本文選題：螺旋管 + 數(shù)值模擬��； 參考：《蘭州交通大學(xué)》2016年碩士論文

【摘要】：螺旋管即可作為纏繞管式換熱器的基本結(jié)構(gòu),亦可單獨作為一種換熱設(shè)備,具有換熱效率高、結(jié)構(gòu)緊湊、可自伸縮性等優(yōu)點,在石油化工、低溫制冷、航空航天等領(lǐng)域具有廣泛應(yīng)用。螺旋管作為一種高效換熱設(shè)備,一直是強(qiáng)化傳熱領(lǐng)域關(guān)注的焦點。目前對于螺旋管的相關(guān)研究主要集中在圓形截面,關(guān)于矩形截面螺旋管內(nèi)流體流動及傳熱性能方面的研究鮮有報道,同時從場協(xié)同角度分析螺旋管強(qiáng)化傳熱內(nèi)在機(jī)理的研究亦不多見。本文總結(jié)了國內(nèi)外螺旋管的研究現(xiàn)狀,簡單介紹了強(qiáng)化傳熱技術(shù)及場協(xié)同理論。在前人的基礎(chǔ)上,應(yīng)用數(shù)值計算方法,建立了三維螺旋管物理及數(shù)學(xué)模型,根據(jù)Fluent軟件工作流程,分別計算了恒壁溫工況下,圓形截面及矩形截面螺旋管內(nèi)流體在層流、湍流時的流動及傳熱情況,通過管內(nèi)流體的平均努塞爾數(shù)Nu及進(jìn)出口壓降損失ΔP來評價不同幾何參數(shù)下這兩種截面螺旋管的傳熱及流阻性能。引用綜合性能評價因子η,對比分析了管內(nèi)流體平均速度v、螺距P、螺旋直徑D及橫截面積對兩種截面螺旋管的流阻、傳熱及強(qiáng)化傳熱性能的影響�？紤]了在橫截面積相等的情況下,改變矩形截面形狀對管內(nèi)流體的流動、傳熱及強(qiáng)化傳熱性能的影響。從場協(xié)同的角度,對這兩種截面螺旋管強(qiáng)化傳熱的內(nèi)在機(jī)理進(jìn)行了對比分析,并通過速度場與溫度場之間的夾角對比分析了兩種截面螺旋管內(nèi)流體的協(xié)同性能隨螺距、螺旋直徑、及橫截面積的變化規(guī)律。結(jié)果表明,這兩種截面螺旋管內(nèi)流體在層流、湍流流態(tài)下流動時均會出現(xiàn)二次流現(xiàn)象,靠近入口處,二次流對管內(nèi)流體流動及傳熱的影響基本可忽略不計,隨著轉(zhuǎn)角上升,二次流作用加強(qiáng),受截面形狀及流態(tài)的影響,管內(nèi)流體的速度、溫度會呈現(xiàn)不同的分布形狀。改變兩種截面螺旋管的幾何參數(shù),管內(nèi)流體的Nu、ΔP及η均會呈現(xiàn)不同的變化規(guī)律,相比較圓形截面螺旋管的流阻、傳熱、強(qiáng)化傳熱性能均要優(yōu)于矩形截面。另外截面面積相等時,寬扁形矩形截面的強(qiáng)化傳熱性能要優(yōu)于窄高形截面。速度場與溫度場的夾角隨螺旋管幾何參數(shù)變化規(guī)律與管內(nèi)流體流動及傳熱的變化規(guī)律基本相一致,說明場協(xié)同理論可解釋螺旋管強(qiáng)化傳熱隨幾何參數(shù)變化規(guī)律的內(nèi)在機(jī)理。
[Abstract]:The spiral tube can be used as the basic structure of the winding tube heat exchanger, or as a separate heat exchange equipment, with the advantages of high heat transfer efficiency, compact structure, self-scalability, etc., in petrochemical industry, low temperature refrigeration, Aerospace and other fields have a wide range of applications. Spiral tube, as an efficient heat exchanger, has always been the focus of attention in the field of heat transfer enhancement. At present, the research on helical tube is mainly focused on the circular section. There are few reports on the fluid flow and heat transfer performance in the rectangular spiral tube. At the same time, it is rare to analyze the internal mechanism of heat transfer enhancement in helical tubes from the point of view of field synergy. In this paper, the research status of helical tube at home and abroad is summarized, and the enhanced heat transfer technology and field synergy theory are briefly introduced. On the basis of previous studies, the physical and mathematical models of three-dimensional spiral tube are established by using numerical method. According to the working flow of Fluent software, the laminar flow in spiral tube with circular section and rectangular section under constant wall temperature condition is calculated, respectively. For turbulent flow and heat transfer, the heat transfer and flow resistance of the two kinds of helical tubes with different geometric parameters are evaluated by the average Nusselle number Nu of the fluid in the tube and the pressure drop loss 螖 P of the inlet and outlet. Based on the comprehensive performance evaluation factor 畏, the effects of fluid average velocity, pitch P, helical diameter D and cross sectional area on the flow resistance, heat transfer and enhanced heat transfer of two kinds of spiral tubes with different cross-sections are compared and analyzed. The effects of changing the shape of rectangular section on the flow, heat transfer and enhanced heat transfer of the fluid in the tube are considered under the condition of equal cross-sectional area. From the point of view of field synergy, the internal mechanism of heat transfer enhancement in these two kinds of spiral tubes is compared and analyzed, and the synergetic performance of the two kinds of helical tubes with helical pitch is analyzed by comparing the angle between velocity field and temperature field. The variation of spiral diameter and cross-sectional area. The results show that the secondary flow occurs in the laminar flow and turbulent flow in the two kinds of spiral tubes, and the influence of the secondary flow on the fluid flow and heat transfer in the pipe is negligible when the flow is near the entrance, and increases with the angle of rotation. Due to the influence of cross section shape and flow state, the velocity and temperature of the fluid in the tube will be distributed in different shapes. By changing the geometric parameters of the two kinds of helical tubes, the flow resistance, heat transfer and heat transfer enhancement of the circular spiral tubes are better than those of the rectangular ones. In addition, when the cross section area is equal, the heat transfer enhancement performance of wide flat rectangular section is better than that of narrow high section. The angle between velocity field and temperature field is basically consistent with the variation law of fluid flow and heat transfer in the helical tube, which indicates that the theory of field synergy can explain the inherent mechanism of the law of heat transfer enhancement of helical tube with the change of geometric parameters.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TU83

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本文編號：1975805