试析双层百叶风口对修建通风的作用及实践

低碳节能型建筑,已经成为当前建筑业热议的话题,其符合长远的绿色健康理念,以及宜居、自然的特点,已经成为一种发展趋势。而其中的自然通风对其意义十分重要,本文在建筑自然通风重要意义的基础上,采用粒子图像测速仪对双层百叶风口等温自由射流流场的过渡段进行研究,比较了张角为45°和垂直出流(张角90°)的流场,结果显示90°张角的风口流速比45°的大10%。同时,将双层百叶风口的特点功能,以及对修建通风的作用和实践问题进行了分析。     

室内空气流动的简捷数值模拟方法

概要介绍了N点风口动量模型、新零方程湍流模型及误差预处理数值算法，利用这些模型和方法对某采用百叶风口的办公室内温度场和速度场进行模拟计算，并与实验数据进行比较，表明计算值与实测值吻合得较好；在普通微机上能快速合理地模拟室内温度场和速度场，可用于实际工程指导通风空调气流组织设计和分析。     

一种新型风口边界条件设置方法的研究

采用CFD方法对圆形喷口单股等温自由射流进行数值模拟研究,提出了一种新的用于风口模拟的盒子分区计算模型。先将计算结果与Elsaadawy(1998)、Hussein(1994)实验数据和经典射流公式进行对比,选定合适的湍流模型,后通过对盒子分区计算模型的结果分析对比,说明该模型的可行性,为复杂风口大空间流场计算提供了一种新的思路。     

超低能耗居住建筑卧室室内环境模拟研究

以超低能耗居住建筑卧室为研究对象,采用ANSYS软件对卧室新风口的不同形式及与空调风口之间的位置关系进行模拟分析,结果表明在空调风口附近设置顶部侧送新风口,其室内的气流组织优于下送散流器新风口;顶部俱侧送百叶新风口与空调风口间距不宜过大;在空调风口附近布置下送散流器新风口时,风口宜尽量靠近空调回风口.     

风口上置置换通风及风口选型实验研究

提出了风口上置的置换通风方案,并给出此种方案的特点和上置式置换通风风口的要求,推导了风口出风速度呈阶梯状分布的射流特性公式。以喷口为基础进行实验,筛选出了满足条件的风口型式,并给出了出风速度呈阶梯状分布时圆形射流轴线速度衰减公式。     

矢流通风卫生间污染物气体扩散数值模拟

在建立传统公共卫生间和经过改造后的卫生间模型的基础上,分别对卫生间内污染物的浓度场和速度场分布进行数值模拟,并对模拟结果进行比较和分析.传统卫生间内气流组织分布杂乱无章,经改造后的卫生间,气流组织形态基本呈单向矢流,气流直接从呼吸区到污染区再排放到室外,污染物浓度分布基本在排风口处较低区域.改变卫生间内进、排风口相对位置以及进风口形式,采用百叶风口,使卫生间内气流整体呈单向矢流,污染物扩散影响范围较其他情况明显减小.     

工位空调送风气流数值模拟风口模型的比较

对工位空调送风进行数值模拟时需要引入入口边界条件,即建立风口模型.作为比较,文中选择了两种风口模型,即基本模型和计算机直接模拟风口形成入口边界条件的方法.并通过实验验证对模拟结果进行了分析比较,发现采用计算机直接模拟风口形成入口边界条件的方法具有相对较高的精度,不但在室内气流模拟中得到了较好的结果,而且也对风口内的气流做出比较好的描述.     

