非稳态风压驱动下单开口自然通风量理论计算及数值模拟

发布时间：2018-06-05 17:22

本文选题：非稳态 + 自然通风量　；参考：《湖南大学》2013年硕士论文

【摘要】：目前有关自然通风的大部分研究均集中在自然风平均特性的基础上，但是自然风的脉动特性对建筑通风效果同样是值得重视的。本文总结了自然风的平均风特性和脉动风特性，分别建立了基于脉动流机理以及平均连续流机理的单开口通风量理论计算模型，最后采用大涡模拟（LES）方法对非稳态流场下的单开口自然通风进行模拟，以验证建立的理论计算模型。首先，重点介绍了脉动风的脉动风速、湍流强度、相关函数、湍流积分尺度以及功率谱密度等特性，并假定脉动风速为具有零均值的平稳高斯随机过程，将Davenport风速谱的统计公式作为目标谱，基于MATLAB平台，采用谐波叠加法（WAWS）对单点风速时程进行了模拟。同时，讨论了谐波叠加法中的可控参数：频率截取区间、频率和时间采样点数的选取范围对模拟结果的影响。然后，针对单开口的脉动流流动机理，考虑空气可压缩性以及开口处空气的惯性，基于非定常伯努利方程，构建了室内外脉动风压传递函数，从而得到室外随机风速输入条件下的通风量计算模型。并分析了风量随开口面积、房间体积、平均风速以及湍流强度等影响因素的变化。针对单开口的平均连续流流动机理，就平均风速的概率统计分布特性，建立了平均风速呈威布尔分布条件下的平均通风量模型。对于小开口，通风量可看作仅由脉动通风组成；而对于大开口，通风量是平均通风和脉动通风两者之和。最后，应用Fluent软件对非稳态流场下单开口自然通风进行大涡模拟，采用谐波叠加法生成随机脉动风速时程数据，同时考虑平均风速随高度变化呈指数分布，，脉动风速经过零散度修正处理后作为数值模拟的入口边界条件。分别对不同开口面积、建筑体积以及平均风速等多个工况条件下的单开口建筑进行模拟，并将模拟计算出的通风量与本文提出的理论通风量模型进行对比分析，验证该模型的科学性和合理性。
[Abstract]:At present, most of the researches on natural ventilation are focused on the average characteristics of natural wind, but the pulsating characteristics of natural wind are also worthy of attention to the effect of building ventilation. In this paper, the average wind characteristics and pulsating wind characteristics of natural wind are summarized, and the theoretical calculation models of single opening ventilation based on pulsating flow mechanism and average continuous flow mechanism are established respectively. Finally, the large eddy simulation (les) method is used to simulate the natural ventilation with single opening under the unsteady flow field to verify the established theoretical model. Firstly, the characteristics of pulsating wind speed, turbulence intensity, correlation function, turbulence integral scale and power spectral density are introduced, and it is assumed that the pulsating wind speed is a stationary Gao Si stochastic process with zero mean. The statistical formula of Davenport wind speed spectrum is taken as the target spectrum. Based on the MATLAB platform, the harmonic superposition method is used to simulate the single point wind speed time history. At the same time, the controllable parameters in the harmonic superposition method are discussed, such as the interval of frequency interception, the influence of frequency and time sampling points on the simulation results. Then, considering the compressibility of air and the inertia of the air at the opening, based on the unsteady Bernoulli equation, the transfer function of fluctuating wind pressure in and out of the room is constructed. Thus, the model of ventilation calculation under the condition of outdoor random wind speed input is obtained. The influence factors of air volume such as opening area, room volume, mean wind speed and turbulence intensity were analyzed. According to the mechanism of average continuous flow with single opening, the model of average ventilation under the condition of Weibull distribution of mean wind speed is established according to the probability and statistical distribution of average wind speed. For small openings, ventilation can be regarded as composed of pulsating ventilation, while for large openings, ventilation is the sum of average ventilation and pulsating ventilation. Finally, Fluent software is used to simulate the large eddy of the unsteady flow field, and the harmonic superposition method is used to generate the random pulsating wind speed time history data, considering the exponential distribution of the average wind speed with the height variation at the same time. The pulsating wind speed is treated by dispersion correction as the entry boundary condition of numerical simulation. The single opening building with different opening area, building volume and average wind speed is simulated, and the calculated ventilation is compared with the theoretical ventilation model proposed in this paper. The model is verified to be scientific and reasonable.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU834.1

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