Research On Transport Properties Of Liquid In Porous Media Under Microgravity

Propellant management is one of the key technologies in the on-orbit refueling.This work is on the background of the orbit refueling and the application of the porous media in space propellant management.The transport properties of the liquid in porous media under microgravity is studied,base on the fractal theoty,molecular dynamics and fluid dynamics.The structure property of the porous media,the flow property and the wettability of the porous media was studied.According to the findings,a porous media gas/liquid separator was developed,which is applied in an experimental satellite tank.Main work of this thesis is:(1)Research on the structure property of the porous media was done based on the stochastic geometry theory.Some basic concepts of the stochastic geometry theory and the fractal geometry theory were introduced in this wor,and the mathematical definition of the porous media structure properties were introduced too.The model of the porous media structure properties was constructed based on the stochastic geometry theory,and the fractal charactors of the porous media were considered in this model.The influence of the particle diameter and the porosity of the porous media were studied.(2)Study of the flow characteristic of the porous media was done theoretically.It is difficult to study the relationship between the stucrture properties and the flow characteristic of porous media,for the complex structure of porous media.In this work,the flow characteristic was researched by introducing the stuctrue properties into the traditional model.The relationship between the hydraulic diameter and the structure parameters was considered in the model.A series of experiments were conducted to prove the accuracy of the theory model.Base on the theory model and the experimental results,the influence of the the structure parameters to the flow characteristic were analized.(3)The wettability of the porous media was analyzed.The equivalent radius considered the structure properties was introduced into the Lucas-Washburn equation.A new contact angle experimental model was deducted.Base on the theory model,a capillary rise experiment was conducted,the experimental result was agreed with the results in existing literatures.What's more,the dynamic contact angle was considered in this model,the influence of the dynamic contact angle was studied.(4)Research on capillary flow in porous media under microgravity was done.A new governing equation of the capillary flow in porous media was deducted in this work in terms of energy.In the terms of the surface force,the viscous loss,the kinetic loss of the governing equation,the structure properties were considered.The flow regime was analized by solving the equation.And the influence of the structure properties to the capillary flow was studied.(5)Research on capillary flow in multi-layer prous media was done theoretically.The model of radial capillary flow and capillary flow in multi-layer porous media were conducted.Base on this two model,the radial capillary flow in multi-layer porous media was constructed.The radial capillary flow in gradient particle diameter and gradient porosity porous media was studied.(6)A porous media gas/liquid separator used in satellite tank was developped.A gradient paricle diameter porous media gas/liquid separator was designed and made,and used in satellite tank as a vent pipe.A computer simulation of the separator was conducted by commercial software.A ground experiment and a seris of drop tower experiments were conducted to test and verify the principle prototype of the separator.The results prove the effectiveness of the separator.Liquid transport property in porous media under microgravity was studied by the methods of theoretical analysis,numerical simulation,experimental test.A lot of findings were obtained,which is useful for the space application of the porous media.And the development of the porous media gas/liquid separator could be a important reference for the space application of the porous media.