关键词: 自然通风, 平面空间划分, 外窗开启扇洞口面积比, 标准层新风换气次数, CFD模拟

Abstract: Improving interior natural ventilation through architectural design instead of relying on specialised equipment and technology is a current research hotspot. This study used CFD tools to construct a standard floor plan model matrix that focuses on interior partition design, aiming to obtain the correlation between floor partitions and interior ventilation performance. The results are significant for instructing architectural design from the preliminary stage.
　　Based on the induction of plenty of built office and teaching buildings, controlling design factors remain unchanged (i.e., standard floor area, usage coefficient, column span, height, standard floor height). This research constructed a standard floor plan model matrix with three factors that change continuously and uniformly (building depth, interior partition density and external window open ratio). An interior ventilation simulation was carried out using PKPM-cfd, inputting a 3m/s southeast wind as a fixed initial condition and setting the simulation parameters such as calculation domain, calculation grid and convergence accuracy according to related standards. The standard floor fresh-air exchange frequency was proposed to be the main evaluation index.
　　The velocity contour obtained by the simulation gave the following rules: (1) The inner corridor is highlighted, demonstrating that the wind speed in the inner corridor is higher than in other rooms. (2) The area between the open external windows and the open doors in each room is brighter than the surrounding areas, which means the wind speed here is higher, demonstrating that wind speed in a single room is unevenly distributed. (3) The velocity contour becomes gradually brighter as the external window open ratio increases, demonstrating that the indoor wind speed increases accordingly. (4) The wind speed distribution in rooms with partition walls is uneven, while the wind speed distribution in rooms without a partition is relatively uniform, which demonstrates the decisive impact of partitions on natural ventilation.
　　The standard floor fresh air exchange frequency obtained by the simulation shows the following relativities: (1) The average of the four values in each column decreases with the increase of building depth, demonstrating that the air exchange frequency decreases significantly when the building depth increases. (2) The average of the four values in each column increases with the external window open ratio, demonstrating that the air exchange frequency increases significantly when the external window open ratio increases. (3) The three values with different interior partition densities in each column are close, demonstrating that the interior partition density has little influence on air exchange frequency. (4) The three values with partitions differ greatly from the one value without a partition in each column, demonstrating that the presence or absence of partitions significantly impacts on air exchange frequency. (5) The five values grow in each row when the external window open ratios increase; however, the wind speed without a partition grows more rapidly than the wind speed with partitions as the external window ratio grows. Therefore, there exists a tipping point when the external window open ratio is approximately 2.5%, indicating a probable change in decision-making about partition wall designs considering air exchange frequency.
　　The conclusions and suggested design strategies are as follows: (1) Shaping the building as a strip-shaped volume of single or double corridors is conducive to natural ventilation.(2) Keeping the external window open ratio above 2.5% is conducive to natural ventilation, equivalent to keeping at least one casement window or two awning windows open every four to six sashes on horizontal continuous windows. (3) The interior partition density has little influence on interior natural ventilation. (4) The presence or absence of partitions has a significant impact on interior natural ventilation and plans without partitions when the external window opening ratio is over 2.5% are conducive to interior natural ventilation.

Key words: natural ventilation, interior partition design, external window opening ratios, standard floor fresh air exchange frequency, CFD simulation