室内空气流动数值模拟的风口模型综述

介绍了目前国际上对室内空气流动进行数值模拟时采用的风口模型方法,并提出了应用于房间空气流动数值模拟的风口模型新思路。     

车用空调风口布置CFD数值仿真研究

本文以轿车空调为研究对象,对车用空调室内夏季冷负荷及送风量进行了设计计算,参照舒适性空调室内计算参数,根据自由射流理论得到了送风口的送风参数,选择RNG湍流模型,采用分区域划分网格的方法,并利用Monte Carlo法分析了太阳辐射引起的车体各固面的附加热流变化,对空调出风口在不同位置时的车内流场特性进行了数值模拟,分析了空调风口布置对车内气流组织的影响,为轿车室内环境的舒适性评价和轿车空调风口布置优化提供了参考。     

灯具式消声风口空气动力性能实验研究

灯具式消声风口是一种集送风、消声和照明三种功能为一体的新型风口，可降低噪声２０ｄＢ（Ａ）左右，属于高效灯具。本文对其空气动力性能进行实验研究，找出射流出口速度与风口全压的关系，以及气流的射程．试验表明，该风口能形成贴附的气幕，均匀而稳定，射程较远．装有灯具式风口的空调系统。风口上方无需调节风阀，就可使各个风口送风均匀．     

室内气流组织和空气品质的数值研究

分析了气流分布性能的评价指标、热舒适性评价指标和室内空气品质的评价指标。将通风方式分为置换通风和混合通风,利用暖通空调专用模拟软件Airpak对室内气流进行模拟。模拟某小型会议室的温度、速度、CO2浓度、平均空气龄、PMV值和PPD值,并依据模拟结果分析不同气流组织下的室内空气品质、人体热舒适性和空调能耗情况。指出不同气流组织对室内空气品质、人体热舒适性和空调能耗的影响不同,置换通风和上侧送上回送风方式能得到较好的空气品质和有效的能量利用。     

Experimental and CFD study of unsteady airborne pollutant transport within an aircraft cabin mock-up

It has been documented that diseases can spread within an aircraft cabin from the sneezing, coughing or breathing of a sick passenger. To understand the spreading mechanism it is very important to quantify the airflow and droplet transmission around a sneezing/coughing incident. In this project, tracer gas experiments were carried out in a full-scale Boeing 767-300 mock-up to study the global transport process of contaminated air within the cabin. Computational fluid dynamics (CFD) simulation was also used to provide additional information for understanding the principle. A steady airflow field was simulated first and then it was compared with the experimental data. The global airflow patterns were similar to those observed experimentally. This velocity field was adopted as the initial condition for further unsteady pollutant transport simulation. Experimental and simulated results were compared and discussed to develop a relationship between concentration and airflow pattern, source location, transport direction, and ventilation rate. Finally, the overall picture of concentration evolution by both experimental and simulated approaches was discussed.     

进风口对变压器室通风效果的影响

通风设计是户内变电站变压器室设计的难点问题。运用CFD方法,对某变压器室温度场和速度场进行模拟,并将模拟值与实测值对比,验证数学模型的有效性。在此基础上,以某变电站变压器室为模拟对象,通过改变进风口位置和面积,设计并模拟6种通风工况,通过对比各工况温度场、速度场和特征温度值的变化规律,重点研究进风口对变压器室通风效果的影响。模拟结果表明：进风口面积不变时,进风口应布置在散热器一侧且其中心高度宜控制在散热器中心高度或稍偏下位置,不宜高于散热器;进风口位置固定时,增大进风口面积改善通风效果时,宜选择沿高度方向增大进风口面积。所得结论可为变压器室通风设计提供技术参考。     

下送风空调气流组织设计方法

介绍了下送风气流组织中影响人体热舒适的四个主要因素：送风口型式，送风口到人体的距离，送风速度，送风温度。按因素重要性和最佳舒适性要求，提出了两种气流组织设计方法。     

不同送风速度下空调房间的气流组织数值模拟

以办公室空调房间为研究对象,运用计算流体力学(CFD)中Fluent软件数值模拟,对不同送风速度下空调房间的速度场、温度场进行三维数值模拟,对比分析不同送风速度对气流组织的影响。通过对几种不同工况下不同空间位置的速度云图、温度等值线图的分析,得到了不同送风速度对房间气流组织及热舒适性的影响。     

