CFD介绍及其在建筑通风中的应用

首先介绍了建筑通风研究的重要性,讨论了建筑通风研究的两种方法,对比实验方法的优缺点,分析了CFD(计算流体动力学)研究方法的特点.接着对CFD的原理及行业应用进行了简要说明,介绍了五个常用的CFD软件.给出了CFD模拟在建筑通风方式设计中的应用情况,对比传统通风工程设计流程,介绍了借助CFD技术的现代通风设计流程及其优点.最后,对今后建筑通风中CFD技术的应用进行了展望.     

置换通风下的湿环境研究

利用CFD方法对一个典型置换通风办公室的湿环境进行了模拟研究，结果表明空间内的湿度呈分层梯度分布，明显区别于混合通风室内湿度一致的特点，与现有实验结果得出的规律一致。置换通风系统的这一特点，有利于对空调空间进行有效的湿度控制和空调系统的节能。     

某化学实验室机械通风模拟

针对三种不同通风方案,运用CFD软件进行数值模拟,研究实验室内污染物浓度场、空气速度场、空气流线图等,分析不同送排风口位置时室内的通风效果,得出最佳通风方案,并对存在的问题提出了建议,对实际工程有一定的参考价值.     

10 kV高压变频器室降温设计方案探讨

对油气田10 kV高压变频器室现有通风系统存在的问题进行了分析及CFD软件模拟验证.提出新的半包裹式通风系统降温方案,应用CFD软件对新方案进行模拟.半包裹式通风系统可以使变频器室室内温度控制在28 ～ 35℃,满足变频器室工作环境温度小于40℃的要求.     

某抗火实验室通风系统改造方案及实施

根据抗火实验室的情况,确定了下部自然进风、屋顶机械排风的全面通风方式;采用CFD模拟的方法确定了机械排风量和屋顶风机位置;通过对污染物浓度的实测,验证了通风改造的效果.     

CFD数值模拟的系统误差反馈及其实现

顾了近年来CFD数值模拟的系统误差及不确定度的研究进展，分析了系统误差反馈的基本程序及CFD在通风空调领域应用过程中所遇到的特殊困难，并介绍了CFD数值模拟的系统误差反馈思路。     

珠海横琴市民艺术中心空调通风设计

介绍了项目的空调通风系统设计,包括室内设计参数、 冷源、 空调水系统及风系统.重点介绍了档案库,图书阅览中心,群众艺术中心,科技展览中心,美术馆,门厅的空调通风系统设计及三个中心的CFD模拟分析.     

寒冷地区住宅室内不同通风方式模拟与分析

住宅室内存在不同的通风方式,对室内风环境产生不同的影响。研究寒冷地区一梯三户中户住宅室内不同通风方式的特点以及效果,探索不同通风方式对住宅室内风速场、空气品质和热舒适度的影响。引用CFD流体力学的原理,运用Airpak3.0软件对住宅室内自然通风、侧送风、置换通风进行模拟计算,模拟三种通风方式室内风速场、温度场、空气平均年龄、PMV、PPD参数值分布,对比分析不同通风方式下室内风速、温度、空气平均年龄、PMV值,得出采用置换通风的寒冷地区一梯三户中户住宅室内通风利用气流上升,提高了室内新鲜空气,满足室内热舒适环境,创造良好的住宅室内环境,是一种舒适高效的通风方式,为寒冷地区一梯三户中户住宅室内通风设计提供科学指导。     

冷却顶板对置换通风系统的影响:CFD研究

以计算流体力(CFD)的模型为基础,采用有限容积法对带有冷却顶板的置换通风系统和不带冷却顶板的普通置换通风系统的温度场、气流分布及人体的热舒适性进行了模拟分析,模拟结果表明,冷却顶板-置换通风系统可以减小室内温度梯度,提高人体热舒适性。     

自然通风热分布系数规律性初探

针对以室内热源为主的一类自然通风,采用CFD软件进行了模拟,并将结果与公式值进行了比较,揭示了自然通风热分布系数的一般性规律。采用CFD软件模拟有一定的误差,但对于工程计算和研究是可行的。     

Experimental and CFD study of ventilation flow rate of a Monodraught™ windcatcher

