Numerical Simulation And Experimental Study On The Unsteady Multiphase Flow Of Siphon Pipelines

The structure of the siphon pipeline,as one of the main core structures of toilets and other sanitary wares,is complex and irregular.The internal flow of the siphon pipeline is very complicated since the three-dimensional unsteady multiphase flow is considered,and also it plays a very important role during the process of flushing.Therefore,characteristics of the internal flow in the siphon pipeline were the focus for many researchers.When concerning the structural design of siphon pipelines,it is not only necessary to meet the overall functional requirements,but also to consider whether the product is energy-saving and water-saving.Considering that the design process entirely relies on the manufacturer’s manual skills and experience,such as modify the mold and test the flushing performance repeatedly,Computational Fluid Dynamics(CFD)is adopted in this thesis as the powerful numerical method to solve engineering design problems.The original model of the siphon toilet is introduced in this thesis,and commercial CFD software FLUENT is applied to simulate the flushing process of the siphon pipeline and obtain the flow characteristics such as pressure and flow velocity distribution during the flushing phase.In the meantime,the effects of various stages of the flushing process on siphon performance and flushing performance were also studied.By adjusting the parameters of the original siphon pipeline model such as the pipeline section shape,the height of the pipeline,the angle of the water blocking section,and the height of the climbing section,several sets of siphon pipeline simulation models were obtained.Furthermore,the flushing processes of different models considering different siphon pipeline parameter were performed by FLUENT.Additionally,three-dimensional unsteady numerical simulation and a comparative analysis are applied to explore the relationship between different siphon pipeline parameters and siphon performance.Based on numerical simulation results,the proposed siphon pipeline structure is optimal to meet the design requirements.Finally,according to the new national standards for sanitary ceramics(GB 6952-2015),the toilet granule emission test,the corresponding siphon pipeline recommended by the cooperation was tested by the flow state.At the same time,the high speed camera was used to take a full shot of the actual siphoning process and the test results were obtained.Comparing with the results of numerical simulation,the accuracy and reliability of the numerical simulation results are verified by the experimental studies.