Impact of dynamic airflow on human thermal response

Airflow fluctuation is an important factor affecting indoor thermal environments and human thermal response. In this study, dynamic airflows with different fluctuation characteristics were generated by a dynamic air supply terminal. The influence of three different kinds of airflows, constant airflow, simulated natural airflow and sinusoidal airflow, on thermal comfort was studied. Subjective experiments indicated that a dynamic airflow can cause a stronger cold sensation, and that air movement with 1/f fluctuations similar to natural wind is more acceptable than other dynamic airflows in warm environments. Moreover, the impact of draughts in dynamic airflows on human thermal response is different in neutral-warm (30 degrees C) and cool-neutral (26 degrees C) thermal environments. PRACTICAL IMPLICATIONS: By means of a dynamic air supply terminal it is possible to generate artificial airflows that simulate natural wind indoors. This kind of airflow with higher velocity is more comfortable and causes less draught sensation than the constant airflows supplied by conventional fans. While the cooling effect of this airflow is utilized in the built environment, the design temperature of air-conditioning system can be increased and the amount of energy consumption can be reduced dramatically.     

Particle dispersion and deposition in ventilated rooms: Testing and evaluation of different Eulerian and Lagrangian models

Indoor particle dispersion in a three-dimensional ventilated room is simulated by a Lagrangian discrete random walk (DRW) model and two Eulerian models: drift flux model and mixture model. The simulated results are compared with the published measured data to check the performance of the three models for indoor particle dispersion simulation. The deposition velocity of the particles is also computed and compared with published data. The turbulent airflow is modeled with the renormalization group (RNG) k−ε and a zero equation turbulence model. Comparison of the calculated air velocities with measurement shows that both the two turbulence models can simulate the airflow well for the presented case. For the Lagrangian DRW model, a post-process program is used to state the particle trajectories and transfer the results to particle concentration distribution. For Eulerian models, the effect of particle deposition towards wall surfaces is incorporated with a semi-empirical particle deposition model. The comparison shows that both the Lagrangian DRW model and drift flux model yield satisfactory predictions, while the predicted results by the mixture model are not satisfied. The deposition velocity obtained by the three models match the experimental data well.     

方形散流器送风参数对气流分布影响实验研究

本文目的是研究方形散流器的送风参数对室内气流分布的影响规律。在模拟建筑内区的空调实验室进行了实验，测出了不同送风参数下室内所有测点的温度和速度。对实验数据分析得出空气分布特性指标、温度不均匀系数以及速度不均匀系数与送风速度的关系曲线，并用TECPLOT软件实现了温度场、速度场的可视化。结果表明在室内热源和控制温度不变时，随着送风速度的增大，送风温度升高，送风温差减小，室内工作区的空气分布特性指标增大。     

地板送风对流热转移

针对下部有集中热源的地板送风空调小室,利用PHOENICS软件,对多种工况下室内气流流动的速度场和温度场进行了模拟,利用模拟结果计算对流热转移量,得出对流热转移量的变化规律。分析了影响对流热转移量的相关因素,主要是由于送风冷射流与热源的热射流在不同的影响因素下对室内气流流动及温度分布产生影响,从而造成对流热转移量的变化。结果表明:地板送风空调小室的对流热转移量与热源数目、送风口密度、热源强度、送风量4个因素有关;回风口数目对对流热转移量的影响很小,可以忽略不计。     

Experimental study on airflow fluctuation characteristic of an underfloor air supply terminal unit

In order to investigate dynamic characteristic of underfloor air supply terminal unit, an IFV900A hot-wire anemometer was used to measure the corresponding velocity field. Turbulence intensity and power spectrum density exponent of air velocity signal were analyzed. The result showed that the outlet velocity distribution of underfloor air supply terminal unit was uniform. With increment of height, the velocity distribution trends to be uniform. Two velocity attenuation regions appear during airflow development. Turbulence intensity changes obviously with height. It is lower than that of mechanical wind. Turbulence intensity goes up with the increment of jetting distance. Power spectrum density exponent trends to the value of natural wind with increase of jetting distance and decrease of wind velocity. The exponent value approaches to the value of typical natural wind for the air velocity is 0.5 m/s under high supply air rate. With airflow diffusion, the fluctuation characteristic of airflow varies obviously with the jetting direction. The fluctuation characteristic of airflow changes to that of natural wind with the increase of height which can improve comfort of indoor environment.