Monodraught™ windcatchers are commercial natural ventilation devices, which are primarily driven by wind to produce both extract and supply air flow. The measurement of the net flow rate (extract minus supply) of a Monodraught™ windcatcher ABS 550 for various wind speeds and directions is introduced. The ventilation measurement system uses a cone flow meter and a blower fan. CFD standard k − ? turbulence model is employed to calculate the flow rate. The situation using a blower fan is considered in modelling and the effect of the manometer sensitivity is also discussed. The comparison has indicated a good agreement between measurement and simulation. CFD modelling of the windcatcher is then carried out for the situation of outdoor far field wind. At the same nominal wind speed, the calculated extract flow rate of the windcatcher in a far field wind is roughly twice that for the situation using a blower fan, the wind direction has a small effect on the extract flow rate. The extract and supply flow rates are also calculated for various room pressure due to various wall openings and installation on a flat roof or a pitched roof. The contribution of the buoyancy effect on the flow rates is discussed in simulation.     

地铁车站火灾的烟气流动状况研究

以地铁火灾与烟气发展过程的数学模型为基础,建立CFD模拟的物理模型,对岛式无屏蔽门的地铁车站列车火灾进行了数值模拟。分析了火灾发生后的烟气流动规律及温度场和气流场的分布,并与实体燃烧试验的结果进行了对比。结果表明,如果方程模型选用恰当,边界条件设置合理,CFD模拟火灾的结果是能够令人满意的。     

Low-temperature baseboard heaters with integrated air supply – An analytical and numerical investigation

The functioning of a hydronic baseboard heating system with integrated air supply was analyzed. The aim was to investigate thermal performance of the system when cold outdoor (ventilation) airflow was forced through the baseboard heater. The performance of the system was evaluated for different ventilation rates at typical outdoor temperatures during the Swedish winter season. Three different analytical models and Computational Fluid Dynamics (CFD) were used to predict the temperature rise of the airflow inside the baseboard heater. Good agreement between numerical (CFD) and analytical calculations was obtained. Calculations showed that it was fully possible to pre-heat the incoming airflow to the indoor temperature and to cover transmission losses, using 45 °C supply water flow. The analytical calculations also showed that the airflow per supply opening in the baseboard heater needed to be limited to 7.0 l/s due to pressure losses inside the channel. At this ventilation rate, the integrated system with one air supply gave about 2.1 more heat output than a conventional baseboard heating system. CFD simulations also showed that the integrated system was capable of countering downdraught created by 2.0 m high glazed areas and a cold outdoor environment. Draught discomfort in the case with the conventional system was slightly above the recommended upper limit, but heat distribution across whole analyzed office space was uniform for both heating systems. It was concluded that low-temperature baseboard heating systems with integrated air supply can meet both international comfort requirements, and lead to energy savings in cold climates.     

Numerical study on temperature stratification in a room with underfloor air distribution system

In this study, numerical prediction using computational fluid dynamics (CFD) was utilized to investigate air temperature stratification in a room with an underfloor air distribution (UFAD) system. The numerical modeling using CFD computation was validated with physical test in a full size experimental room with an UFAD system. The different supply air conditions and heat loads were discussed. The results show that the effect of three parameters, heat load, supply volume flux and supply air velocity, on room air temperature would be expressed by the length scale of the floor supply jet. When the length scale increased from 0.8 to 1.56 m, the ratio of vertical temperature difference between 2.5 and 0.1 m at the occupied zone to the difference between return and supply air temperature decreased from 0.62 to 0.25. When there was only one local heat source in the room, there was a thermal stratified interface at the occupied zone. The interface height was about 1.42 times the length scale. The results may suggest ways to optimize UFAD design and operation.     

CFD在夏季室内自然通风中的应用

针对一般家庭中的典型客厅类型,运用计算流体力学方法对其夏季自然通风特性进行了数值模拟,分析了不同风道口高度对房间的速度场、温度场的影响,结果可为住宅设计提供相关的参考依据。     

Eulerian-Lagrangian model for traffic dynamics and its impact on operational ventilation of road tunnels

