| With the development of electronic equipment,heat dissipation has gradually become a key factor restricting its performance.Air cooling method,the most widely used by now,is difficult to meet the growing demand for heat dissipation.It’s more and more important to develop cooling components with new principles,smaller size and higher efficiency.Piezoelectric air pump can achieve a relatively large flowrate,but compared to the high frequency response of the piezoelectric material,the existence of check valve restricts its frequency response and flowrate output.Applying synthetic jet technology to piezoelectric air pump has become a feasible way to solve these problems.Synthetic jet-based piezoelectric air pump eliminates the need of check valve and air source,and can also achieve continuous high-speed output,so it has broad application prospects in the field of heat dissipation.In this thesis,based on the research about piezoelectric pumps and synthetic jet devices at home and abroad,synthetic jet-based piezoelectric air pumps with single chamber and dual chambers are developed respectively.Theoretical,simulation and experimental researches are carried out for their flowrate characteristics.Firstly,the basic theories involved in the synthetic jet-based piezoelectric air pump are studied.The piezoelectric effect and equation are introduced.The theoretical calculation of the piezoelectric vibrator’s amplitude distribution and volume change are given out.The principle of the synthetic jet is introduced.The theoretical expression for judging the formation of synthetic jet is given out.Secondly,the synthetic jet-based piezoelectric air pump with single chamber and dual chambers are developed respectively,the structural parameters are determined,the working principle and process are analyzed.The fluid-solid coupling simulation model of these single/dual-chamber synthetic jetbased piezoelectric air pumps are established using simulation software COMSOL Multiphysics.The flow field distribution and output flowrate in different working stages are obtained.The influence of each structural parameter on the output flowrate is analyzed,which lays the foundation for the experimental research.Thirdly,prototypes of single and dual-chamber synthetic jet-based piezoelectric air pumps are manufactured,and the experimental researches on output flowrate and structure optimization are carried out.The experimental results show that the pump with single chamber has a maximum output flowrate of 2.10L/min before optimization and 2.79L/min after optimization,which increased by 32.9%.The pump with dual chambers has a maximum output flowrate of 2.43L/min when the upper inlet channel is open and the driving signals are asynchronous.The maximum output flowrate of the pump with dual chambers is between that of the pump with single chamber before and after optimization.Finally,the prototype with the largest output flowrate is used as the cooling component to establish an open-loop detection and closed-loop control system for heat dissipation.Experiments are conducted to study its cooling effect on the heater with a rated power of 16 W.The results show that the optimal cooling distance is 60 mm,under which the heater’s surface temperature can reduced by 32.5%.The closed-loop system can control the temperature within the set interval.The main innovative work in this thesis are: Synthetic jet-based piezoelectric air pumps are developed to meet the requirement of large flowrate cooling components.Different from the conclusion drawn from the previous studies: the vibrator’s first order resonant frequency is the pump’s optimal working point,experimental study in this thesis find that the maximum output flowrate appears at a higher order resonant frequency.The output flowrate can be further improved by optimizing the key structural parameters,while the overall dimensions remain unchanged.The optimized pump can show a good application effect in the cooling system. |
