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Establishment of high-precision model for ventilation flow rate and proposal of natural ventilation design method

高精度通风流量模型的建立及自然通风设计方法的提出

基本信息

批准号：
13555163
负责人：
OHBA Masaaki
金额：
$ 8.7万
依托单位：
Tokyo Polytechnic University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Ventilation is a phenomenon of complicated turbulent flow, which exhibits reversible and irreversible changes of energy between dynamic pressure and static pressure associated with extreme deformation of airflows near openings. The wind tunnel experiment and numerical analyses have been carried out.The findings of the study can be summarized as follows.(1)The primary cause of the inflow downfall at inflow opening lies in the pressure gradient due to the re-circulation at the lower portion of the windward surface.(2)The defects of the model characteristic to the standard k.-ε.model could be improved to a certain extent by application of the modified models. On the other hand, when LES is used, the factors such as wind pressure coefficient, turbulence energy, etc. are more accurately reproduced than k-εtype models.(3)To elucidate the mechanism of total pressure loss, the shape of a virtual flow tube passing through the inflow opening was calculated by tracing the trajectories of passive … More markers. The flow passing through the opening changes to a complicated flow where acceleration and deceleration occur within short distance. When the wind direction is other than 0℃, the stream tube contacts the wall surface before it reaches the opening. When the wind direction is set to 67.5°, the stream tube changes to a flow along the wall surface and then reaches the opening.(4)The total pressure at the opening is constant until the wind direction reaches 45℃, When the wind direction exceeds 45℃, the airflow separates at the windward corner, and the total pressure greatly decreases.(5)The proposed local dynamic similarity model could predict the ventilation flow rate with better accuracy than the conventional orifice model when discharge coefficients decreased due to changes of wind directions.(6)The simplified method using a single wire type hot-wire anemometer could roughly estimate total pressure at the opening for an inflow surface if the dynamic pressure of velocity parallel to the wall at a point away by one-tenth of building height was added to the wind pressure. Less

通风是一种复杂的湍流现象，它表现出动压和静压之间的可逆和不可逆的能量变化，并伴随着洞口附近气流的极端变形。进行了风洞试验和数值分析。研究结果表明：(1)迎风面下部再环流引起的压力梯度是造成来流口落差的主要原因。(2)修正后的模型可以在一定程度上改善标准k.-ε模型的缺陷。另一方面，当使用大涡模拟时，风压系数、湍动能等因素比k-ε模型更准确地再现。(3)为了阐明总压损失的机理，通过跟踪被动…的轨迹，计算了通过入口处的虚拟流管的形状更多的记号笔。流过孔口的流动变成了一种复杂的流动，在很短的距离内发生了加速和减速。当风向不是0℃时，流管在到达洞口之前与墙表面接触。当风向设置为67.5°时，流管沿壁面变为流动，然后到达开口处。(4)开口处的总压保持不变，直到风向达到45℃，当风向超过45℃时，气流在迎风角处分离。当风向变化导致流量系数减小时，所提出的局部动力相似模型可以比传统的孔板模型更准确地预测风量。(6)采用单线式热线风速仪的简化方法，如果在风压中加上与墙面平行的一点的速度动压与建筑物高度的十分之一相加，则可以粗略估计入风面开口处的总压。较少