simulation result.