共查询到20条相似文献,搜索用时 125 毫秒
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基于低渗透多孔介质渗透率的渐变理论,确定了能精确描述低渗透多孔介质渗流特征的非线性运动方程,并通过实验数据拟合.验证了非线性运动方程的有效性。非线性渗流速度关于压力梯度具有连续-阶导数,方便于工程计算;由此建立了低渗透多孔介质的单相非线性径向渗流数学模型,并巧妙采用高效的Douglas-Jones预估一校正有限差分方法求得了其数值解。数值结果分析表明:非线性渗流模型为介于拟线性渗流模型和达西渗流模型之间的一种中间模型或理想模型,非线性渗流模型和拟线性渗流模型均存在动边界;拟线性渗流高估了启动压力梯度的影响,使得动边界的移动速度比实际情况慢得多;非线性越强,地层压力下降的范围越小,地层压力梯度越陡峭,影响地层压力的敏感性减弱,而影响地层压力梯度的敏感性增强。 相似文献
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针对稠油松散岩心的相对渗透率曲线计算问题,根据渗流力学及最优化理论,给出了描述岩心内部油、水两相渗流的简化方程,并利用约束变尺度法求解最优化问题,基本解决了岩心堵塞以及结果对初值的敏感性问题。通过实例计算,说明了本方法的可靠性和可行性。 相似文献
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国家地震局兰州地震大队渗流力学研究组 《力学进展》1973,3(3):0-0
渗流力学是现代流体力学的一个分支,它是研究流体在孔隙介质中运动规律的科学。流体所通过的孔隙介质具有极其复杂的连通形式和孔隙结构、各种不同的表面性质以及很大的比面等特点,而流体流过孔隙介质时受到很大的流动阻力、显著的表面力以及一些在流动过程中发生的物理化学现象等因素的影响,这些特点使渗流力学与一般的流体力学明显地区别开来。自从法国工程师达西于1856年发现渗流基本定律——达西定律,从而正式揭开渗流力学的历史以来,近几十年,渗流力学得到相当迅速的发展。特别是近年来在渗流理论方面又有 相似文献
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双重孔隙介质非线性流固耦合渗流 总被引:4,自引:0,他引:4
本文给出了考虑双孔双涌介质生变形的流固耦合渗流模型。不仅考虑了固结对渗流的影响,同时也考虎了固体变形对渗流参数(孔隙度和渗透率)的影响。这样。渗流就成了双孔双渗介质中非线性流固耦合渗流。在此基础上,本文还推导了双重孔隙介质非线性流固耦合渗流计算。给出了算例并作了对比。结果表明,固体变形引起的介质参数变化对流体渗流早中期过程有重要的影响,对渗流后期影响并不大。这对于石油开采有重要的参考价值。 相似文献
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以多孔自润滑材料为研究对象,分析载荷作用下多孔基体变形和润滑液在孔隙中的流动特性,探讨多孔表面渗流速度随加载时间变化,分析固-液双相作用下多孔表面渗流与润滑行为.结果表明,多孔基体变形后,孔隙内储存的润滑液受迫流动,在多孔表面发生渗入和析出的流动现象.润滑液在接触区向多孔基体渗入,在接触区入口向多孔表面析出.恒定载荷下,入口两侧润滑液不能保持稳定的渗流现象,而随加载时间呈现出扩散和波动的变化过程.在竖直方向上,多孔材料内的最大流体压力发生在上表面,最大固相应力发生在靠近上表面的次表面位置.随加载时间延长,磨擦界面的液相承载力先增大后降低,固相承载力先降低后增大,最终液相承载力降低为零,外载荷全部由固相材料承担.适当增加载荷能提高润滑液在多孔表面上的渗流速度,改善润滑状态,但也使得润滑液的渗流速度波动更为剧烈. 相似文献
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M. A. Rady 《Heat and Mass Transfer》2009,45(5):545-561
Enhanced efficiency of the adsorption process in the dehumidifier is a key element for improved performance of desiccant cooling
systems. Due to the exothermic nature of the adsorption process, the dehumidification and cooling capacity are limited by
significant temperature changes in the adsorption column. In the present study, the effects of integration of sensible and
latent heat storage particles in the desiccant bed for in situ management of released adsorption heat are investigated. For
this purpose, column experiments are performed using an initially dry granular bed made of silica-gel particles or a homogeneous
mixture of silica gel and inert sensible or latent heat storage particles. The packed bed is subject to a sudden uniform air
flow at selected values of temperature and humidity. Also, a packed bed numerical model is developed that includes the coupled
non-equilibrium heat and moisture transfer in the solid and gas phases. Investigations of the heat and mass transfer characteristics
are reported using the composite structure and the results are compared with the base case of simple silica gel bed. Improved
desiccant cooling system performance can be obtained by appropriate adjustment of desiccant cycle operation and proper choice
of the volume ratio of thermal energy storage particles. 相似文献
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《Particuology》2022
Static electricity has an important effect on gas–solid fluidized bed reactor fluidization performance. In the process of fluidization, electrostatic interaction between particles will obviously accelerate particle agglomerate formation, which consequently reduces the fluidization performance. Pulsed gas flow injection is an efficient method to enhance particle mixing, thereby weakening the occurrence of particle agglomerate. In this study, the two-dimensional hybrid pulsed fluidized bed is established. The flow characteristics are studied by using the coupled CFD-DEM