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果园喷雾机五指式喷筒流场数值模拟与分析 预览
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作者 陶涛 魏新华 《农机化研究》 北大核心 2020年第5期40-45,共6页
为提高果园风送式喷雾机喷幅及整体施药效果,在课题组前期研究基础上设计了一种新型五指式喷筒。通过CFD仿真模拟对五指式喷筒内部的流场进行数值分析,对不同风机转速下喷筒进出口风速和Z=0截面上速度、压力展开对比分析。仿真结果表明... 为提高果园风送式喷雾机喷幅及整体施药效果,在课题组前期研究基础上设计了一种新型五指式喷筒。通过CFD仿真模拟对五指式喷筒内部的流场进行数值分析,对不同风机转速下喷筒进出口风速和Z=0截面上速度、压力展开对比分析。仿真结果表明:在风机3个转速下(1 450、1 080、960r/min),喷筒进口风量随风机转速的增大随之增加;各个转速下喷筒进出口流量差值很小,从而确定仿真结果可靠;五指式喷筒各个出风口风量相等;五指式的喷筒中气流出现紊流的区域较小,风速分布均匀,五指式喷筒内部压强分布均匀,各出风口之间变异较小。减少了风机能量损失,扩大喷雾机喷幅,满足了果园风送喷雾机的设计要求。 展开更多
关键词 风送式喷雾机 喷筒 数值模拟 流场分析
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秧盘干燥机气流分配室流场均匀性仿真分析 预览
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作者 于海明 李海源 +4 位作者 汪春 李海亮 张欣悦 梁琦 余兵兵 《农机化研究》 北大核心 2020年第2期15-21,共7页
干燥定型是水稻'秸秆'营养穴盘生产工艺中非常重要的一个环节,干燥质量的好坏将影响水稻'秸秆'营养穴盘的强度和翘曲等品质指标,进而影响播种、育秧、插秧和运输的要求。在微波热风耦合干燥机中,气流分配室是决定干燥... 干燥定型是水稻'秸秆'营养穴盘生产工艺中非常重要的一个环节,干燥质量的好坏将影响水稻'秸秆'营养穴盘的强度和翘曲等品质指标,进而影响播种、育秧、插秧和运输的要求。在微波热风耦合干燥机中,气流分配室是决定干燥机干燥质量的关键部件之一,其结构是否合理将严重影响水稻秧盘的干燥质量。为此,利用计算流体力学FLUENT软件对气流分配室结构对内部流场均匀性的影响进行仿真分析。结果表明:通过改变气流分配室腔体结构腔前板高度、上顶角角度及边壁倾斜角角度对气流分配室出风口均匀性皆产生了积极的影响。其取值范围为腔前板高度为28~36mm,上顶角角度为105°~115°,边壁倾斜角角度为85°~75°。该研究可为气流分配室出风口均匀性的进一步优化提供参考。 展开更多
关键词 水稻“秸秆”营养穴盘 气流分配室 微波热风耦合干燥机 计算流体力学 数值模拟
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含瓦斯抽放钻孔沿空掘巷窄煤柱合理宽度研究 预览
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作者 李尧 杜刚 《采矿与岩层控制工程学报》 北大核心 2020年第1期71-79,共9页
以石泉煤业30108综放工作面轨道巷沿空掘巷为背景,通过理论分析计算了最小煤柱宽度,并采用UDEC软件对不同区域——钻孔段、钻孔延伸段(合称钻场内)、不布置钻孔段内不同宽度(5~20m)煤柱下的弹塑性区和垂直应力分布进行模拟,从而分析了... 以石泉煤业30108综放工作面轨道巷沿空掘巷为背景,通过理论分析计算了最小煤柱宽度,并采用UDEC软件对不同区域——钻孔段、钻孔延伸段(合称钻场内)、不布置钻孔段内不同宽度(5~20m)煤柱下的弹塑性区和垂直应力分布进行模拟,从而分析了不同条件下围岩稳定性与煤柱承载能力。研究结果表明:①根据岩体极限平衡理论,煤柱最小宽度为8.94m;②在数值模拟中,煤柱宽5,6m时,3种煤柱内的大部分区域处于破坏状态;煤柱宽10m以上时,钻场内煤柱顶底板剪切破坏区域相互贯通;在钻场延伸段8,9m的煤柱应力集中较10m的明显,在钻场内7~9m的煤柱边缘拉伸破坏区域较10m的大。综合理论分析和数值模拟结果,建议煤柱宽度应选为10m。现场实践验证了煤柱宽度的合理性,并取得了显著的经济效益。 展开更多
关键词 窄煤柱宽度 钻孔 数值模拟 沿空掘巷 围岩稳定性
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气吸式红枣捡拾装置吸气室的设计及流场模拟 预览
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作者 张学军 白圣贺 +4 位作者 靳伟 袁盼盼 于蒙杰 鄢金山 张朝书 《农机化研究》 北大核心 2020年第8期91-95,共5页
针对红枣气吸捡拾易堵塞风管及吸气室内部结构尚需优化等问题,首先阐述了气吸式红枣捡拾装置工作原理和结构设计,然后对吸管口与吸气室进行建模并运用Gambit软件进行网格划分。根据理论分析与前期调研,设置气流速度为42m/s,采用Fluent... 针对红枣气吸捡拾易堵塞风管及吸气室内部结构尚需优化等问题,首先阐述了气吸式红枣捡拾装置工作原理和结构设计,然后对吸管口与吸气室进行建模并运用Gambit软件进行网格划分。根据理论分析与前期调研,设置气流速度为42m/s,采用Fluent软件对其内部结构进行流场分析和数值模拟,结果表明:吸气管与吸气室流速稳定并小于吸气室气流速度,确定吸管口直径为135mm,吸气室进出口直径分别为137、180mm。田间试验表明:当气流速度为42m/s时,捡拾率为93.11%,含杂率2.92%,工作性能稳定。该结果为研究气吸式红枣检拾装置奠定了理论基础。 展开更多
关键词 红枣 捡拾装置 气吸式 流场分析 数值模拟
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ZK60镁合金中空型材挤压成形的有限元模拟及组织和性能 预览
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作者 郭丽丽 苑菁茹 +1 位作者 汪建强 李永兵 《材料导报》 EI CAS CSCD 北大核心 2020年第2期2072-2076,共5页
运用HyperXtrude软件对ZK60镁合金中空型材挤压过程进行有限元数值模拟,得到了型材断面的温度场、速度场、位移场及应变场。由模拟结果可知,出口型材温度和速度呈平面对称分布,从型腔到挤压模具出口,温度呈梯段式下降。微观组织分析结... 运用HyperXtrude软件对ZK60镁合金中空型材挤压过程进行有限元数值模拟,得到了型材断面的温度场、速度场、位移场及应变场。由模拟结果可知,出口型材温度和速度呈平面对称分布,从型腔到挤压模具出口,温度呈梯段式下降。微观组织分析结果表明,ZK60镁合金中空型材的平均晶粒尺寸为8.9~23.1μm,顶面的晶粒最大,底边拐角处晶粒尺寸最细小,这是由于型材断面各位置的温度、速度和应变不同导致动态再结晶程度不同。型材的(0002)基面织构是向挤压方向偏转10~15°的基面取向,型材顶面和侧面的(0002)极密度差异较大,顶面的(0002)极密度值为19.3,侧面的(0002)极密度值为6.9。型材抗拉强度约为310 MPa,侧面的延伸率最高为18.9%,顶面的延伸率最低为13.4%,这是由于侧面的(0002)基面织构向横向分散,降低了(0002)极密度。顶面的延伸率较低是较大的晶粒尺寸、较强的(0002)基面织构以及第二相分布情况综合作用的结果。 展开更多
关键词 ZK60镁合金 挤压型材 数值模拟 显微组织 织构
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Numerical simulation of incipient particle motion 预览
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作者 Ali Nasrollahi Ali Akbar Salehi Neyshabouri +1 位作者 Goodarz Ahmadi Masoud Montazeri Namin 《国际泥沙研究:英文版》 SCIE 2020年第1期1-14,共14页
