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Liquid Filtration Characteristics of Metal Rubber Material and Experimental Study

Author: GuoYaDong
Tutor: ChenZhaoBo；JiangHongYuan
School: Harbin Institute of Technology
Course: Mechanical Design and Theory
Keywords: metal rubber(MR) filtering material pore structure filtration performance
CLC: TQ336.43
Type: PhD thesis
Year: 2010
Downloads: 177
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Abstract

The Metal Rubber(MR) porous material compacted by stainless steel thread is possessed of dual properties of metals and rubber. It can keep a series of excellent performances such as damping, filter, noise reduction, heat insulation and sealing even under rugged environment of high and low temperature and erosion, so it boasts the great potentiality in the field of aviation, aerospace and interspace. Liquid filtration properties and experimental study of the MR porous material become an important component of MR technology. Because of the simple and unique fabrication process, the high carrying capability, the strong capability of resisting large temperature difference as well as the devisable characteristics of automatic absorption and good adjustment when fluid velocity and pressure were fluctuant and of the large distribution range of porosity, the MR filtering materials and filtering device are widely utilized in the domain of aviation, national defense and the special condition of civilian products. The MR porous material is in the possession of excellent filtering capability which other interrelated material are unmatched to, and Russian made it successful utilized and researched. Data shows that Chinese study on the MR technology is still in special research where attention is mainly focused on the application field of damping and vibration reduction, sealing and noise absorption. In order to make up the lack technology of new material about its filtration, the pioneering study was made about inner pore structure and filtering technology of the MR porous material, which provided theoretical and experimental foundation for its large use.The background of the issue and the research situation home and abroad was detailed introduced in this paper where the feasibility and distinct characteristic of the using of the MR porous material in the filtering domain was also stated. Several important factors affecting the pore character of the MR porous material was deeply studied such as the porosity, equivalent diameter, the pore maximum diameter and the distribution range of pore diameter. The main results are as followings: the calculating formula of average and minimum porosity and the dynamic formula of porosity were deduced. By means of the capillary model, the equivalent diameter(hydraulic diameter) formula of the MR porous material was obtained. On the basis of reasonable simplification of inner pore structure, the theoretical formula describing maximum pore size of MR filtering material is derived by statistical method and was proved by bubble test pore size. The results show that the formula precisely illustrates the influencing factors on maximum pore size of MR and their interrelation. With the help of Poisson Polyhedron Theory, theoretical pore size distribution of MR was worked out and was verified by mercury porosimetry method. The experimental results are well matched to the theoretical formulas.Based on the flow continuity equation of fluid, the Reynolds Equation of cylindrical MR filtering material was done. Precise formula of pressure loss was deduced using Reynolds Equation of MR filtering material in terms of combining the theory and the experiment. On account of Darcy law and the formula of fluid seepage velocity, theoretical formula of permeability coefficient was figured out.Relation curves of the porosity, thread diameter and the thickness of formed specimen to the filtering effectiveness and the filtering pressure-drop were obtained from a large number of successful experiments on elements of cylindrical MR filtering material with different structural parameters. There was a compared study on filtering capacity of annular and cylindrical MR filtering material, the results of which show that filtering capacity of the MR is not affected by its structural form at low porosity and while on high porosity filtering effectiveness of annular MR filtering material is higher than that of cylindrical MR filtering material. Combined MR was researched through doing experiments and the result indicates its filtering capacity is better than the others. At the same filtering capacity, combined MR filtering material is in the nature of lower filtering pressure-drop, better fluid traffic ability, containing more contamination before reaching its ultimate pressure-drop and of longer working life so that it was capable of giving full play of its filtering capability. The theoretical formula describing filtering precision of MR was obtained from theoretical deducing and experimental study so that function of porosity, thread diameter and filtering precision was determined. Meanwhile, the formed thickness had great effect on filtering precision of MR filtering material and the thickness addition helped filtering effectiveness tend to a stabilized value.The filtration mechanism of the MR porous filtering material was analyzed, which will provide the reference for the understanding of the performance of the MR filtering. The mechanics balance equations were established considering the suspended particle deposition, the dispersion and the migration during the filtration process. The decision condition of the particle disperses and the migration were given, and the force and the moment that carries in the particle are analyzed one by one. The decision condition of the motive particle deposition, the dispersion and the migration were given in the paper.

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