scholarly journals A High-Similarity Modeling Method for Low-Porosity Porous Material and Its Application in Bearing Cage Self-Lubrication Simulation

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5449
Author(s):  
Jiannan Sun ◽  
Ke Yan ◽  
Yongsheng Zhu ◽  
Jun Hong
Keyword(s):  
Pore Structure ◽  
Simulation Analysis ◽  
Ct Scanning ◽  
Modeling Method ◽  
The Self ◽  
Field Analysis ◽  
Lubricating Oil ◽  
Pore Characteristics ◽  
Structure Generation ◽  
Porous Model

The porous oil-containing cage achieves the storage, spillage, and suction of lubricating oil by its micro-pore structure, thus ensuring the self-lubricating performance of the bearing. Carrying out fast and accurate modeling of the cage microscopic pore structure is the key to the analysis of the self-lubricating mechanism of bearings. In response to the issues where current modeling methods of porous materials have a low similarity of pore distribution, morphology, structure, and size characteristics, and the transition of pore surfaces is sharp, this paper proposed a modeling method of a highly similar micro-pore structure based on the idea of median filtering, the quartet structure generation set (QSGS), and the slice method. By extracting and analyzing the pore characteristics of the porous model and comparing them with the experimental results of CT scanning, the advantages of the modeling method in terms of morphology and pore connectivity were verified. Finally, by carrying out simulation analysis of the centrifugal force of oil splashing and capillary oil absorption on the constructed model by combining the parameters of porous structures such as porosity and tortuosity, the advantages of the modeling method in the construction of the porous model and multi-physical field analysis were further verified.

scholarly journals Flow Mechanism Characterization of Porous Oil-Containing Material Base on Micro-Scale Pore Modeling

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3896
Author(s):  
Ke Yan ◽  
Tingting Yin ◽  
Jiannan Sun ◽  
Jun Hong ◽  
Yongsheng Zhu
Keyword(s):  
Pore Structure ◽  
Internal Flow ◽  
The Self ◽  
Lubricating Oil ◽  
Structural Parameter ◽  
Material Base ◽  
Flow Process ◽  
Micro Scale ◽  
Scale Resistance ◽  
Resistance Model

The self-lubricating effect of the porous oil-containing cage is realized by storing and releasing lubricants through its internal micro-scale pore structure. The internal flow and heat transfer process in the micron-submicron pore structure is crucial to the self-lubricating mechanism of the porous oil-containing cage. To this end, a new modeling method of porous cage was proposed based on random seeds theory, and the local two-dimensional models of porous cage with different micro-scale pore structure were established. The multiphysics coupling simulation analysis of lubricating oil inside the porous cage with the effect of centrifugal force and thermal expansion was carried out based on the COMSOL Multiphysics platform. In order to characterize the micro-scale pore structure, new structural parameter indicators, such as relative surface perimeter, effective porosity, tortuosity and fluid properties related to the internal flow process, were all extracted from the above models. Combing with the Hagen–Poiseuille equation, a flow resistance model of oil flow inside the porous oil-containing cage was obtained. Finally, comparison of simulation results and analytical solutions of the micro-scale resistance model was carried out to verify the correctness of the micro-scale resistance model. The work provides a new direction for the study of the lubrication mechanism of the porous oil-containing cage.

scholarly journals Characteristics of Lightweight Cellular Concrete and Effects on Mechanical Properties

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2678 ◽  
Author(s):  
Wei Yu ◽  
Xu Liang ◽  
Frank Mi-Way Ni ◽  
Abimbola Grace Oyeyi ◽  
Susan Tighe
Keyword(s):  
Mechanical Properties ◽  
Pore Structure ◽  
High Definition ◽  
Pore Characteristics ◽  
Software Applications ◽  
Solid Part ◽  
Electron Microscopes ◽  
Lab Test ◽  
Scanning Electron Microscopes ◽  
Cellular Concrete

This study investigated the pore structure and its effects on mechanical properties of lightweight cellular concrete (LCC) in order to understand more and detailed characteristics of such structure. As part of investigation, environment scanning electron microscopes (ESEM) and industrial high-definition (HD) macro photography camera were separately used to capture and compare images of specimens. Physical properties of the pore structure, including pore area, size, perimeter, fit ellipse, and shape descriptors, were studied based on the image processing technology and software applications. Specimens with three different densities (400, 475, and 600 kg/m3) were prepared in the laboratory. Firstly, the effects of density on the characteristics of pore structure were investigated; furthermore, mechanical properties (compressive strength, modulus of elasticity and Poisson’s ratio, flexural strength and splitting tensile strength of LCC) were tested. The relationships among pore characteristics, density, and mechanical properties were analyzed. Based on the results obtained from the lab test—comparisons made between specimens with high-densities and those with low-densities—it was found significant variability in bubble size, thickness, and irregularity of pores. Furthermore, the increase of density is accompanied by better mechanical properties, and the main influencing factors are the thickness of the solid part and the shape of the bubble. The thicker of solid part and more regular pores of LCC has, the better mechanical properties are.