A two-dimensional(2D)computational model for simulation of incipient sediment motion for noncohesive uniform and non-uniform particles on a horizontal bed was developed using the Discrete Element Method(DEM).The model... A two-dimensional(2D)computational model for simulation of incipient sediment motion for noncohesive uniform and non-uniform particles on a horizontal bed was developed using the Discrete Element Method(DEM).The model was calibrated and verified using various experimental data reported in the literature and compared with different theories of incipient particle motion.Sensitivity analysis was done and the effects of relevant parameters were determined.In addition to hydrodynamic forces such as drag,shear lift and Magnus force,the particle-particle interaction effects were included in the model.The asymptotic critical mobility number was evaluated for various critical particle Reynolds numbers(R*)in the range of very small and very large R*.The obtained curve is classified into four regions.It was found that in the linear region,the drag force has the principal role on the initiation of motion.Moreover,the critical mobility number is independent of particle diameter.A procedure for estimating the critical shear velocity directly from the information on particle diameter and roughness height was developed.Finally,the mechanism of incipient motion for the different regions was studied and the effect of different forces on the incipient particle motion was obtained.It was found that the maximum effects of lift and Magnus forces were,respectively,less than ten and twenty percent of the total force.The drag force,however,was typically the dominant force accounting for majority of the net hydrodynamic force acting on sediment particles at the onset of incipient motion. 展开更多
关键词 Incipient motion Shields curve Numerical simulation Drag force Lift force
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One-Dimensional Explicit Tolesa Numerical Scheme for Solving First Order Hyperbolic Equations and Its Application to Macroscopic Traffic Flow Model 预览
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作者 Tolesa Hundesa Legesse Lemecha Purnachandra Rao Koya 《应用数学(英文)》 2019年第3期119-137,共19页
In this paper, a new numerical scheme for solving first-order hyperbolic partial differential equations is proposed and is implemented in the simulation study of macroscopic traffic flow model with constant velocity a... In this paper, a new numerical scheme for solving first-order hyperbolic partial differential equations is proposed and is implemented in the simulation study of macroscopic traffic flow model with constant velocity and linear velocity-density relationship. Macroscopic traffic flow model is first developed by Lighthill Whitham and Richards (LWR) and used to study traffic flow by collective variables such as flow rate, velocity and density. The LWR model is treated as an initial value problem and its numerical simulations are presented using numerical schemes. A variety of numerical schemes are available in literature to solve first order hyperbolic equations. Of these the well-known ones include one-dimensional explicit: Upwind, Downwind, FTCS, and Lax-Friedrichs schemes. Having been studied carefully the space and time mesh sizes, and the patterns of all these schemes, a new scheme has been developed and named as one-dimensional explicit Tolesa numerical scheme. Tolesa numerical scheme is one of the conditionally stable and highest rates of convergence schemes. All the said numerical schemes are applied to solve advection equation pertaining traffic flows. Also the one-dimensional explicit Tolesa numerical scheme is another alternative numerical scheme to solve advection equation and apply to traffic flows model like other well-known one-dimensional explicit schemes. The effect of density of cars on the overall interactions of the vehicles along a given length of the highway and time are investigated. Graphical representations of density profile, velocity profile, flux profile, and in general the fundamental diagrams of vehicles on the highway with different time levels are illustrated. These concepts and results have been arranged systematically in this paper. 展开更多