This contribution deals with a computational Eulerian-Lagrangian model that simulates movement of cars inside a road tunnel and its impact on operational ventilation. The model simulates moving cars as discrete objects that “fly” through the tunnel. The objects are treated with a Lagrangian momentum equation and their velocity is solved along their trajectories that are determined by the shape of the roadway. The flow of the ambient air is solved with a commercial CFD code StarCD. Due to drag force, the cars virtually change their velocity, but the latter is continuously re-set to its original value. The momentum equation for the continuous phase contains an additional source term that results from the net efflux of momentum of cars when they enter and leave a particular control volume of the solution domain. The model by Jicha et al. (Int. J. Environ. Monit. Asses. 65 (2000) 343) can simulate cars moving at different speeds and traffic rates in individual traffic lanes. As a result we obtain flow rate generated by moving vehicles as a function of traffic speed and traffic rates. Turbulence was modelled using standard k-ε model with three different formulas for extra sources of the kinetic energy of turbulence that account for additional turbulence generated by moving vehicles. The traffic-induced turbulence shows a non-negligible effect on the total flow rate inside the tunnel. The model was validated with experimental data from Chen et al. (Int. J. Wind Eng. Ind. Aerod. 73 (1998) 99), where the small-scale tunnel 1:20 was investigated. The experiments were carried out with a moving belt carrying small car-like objects. The tunnel length was 20 m, the height 36.5 cm and the tunnel had two parallel lanes. Several traffic densities and speeds were simulated, namely 10,000, 20,000 and 30,000 cars/h per lane with speeds of 20 km/h and 40 km/h.     

地铁岛式站台空调气流CFD模拟

为给岛式站台的气流组织设计提供依据,评价气流组织设计方案,确定合适的送风温差以优化岛式站台空调系统的设计。建立典型岛式站台的三维几何模型,应用标准湍流模型作为站台气流的物理模型,根据实际测试的站台热湿负荷设定数值模拟的边界条件,应用CFD（计算流体力学）对地铁岛式站台空调系统进行模拟。岛式站台的温度场模拟结果与实际测试的站台温度场吻合较好,表明在合理的简化条件下,采用标准湍流模型的计算流体力学模拟能够较为准确地模拟和预测地铁岛式站台的温度场,可以为岛式站台空调系统的气流组织设计提供依据。     

下送上回通风方式供冷与供暖运行性能比较

下送上回通风方式目前得到了广泛的研究应用,其供冷运行时就是置换通风,但同样一套通风系统在一些地区的寒冷季节则有可能需要作供暖运行.为了获得下送上回通风系统在分别作供冷与供暖运行时的具体性能参数,本文应用实验测试与计算流体力学(CFD)模拟的方法研究了置于环境实验室内的某办公环境.研究中分析比较了该办公环境内的空气速度、温度以及追踪气体污染物的浓度分布.研究结果表明,下送上回通风方式作供冷运行时空气温度及污染物浓度分层现象明显,空气处于半混合状态,置换效果较好;作供暖运行时,温度及污染物浓度趋于均匀,通风系统性能接近于混合送风系统,不具备良好的抑制交叉污染的能力.     

Characterizing transportation of indoor gaseous contaminant using the state space method

This paper employs the state space method to characterize transportation of indoor gaseous pollutant in steady airflow field. From the differential equations governing contaminant transportation in space, the state space equation for transportation is proposed and the analytical solution is obtained. In the method, the matrix covering hologram of the transportation is derived. The state space equation is validated with the analytic solution for the case of the simultaneous transportation of the pollution for piston flow. Similarly, the concentration from the proposed method for a 2-D case also agrees well with the result from CFD method based on the experimentally validated flow field. Based upon the analytic solution of the state equation, it is easily known that the influence of the initial concentration distribution and the pollution source on the concentration at the specific point. In addition, assisted by Chen’s zero equation turbulence model [1], the concentration field for a 3-D case is simulated by the presented method. It is found that there exists a regular stage at which the relative effect of the initial concentration distribution and the source on the concentration field will not change with time.     

双层幕墙冬季内循环送风的CFD气流及热工模拟

本文借助功能强大的CFD通用软件FLUENT,对广东省中医院的双层玻璃幕墙在冬季内循环运行的情况下进行了热工模拟,得到自然热气流及增强热气流两种工况下双层玻璃幕墙热通道内的速度场和温度场。在此基础上,得到出风口的空气流量、平均温度、平均风速等物理量,进而求出通风增热效率h及K值,最后对双层幕墙的冬季增热综合性能进行评估。