扁鋼胚加熱爐熱流場之非耦合模擬研究

A Decoupled Numerical Study of Thermal Fluid Field In The Slab Reheating Furnace

蕭百佑(Pai-Yu Hsiao)

指導教授 ： 黃美嬌

國立臺灣大學/工學院/機械工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02977

摘要

本論文針對中國鋼鐵公司現有的扁鋼胚加熱爐，利用CD asapco公司之商用計算流體力學軟體Star-CD，建立一個三維熱流場模型。採用的數學模式包括：高雷諾數的k-ε紊流模式，單一擴散係數、瞬間反應(反應速率無窮大)之PPDF(Prescribed Probability Density Function)燃燒化學反應模式，並且考慮由高溫燃燒所造成的熱輻射模式。其中熱輻射傳遞方程式採用離散座標法(DOM，Discrete Ordinate Method)求解，用來計算能量方程式中的輻射熱通量；而氣體的輻射吸收係數則用WSGGM(Weighted-Sum-of-Gray-Gases Model)求得。
文中的熱流場模型採非耦合法計算。即先假設鋼胚表面溫度為已知，用來當作加熱爐內的爐氣熱流場，因此計算出鋼胚表面熱通量。接著建立一鋼胚模型，將加熱爐求得的鋼胚表面熱通量當作鋼胚模型的邊界條件，求出鋼胚表面溫度。鋼胚計算所得之表面溫度與加熱爐假設之鋼胚表面溫度必須加以比較，若兩者溫度差異過大，必須進行加熱爐與鋼胚之迭代運算，直到兩者溫度差值小於一定誤差範圍內。最後我們利用收斂之計算結果探討因動靜樑系統的輻射遮蔽效應，對鋼胚所造成的冷痕進行深入的研究。
關鍵詞：再加熱爐、非耦合計算、輻射遮蔽效應、冷痕

關鍵字

再加熱爐 ； 非耦合計算 ； 輻射遮蔽效應 ； 冷痕

並列摘要

In this paper, we aim at the walking beam type slab reheating furnace of China Steel Corporation, and we use computational fluid dynamic software, Star-CD, to build a three-dimensional aerothermal model. The study employs the high-Reynolds- number k-ε turbulence model based on Favre-averaged governing equations. The pre-assumed PDF model associated with the fast chemistry assumption and a single diffusivity is used to account for turbulent combustion. The absorption coefficient of the gases mixture is calculated by WSGGM (weighted-sum-of-gray-gases model). The discrete ordinates method is adopted to calculate the radiactive heat transfer.
Here we use the decoupled method to simulate the reheating furnace. It means we assume the surface temperature of the slab first, and then we exploit the assumed temperature to get gas temperature and heat flux of the slab. We use heat flux of the slab to get the surface temperature of the slab after the slab model is established. We should iterate the case until the calculating surface temperature of the slab converges to the assumed one. Finally, we use the convergent results to discuss the skid mark of slab caused by the radiative shielding by the beams.
Keywords：Reheating furnace, Decoupled method, Radiative shielding, Skid mark.

並列關鍵字

reheating furnace ； decoupled method ； radiative shielding ； skid mark

參考文獻

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