关键词 HYPERBOLIC EQUATION Advection EQUATION Tolesa NUMERICAL Scheme Traffic Flow NUMERICAL Simulation
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Research and Application of Water Flooding Timing and Method for Blocky Bottom Water Fractured Buried Hill Reservoir 预览
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作者 Xiaolin Zhu Hui Cai +2 位作者 Xinran Wang Qin Zhu Zhiqiang Meng 《电力能源(英文)》 2019年第9期1-10,共10页
Oilfield A is a fractured buried hill reservoir in Bohai bay of China. In order to solve the difficult problem of water flooding timing and method in oilfield. Considering the characteristics of the buried hill fractu... Oilfield A is a fractured buried hill reservoir in Bohai bay of China. In order to solve the difficult problem of water flooding timing and method in oilfield. Considering the characteristics of the buried hill fractures with stress sensitivity and strong heterogeneity, the ECLIPSE software was used in the research, and a three-dimensional injection-production numerical model for horizontal wells in buried hill reservoirs is established. According to the main research factors in water flooding, a series of water flooding schemes are designed, and the optimization of water flooding timing, oil recovery rate and water flooding mode in buried hill reservoirs were carried out. The results show that the optimum pressure level of fractured reservoir is about 70% of the original reservoir pressure. The optimal water flooding method is the conventional water flooding in the initial stage, when the water cut reaches 80%, it is converted into periodic water flooding. The oil recovery is the highest when the water injection period is 4 months. Field tests show that conventional water flooding is carried out in the initial stage of the oilfield A when the pressure is reduced to 70% of the original. Periodic water flooding is carried out when water cut is 80%. Good development results had been achieved in the 10 years since oilfield A was put into production. The average productivity of single well reached 300 m3/d in the initial stage, at present, the water cut is 60%, and the recovery degree is 18.5%, which is better than that of similar oilfields. This technology improves the water flooding effect of blocky bottom water fractured dual media reservoirs in metamorphic buried hills, and provides a reference for the development of similar reservoirs. 展开更多
关键词 Fractured BURIED HILL Reservoir WATER FLOODING TIMING WATER FLOODING METHOD Numerical Simulation
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3D Numerical Simulation of Aerodynamic Characteristics of a Gas Filter 预览
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作者 Fangfang Si Pengfei Lian +3 位作者 Derui Yang Guolin Han Shaoyue Hao Pingwei Ye 《应用数学与应用物理(英文)》 2019年第8期1920-1928,共9页
