Numerical Simulation On High-speed Spiral Flow In Lifting Pipe For Deep-sea Mining

With the rapid development of global economy,the quantities and types of mineral resources are needed to human,and the contradiction between resources supply and demand is increasingly highlighted.As the non-renewable land metal mineral resources are drying up step by step,the world will focus their attention on marine mineral resources,therefore,it is very significant to study hydraulic lift system in the field of deep-sea mining.Nowadays,the effective mining method is urgently needed to transport the mineral products which were hosted in the deep-sea floor to the land efficiently.And hydraulic lifting system of high-speed spiral flow,which is operated by a tornado effect and based on the traditional straight flow,can take advantage of strong entrainment effect of high-speed spiral flow to realize hydraulic transmission of manganese nodules particles,which is high concentration transportation and low energy consumption.However,there are some issues in hydraulic lifting system of high-speed spiral flow,for instance,the way of generating the spiral flow,the mechanical properties of particles in lifting pipe,the mechanism of entrainment effect,the distribution features of flow field and the calculation of resistance loss in the transmission process.Therefore,the above problems on high-speed spiral hydraulic transmission technology were studied in detail in this thesis,the content is as follows:(1)The way of generating spiral flow and device characteristics were analyzed,from the viewpoint of high energy utilization,the tangential jet to produce spiral flow was chosen,then the hydraulic lift mining system of high-speed spiral flow was established.And the mechanism of entrainment effect was discussed.(2)Based on the force analysis of manganese nodules particles in lifting pipe,which were on the rise in a spiral movement,the mathematical model of particle movement was established.And the corresponding flow parameters were obtained through numerical calculation of the software CFD.(3)The characteristics and application range of multiphase flow model and turbulent model were summarized,on the basis of the actual delivery situation of high-speed spiral flow hydraulic lift system,the initial conditions and boundary conditions of particles rise vortex motion were determined,and eulerian two-fluid model and RNG turbulent model were chosen ultimately,then the seawater was regarded as flow medium,the manganese nodules particle and seawater solid-liquid two-phase flow was numerically simulated.And using a certain numerical method,the basic control equation was solved.The velocity field,pressure field and particle distribution in different section of high-speed spiral flow were acquired in the end.(4)According to energy theory,the additional resistance losses under different working conditions in the lifting pipe for high-speed spiral flow were calculated.The formula on resistance loss of transportation for high-speed spiral flow in the lifting pipe was deduced with the help of the multiple linear regression models in MATLAB software,which was verified by examples.So the reliability of the formula about the resistance loss of transportation was confirmed.(5)A set of experimental project of hydraulic lift system on high-speed spiral flow was designed,which can verify the flow pattern of numerical simulation and pressure loss model.