本文選題：呼吸 + 微環(huán)境��； 參考：《湖南大學(xué)》2014年博士論文

【摘要】：越來越多的研究開始關(guān)注人的呼吸活動以及人體周圍微環(huán)境，因?yàn)檫@個(gè)靠近身體的吸氣及呼氣區(qū)域直接關(guān)系到人體健康和疾病的傳播。但是，人的呼吸活動非常復(fù)雜，受到很多因素的影響，例如，人體代謝水平及活動狀態(tài)、通風(fēng)策略、室內(nèi)空氣穩(wěn)定性、人體周圍空氣溫度、濕度及速度等。本文主要針對室內(nèi)空氣穩(wěn)定性與人體呼吸微環(huán)境的關(guān)系進(jìn)行詳細(xì)的研究。 一些研究指出當(dāng)室內(nèi)采用置換通風(fēng)方式時(shí)，由于溫度分層的存在，可能造成呼氣中的污染物如CO2、飛沫等在一定的高度分層凝滯，因而對室內(nèi)其他人員造成潛在的疾病傳播風(fēng)險(xiǎn)。本文利用室內(nèi)空氣穩(wěn)定性的概念對這一現(xiàn)象進(jìn)行解釋。室內(nèi)空氣穩(wěn)定性指室內(nèi)空氣抵抗豎直方向運(yùn)動的能力，可以通過室內(nèi)溫度梯度的方向進(jìn)行判定。通過利用假人實(shí)驗(yàn)、真人實(shí)驗(yàn)以及仿真人體模型計(jì)算三種手段，針對混合通風(fēng)形成的中性狀態(tài)以及置換通風(fēng)形成的穩(wěn)定狀態(tài)對人體呼吸周圍微環(huán)境的影響進(jìn)行研究。 三種方法相互驗(yàn)證。按可靠性高低排序，依次為真人實(shí)驗(yàn)、假人實(shí)驗(yàn)以及CFD模擬，，但操作難度及實(shí)驗(yàn)成本的依次降低。真人實(shí)驗(yàn)可以為其他兩種方法提供了可靠的驗(yàn)證，但是操作難度較大。假人模型及計(jì)算機(jī)人體模型在一定程度上能夠模擬人體的呼吸特點(diǎn)，由于模型的簡化可能導(dǎo)致模擬結(jié)果與實(shí)際人體呼吸之間的偏差，更準(zhǔn)確可靠的模型及模擬方法需要進(jìn)一步的研究。 本文的另一條主線是圍繞室內(nèi)空氣穩(wěn)定對人體呼吸微環(huán)境的作用展開。利用上述三種方法對人體呼氣氣流擴(kuò)散規(guī)律以及身體周圍熱羽流發(fā)展進(jìn)行了詳細(xì)的研究，主要得到如下幾個(gè)結(jié)論： （1）通過煙氣可視化實(shí)驗(yàn)，發(fā)現(xiàn)通過假人嘴巴的間歇呼氣與持續(xù)射流有很多相似之處，比如卷吸作用、射流形狀等。利用峰值速度描述脈動的呼氣氣流速度剖面時(shí)，發(fā)現(xiàn)了與自由射流類似的速度分布特點(diǎn)。據(jù)此，呼氣速度、濃度與溫度衰減規(guī)律利用與自由射流相似的表達(dá)式進(jìn)行描述。無論是持續(xù)呼氣還是間歇呼氣，氣流軌跡及彎曲程度都會受到呼氣初始角度、阿基米德數(shù)（Ar）、室內(nèi)空氣穩(wěn)定性以及身體散熱量的影響�？梢杂^察到，穩(wěn)定狀態(tài)的空氣會抑制呼氣氣流向上彎曲的程度，并會削弱呼氣氣流發(fā)展過程中的卷吸作用，降低了呼氣與周圍空氣的摻混的能力。 （2）不同的氣流組織形式及不同的身體代謝水平導(dǎo)致人體周圍氣流分布特點(diǎn)不同，并且造成呼氣氣流穿透距離以及速度與濃度衰減率不同。穩(wěn)定狀態(tài)導(dǎo)致呼出的污染物濃度分層，而中性狀態(tài)下污染物可以迅速地被通風(fēng)稀釋。隨著溫度梯度的增大，污染物在室內(nèi)分層的高度會下降。室內(nèi)空氣穩(wěn)定性影響呼氣的速度及濃度在水平方向的衰減速率。置換通風(fēng)由于帶來穩(wěn)定的室內(nèi)溫度層結(jié)，在一定程度上會抑制污染物在豎直方向的擴(kuò)散，因此不適合如病房、診所等有污染源的場合。 （3）通過對比實(shí)驗(yàn)結(jié)果發(fā)現(xiàn)，人體模型的尺寸對于身體周圍氣流分布影響明顯，利用與人體尺寸接近的數(shù)值模型對于研究人體微環(huán)境問題更具有優(yōu)勢。而且，模擬結(jié)果發(fā)現(xiàn)，研究此類問題時(shí)選擇適當(dāng)?shù)暮粑Ｊ揭卜浅Ｖ匾�。�?shù)值模擬方法一方面彌補(bǔ)了實(shí)驗(yàn)方法的不足，提供了更詳盡的人體呼吸微環(huán)境的信息，另一方面數(shù)值模擬的可靠性需要通過實(shí)驗(yàn)數(shù)據(jù)進(jìn)行驗(yàn)證。模擬結(jié)果顯示，室內(nèi)空氣穩(wěn)定性作用隨著溫度梯度的增大而增強(qiáng)，進(jìn)而對身體熱羽流的抑制作用以及對呼氣彎曲趨勢的抑制作用增強(qiáng)。穩(wěn)定的空氣除了抑制氣流豎直方向運(yùn)動以外，還可能造成水平方向的呼氣氣流擴(kuò)散作用增強(qiáng)。 室內(nèi)空氣穩(wěn)定性對呼吸的作用主要體現(xiàn)在影響呼氣氣流的擴(kuò)散、抑制身體周圍熱羽流的發(fā)展以及改變?nèi)梭w周圍污染物分布等方面。不同的通風(fēng)策略可能形成不同的穩(wěn)定性條件，進(jìn)而影響呼氣中污染物在室內(nèi)的擴(kuò)散規(guī)律，為了降低疾病傳播風(fēng)險(xiǎn)，充分考慮特定氣流組織形式下的室內(nèi)空氣穩(wěn)定性特點(diǎn)是非常必要的。
[Abstract]:More and more research has begun to pay attention to the breathing activity of people and the microenvironment around the human body , because the inspiratory and expiratory regions close to the body are directly related to the health of the human body and the spread of the disease . However , the human respiratory activity is very complex and is influenced by many factors , for example , the human body metabolism level and the active state , the ventilation strategy , the indoor air stability , the air temperature , humidity and speed around the human body , and the present paper mainly studies the relationship between the indoor air stability and the human breath microenvironment .

