Analysis of wave propagation and pulsation in an elastic tube using a diaphragm pump

In this research, the flow wave propagation, speed, and pulsation suppression in an elastic tube were studied using a diaphragm pump. The flow fluctuations with shocking pressure fluctuations occur in the elastic tube because the check ball was blocked, thereby preventing reverse flow. Consequently, the check ball is one of the causes of pulsating flows in diaphragm pumps. However, only a few studies have analyzed the relationship among the check ball movement, pressure, and flow fluctuations. In this study, we constructed several elastic tube experiments: (i) single-tube model; (ii) two-tube model. To predict the flow wave propagation and pulsation in an elastic tube, we developed an axisymmetric theoretical model and compared into the experimental results. Based on our study, the main results were as follows: the relationship among the check ball movement, pressure, and flow fluctuations showed that the pressure and flow rate pulsation were caused by the asymmetry of the check ball movement. Additionally, we observed that the theoretical flow wave propagation trend had a good agreement with the experimental results, although the flow wave speed in the urethane-tube experiment differed considerably from the theoretical prediction. Furthermore, the amplitude of the pulsation increased considerably owing to the reflected wave at the tube exit, although it did not increase when the resistance was added at the exit. Finally, we observed that the pulsation reduced more in the silicon tubes compared to the urethane tubes because the deformation of the silicon tubes was larger than that of the urethane tubes.