發(fā)布時間：2018-06-05 17:22

  本文選題：非穩(wěn)態(tài) + 自然通風量��； 參考：《湖南大學》2013年碩士論文

【摘要】：目前有關自然通風的大部分研究均集中在自然風平均特性的基礎上，但是自然風的脈動特性對建筑通風效果同樣是值得重視的。本文總結(jié)了自然風的平均風特性和脈動風特性，分別建立了基于脈動流機理以及平均連續(xù)流機理的單開口通風量理論計算模型，最后采用大渦模擬（LES）方法對非穩(wěn)態(tài)流場下的單開口自然通風進行模擬，以驗證建立的理論計算模型。 首先，重點介紹了脈動風的脈動風速、湍流強度、相關函數(shù)、湍流積分尺度以及功率譜密度等特性，并假定脈動風速為具有零均值的平穩(wěn)高斯隨機過程，將Davenport風速譜的統(tǒng)計公式作為目標譜，基于MATLAB平臺，采用諧波疊加法（WAWS）對單點風速時程進行了模擬。同時，討論了諧波疊加法中的可控參數(shù)：頻率截取區(qū)間、頻率和時間采樣點數(shù)的選取范圍對模擬結(jié)果的影響。 然后，針對單開口的脈動流流動機理，考慮空氣可壓縮性以及開口處空氣的慣性，基于非定常伯努利方程，構建了室內(nèi)外脈動風壓傳遞函數(shù)，從而得到室外隨機風速輸入條件下的通風量計算模型。并分析了風量隨開口面積、房間體積、平均風速以及湍流強度等影響因素的變化。針對單開口的平均連續(xù)流流動機理，就平均風速的概率統(tǒng)計分布特性，建立了平均風速呈威布爾分布條件下的平均通風量模型。對于小開口，通風量可看作僅由脈動通風組成；而對于大開口，通風量是平均通風和脈動通風兩者之和。 最后，應用Fluent軟件對非穩(wěn)態(tài)流場下單開口自然通風進行大渦模擬，采用諧波疊加法生成隨機脈動風速時程數(shù)據(jù)，同時考慮平均風速隨高度變化呈指數(shù)分布，，脈動風速經(jīng)過零散度修正處理后作為數(shù)值模擬的入口邊界條件。分別對不同開口面積、建筑體積以及平均風速等多個工況條件下的單開口建筑進行模擬，并將模擬計算出的通風量與本文提出的理論通風量模型進行對比分析，驗證該模型的科學性和合理性。
[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.
【學位授予單位】：湖南大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU834.1

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本文編號：1982820