The filter paper and activated carbon which filled inside the gas filter have porous media characteristics. In order to study the flow field structure in the filter layer and the activated carbon layer, Computational ... The filter paper and activated carbon which filled inside the gas filter have porous media characteristics. In order to study the flow field structure in the filter layer and the activated carbon layer, Computational Fluid Dynamics method is used to simulate the aerodynamic characteristics of a simplified gas filter. The inertial and viscosity parameters of porous media are solved by Forchheimer equation. The three-dimensional N-S equation and the modified low Reynolds number k-ε turbulence model are adopted to analyze the influence of the explosion-proof plate on the gas filter’s aerodynamic characteristics. The results showed that the air age in the upstream of the activated carbon plates was small, which easily caused the rapid penetration of the Poisonous gas. And in the downstream and around of the activated carbon plates, the air age is larger, formed dead zone, the utilization rate of activated carbon is lower. The explosion-proof plate increases the pressure drop of the gas filter, the air age distribution in the filter layer is more uniform and the utilization rate of filter paper is improved. However, the explosion-proof plate has little influence on the flow field structure of the activated carbon layer. 展开更多
关键词 NUMERICAL Simulation GAS FILTER Air Age POROUS MEDIA
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On Transient Simulation of Field Equations 预览
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作者 Peter Chen 《应用数学(英文)》 2019年第9期719-727,共9页
We investigate under what conditions transient simulation could be used to integrate backward in time so that the initial field could be recovered from later histories. In this paper we use realistic examples and find... We investigate under what conditions transient simulation could be used to integrate backward in time so that the initial field could be recovered from later histories. In this paper we use realistic examples and find that, in long histories, traces of the initial field would be present only in the exact analytical solutions. We conclude that the recovery of initial field is possible only if the equations could be solved analytically or only short time periods are involved. In practice, it is not possible to detect those traces by measurements or observations. If numerical procedures are used, truncation and discretization errors are always present. Fine-tuning of system parameters used or transforming time into another pseudo time frame may allow numerical integration to be carried out backward in time. But numerical instability is still a problem. Large spurious increases found by numerical procedures are most likely due to numerical inaccuracy and instability. 展开更多
关键词 Solution of Differential EQUATIONS TRANSIENT Simulation Numerical INSTABILITY MATHEMATICAL MODELLING BACKWARD Time Integration
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Design and Strength Verification of LNG Cargo Enclosure System FSP Type 预览
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作者 Zeng Ji Yuan Bo +1 位作者 Feng Qi Chen Yan 《现代机械工程(英文)》 2019年第2期49-56,共8页
The demand for natural gas in the world is increasing day by day. The efficient and flexible LNG becomes the preferred method for natural gas storage and transportation and has gradually entered people’s daily life. ... The demand for natural gas in the world is increasing day by day. The efficient and flexible LNG becomes the preferred method for natural gas storage and transportation and has gradually entered people’s daily life. The enclosure system is the key core of LNG transport and storage vessels for storage of LNG at -163°C for isolation and thermal insulation. A new type of flat half-film prismatic LNG enclosure system has been developed for the shortcomings of the existing LNG cargo enclosure system. Through the breakthrough and mastery of key core technologies such as the overall layout and integration of the system, anti-leakage technology, liquid tank fixing technology, and large-scale friction stir welding (P-FSW) flat-line pipeline development technology, we’ll strive to fill the gap in the intelligent construction technology of large aluminum alloy tanks in China. The tank was subjected to water vapor test and numerical simulation. The results show that the structural strength of the FSP-LNG tank meets the strength check standard of IGC Code. 展开更多
