Method for calculating the characteristics of a linear type peristaltic pump with incomplete compression of the working member

Abstract

The introductory part of the work contains brief information about the existing peristaltic pumps and their application areas. Special attention is paid to the use of miniature peristaltic pumps with a linear located tube. For such pumps, there is a sufficient number of experimental studies, but a very limited number of studies are devoted to modeling the flow in such pumps. The aim of the work is to develop a technique for calculating the characteristics of a peristaltic pump with a linear located tube and several squeezing elements that not completely compress it in the transverse direction, , based on a quasi-stationary model and verifying the applicability of the developed model by numerical modeling. A quasistationary model is obtained by compiling the Bernoulli equation for the instantaneous velocities and pressures for the current movements of the squeeze element. To evaluate the limitations of the applicability of the quasi-stationary model, numerical experiments were performed in the STAR-CCM + program taking into account the possibility of cavitation, for which the Eulerian polyphase model was used. Numerical experiments have shown that cavitation takes place at intervals when the pump discharge member returns to its initial position and the pressure in the compression area decreases. From a comparison of calculations with different pump cycle times, it is established that cavitation is essential only if the squeeze elements move too fast and the pump cycle time is sufficiently short. It was also found that fluctuations in fluid velocity within the pump are observed under the same conditions as cavitation. Comparison of the results of numerical simulation and calculations using a quasi-stationary model has shown that the calculations give an error in the time intervals when there is a simultaneous movement of pump squeeze elements. As a result of the analysis of the obtained results, it is concluded that the developed quasi-stationary model can be used for calculations if the viscosity of the pumped liquid is not less than 40 mPa •s and if the pump operating frequency is sufficiently small that the pump does not experience the specified cavitation and speed fluctuations.