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  本文選題：傳熱　切入點：阻力系數(shù)　出處：《蘭州交通大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：作為熱量傳遞過程中的關(guān)鍵設(shè)備,管翅式換熱器應(yīng)用在很多場合,它的出現(xiàn)不僅帶動了社會的經(jīng)濟(jì)發(fā)展而且給我們的生活帶來了便利,同時管翅式換熱器的運行又消耗了非�？捎^的高品位能量。為了節(jié)能及能源的充分利用,就需要研究強化傳熱技術(shù)以進(jìn)一步提升管翅式換熱器的傳熱特性。管翅式換熱器中翅片型式很多,可根據(jù)翅片的幾何形狀把翅片分為:平片型翅片、條縫型翅片、波紋型翅片、百葉窗型翅片以及近年來逐漸興起的渦發(fā)生器型翅片。在該翅片管換熱器中,空氣側(cè)熱阻為其熱環(huán)節(jié)的主要熱阻,約占總熱阻的70%-90%,也就是說空氣側(cè)換熱性能的好壞對整個換熱器的換熱性能起著決定性作用。因此,要提高換熱器的總體換熱性能,對空氣側(cè)的換熱性能進(jìn)行強化。論文通過數(shù)值模擬的方法來對三角形波紋翅片管換熱器的翅片側(cè)傳熱性能進(jìn)行深入的研究。首先建立相應(yīng)的數(shù)學(xué)及物理模型,然后選取合適的翅片單元作為計算區(qū)域,對計算區(qū)域進(jìn)行合理的網(wǎng)格劃分,確定數(shù)值計算所用的網(wǎng)格數(shù)目的大小,通過數(shù)值結(jié)果與實驗結(jié)果的對比確定所用算法的合理性。然后用數(shù)值方法獲得在各種翅片參數(shù)及工作條件下的翅片側(cè)努塞爾數(shù)、阻力系數(shù),運用線性回歸法擬合出努塞爾數(shù)、阻力系數(shù)與各幾何參數(shù)之間的關(guān)聯(lián)式,對比三角形波紋翅片與平直翅片傳熱性能的區(qū)別,例如阻力系數(shù)和努塞爾數(shù)隨雷諾數(shù)的變化規(guī)律,橫向和縱向截面的流場分布等。為了深入揭示三角形波紋翅片的強化傳熱機理,計算并討論縱向渦強度、橫向渦強度與努塞爾數(shù),阻力系數(shù)的關(guān)系。研究結(jié)果表明:與平直翅片相比,三角形波紋翅片表面的局部努塞爾數(shù)較大,三角形波紋翅片的換熱性能更好;對三角形波紋翅片與圓管形成的通道內(nèi)的流場進(jìn)行了分析,發(fā)現(xiàn)在波峰及波谷處,二次流現(xiàn)象十分明顯。由于三角形波紋翅片與圓管形成的通道內(nèi)能夠產(chǎn)生縱向渦和橫向渦,而縱向渦和橫向渦能夠強化傳熱;努塞爾數(shù)、縱向渦強度、橫向渦強度都隨著翅片間距、波紋角、波紋數(shù)的增大而增大。阻力系數(shù)隨著翅片間距、波紋角、波紋數(shù)的增大而減小;在同一雷諾數(shù)下,三角形波紋翅片的平均努塞爾數(shù)及阻力系數(shù)都高于平直翅片的,同時還擬合得到了三角形波紋翅片努賽爾數(shù)和阻力系數(shù)與雷諾數(shù)及二次流強度的關(guān)聯(lián)式。
[Abstract]:As the key equipment of heat transfer in the process of tube fin heat exchanger used in many occasions, it not only promoted the development of social economy and bring convenience to our life, at the same time running tube fin heat exchanger and consumes considerable high-grade energy. In order to make full use of energy and energy the need to study the heat transfer technology to further enhance the heat transfer characteristics of fin tube heat exchanger. The tube fin heat exchanger fin type many, according to the geometry of the fin fin is divided into: flat fin, fin, corrugated fin, louver fin and vortex generator fin has gradually emerged in recent years. In the finned tube heat exchanger, the main thermal resistance of air side thermal resistance is the thermal link, about the total thermal resistance of 70%-90%, that is to say the air side heat transfer performance of the heat transfer performance of the heat exchanger Play a decisive role. Therefore, to improve the heat exchanger overall heat transfer performance, the heat transfer performance of the air side was strengthened. Methods by numerical simulation of wavy fin and tube fin heat transfer performance of heat exchanger are discussed in detail. Firstly, the corresponding mathematical and physical model, and then select the appropriate fin unit as the calculation region, reasonable meshing of the computational domain to determine the number of mesh used for numerical calculation of the size of rationality by comparing the numerical results and experimental results confirm the algorithm used. To get the number of fin side Nusselt in various parameters and working conditions of the fin resistance by numerical method coefficient, using linear regression method to fit the Nusselt number, the relationship between the resistance coefficient and the geometric parameters, contrast the wavy fin and flat tube heat transfer performance difference, For example, the resistance coefficient and Nusselt number with Reynolds number variation of transverse and longitudinal section of the flow field. In order to reveal the mechanism of heat transfer enhancement in the wavy fin, discuss the longitudinal vortex intensity calculation and transverse vortex intensity and the Nusselt number, the relationship between the resistance coefficient. The results showed that compared with the straight fin, local Nusselt triangle a large number of wavy fin surface, better thermal performance for wavy fin; flow field of the wavy fin and tube formation in the channel are analyzed, found in the peak and trough, two secondary flow phenomenon is very obvious. Due to the wavy fin and tube formation in the channel can generate longitudinal and transverse vortex the longitudinal vortex, vortex and vortex can enhance heat transfer; the Nusselt number, longitudinal vortex strength, transverse vortex strength with fin spacing, corrugation angle, wave number and gain increases . the drag coefficient with fin spacing, corrugation angle, wave number increases and decreases; at the same Reynolds number, the average Nusselt number and resistance coefficient of wavy fin is higher than the straight fin, also fitted the wavy fin and the Nusselt number and resistance coefficient and Reynolds number and two flow intensity correlation type.

【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】：TK172;TK124

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本文編號：1621945