Research on Wave Phenomena in Hydraulic Lines : 6th Report, Transient Properties of Non-linear Elements

Abstract

A new method is presented which gives complete plots of transient waves in hydraulic pipes with non-linear boundaries. The numerical procedure of the Laplace inversion plays an effective role there. The availability of the method is confirmed in the experiment to observe dispersions of pressure pulses by an air bubble placed in an oil pipe. This method also makes it possible to experimentally investigate transient flows in a pipe with a circular orifice. The results show that the characteristics of an orifice placed in a transient wave transmission line are approximated by the steady-state ones, if there is no reserve flow at the orifice. Moreover transient variations of flow-rate are measured by a modified "impedance tube" method which is realized by virtue of the present analytical technique. The measurement reveals the hysteresis in the relation between the instantaneous pressure drop across, and flow-rate through, the orifice.