关键词 LNG TANK Water Vapor Test NUMERICAL SIMULATION STRENGTH
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Effect of Rotation and Revolution on Performance of Blade-Free Planetary Mixer 预览
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作者 Takayuki Yamagata Nobuyuki Fujisawa 《流量控制、测量及可视化(英文)》 2019年第1期1-10,共10页
In this study, flow structures and mixing performance in a blade-free planetary mixer, which combines rotation and revolution motions inside a cylindrical vessel, are numerically investigated. Flow fields in the mixer... In this study, flow structures and mixing performance in a blade-free planetary mixer, which combines rotation and revolution motions inside a cylindrical vessel, are numerically investigated. Flow fields in the mixer vessel are simulated in a single rotating reference frame with various revolution speeds and a fixed rotation speed. The mixing process is investigated by a Lagrangian particle tracking method and the mixing performance is evaluated based on particle concentration. The results of the numerical simulations show that a vortical flow with an axis inclined with respect to the rotation axis of the vessel is generated by the combined influence of the rotation and revolution motions. The flow structure and vortical flow intensity vary as a function of the precession rate, which is the ratio of the revolution speed to rotation speed. The mixing performance of the blade-free planetary mixer is found to be maximum at aspecific precession rate. 展开更多
关键词 Blade-Free PLANETARY MIXER Numerical Simulation Particle Tracking Flow Visualization MIXING
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A Novel Simulation Framework for Predicting the Formation Parameters Variation in Unconsolidated Sandstone Reservoir 预览
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作者 Hongying Li Wei Zhang +2 位作者 Bin Liu Xinran Wang Xilin Liu 《地球科学和环境保护期刊(英文)》 2019年第7期172-183,共12页
After long-term waterflooding in unconsolidated sandstone reservoir, the high-permeability channels are easy to evolve, which leads to a significant reduction in water flooding efficiency and a poor oilfield developme... After long-term waterflooding in unconsolidated sandstone reservoir, the high-permeability channels are easy to evolve, which leads to a significant reduction in water flooding efficiency and a poor oilfield development effect. The current researches on the formation parameters variation are mainly based on the experiment analysis or field statistics, while lacking quantitative research of combining microcosmic and macroscopic mechanism. A network model was built after taking the detachment and entrapment mechanisms of particles in unconsolidated sandstone reservoir into consideration. Then a coupled mathematical model for the formation parameters variation was established based on the network modeling and the model of fluids flowing in porous media. The model was solved by a finite-difference method and the Gauss-Seidel iterative technique. A novel field-scale reservoir numerical simulator was written in Fortran 90 and it can be used to predict 1) the evolvement of high-permeability channels caused by particles release and migration in the long-term water flooding process, and 2) well production performances and remaining oil distribution. In addition, a series of oil field examples with inverted nine-spot pattern was made on the new numerical simulator. The results show that the high-permeability channels are more likely to develop along the main streamlines between the injection and production wells, and the formation parameters variation has an obvious influence on the remaining oil distribution. 展开更多
