A Study on the Extreme use of cross-ventilation as a potential energy for air-conditioning purpose

首先，将局部动力相似模型应用于出流口，重点考虑了交叉通风的动力相似性。通过大涡模拟和风洞实验研究了出流侧开口处的气流结构，评价了出流侧开口处的交叉通风性能。结果表明，大涡模拟能较好地再现风洞实验结果，如在P_R^* 值较低的小范围内流量系数的大幅度增加。通过大涡模拟对压力场的分析表明，气流中动压的残余和出流口附近压力场的变化对流量系数有很大的影响。此外，通过识别通风气流的流管的配置，发现流量系数根据气流如何出去而变化。一般而言，在流出开口处与壁面相切的动压力被认为是 关于我们 低于流入侧。通过实际尺寸的试验研究了P_R^* 的出现频率，并阐明了流量系数大幅度降低的P_R^* 区域很少出现。其次，在利用CFD（计算流体力学）评估建筑物上的风压分布时，通常使用k-ε模型。然而，众所周知，使用标准k-ε模型存在诸如高估风冲击建筑物的迎风面上的风压系数和湍流动能等缺点。为了克服这些问题，已经提出了对k-ε模型的各种修改。采用修正的k-ε模型和k-ω模型对平行六面体结构的风压分布进行了计算，并对各模型的特点进行了验证。研究结果表明，引入Durbin限制器（模型参数α=0.5）的修正k-ε模型对风压分布的估计具有较好的效果。在综合评价中，修正的k-ε模型（包括Durbin限制器（α=0.65）、RNG模型（重整化群理论）和二次型模型）都给出了较好的结果，最后，利用建筑模拟程序TRNeclampswith COMIS对引入交叉通风的冷负荷减少量进行了估算。结果表明，建筑物的特点和窗户的操作方式决定了建筑物的减载效果。通常，较低的参考温度，即较高的内部热增益和较低的热损失系数，带来较高的负荷减少。较大的建筑热容量也与这种效应有关。对于Windows操作，对几种操作方式进行了测试和比较。在日本郊区的木制独立式住宅中，减少率从10%到20%不等，这取决于窗户的操作方式。在占用和清醒期间，仅通过打开窗户不能大幅减少冷负荷。频繁的窗户操作对环境条件很敏感，特别是在夜间和空闲期间，增加了交叉通风的效果。少

At first, Local Dynamic similarity model giving special notice on dynamic similarity of cross-ventilation was applied to the outflow openings. Cross-ventilation performance at the openings on outflow side was evaluated, and the structure of air flows around the outflow openings was studied by LES and wind tunnel experiment. It was found that LES reproduces the results of the wind tunnel experiment fairly well such as extensive increase of discharge coefficient in a small region where P_R^* value is low. The evaluation of the pressure field by LES revealed that the remainder of dynamic pressure in the air flows and the change of pressure field around the outflow openings give strong influence on discharge coefficient. Also, by identifying the configuration of the stream tube of ventilation air flow, it was found that discharge coefficient is changed depending on how the air flows go out. In general, dynamic pressure tangential to wall surface at the outflow openings is considered to be … More lower than that of the inflow side. The frequency of occurrence of P_R^* was investigated by actual-size experiment, and it was elucidated that the region of P_R^* where discharge coefficient is extensively decreased develops only very rarely.In the second place, to evaluate wind pressure distribution on a building by using CFD (computational fluid dynamics), it has been generally practiced to use k-ε models. However, it is known that the use of the standard k-ε model has disadvantages such as overestimation of wind pressure coefficient and turbulent kinetic energy on the windward surface where wind impinges on the building. To overcome these problems, various modifications of the k-ε model have been proposed. In the present study, a number of modified k-ε models and k-ω model were applied for the estimation of wind pressure distribution on the building, which was designed in parallelepiped shape, and the characteristics in each of these models were confirmed. The results of the present study suggest that the modified k-ε model incorporating Durbin's limiter (model parameter α=0.5) showed satisfactory results for the estimation of wind pressure distribution. In the overall evaluation, the modified k-ε models (incorporating Durbin's limiter (α=0.65), RNG model (renormalization group theory) and Quadratic model) provided good results.At the last, cooling load reduction by introducing cross-ventilation is estimated trough use of building simulation program, TRNSYS with COMIS. Results show the load reduction depends on the building characteristics and way of windows operation. Generally, lower reference temperature, i.e. higher internal heat gain, and lower heat loss coefficient, brings higher load reduction. Larger amount of building thermal capacity also associates the effect. For windows operation, several ways of operations are tested and compared. The reduction rate varies from 10 to 20 % for wooden detached house in suburban area in Japan, depending the way of windows operation. The cooling load is not drastically reduced solely by opening windows during occupied and waking period. Frequent window operations sensitive to ambient conditions especially during night and unoccupied period increase the effect of cross-ventilation. Less