EXPERIMENTAL STUDY OF VOID FRACTION EFFECT ON FLOW CONTINUITY IN A SIPHON

A siphon is a Ƞ-shaped conduit employed to transfer liquid from a higher elevation to a lower elevation via gravity. It has application when the liquid is required to be transferred without an external pump as a power source. All siphon applications require initial priming, followed by a natural siphoning process to continue the liquid flow without interruption. However, when the fluid is at the saturated condition or contains an abundance of dissolved gases, the suction process will produce a large amount of gas or vapor bubbles that may eventually disrupt the natural siphoning process. The motivation for this study is to prevent the discontinuity of the siphoning process by investigating the critical void fraction (CVF) of gas/vapor bubbles that can suspend in the liquid flow before the natural siphoning is interrupted. The volume and weight methods are used to determine the amount of air bubbles inside the liquid siphon before the flow is interrupted. The experimental results show that the natural siphon can sustain up to 65% of the void fraction before the flow is interrupted. A series of qualitative experiments are performed on the siphon to present means of rejuvenating (or repriming) a stalled siphon. The results from this study will help in determining the operating characteristics of two-phase flow necessary to sustain a naturally siphoned condition in many applications associated with two-phase flow transports. Understanding of the physics with the quantitative data obtained from this study can help reduce the pumping power and reduce the energy consumption of two-phase flow transports.