关键词 Formation Parameters VARIATION Network Modeling NUMERICAL Simulation High-Permeability CHANNELS REMAINING Oil Distribution Unconsolidated SANDSTONE RESERVOIR
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Abutment pressure distribution for longwall face mining through abandoned roadways 预览
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作者 Yang Li Mingxing Lei +4 位作者 Haosen Wang Cheng Li Weiwei Li Yang Tao Jingyi Wang 《矿业科学技术学报:英文版》 CSCD 2019年第1期59-64,共6页
Abutment pressure distribution is different when a longwall panel is passing through the abandoned gate roads in a damaged coal seam. According to the geological condition of panel E13103 in Cuijiazhai Coal Mine in Ch... Abutment pressure distribution is different when a longwall panel is passing through the abandoned gate roads in a damaged coal seam. According to the geological condition of panel E13103 in Cuijiazhai Coal Mine in China, theoretical analysis and finite element numerical simulation were used to determine the front pressure distribution characteristics when the longwall face is 70, 50, 30, 20, 10, and 5 m from the abandoned roadways. The research results show that the influence range of abutment pressure is 40 to 45 m outby the face, and the peak value of front abutment pressure is related to the distance between the face and abandoned roadways. When the distance between the longwall face and abandoned roadways is reduced from 50 to 10 m, the front abutment pressure peak value kept increasing. When the distance is 10 m, it has reached the maximum. The peak value is located in 5 to 6 m outby the faceline. When the distance between the longwall face and abandoned roadways is reduced from 10 to 5 m, the front abutment pressure sharply decreases, the intact coal yields and is even in plastic state. The peak value transfers to the other side of the abandoned roadways. The research results provide a theoretical basis for determining the advance support distance of two roadways in the panel and the reinforcement for face stability when the longwall face is passing through the abandoned roadways. 展开更多
关键词 Abandoned roadways ABUTMENT PRESSURE THEORETICAL CALCULATION NUMERICAL simulation
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软弱土层条件沉淀池基坑开挖与回填数值分析 预览 被引量:1
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作者 王戡 《工程建设与设计》 2019年第1期56-57,60共3页
以污水处理厂沉淀池基坑的开挖与回填工程为例,采用非线性有限元方法借助FLAC3D软件对不良地质条件下基坑开挖与回填进行模拟分析,同时通过有限元方法模拟计算作业区内土体的应力及相应位移,根据模拟得出的应力场及位移场指导现场施工... 以污水处理厂沉淀池基坑的开挖与回填工程为例,采用非线性有限元方法借助FLAC3D软件对不良地质条件下基坑开挖与回填进行模拟分析,同时通过有限元方法模拟计算作业区内土体的应力及相应位移,根据模拟得出的应力场及位移场指导现场施工作业。 展开更多
关键词 数值模拟 基坑开挖 有限元数值模拟
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Results of Numerical Modeling of the Origin of Cyclones and Anticyclones in the Vicinity of the Intertropical Convergence Zone 预览
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作者 Igor V. Mingalev Konstantin G. Orlov Victor S. Mingalev 《大气和气候科学(英文)》 2019年第2期213-228,共16页
