Airflow characteristics in the occupied zone of ventilated spaces
Airflow characteristics in the occupied zone of ventilated spaces
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发表时间：
1987
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通讯作者：
H. Hanzawa;A. Melikov;P. Fanger
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作者：
H. Hanzawa;A. Melikov;P. Fanger
A.K. Melikow博士P.O. Fanger ASHRAE Fellow Draft是通风或空调空间中最常见的投诉原因之一。因此，了解这些空间中的湍流气流以及这种气流对气流感觉的影响非常重要。湍流特性（湍流强度、湍流长度尺度、湍流动能等）在20个典型的通风空间进行了调查。结果表明，所有通风空间的平均速度和湍流强度变化范围很大，平均速度从小于0.05 m/s到0.40 m/s，湍流强度从10%到70%。湍流能量谱与充分发展的湍流能量谱相似。光谱揭示了在低波数范围内的大涡对总湍流能量的主要贡献。一些实验结果与现有的数值预测进行了比较。介绍通风，定义为不必要的局部冷却人体所造成的空气流动，也许是最常见的原因之一，投诉通风或空调空间。气流可能导致人们停止通风系统和堵塞空气扩散器。居住者也可能试图通过提高空气温度来抵消气流，在冬季，这通常会增加能源消耗。早期的标准草案基于气候室研究，受试者暴露于层流或低湍流气流（霍顿1938;麦金太尔1979）。然而，通风空间中的气流通常不是层流。通常，空气速度会波动，Fanger和Pedersen（1977）已经表明，周期性波动的气流比无波动（层流）气流更不舒适。暴露主题明确的周期性速度波动的气候室，他们发现，不适有一个最大的速度频率在0.3 - 0.5赫兹左右。后来，Fanger和Christensen（1986）将100名受试者暴露在湍流气流中，并将结果绘制成一张草图，预测不满意的居住者的百分比作为平均速度和温度的函数。Thorshauge（1982）在一项现场研究中，通过在几个通风空间中的测量，确定了实际中发生的速度波动。他发现了平均速度和速度波动的标准差之间的线性关系。但是仍然缺乏关于通风房间中实际气流的信息。本研究的目的是确定，通过现代测量技术，湍流气流的特点发生在占用区的通风范围广的Hisashi Hanzawa工作在这项研究作为访问研究助理在实验室的供暖和空调，技术大学丹麦。他隶属于竹中通信株式会社，东京都江东区南须名2丁目5-14技术研究室环境机械工程部阿森湾Melikow是研究助理和P.O. Fanger是丹麦技术大学供暖和空调实验室的教授，地址是丹麦林比DK-2800号楼402。实践中的524个空间。这些信息对于评估以前的研究，规划未来关于湍流气流对人的通风感觉的影响的研究以及模拟通风空间中的气流是必不可少的。有几项研究采用了二维或三维模型对气流进行数值计算，使用的是在简化模型中测得的实验数据（Nielsen 1974; Gosman等1980; Unno等1983; Sakamoto和Matsuo 1980）。在简化模型中，平均速度分布的预测值与实测值吻合较好，但气流的湍流特性的预测值与实验值（Sakamoto and Ma tsuo 1980）存在一定的差异。Moog（1981）讨论了房间气流的复杂性及其预测。为了修正数值模型，目前在1：1比例尺上测量的房间气流特性将是有用的。空间中紊流气流的特性空间中的紊流气流可以用下列量值来表征。瞬时速度V = V + V'，它被假定为平均速度V和主要流动方向上的速度波动V'之和。平均速度V是瞬时速度V在时间间隔t1上的平均值
A.K. Melikow, Ph.D. P.O. Fanger ASHRAE Fellow Draft is one of the most common causes of complaint in ventilated or air-conditioned spaces. Therefore, knowing the turbulent airflow in these spaces and the impact of this flow on the sensation of draft is very important. The characteristics of turbulent flow (turbulence intensity, length scales of turbulence, turbulence kinetic energy, etc.) were investigated in 20 typically ventilated spaces. Relationships between these characteristics and the mean velocity were found. The mean velocities and turbulence intensities of all ventilated spaces varied widely the mean velocity from less than 0.05 mis to 0.40 m/s and the turbulence intensity from 10% to 70%. The turbulence energy spectra are similar to those in a fully developed turbulent flow. The spectra reveal the major contribution to total turbulent energy made by the larger eddies in the low-wave number range. Some of the experimental results were compared with existing numerical predictions. INTRODUCTION Draft, defined as unwanted local cooling of the human body caused by air movement, is perhaps one of the most common causes of complaint in ventilated or air-conditioned spaces. Draft may cause people to stop ventilation systems and to plug up air diffusers. The occupants may also try to counteract the draft by elevating the air temperature, and during the winter this will normally increase energy consumption. Earlier draft criteria were based on climate chamber studies where subjects were exposed to laminar or low turbulent airflow (Houghton 1938; Mcintyre 1979). However, the airflow in ventilated spaces is not normally laminar. Typically the air velocity fluctuates and Fanger and Pedersen (1977) have shown that periodically fluctuating airflow is more uncomfortable than nonfluctuating (laminar) airflow. Exposing subjects to well-defined periodic velocity fluctuations in a climate chamber, they found that the discomfort had a maximum at velocity frequencies around 0.3 0.5 Hz. Later, Fanger and Christensen (1986) exposed 100 subjects to turbulent airflow and presented the results in a draft chart predicting the percentage of dissatisfied occupants as a function of mean velocity and temperature. In a field gtudy, Thorshauge (1982) identified the velocity fluctuations that occurred in practice through measurements in several ventilated spaces. He found a linear relationship between the mean velocity and the standard deviation of the velocity fluctuations. But still there is lack of information about the actual airflow in ventilated rooms. The purpose of this study is to identify, by means of modern measuring techniques, the characteristics of turbulent airflow occurring in the occupied zone of a wide range of ventilated Hisashi Hanzawa worked on this study as visiting Research Associate at the Laboratory of Heating and Air Conditioning, Technical University of Denmark. His affiliation is Takenaka Komuten Co. Ltd., Environmental and Mechanical Engineering Unit, Technical Research Laboratory, 5-14, 2-Chome, Minamisuna, Koto-ku, Tokyo. Arsen K. Melikow is Research Associate and P.O. Fanger is Professor at the Laboratory of Heating and Air Conditioning, Technical University of Denmark, Building 402, DK-2800 Lyngby, Denmark. 524 spaces in practice. Such information is essential for assessing previous studies, for planning fut ure studies on the impact of turbulent airflow on man's sensation of draft, and for modelling airflow in ventilated spaces . Several studies have applied twoor three-dimensional models for numerical calculation of airflow, using experimental data measured in reduced models (Nielsen 1974; Gosman et al. 1980; Unno et al. 1983; Sakamoto and Matsuo 1980). The predicted mean velocity distribution was in good agr eement with measured data in reduced models, but there are discrepancies between the predicted turbulent characteristics of airflow and the experimental results of these characteristics (Sakamoto and Ma tsuo 1980). Moog (1981) discusses the complexity of the room airflow in connection with its prediction. To modify the numerical models, the present measurements of characteristics of room a irflow on the scale 1:1 will be useful. CHARACTERISTICS OF TURBULENT AIRFLOW IN SPACES The turbulent airflow in spaces may be characterized by the following magnitudes. The instantaneous velocity V = V + V' which was assumed to be the sum of the mean velocity, V, and the velocity fluctuations, V', in the main direction of the flow. The mean velocity, V, is the average of the instantaneous velocity, V, over an interval of time, t1