溫度場的數(shù)值模擬
(北京有色金屬研究總院 國家有色金屬復(fù)合材料工程技術(shù)研究中心，北京 100088)
摘 要: 建立了鋁合金半固態(tài)漿料電磁攪拌過程宏觀傳輸物理量耦合的數(shù)學(xué)模型，采用有限元和有限差分相結(jié)合的方法實現(xiàn)電磁攪拌條件下電磁場、流場和溫度場的耦合模擬分析，研究電磁攪拌工藝參數(shù)對流場和溫度場的影響規(guī)律，并進行實驗驗證。結(jié)果表明：水平旋轉(zhuǎn)的電磁力場在鋁合金熔體內(nèi)均勻分布，其方向與交變電磁場的旋轉(zhuǎn)方向一致，大小則因集膚效應(yīng)從邊部到中心遞減；熔體內(nèi)速度場分布與電磁力相似，但隨著攪拌時間的延長，熔體溫度降低，速度不斷降低；電磁攪拌條件下熔體凝固速度加快，熔體心部和邊部的溫度梯度變小；攪拌電流強度和頻率對電磁場、速度場和溫度場分布的影響非常明顯。
關(guān)鍵字: 電磁攪拌；半固態(tài)漿料；電磁場；流場；溫度場；數(shù)值模擬
field in semi-solid slurry preparation by electromagnetic stirring
（National Engineering & Technology Research Center for Non-ferrous Metal Matrix Composites,
General Research Institute for Non-ferrous Metals, Beijing 100088, China）
Abstract:A two-dimensional computational model coupling a macroscopic heat and fluid flow analysis with electromagnetic stirring (EMS) in semisolid slurry preparation was developed. The method combining finite element and finite difference was used to deal with coupling electromagnetic field with flow field and temperature field. The characteristics of electromagnetic field, flow field and temperature field under electromagnetic stirring were analyzed, considering the influences of the stirring current and frequency. The dynamic evolution of transport phenomena during solidification under electromagnetic stirring was presented successfully. The simulated results show that a horizontal rotational electromagnetic force with the same rotating direction with the magnetic flux density is uniformly distributed in the stirred melt, but its magnitude decreases from edge to center due to the skin effect of the induced current. The velocity field distribution is similar to the electromagnetic field, but the velocity quickly decreases with the stirring time increasing when the temperature decreases in the melt. The electromagnetic stirring accelerates the solidification rate, and the temperature difference between the melt edge and the melt center becomes small. The altering stirring current and frequency markedly influence the distribution of electromagnetic field, flow field and temperature field.
Key words: electromagnetic stirring; semisolid slurry; electromagnetic field; flow field; temperature field; numerical simulation