Simulation Analysis and Optimization of Lubricating Oil System

2021 ◽  
Author(s):  
Qiongxiao Wu ◽  
Jianjun Wang ◽  
Jingming Chen ◽  
Pengzheng Li
Keyword(s):  
Simulation Model ◽  
Simulation Analysis ◽  
Sudden Change ◽  
Pressure Change ◽  
Lubricating Oil ◽  
Maximum Pressure ◽  
Closing Time ◽  
Original Design ◽  
Relief Valve ◽  
Simulation Results

Abstract Based on the one-dimensional simulation model of lubricating oil system is established and analyzed by using FLOWMASTER software, this paper proposes a new method of optimizing lubricating oil system by PID technology. Ensure that the configuration requirements and control strategies of the relevant accessories of the simulation model are satisfied with the design requirements. Firstly, by simulating lubricating oil pressure fluctuation and lubricating oil flow distribution under Open/Close Valve in different opening and closing time, the optimal opening/closing time of Open/Close Valve is determined to be 0.2 s and 0.5 s respectively. Secondly, by writing the controller script file combined with a controller to realize automatic unloading relief valve simulation, determine the relief valve pressure regulating range of 0∼0.38 MPa, For precision of constant pressure valve of oil spill, the simulation results show that the average 10 m3/h flow caused by pressure changes of about 0.06 MPa. Under the flow sudden change signal of about 40 m3/h, the maximum pressure change is less than 0.1 MPa. Through the simulation results, it is found that most of the lubrication parts in the original design have the phenomenon of flow redundancy, which causes unnecessary pump power loss. The system is optimized by PID technology. By comparing the simulation results before and after optimization, it is found that the speed of constant displacement pump could be changed in time by PID controller, and the flow redundancy could be improved significantly, so the lubricating oil system could be lower consumption and achieve the purpose of optimization.

Catalytic self-etherification of 5-hydroxymethylfurfural to 5,5′(oxy-bis(methylene))bis-2-furfural over zeolite catalysts: effect of pore structure and acidity

2020 ◽  
Vol 10 (14) ◽  
pp. 4684-4692
Author(s):  
Pilan Zhang ◽  
Jie Yang ◽  
Hualei Hu ◽  
Danxin Hu ◽  
Jiang Gan ◽  
...  
Keyword(s):  
Pore Structure ◽  
Zeolite Catalyst ◽  
The Self ◽  
Zeolite Catalysts

Understanding the role of pore structure and acidity of zeolite catalyst in the self-etherification of 5-hydroxymethylfurfural to 5,5′(oxy-bis(methylene))bis-2-furfural.

scholarly journals Experimental Study on Pore Characteristics and Fractal Dimension Calculation of Pore Structure of Aerated Concrete Block

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jun Fu ◽  
Yue Yu
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Fractal Theory ◽  
Concrete Block ◽  
Average Diameter ◽  
Pore Characteristics ◽  
Average Pore ◽  
X Ray ◽  
Matlab Program ◽  
Aerated Concrete

It is important to control and predict the macroscopic properties through pore structure parameters of cement-based materials. Microscopic pore structure of concrete has many characteristics, such as sizes and disordered distribution. It is necessary to use fractal theory to describe the pore structure of concrete. In order to establish the relationship between the pore structure characteristics of aerated concrete and porosity, shape factor, pore superficial area, average pore diameter, and average diameter, the fractal dimension of the pore structure was used to evaluate the pore structure characteristics of aerated concrete. The X-ray computed tomography (CT) images of the aerated concrete block pore structure were obtained by using the XTH320 series X-ray three-dimensional microscope. The pore characteristics of aerated concrete block were studied according to Image-Pro Plus (IPP). Based on the research of the fractal dimension measurement methods, the proposed MATLAB program automatically determined the fractal dimension of the aerated concrete block pore structure images. The research results indicated that the small pores (20 μm∼60 μm) of aerated concrete block account for a large percentage compared with the large pores (60 μm∼400 μm or more) from pore diameter distribution and the pore structure of aerated concrete block has obvious fractal features and the fractal dimension of aerated concrete block pore structure images were calculated to be in the range of 1.775–1.805. The pore fractal dimension has a strong correlation with the pore fractal characteristics of aerated concrete blocks. The fractal dimension of the pore structure linearly increases with porosity, shape factor, and pore surface area. The fractal dimension of the pore structure decreases with the average pore size and average diameter. Thus, the fractal dimension of the pore structure that is calculated by the MATLAB program based on fractal theory can be assumed as the integrative evaluation index for evaluating the pore structure characteristic of aerated concrete block.