A review of simulation results, devoted to time-dependent modeling of the initial stage of the formation of large-scale vortices in the troposphere in the vicinity of the intertropical convergence zone, is presented. ... A review of simulation results, devoted to time-dependent modeling of the initial stage of the formation of large-scale vortices in the troposphere in the vicinity of the intertropical convergence zone, is presented. The simulation results were obtained not long ago with the help of the mathematical model of the neutral wind system of the lower atmosphere, developed earlier in the Polar Geophysical Institute. The utilized mathematical model produces three-dimensional distributions of the atmospheric parameters in the height range from 0 to 15 km over a limited region of the Earth’s surface. Simulation results were obtained for the case when the limited three-dimensional simulation domain, situated at low latitudes, is intersected by an intertropical convergence zone in the west-east direction. The reviewed simulation results were obtained for various initial configurations of the intertropical convergence zone. Results of numerical modeling have indicated that the origin of convexities in the form of the intertropical convergence zone can lead to the formation of different large-scale vortices in the lower atmosphere, in particular, a tropical cyclone, pair of cyclonic vortices, pair of cyclonic-anticyclonic vortexes, and triplet of cyclonic vortices. The simulation results, obtained earlier and presented individually in various editions, are reviewed and summarized in the present paper. A physical mechanism, responsible for the formation of the simulated large-scale vortices in the vicinity of the intertropical convergence zone, is discussed. 展开更多
关键词 NUMERICAL Simulation Air Flow Lower ATMOSPHERE TROPICAL CYCLONES
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Evaluation of the Impact Force of Dry Granular Flow onto Rock Shed 预览
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作者 Chun Liu Zhixiang Yu Junfei Huang 《地球科学和环境保护期刊(英文)》 2019年第5期1-15,共15页
In the design of rock sheds for the mitigation of risk due to rapid and long landslides, a crucial role is played by the evaluation of the impact force exerted by the flowing mass on the rock sheds. This paper is focu... In the design of rock sheds for the mitigation of risk due to rapid and long landslides, a crucial role is played by the evaluation of the impact force exerted by the flowing mass on the rock sheds. This paper is focused on the influencing factors of the impact force of dry granular flow onto rock shed and in particular on the evaluation of the maximum impact force. The coupled DEM-FEM model calibrated with small-scale physical experiment is used to simulate the movement of dry granular flow coupled with impact forces on the rock-shed. Based on the numerical results, three key stages were identified of impact process, namely startup streams slippery, impact and pile-up. The maximum impact force increases linearly with bulk density, and the maximum impact force exhibits a power law dependence on the impact height and slop angle respectively. The sensitivities of bulk density, impact height, and slope angle on the maximum impact force are: 1.0, 0.496, and 2.32 respectively in the benchmark model. The parameters with high sensitivity should be given priority in the design of the rock shed. The results obtained from this study are useful for facilitating design of shed against dry granular flow. 展开更多
关键词 Coupled DEM-FEM Method DRY GRANULAR Flow ROCK SHED Impact FORCE Sensitivity Analysis Numerical Simulation
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五对角紧致差分格式优化及二维声波传播波动方程数值模拟 预览
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作者 汪勇 穆鹏飞 +2 位作者 蔡文杰 王鹏 桂志先 《石油物探》 EI CSCD 北大核心 2019年第4期486-498,共13页
