Fluctuation of periods in multisurface oscillation system

Cover gas is constantly supplied to a main tank the bottom of which is conn ected to that of a subtank. The water levels in the tanks oscillate alterna tely until the free surface in the main tank pushed by the gas reaches the bottom end of a vertical release pipe. Then the gas is ejected from the mai n tank, resulting in a sudden surface rise and plugging of the pipe inlet. The cover gas pressure increases again,;thus, gas ejection occurs intermitt ently. The behavior of the oscillation system can be expressed by a set of linear equations that are properly selected according to the water surface position. The calculated interval between the ejections exhibits chaotic fe atures: a simple return map of the disorderly fluctuating interval and over sensitiveness to the initial condition. The effect of superimposed random n oise is examined.