FLUID-DYNAMICS IN COLLAPSIBLE TUBES - PRESSURE DISTRIBUTION AND RESISTANCE CHARACTERISTICS

Regarding a collapsible tube with low downstream resistance, the pressure distributions were measured with Pitot tubes, which were inserted from the downstream bifurcation part. Examining the result of total pressure distributions, it was found that there are a high speed jet at the throat and a ceased water region just after the throat. It was also indicated from the static pressure distributions that the effective flow section area might be far smaller than the geometric section area of the tube. Concerning this, the flow visualization disclosed asymmetric flow separation. On the other hand, the measurement of throat pressure vs. flow rate clarified that the resistance between the throat and the downstream outlet does not necessarily cause self-excited oscillations.