提高波动方程有限差分数值模拟的精度和效率对于地震勘探有着重要意义.基于频散关系保持的思想,利用最小平方法和拉格朗日乘数法,对二阶导数的五对角紧致有限差分格式进行了差分系数优化,并对优化前后的模拟精度、频散关系及稳定性条件... 提高波动方程有限差分数值模拟的精度和效率对于地震勘探有着重要意义.基于频散关系保持的思想,利用最小平方法和拉格朗日乘数法,对二阶导数的五对角紧致有限差分格式进行了差分系数优化,并对优化前后的模拟精度、频散关系及稳定性条件进行了分析和对比.研究结果表明,对于同样的差分精度,优化格式具有更小的截断误差和更低的数值频散以及更高的计算精度,适用于更粗的空间网格.对简单的均匀介质模型和复杂的Marmousi模型进行了声波方程数值模拟,结果表明,2N阶优化格式在压制数值频散方面优于2N阶原格式,也优于2N+2阶原格式,这意味着在对同一模型进行数值模拟时,可以使用更大的空间步长和更少的计算节点,从而减少计算内存和时间,提高计算效率. 展开更多
关键词 紧致有限差分 频散关系保持 数值模拟 数值频散 稳定性条件 完全匹配层 模拟精度 差分系数
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Wind Field Flow Characteristics Analysis of T4-72 Type Centrifugal Fan 预览
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作者 Xiaoke He Ding Tian Xiaoyong Song 《流体动力学(英文)》 2019年第3期241-252,共12页
In order to explore the internal wind field flow characteristics of T4-72 type centrifugal fan, the three-dimensional model was established based on PRO/E software. Combined with computational fluid Dynamics Software ... In order to explore the internal wind field flow characteristics of T4-72 type centrifugal fan, the three-dimensional model was established based on PRO/E software. Combined with computational fluid Dynamics Software Fluent 6.3, the standard model and SIMPLEC algorithm were used to simulate the wind field inside the fan. Analysis of the flow characteristics, velocity distributed and pressure distributed of the internal fluid model of the T4-72 centrifugal fan, combined with the theoretical formula to obtain the full pressure, power and efficiency performance parameters of the fan. The centrifugal fan performance curve is drawn. While compared with the experimental data, it is found that the internal flow disturbance is strong when the fan is running under low load condition and high load condition, which affects the performance of the fan and reduces the life of the fan. The numerical simulation results are consistent with the experimental results. The overall performance parameters of the fan are in good agreement, verifying the reliability of the simulation results;when the fan works between 1 - 1.4 times the rated flow rate, it can obtain a more stable flow field while maintaining higher efficiency, which provides a new idea for the optimization of the subsequent fan. 展开更多
关键词 CENTRIFUGAL FAN NUMERICAL Simulation WIND Field Flow ANALYSIS
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The Fluid Identification Forward Modeling Study of Carbonate Cave Reservoir 预览
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作者 Xiaoming Yang Yanchun Wang +1 位作者 Jianxin Wei Bangrang Di 《地球科学国际期刊(英文)》 2019年第4期367-376,共10页
The fluid identification of carbonate reservoir is a key factor to hydrocarbon exploration and reservoir development. In order to simulate the seismic response characteristics of the cave in the carbonate reservoir, t... The fluid identification of carbonate reservoir is a key factor to hydrocarbon exploration and reservoir development. In order to simulate the seismic response characteristics of the cave in the carbonate reservoir, three sets of models were designed, including the caves varied in width, the caves filled with different solids, and the oil-gas-water model. The numerical simulation technique was used to carry out the forward modeling and the AVO (Amplitude varies with offset) response characteristics of the three groups of models were analyzed. The results show that the AVO characteristics can be observed when the cave reaches a certain extent in the horizontal direction. When the surrounding rock is constant, the absolute value of the intercept of the AVO curve increases with the Vp/Vs decrease. The AVO technology can effectively identify the gas cave. The effect is not obvious to water or oil cave. 展开更多
关键词 CARBONATE RESERVOIR FLUID Identification NUMERICAL Simulation AVO Response
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