numerical simulation model considering electrostatic effects. Influences of different pulsed frequencies and gas flow ratios on fluidized bed fluidization performance are investigated to obtain the optimal pulsed gas flow condition. Results show that in the presence of static electricity, the bubble generation position is lower, which is conducive to the particle flow. Pulsed gas flow can increase the particle velocity and improve the diffusion ability. The bubble generation time is different at different frequencies, and the frequency of 2.5 Hz has the most obvious effect on the flow characteristics. Different gas flow ratios have significant impacts on the particle movement amplitude. When the pulse gas flow accounts for a large ratio, the particle agglomerate tends to be larger. Therefore, in order to improve the fluidization effect, the ratio of pulsed gas flow to stable gas flow should be appropriately reduced to 0.5 or less. 相似文献
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In the feeding process, the feed stream forms a moving packed bed of particle from the feedstock in the feed channel. When the feeding is at emergency interruption especially in the case of flooding and uncontrollable discharge, the hot gases from reactor would infiltrate into the feed stream. The high heat penetration into feed stream would affect the feeder performance. In this paper, transient thermal response of feed stream within horizontal pipe is described mathematically with a gas flow and heat transfer model. Influences of varied factors on the thermal penetration into feed stream are examined for different conditions. The temperature of the packed-bed particles and the gas velocity distribution curves are obtained for the feeding service at interruption and at normal operating conditions. The numerical results show that the thermal penetration to the packed-bed particles by the seepage flow fluid is high only in the position near the gas entrance. The thermal penetration depth tends to increase with the seepage flow velocity and decrease with feeding rate. There is no appreciable thermal penetration in the feed stream when the feeding service is at normal running. The operating conditions and the porosity of solid bed have importance effects on the gas velocity and temperature field in the thermal penetration zone. A test system is set up to determine the transient thermal response experimentally for the packed bed of particles within a horizontal pipe. The model results are found to compare favorably with the experimental data. 相似文献
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页岩储层孔隙结构复杂, 气体赋存方式多样. 有机质孔隙形状对受限空间气体吸附和流动规律的影响尚不明确, 导致难以准确认识页岩气藏气体渗流机理. 为解决该问题, 本文首先采用巨正则蒙特卡洛方法模拟气体在不同形状有机质孔隙(圆形孔隙、狭长孔隙、三角形孔隙、方形孔隙)内吸附过程, 发现不同形状孔隙内吸附规律符合朗格缪尔单层吸附规律, 分析了绝对吸附量、过剩吸附浓量、气体吸附参数随孔隙尺寸、压力的变化, 研究了孔隙形状对气体吸附的影响. 在明确不同形状有机质孔隙内气体热力学吸附规律基础上, 建立不同形状有机质孔隙内吸附气表面扩散数学模型和考虑滑脱效应的自由气流动数学模型, 结合分子吸附模拟结果研究了不同孔隙形状、孔隙尺寸有机质孔隙内吸附气流动与自由气流动对气体渗透率的贡献. 结果表明, 狭长孔隙内最大吸附浓度和朗格缪尔压力最高, 吸附气表面扩散能力最弱. 孔隙半径5 nm以上时, 吸附气表面扩散对气体渗透率影响可忽略. 本文研究揭示了页岩气藏实际生产过程中有机质孔隙形状对页岩气吸附和流动能力的影响机制. 相似文献
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The monotonous instability of the adsorption front formed in a two-component gas filtered vertically through a fixed bed of adsorbent is demonstrated. A threshold value of the Archimedes adsorption criterion is calculated and the corresponding critical gas flow is considered. 相似文献
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WolfgangKlose Amdt-PeterSchinkel 《中国颗粒学报》2004,2(3):107-112
