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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，在通风口附近的气流会发生极大的变形，从而导致动压和静压之间的能量发生可逆和不可逆的变化。本文进行了风洞实验和数值分析，主要研究结果如下：（1）来流口处来流下降的主要原因在于迎风面下部的再循环引起的压力梯度。（2）模型特征对标准k的缺陷。修正后的模型在一定程度上改善了ε模型。另一方面，当使用LES时，诸如风压系数、湍流能量等因素比k-ε型模型更准确地再现。(3)To为了阐明总压损失的机理，通过跟踪被动段的运动轨迹，计算了通过来流口的虚拟流管的形状 ...更多信息标记。通过开口的流动变为在短距离内发生加速和减速的复杂流动。当风向不为0℃时，流管在到达开口之前与壁面接触。当风向设置为67.5°时，流管变为沿着壁面流动，然后到达开口。（4）开口处的总压在风向达到45℃之前是恒定的，当风向超过45℃时，气流在迎风角处分离，总压大大降低。（5）当流量系数因风向变化而降低时，局部动力相似模型比传统的孔口模型能更准确地预测通风量。（6）若将1/10建筑高度处平行于墙的速度动压加到风压上，则用单线式热线风速计的简化方法可粗略估算出来流面开口处的总压。少