Corn-Seed Modeling and Simulation Analysis Based on Shape Features

2014 ◽  
Vol 602-605 ◽  
pp. 779-782 ◽  
Author(s):  
Hui Yan ◽  
Duo Long
Keyword(s):  
Modeling And Simulation ◽  
Simulation Analysis ◽  
Modeling Method ◽  
Combination Method ◽  
Shape Features ◽  
Analysis Model ◽  
Corn Seed ◽  
Simulation Results ◽  
Analysis Models

Based on the shape features of corn seed, this paper proposes the modeling method of manual combination of eight spheres, which constructs the analysis models for corn seed Ji Feng 218 and Chang Dan 228 with the purpose of better simulation of corn seeds. Furthermore, another analysis model for Chang Dan 228 is also built with reference to the four-sphere combination method. The comparison between the simulation results from these two models demonstrates the feasibility and superiority of the model of combination of eight spheres.

Pore Structure Characterization of Tailing Bed and Dewatering Mechanism at nm-µm Scales Under Shearing

2021 ◽  
Vol 21 (1) ◽  
pp. 354-361
Author(s):  
Hua-Zhe Jiao ◽  
Shu-Fei Wang ◽  
Tian-Rang Jia ◽  
Yi-Wen Ju
Keyword(s):  
Pore Structure ◽  
Fine Particles ◽  
Seepage Flow ◽  
Structure Characterization ◽  
Surface Velocity ◽  
Pore Channel ◽  
Pore Network Model ◽  
Pore Characteristics ◽  
Fine Tailings ◽  
Paste Backfill

The preparation of high-density tailings is a prerequisite for cemented paste backfill technology, and the flocculated fine tailings of sealed water leads to challenges in the slurry thickening of tailings. Shearing conditions can compact the micro floc structure to improve the underflow concentration. The nm-μm scales of pore characteristics and connectivity are essential for the dewatering process. The computed tomography (CT) results show that the underflow concentration increases from 62.3 wt% to 68.6 wt% after undergoing rake shearing at 2 rpm, and the porosity decreases from 42.7% to 35.54%. The shearing conditions reduces the spheres and sticks by 43.14% and 43.3%, respectively, from the pore network model (PNM). The seepage flow states were affected by the changes in the pore structure. The maximum surface velocity and the maximum internal pressure decrease after undergoing shearing. Shearing conditions can break the micro floc structures, and the fine particles can fill in the micron-scale pores by gravity and shearing conditions, resulting in the forced drainage of water into the pores. Shearing conditions can break the thickening floc network structures; natural fine particles can fill the micron-scale pores by gravity and shearing conditions. The upward seepage of sealed water along the μm-scale pore channel causes a higher bed concentration. However, the sealed water in the nm-scale pores cannot flow upward due to water cohesion and particle adhesion resistance.

Experimental Research on Pore Structure of RCA and its Impact on Drying Shrinkage

2011 ◽  
Vol 335-336 ◽  
pp. 1141-1144 ◽  
Author(s):  
Yun Xiang He
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Drying Shrinkage ◽  
Recycled Aggregate ◽  
Structure Theory ◽  
Replacement Rate ◽  
Pore Characteristics ◽  
Cement Ratio ◽  
Mix Proportion ◽  
The Impact

Pore structure is one of the main influencing factors of materials drying shrinkage. C30 natural mix proportion is used as reference, the impact of replacement rate of recycled aggregate, the mixing amount of fly ash, water reducer, expansion agent and water-cement ratio on recycled aggregate concrete’s porosity and pore characteristics was studied. Based on the pore structure theory, the influence of porosity and pore characteristics on recycled aggregate concrete’s drying shrinkage is analyzed.

Flow Field Analysis and Structure Optimization of Water Hydraulic Poppet Valve Based on the CFD

2013 ◽  
Vol 791-793 ◽  
pp. 734-737 ◽  
Author(s):  
Qiu Xia ◽  
Xiang Pan Guang
Keyword(s):  
Flow Field ◽  
Simulation Analysis ◽  
Internal Flow ◽  
Turbulent Energy ◽  
Field Analysis ◽  
Value Differences ◽  
Poppet Valve ◽  
Traditional Structure ◽  
Fluent Software ◽  
Water Hydraulic

This paper builds two water hydraulic poppet valve models which are of different structure, and simulation analysis used by FLUENT software on it’s internal flow field. The analysis results show that, after improving the structure of water hydraulic poppet valve, import and export pressure value differences decreased, effectively restrains the generation of cavitation, reduces the vibration amplitude and turn down noise, reduces loss of turbulent energy, the overall performance is superior to the traditional structure.

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