The transport mechanisms of momentum,mass,species,and energy are invertigated in detail for the ro-tary kiln process.The residence time prediction of the granular bed is well improved by considerng differet flow patterns in the drum.Introducing a mixed flow pattern of the basic slipping and slumping behaviour has the most important effect on the improvement of the residence time prediction.The granular bed is assumed to hehave as a Bingham fluid in the active layer of the bed.The transport mechanisms of momentum,species,and energy are modelled on the basis of this assumption and using the kinetic gas theory.Additionally,a mathematical transformation is presented to save comput a-tional time.The model results of the temperature field are in very good agreement with experimental data. 相似文献
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We extended the standard approach to countercurrent gas–solid flow in vertical vessels by explicitly coupling the gas flow and the rheology of the moving bed of granular solids, modelled as a continuum, pseudo-fluid. The method aims at quantitatively accounting for the presence of shear in the granular material that induces changes in local porosity, affecting the gas flow pattern through the solids. Results are presented for the vertical channel configuration, discussing the gas maldistribution both through global and specific indexes, highlighting the effect of the relevant parameters such as solids and gas flowrate, channel width, and wall friction. Non-uniform gas flow distribution resulting from uneven bed porosity is also discussed in terms of gas residence time distribution (RTD). The theoretical RTD in a vessel of constant porosity and Literature data obtained in actual moving beds are qualitatively compared to our results, supporting the relevance under given circumstances of the coupling between gas and solids flow. 相似文献
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V. P. Kharitonov 《Fluid Dynamics》2013,48(3):283-290
A one-dimensional motion of an incompressible fluid (gas) through a fixed bed of a granular material under a short thermal pulse at the bed inlet is considered. An analytical dimensionless solution of the boundary-value problem is presented in quadratures. Specific features of the propagation of convective thermal waves due to the fluid (gas) flow are studied. The data on the propagation velocity, amplitude, temperature difference between the fluid (gas) and the bed, and the length of the zone of intense heat transfer are obtained. The examples of the analysis of a continuum flow in engineering apparatuses which use convective thermal waves are presented. 相似文献
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《Particuology》2023
This paper reports on the hydrodynamics of a bubble-induced inverse fluidized bed reactor, using a nanobubble tray gas distributor, where solid particles are fluidized only by an upward gas flow. Increasing the gas velocity, the fixed layer of particles initially packed at the top of the liquid starts to move downwards, due to the rise of bubbles in this system, and then gradually expands downwards until fully suspended. The axial local pressure drops and standard deviation were examined to delineate the flow regime comprehensively under different superficial gas velocities. Four flow regimes (fixed bed regime, initial fluidization regime, expanded regime, and post-homogeneous regime) were observed and three transitional gas velocities (the initial fluidization velocity, minimum fluidization velocity, and homogeneous fluidization velocity) were identified to demarcate the flow regime. Three correlations were developed for the three transitional velocities. As the fine bubbles generated from the nanobubble tray gas distributor are well distributed in the entire column, the bed expansion process of the particles is relatively steady. 相似文献