| Piezoelectric pump is a new type of fluid pump. It is simple and compact structure, easy miniaturization and low fabrication costs. Piezoelectric pump has been widely applied in many areas, such as aerospace, robotics, biological genetic engineering, medical apparatus, chemical analysis and many other micro-mechanical fields. The valveless piezoelectric pump is using a pair of nozzle/diffuser working together with a piezoelectric vibrator to achieve unidirectional transport. It has a more simplified structure, higher working frequency. Furthermore, the valveless piezoelectric pump can transport liquids, gases and the mixture fluid containing suspended particles, so that it can be applied to the fluid delivery for some special occasions. But it also has disadvantages of low discharge and low output pressure. By analyzing the working principle of the nozzle/diffuser valveless pump, this paper proposes a new kind of valeveless piezoelectric pump, which has two different cone angle conical tubes on both ends of the pump chamber. We call it asymmetric nozzle/diffuser valveless piezoelectric pump. This kind of pump has a better output capability. This dissertation includes following contents:1. The working principle and vibration mode of a circular piezoelectric vibrator were analyzed. Then, the deformations of the piezoelectric vibrator under different conditions were tested in experiments. Considering the experimental results, the structure and size of the pump can be designed rationally, and the drive signal can be choosed appropriately.2. Based on correlative hydrodynamics-based principle, the liquid flow characteristics of the diffuser and the nozzle were analyzed. Then the working principle of the nozzle/diffuser valveless piezoelectric pump was studied. It has got calculation methods for the output and efficiency of the pump. A conclusion is presented that the flow resistance coefficient ratio of diffuser and nozzle is a key factor which determine the output performance of the valveless piezoelectric pump. 3. The three-dimensional model of asymmetric nozzle/diffuser piezoelectric pump was constructed before it was meshed by ICEM CFD and analyzed by ANSYS CFX software. Then, simulation results for different pump design parameters were obtained. Pressure contours, velocity vector graph and the diffuser/nozzle instantaneous flow changing curve in one cycle were presented. According to the simulation analysis of the pumps which in different structural parameters, this paper discussed the influence law of the taper angle proportion, the length and the minimum orifice size of the asymmetric taper tubes on the output capability of the valveless pumps.4. According to experimental scheme, a common nozzle/diffuser valveless piezoelectric pump prototype and several asymmetric nozzle/diffuser valveless piezoelectric pump prototypes were processed. In the experiment, this paper tested the effects of the output flow of valveless piezoelectric pump in different structural parameters. The experimental results were analyzed to verify the feasibility of the design ideas of asymmetric nozzle/diffuser valveless piezoelectric pump. |
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