Contribuição ao projeto de sistemas de propulsão de fluidos.

Abstract

This paper deals with conception, design, development and implementation of propulsion components for micro-fluidic systems that operate within the flow rate range from 30 l=min to 70 ml/min. Three principles of flow propulsion have been investigated: a valve free linear and bidirectional peristaltic pump, driven by three actuators; a unidirectional diaphragm pump that comprises the nozzle/diffuser structure; and the vacuum pump, driven by a single actuator. In order to develop an optimized flow propulsion system, a new design methodology has been implemented. It relies on a finite-element based simulation approach to assess crucial mechanical and flow design features, associated with the fluid transport system. The mechanical design study basically considers the generation of forces, required to squeeze or deform tubings and membranes by means of electric or magnetic fields, i.e., the definition of an appropriate actuator design. Furthermore, the mechanical design study explores and defines the appropriate geometric spacing as well as the optimum number of actuators to provide bidirectional flow, without the use of flow valve control. The fluid-dynamic design aims to define the optimal sequence of drive actuators in order to provide a better pump performance of the outlet flow. Also a computational model based on fluid-structure interaction has been used in this design. On the other hand, a computational model has been also developed for the vacuum pump design, by using a multiphase (air/water) flow approach. It aims to evaluate the outlet flow behavior with the presence of oscillations and as a function of the air input. For the conception of the diaphragm pump, the design methodology previously used for the peristaltic pump has been adopted with a few modifications to fit the pump type. Eventually, hardware circuits were designed in accordance of the simulation results. These results have shown good agreement with experimental data, which validates the developed methodology and modeling.