| Along with the development of the processing technology and its rapid expansion application in the biomedical domain, as core of the MEMS technology, the pump technology is also increasingly became the hot spot in many countries’ micro technology research. Researchers have put forward many micro pump models based on different principles, Some have already been applied in practice. But, whether the micro pump or no valve pump based on electro osmosis, electric hydraulic principles, has its fatal weakness which seriously limits its scope of application and fields. For this reason, this paper puts forward a new type of no valve micro pump, it is based on the theory of ultrasonic traveling wave, simple mechanism, strong driving force, without restriction in the liquid kinds. Ultrasound traveling wave micro pump which is based on three principles:1. The traveling wave spread on the pipe wall, while the particles on the pipe wall moving as elliptic track. Because of fluid viscosity, the elliptical movement promotes the fluid flow.2. The traveling wave spread in the pipe wall caused wall peristalsis, this peristalsis spread in a single direction while maintain a certain shape, for space replacement, the peristalsis promote fluid flows forward.3. Ultrasonic spread into the fluid interface between fluid and solid, form the sound flow, the acoustic radiation promote a fluid flow along a certain angle.In order to make finite element analysis for the traveling wave pump system, in this paper, we firstly introduce the present development situation of micro electro mechanical and micro fluid drive equipment. The current popular micro fluid driving device is also reviewed, including the structure and principle and their weaknesses, etc. Then in this paper we introduce the composition of the pump’s material, including the structure of the piezoelectric resonators, the arrangement of the loading on the piezoelectric resonators, structure parameters and materials parameters of the tiny tubes. Using finite element analysis software to modeling the pump, do response analysis and modal analysis, to determine the best mode driver frequency. Combined with voltage load, we did transient dynamic analysis for the model, and in post-processing observed the particle trajectory in the wall inside the pump. Finally discusses the fluid-structure coupling of the pump model, firstly we brief analysis the method and steps to make fluid-solid coupling of the finite element analysis software, especially introduce the two-way flow-solid coupling principle and its procedure and setting up of the CFX software. Then did fluid-solid coupling analysis of the different voltage amplitude, different frequency load, different surface roughness and different fluid dynamic viscosity, got some useful conclusions through the results of post-processing data include streamline, velocity analysis. The conclude as:the size of driving voltage amplitude is proportional to the flow velocity, and when driving frequency is equal to the resonant frequency the driving effect is most obviously; When the fluid dynamic viscosity is less than0.001kg/(m·s), the flow velocity increases in linear, and then slow drop. When surface roughness is different, the flow velocity peak in the wall increases as the roughness increases, but it also can be seen that average flow velocity has not increased obviously. In addition, through the CFX post-processing we got the pipeline section of the velocity vector diagram, and through the graphic we can see that the distribution of flow velocity decrease gradually from top to bottom. The flow velocity section is approximate present parabolic shapes where the traveling wave effect very weak. The conclusions provide a meaningful basis for future pump model optimization or the selection of pump parameters when driving different fluids. |
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