Abstract: In order to provide a theoretical basis for designing water-saving toilets,the internal flow-field of siphon pipeline was simulated by the Fluent software to study the flow law of gas-liquid two-phase flow.The VOF model and the RNG k-ε model were applied to study the internal pipeline structure affected to the properties of siphon.The numerical simulation results showed the distribution of the internal gas-liquid two-phase flow state,the pressure and the flow velocity.Through the cold model experiment,validates the reliability of numerical simulation.The results also showed that:1)the gas-liquid two-phase flow numerical simulation was effective in analysis of siphon pipeline;2)the negative pressure and velocity magnitude had a direct effect on siphon action;3)the negative pressure was formed by high-speed flow from the jet;and 4)the pressure gradient was caused by jet and outlet confirmed stability of the siphon.

Key words: siphon pipeline, gas-liquid two-phase flow, negative pressure, cold model experiment