| Piezoelectric Pump is a new type of fluid conveying device that developed in recent years. Its advantages include: high output volume accuracy, easy to control, simple structure, small size and low cost, etc. These advantages make it suitable to be applied in medical treatment, biotechnology, chemistry and instrument development, etc. Usually, piezoelectric pumps can be categorized into two types—valveless and valve based. Valveless piezoelectric pump is based on the expansion / contraction theory that show a resistant difference between input and output ports drives fluid flowing in one direction.This research is part of "863" National High Technology Research and Development project "Study of Micro-Piezoelectric Pump with Self-Detect Functions" (Project Number: 2007AA04Z336) and National Science Foundation project "Principle and Key Technology Study on Initiative Valve Piezoelectric Pump" (Project Number: 50575093) . This dissertation brings forward a novel Flat-Cone-Shape Chamber Valveless Piezoelectric Pump (FCSCVPP) that can convey fluid flowing in one direction by the coaction of piezoelectric actuator and chamber shape. In the dissertation, FCSCVPP's working principle, structure and other related theories will be introduced and analyzed. Based on pump prototype, a series experiments are applied to prove theoretical and simulation analysis. This dissertation includes following chapters:1,History, Recent Development and Application of Piezoelectric PumpAccording to the research of current Piezoelectric Pump developments in the world, valveless piezoelectric pump is one of the hot-points in this field. In this paper, the FCSCVPP piezoelectric pump structure that is based on the expansion / contraction theory is brought forward.2,Piezoelectric Actuator Working Principle and Characteristics AnalysisCircle piezoelectric actuator—the heart part of FCSCVPP is studied. First, actuator's dynamics state is analyzed, and then, the curved face differential equation and vibration equation of actuator are derived and analyzed based on multi-support conditions. Based on theoretical conclusion, according experimental tests are applied on the actuator. Experimental results and theoretical analysis both prove that structure, size dimension, support method and material characteristics are the main factors that affect actuator vibration. When rectangular stimulate voltage is applied on the actuator, actuator has biggest vibration, and the vibration is directly related to the voltage volume.3,FCSCVPP Structural Design and StudyFirst, based on the research of the Piezoelectric Pumps that developed in the world, and the expansion / contraction tube fluid flowing theory, FCSCVPP's structural design and working principle are analyzed. Then, based on the coaction of actuator vibration and flat-cone-shape chamber, fluid resistance and force situation are derived. Next, the fluid volume and resistance relationship equation is worked out on both input and output processes. According to this equation, the net input volume in the input process and the net output volume in the output process are also calculated. Theory analysis show that there are both laminar and eddy flow existing in pump chamber. Theory analysis also shows that pump has better performance when bigger cone side as the output side and small cone angle can generate bigger output volume. Finally, pump self-suction ability is analyzed, the reason and affect factors are explained.4,FCSCVPP Chamber Flow Simulation and Analysis Using "Fluent"FCSCVPP's chamber flow three dimension model is created by "GAMBIT" before it is input into "Fluent" software, then, simulation results are obtained for different pump design parameters. According to simulation results, the relationship between FCSCVPP's output performance and chamber angel, chamber height and other parameters are obtained. Results show that: when the input speed is slow and pressure is low, the water flows faster from small side of flat cone chamber than from the big side of flat cone chamber; the bigger is the flat cone angle, the more is spire number and the bigger is spire area; on the opposite, the smaller is the flat cone angle, the less is spire number and the smaller is spire area, till last, the water flows linearly through; when the chamber, input port and output port fluid speed is in high situation, the higher is the flat cone chamber, the easier is spire area generated and the bigger is energy loss, thus, the worse is the output performance. This simulation result agrees with the speed / volume analysis of expansion / contraction dynamic theory, it also agrees with the prototype experimental results.5,FCSCVPP Prototype and ExperimentsFCSCVPP prototypes with different flat cone angles and chamber heights are designed and assembled. In order to reduce the assembly and stimulation errors between these prototypes, all the prototypes and built in one unit, and stimulated by the same voltage and frequency signal. In this section, FCSCVPP prototype experimental materials and equipments are introduced and experimental process and structural parameters are detailed. In these experiments, pure water is used as the pump fluid, and different stimulation voltage and frequency are tested:(1) For the same FCSCVPP, different frequency stimulate signals have different output characteristics. At low frequency range, flat cone small side has better output than the big side; at high frequency range, opposite results will be obtained. There is an optimal frequency for both situations to make best output performance.(2) For the FCSCVPPs with different flat cone angles, among the output performances of 25°, 30°, 45°and 60°, 25°pump has the best output characteristics. The bigger is the angle; the worse is the output performance. The smaller is the angle, the stronger is the pump self-suction. (3) For the same FCSCVPP, the output volume and pressure have direct relation with pump's stimulation voltage.(4) For the FCSCVPPs with different chamber heights, stimulation frequency is different for each of them. The smaller flat cone angle has better output performance.6,FCSCVPP Glycerin-Water Mixed Fluid ExperimentsIn order to test valveless pump's ability of conveying macromolecule and suspend kernel fluid, and further test the relationship between output performance and different types of flowing fluid, different viscosities glycerin-water mixed fluids are used as pump fluid. 100%, 90% and 50% glycerin-water mixed fluids are tested on the prototypes. Experiments show: FCSCVPP can not pump out 100% glycerin fluid at all; for the 90% glycerin-water mixed fluid, at high stimulate voltage, FCSCVPP can pump it out. but volume is low with almost no noise; for the 50% glycerin-water mixed fluid, FCSCVPP works fine without bubbles. All experiments show that smaller flat cone angle has better output performance.The FCSCVPP design is first time brought forward in this dissertation. According to related literature search, no same kind of piezoelectric pumps are published or studied in the world, it is a novel idea. |
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