Abstract
Since the micro-two-phase flows are sensitive to the pressure fluctuations, which are induced by, e.g., syringe pumps or bubbles in the channels, effects of the external factors on the pressure drop in microchannels were investigated experimentally. The experiment was conducted by measuring the pressure difference between a channel inlet and atmospheric pressure by a pressure transducer in every one millisecond. With a circular glass channel (d = 1.0 mm) and water as the test channel and the test fluid, respectively, it was found that the measured frequencies and amplitudes of the pressure fluctuations induced by syringe pumps with the flow rate of 0.1-2.0 ml/min were 0.063-53 s and 4-183 Pa, respectively for the single-phase flow case. For two-phase flow case, in which only a single bubble was inserted in the channel, it was found that a bubble exiting the channel outlet induced larger (〜 Laplace pressure) temporal pressure fluctuations and it can be reduced to half by modifying the outlet condition.
