An experimental investigation of collapsible tube flows at the onset of self-excited oscillations

In this paper, sullenly arisen self-excited oscillations which were observed during airflow through some collapsible rubber tubes are analysed and evaluated without paying attention to the rnechanisms originating the oscillations. The principal experimental results are the pressure and velocity measurements corresponding to the instant at which oscillations are emerged and frequency determined frorn those measurements. The time-dependent pressure values were obtained by means of pressure transducers while a hot wire anemometer was used for measuring the velocity of the flow. It was verified that the flow had been highly unsteady and chaotic during the oscillations. The variety of experimental parameters (tube material, tube-wall thickness, tube length, flow rate) presented in the study should be useful on account of acquiring more general results related to the subject. It had been noticed that all of these parameters directly affected behaviour of the oscillations and conditions of their appearance; therefore it has been emphasized that they should be carefully taken into consideration in the collapsible tube flow investigations. The results of this study should also be important in of using air instead of water which had been widely preferred as fluid almost in all of the previous experimental investigations.