密集烤房内温度与气流分布数值模拟研究

提高烤房内温度及气流组织分布的均匀性,不仅可有效提高烟叶烘烤质量,而且可在一定程度上缩短烘烤时间,从而降低烘烤能耗。以密集型标准烤房为模拟研究对象,建立了装烟室内空气流动的k-ε两方程三维紊流模型。利用大型计算流体力学软件Fluent,对密集烤房内温度场及速度场进行了系统地数值模拟。分析了装烟室内温度及气流分布的均匀性,并获得了密集烤房合理的送风量。相关的数值模拟结果可为密集烤房结构、气流组织分布优化及循环风机选型提供参考。     

Numerical Simulation on Confluence of the Two Rivers in Chongqing City

Flows of the confluence of Yangtze River and Jialing River in the city of Chongqing are numerically simulated by using Delft3D Model with staggered grids and ADI integral method. The water level, flow velocity and drogue trace are studied. Comparing the numerical results with observed data shows good agreement. Therefore the computational model and the simplified parameters are of good accuracy and have practical meaning. The results show that the contamination will linger near the Caiyuanba area and drift to Chaotianmen and the right bank of Yangtze River upstream. The results can be used to forecast flood, inspect contamination and management of riverway in the city.     

Numerical Simulation of Groundwater Flow and Quality

With societal development, wastes exist in industry, agriculture and human life. In particular, a large volume of urban industrial sewage is discharged and pesticides and fertilizers are widely used, leading to groundwater pollution in many areas. Based on a water quality model of hydrodynamic dispersion and the multi element balance (MEB) method, a general program for simulating groundwater flow and quality is carried out using the program VC++ for visual presentation. Using this program in a case study, the transportation mechanism of groundwater flow and quality is simulated numerically. The result indicates that the program is visual and can be manipulated well. It offers a point of reference for the reasonable exploitation, protection and utilization of the groundwater.     

Numerical Simulation of the Solidification Process Under the Effect of Nature Convection

The process of solidification is numerically simulated with control volume method. The authors study the nature convection in the liquid phase and flow pattern of nature convection during the process of solidification. The result of simulation shows that there are the global flow cells inside the liquid phase, and the local circumfluence exists in the global cells. Especially, the authors analyze transformation of the interface between phases under the effect of free convection on the process of solidification.     

Numerical Simulation of Mechanical Behaviors of Articular Cartilages

Articular cartilage, which is composed with a solid phase of collagen fibers and proteoglycan and a pore fluid phase, can be depicted with two-phase porous medium model based on mixture theory. This paper analyzed the creep and stress relaxation responses of confined compression problems of articular cartilage with the developed finite element method. The obtained responses of velocities of both solid and fluid phases and the effective stresses of solid phase as well as the pore pressures during the creep and stress relaxation processes of articular cartilage tissues under confined compression can be used as a theoretical reference for man-made cartilage materials, and behave important significance for the research in bio-mechanical engineering area.     

河南省2018年1月3—4日暴雪天气的诊断分析与数值模拟

为进一步探讨河南省暴雪天气过程的成因和机理,分析WRF模式对暴雪过程的模拟效果,提高预报准确率,笔者利用NCEP 1°×1°再分析资料和常规观测资料,对2018年1月3—4日河南省大范围的暴雪天气过程进行诊断分析,并对WRF模式模拟结果进行分析。结果表明,高空槽、低层的切变和急流、地面冷空气是这次暴雪的主要影响系统。水汽条件好,水汽通量低层辐合,高层辐散,伴有较强的上升运动,更有利于暴雪天气的发生。WRF模式模拟的降雪量范围和强度都与实况较为一致,表明模式对暴雪天气的预报有一定的参考价值。     

Numerical Simulation of Frost Characteristic on Refrigeration System Evaporator

In order to analyze the running performance of refrigeration air conditioning system and confirm thaw periods in reason, frost process and change process of frost thickness of evaporator surface are studied. Based on basic theory and experiential formula of heat transfer process and mass transfer process, the math model of mass transfer of vapor on evaporator outside and growth process of frost are established. Aiming at a sort of finned-tube evaporator, frost process and change process of frost thickness are simulated numerically. The influence of environment parameters is analyzed.     

Numerical Simulation on Drying Characteristics of a Combined Microwave-convection Process

Combined microwave-convection drying characteristics are investigated by numerical simulation. Combined microwave-convection drying has advantage of swift drying and sterilization. Based on qualitative analyses on the mechanism of combined microwave-convection drying, the differential equations are established and the numerical simulation method is described. The humidity, vapor pressure and temperature, along the radius in a spherical pill, are calculated by the numerical simulation during drying process. The calculation results show the relationship between humidity, vapor pressure, temperature and drying time, and that drying process is greatly influenced by input microwave power. The calculation results are good consistent with the experimental datum.     