According to the concept of indoor air stability , this paper explains the effect of indoor air stability on the micro - environment around human breath by using the concept of indoor air stability . The indoor air stability refers to the ability of indoor air to resist vertical movement and can be determined by the direction of indoor temperature gradient .

The real - person experiment can provide reliable verification for the other two methods , but the operation difficulty and the experimental cost are reduced in sequence . The real - person experiment can provide reliable verification for the other two methods , but the operation difficulty is large . The dummy model and the computer human body model can simulate the breathing characteristics of the human body to a certain extent .

Another main line of this paper is to study the effect of indoor air stabilization on human breathing microenvironment . The diffusion law of expiratory flow and the development of hot plume around body are studied in detail using the above three methods .

( 1 ) Through the visualization experiment of flue gas , it is found that the intermittent exhalation through the artificial mouth has many similarities with the continuous jet , such as the suction effect , the shape of the jet , etc . The velocity profile of the expiratory flow similar to that of the free jet is described by means of the velocity profile of the expiratory flow .

( 2 ) Different forms of air flow and different levels of body metabolism result in different characteristics of airflow distribution around the body , and the penetration distance and velocity of the expiratory flow are different . The steady state results in the concentration stratification of exhaled pollutant . As the temperature gradient increases , the pollutant can be rapidly diluted by ventilation . As the temperature gradient increases , the pollutant can be rapidly diluted in the horizontal direction . The displacement ventilation can inhibit the diffusion of pollutants in the vertical direction due to the stability of the indoor temperature stratification . Therefore , it is not suitable for occasions such as wards , clinics and the like .

( 3 ) By comparing the experimental results , it is found that the size of the human body model has obvious influence on the distribution of the air flow around the body , and the numerical model which is close to the size of the human body is very important for the study of the human micro - environment problem .

The effect of indoor air stability on respiration is mainly reflected in the influence of the diffusion of expiratory flow , the inhibition of the development of hot plume around the body , and the change of the distribution of pollutants around the body . Different ventilation strategies may form different stability conditions , thus affecting the diffusion law of pollutants in the chamber . In order to reduce the risk of disease transmission , it is necessary to take fully into account the characteristics of indoor air stability in the form of specific air flow tissue .

【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU834

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 龔光彩;徐春雯;羅泓鋒;韓冰;;基于室內(nèi)空氣穩(wěn)定性的污染物側(cè)送風(fēng)數(shù)值模擬[J];科技導(dǎo)報(bào);2011年04期

2 劉恩梅;;新發(fā)現(xiàn)呼吸道病毒感染的流行病學(xué)及其臨床特征[J];臨床兒科雜志;2008年07期

本文編號：1865893