Numerical Simulation And Cavitation Study On Valve-less Piezoelectric Micropump With Single Bimorph-Double Chambers And V Shape-tube

With many merits such as simple structure, small body, no interfering of electromagnetism and good output ability down low applied voltage etc, the piezoelectric micropump is one of key parts and widely be used in medical devices, bio-genetic engineering and other fields. It is a complex coupling system of multiple physical factors, but not the micromation of conventional pump. Because the structure size, shape and flow characteristics of fluid all have significant influence to micropump. With the development of micro fluidics technology, the piezoelectric micropump with the smaller size and greater flow rate has become one aspects of the study. Therefore, a new type of valve-less piezoelectric micropump with single bimorph-double chambers and V shape-tube is presented to solve it. In order to investigate the flow pattern within the piezoelectric micropump, there are mainly specific works in the following areas:1. A brief overview of the micro micropump based on the micro electro mechanical systems (MEMS) is done and the present situation in domestic and abroad and the development in the future of piezoelectric micropump are summarized.2. The basis theory of micro fluid is introduced. There is a theoretical analysis of flow characteristics about micropump.3. Based on the piezoelectric theoretical knowledge, vibration analysis and fatigue analysis are done to the circular bimorph piezoelectric vibrator driven by sinusoidal voltage using the finite element analysis software ANSYS and the factors are found which can affect the fatigue life of the piezoelectric vibrator. Using The Miner Rule, it is judged whether the piezoelectric vibrator satisfy the strength requirements and the piezoelectric actuator fatigue life can be predicated effectively comparing with the single-chip piezoelectric vibrator. It is studied that the different effects resulted from the different base materials and structural parameters for the piezoelectric fatigue life. The study supplies theoretical basis and reference valve for improving on the structure of piezoelectric actuator and increasing its lifetime. 4.C language is used to a program of the dynamic characteristics of piezoelectric vibrator, and then the program is called in Fluent with dynamic mesh model to calculate. Then, through the indirect coupling method, dynamic numerical simulation is done to the valve-less piezoelectric micropump with single bimorph-double chambers and V shape-tube. Internal flow field of the piezoelectric micropump is obtained, it demonstrates that it is feasible and right to use dynamic mesh model to set the vibrator moving boundary. Dynamic mesh model is also used to study effects of driving frequency, amplitude of the piezoelectric vibrator, pump chamber height and pipeline location to pumping of the piezoelectric micropump, which provides a basis and reference valve to design the piezoelectric micropump.5. The theory of cavitation is introduced. Dynamic numerical simulation is done to the valve-less piezoelectric micropump with single bimorph-double chambers and V shape-tube using the Mixture model in Fluent. The distribution of gas-liquid and cavitation are obtained and studied. Moreover, painstakingly measures adopted can inhibit effectively the generation bubble in the piezoelectric micropump, thus enhancing performances of the piezoelectric micropump.