Numerical Simulation in Flow Field of CNG Vehicle Catalytic Converters

The steady flow in the catalytic converters of CNG was simulated. The gas can breakaway in the entering pipe and the flow of the gas can convergence well in the exhaust pipe. The flow distributing mainly depends on the flow capability of the expanding pipe. The pressure falls apparently in the carrier of catalytic converters. The noble metals in the center of the catalytic converters are consumed more quickly than the edge zone.     

Numerical Simulation of Strata Movement Behavior in Deep Excavation

According to the complex conditions of deep excavation in Nantong mine, FLAC program are carried out for strata movement, ground pressure and surface displacement due to coal extraction. Based on the analysis of Nantong mine, the basic features of strata movement, the fundamental behavior of ground pressure and the related parameters of surface displacement are obtained. The results are of referential value for mining, supporting and preventing of surface displacement.     

沿海防护林网防风效应数值模拟研究

为研究沿海防护林网的防风效能,采用计算流体力学软件FLUENT对上海浦东新区的水杉林网周围的气流场分布进行了数值模拟。结果表明：水杉林网对气流有着明显的削弱作用,风速在林带前5 H左右处逐渐下降,在林带后出现回流现象,随后林带对气流的作用逐渐减弱,风速逐渐恢复。各林带的有效防护距离在10 H左右,因此,林网中林带间距设置在15 H左右比较合适。     

Numerical Simulation of HVAC in Vehicle Air Conditioning System

Through applying the theory of Computational Fluid Dynamics(CFD),this paper describes the numerical simulation of a typical HVAC in vehicle air conditioning system for improving on the structure of HVAC,shortening the time periods of product design and reducing the costs of design. By applying CFD to simulate designs and improve on the inconsepuential designs,it can make the symmetrical distributing of velocity and temperature of air in HVAC,obtain a proper value of velocity and reduce the yawp value.From the result of simulation,the numerical model has been optimized.It advances the capability of air-conditioning system.While applying CFD to the design of HVAC,it carry the purpose of shortening design the periods of HVAC and reducing the costs of empolderings and tests.     

Numerical Simulation of the Flow Resistance in TWC with Guiding Components

The steady flow resistance in the Three Catalytic Converters(TWC) with guide components of CNG(Compressed Natural Gas)cars is simulated.The location set guide flow equipment has great impact on pressure losing which can be adjusted to the optimal while adopting some measures.Pressure losing by adding combination flow-guide plate which can evidently improve flow field uniformity has a little impact on engine.Pressure losing will be small while adopting optimal location and guiding-flow construction.     

一次黄渤海海上大风过程模拟分析

2009 年2 月13 日黄渤海海域冷锋过境,出现海上大风天气过程。为分析此次大风过程的形成机理以及物理量场的分布特征,利用WRF数值模式对此次大风过程进行数值模拟。研究发现,WRF数值模式对这次冷锋型天气过程的高、中、低空天气系统的演变和强度模拟效果较好,成功揭示了黄渤海沿海地区大气环流形势及控制天气系统演变的主要特征：此次大风过程主要是冷锋过境引起的大风降温过程,冷空气开始入侵,地面气压梯度力增强,风速开始增大,同时明显反映出冷暖气团的斜压性,锋面的斜压性增强地面风速。物理量场的模拟说明,当测站上空由上升运动转为下沉运动时,风速逐渐增大,风速的大小与下沉运动的强度呈正比。温度和相对湿度场的分布反映了锋面过境的系统演变。     

Numerical Simulation on Whole Construction Process of High-Rise CFST Structures

The time-changing analysis model for concrete filled steel tubes was established based on the time-changing concrete model of CEB-FIP MC90, in which the interaction between steel tube and concrete core was considered by the restraint conditions of master and slave nodes. The numerical simulation method was developed for analyzing the whole construction process of high-rise CFST structures. A real structure was taken as numerical example, in which the influence of concrete creep and shrinkage as well as construction process was considered. The results of numerical simulation are compared with those obtained from on-site monitoring. It is shown that the concrete creep and shrinkage as well as construction process have big influence on high-rise CFST structures, which should be taken into account in designs and constructions.     

Numerical Simulation and Analysis of Control Rod Dropping of Qingshan 300 MW Nuclear Reaction

This paper provides a theoretic basis to analyze the mechanism of control rod dropping and a solution method to solve the process of dropping. The authors analyze the effect of different forces acting on the control rod in detail. A mathematical model is built and a program is written to solve the process of downward motion. Finally, the model and relative coefficients of the model are modified according to the experimental data. The modified model can well simulate the process of dropping of the control rod, which gives a powerful proof to the accuracy of the model.