【摘要】：隨著時代發(fā)展,電子設備不斷朝著小型化和集成化方向進展,隨之,電子設備的散熱問題成為影響其壽命的直接原因,是學者們關注的焦點,也是本文關注的問題。非線性科學是發(fā)展起來的新型交叉學科。非線性,是指兩個變量間的數學關系,不是直線,而是曲線、曲面、或不確定的屬性,是不成簡單比例(即線性)關系的。它是自然界復雜性的典型性質之一,非線性更接近客觀事物性質本身。因此,研究非線性現象的價值即為改變傳統(tǒng)的認知,加深對自然界的認知。在現代的物質世界中,非線性現象無處不在,如氣候的變化中會出現非線性現象,數學、物理、經濟學、社會學、音樂等領域中也滲透著非線性。而在小型電子設備工作的時候,由發(fā)熱單元產生的熱量與周圍溫度形成的溫差,導致設備內部空氣的流動,也存在著非線性現象。本文以小型電子設備散熱為應用背景,在自然對流的情況下,將電子設備模型抽象為帶有不同類型熱源的腔體,通過數值模擬和實驗研究分析其內部存在的振蕩及混沌等非線性特性及自然對流換熱規(guī)律。本文首先采用FLUNT軟件對底部加熱無內熱源的長方體腔,底部帶有單熱源和底部帶有雙熱源的長方體腔內空氣的自然對流換熱問題進行了數值模擬。得到如下成果:隨著Rayleigh數的增大,無內熱源的長方體腔內的空氣流動經歷了穩(wěn)定,單倍周期,擬周期,通過振蕩最終到達混沌的流動狀態(tài);帶有長度接近腔體長度單熱源的腔內空氣流動經歷了穩(wěn)定,單倍周期,擬周期,帶有雙熱源的腔內空氣流動狀態(tài)始終為混沌狀態(tài),空氣的流態(tài)與腔內換熱強度有關;在分析熱源數量對換熱強度的影響中可知,腔內無內熱源的腔頂平局Nusselt最高,其次是帶有長熱源的腔體,最后為帶有雙熱源的腔體;腔內帶有單熱源時,換熱強度隨熱源長度增加而增大,換熱速率隨長度增大而減慢;當腔內帶有兩個內熱源,熱源和上下壁面的溫差恒定時,熱源間的距離增大,換熱強度先增大后減小,熱源間的距離恒定時,隨溫差增大換熱強度增大;通過數值模擬分析二維模型和三維模型腔頂平均Nusselt數大小可知,二維模型不可代替三維模型。其次,本文采用無接觸激光干涉技術和煙可視化手段對上述模型進行實驗分析。探討了腔體尺寸、溫差、熱源間距離對渦卷初始態(tài)的影響并觀察了渦卷的數量及形態(tài),也分析了模擬中混沌出現的原因。本文從以上幾個方面進行了研究,同時為小型電子設備散熱提供了一定的理論參考價值。
[Abstract]:With the development of the times, electronic equipment is developing towards miniaturization and integration, and the heat dissipation of electronic equipment has become the direct cause of affecting its life, which is the focus of scholars' attention, and is also the focus of this paper. Nonlinear science is a new interdisciplinary discipline. Nonlinearity refers to the mathematical relationship between two variables, not a straight line, but a curve, surface, or uncertain attribute, which is not simply proportional (that is, linear). It is one of the typical properties of the complexity of nature, and the nonlinearity is closer to the nature of the objective thing itself. Therefore, the value of studying nonlinear phenomena is to change the traditional cognition and deepen the cognition of nature. In the modern material world, nonlinear phenomenon is everywhere, such as climate change will appear nonlinear phenomenon, mathematics, physics, economics, sociology, music and other fields are also permeated with nonlinearity. While the small electronic equipment is working, the temperature difference between the heat generated by the heating unit and the surrounding temperature leads to the flow of air in the equipment, and there is also a nonlinear phenomenon. In this paper, the model of electronic equipment is abstracted as a cavity with different types of heat source under the condition of natural convection, taking the heat dissipation of small electronic equipment as the application background. The nonlinear characteristics of oscillation and chaos and the law of natural convection heat transfer are analyzed by numerical simulation and experimental study. In this paper, the FLUNT software is used to simulate the natural convection heat transfer in a rectangular cavity with single heat source and double heat source at the bottom and in a rectangular cavity with no inner heat source at the bottom, and the natural convection heat transfer problem in the rectangular cavity with two heat sources at the bottom is numerically simulated. The results are as follows: with the increase of Rayleigh number, the air flow in a rectangular cavity without internal heat source goes through a stable, single period, quasi-period, and finally reaches the chaotic flow state by oscillation; The air flow in the cavity with the length close to the length of the cavity has experienced a stable, single period and quasi-period. The air flow state with double heat sources is always chaotic, and the air flow pattern is related to the heat transfer intensity in the cavity. In the analysis of the effect of heat source quantity on heat transfer intensity, it can be seen that the top level Nusselt of cavity without internal heat source is the highest, the cavity with long heat source is the next, and the cavity with double heat source is the last one. When there is a single heat source in the cavity, the heat transfer intensity increases with the increase of the heat source length, and the heat transfer rate decreases with the increase of the heat source length. When there are two internal heat sources in the cavity and the temperature difference between the heat source and the upper and lower wall is constant, the distance between the heat sources increases, the heat transfer intensity increases first and then decreases, and when the distance between the heat sources is constant, the heat transfer intensity increases with the increase of the temperature difference. Through numerical simulation and analysis of the average Nusselt number of two-dimensional model and three-dimensional model, it can be seen that the two-dimensional model cannot replace the three-dimensional model. Secondly, the above-mentioned models are analyzed by non-contact laser interferometry and smoke visualization. The effects of cavity size, temperature difference and the distance between heat sources on the initial state of the scroll are discussed. The number and shape of the scroll are observed, and the causes of chaos in the simulation are also analyzed. This paper has carried on the research from the above several aspects, at the same time has provided the certain theoretical reference value for the small electronic equipment heat dissipation.
【學位授予單位】：吉林建筑大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN60

【相似文獻】

相關期刊論文 前5條

1 向澤銳;;采用鋁壓鑄盒設計小型電子設備的方法[J];電訊技術;2010年08期

2 袁心紅;楊汝禧;;小型電子設備的干電池供電回路[J];集成電路應用;1994年04期

3 ;其它工藝與設備[J];電子科技文摘;2003年08期

4 生建友;小型電子設備機箱的密封設計[J];電子工藝技術;2001年05期

5 ;愛迪生的復仇[J];21世紀商業(yè)評論;2013年21期

相關碩士學位論文 前1條

1 徐s，

本文編號：2452155