Simulation And Optimization On Pipeline Transportation System Of Sewage Suction Truck Based On Solid-liquid Two-phase Flow Analysis

As a new underground pipeline dredging equipment,the sewage suction truck gradually enters the Chinese market in recent years,and it has received remarkable achievements in the field of urban sanitation.In order to get rid of the dependence on imported products,several domestic special vehicle enterprises also get involved in research and development of this type of special truck these years.However,limited by the lack of some key technologies,our development stays in the stage of analogy design with reference to foreign advanced products even by now.As the key component of the sewage suction truck,the pipeline transport system works in the essence of hydraulic transport of solid-liquid two-phase flow,and its performance directly reflects the design level of the vehicle,so it's necessary to focus on the optimization design of this system.Started from the analysis of solid-liquid two-phase flow movement mechanism in pipeline,several problems involved in this form of movement are discussed,such as the force on particles,the identification on flow pattern,the resistance loss and the determination of critical flow velocity.Based on a typical vacuum sewage suction truck developed under university-industry cooperation,the parameterized model of the pipeline transport system is build in CATIA,a professional 3D modeling software,and the computational fluid dynamics(CFD)software FLUENT is utilized here to simulated the internal flow field of main components in the system,including the feed cavity and the three-way pipe.Through the comparison of internal flow field and pressure drop in each component under different structure parameters,optimal structure schemes of the feed cavity and the three-way pipe are obtained.Meanwhile,the fact is revealed that the smoothness of the flow is impacted by the mutations of flow section and flow direction.Based on the research conclusions of the main components,an optimized structure of the pipeline transport system is obtained.Under two practical working condition,the flow field in both of the initial structure and the optimized structure are simulated,and the discrete phase model(DPM)is adopted to track the trajectory of solid particles.The static pressure contours,velocity vectors and path lines of liquid within the system are compared,furthermore,the average effective transport velocity and particle transport efficiency are brought in to quantitatively evaluate the effect of optimization.Simulation and research work based on CFD technology in this thesis provides an efficient way and theoretical support for the development of new sewage suction truck products,and it can also provide some reference and guidance for the parametric design of pipeline hydraulic transport system in related fields.