温度场有限元模拟.ppt

受热载荷作用的正方形截面的烟囱的建模与温度场求解 题目 正方形截面的烟囱如图 4-1 所示，烟囱由混凝土建造，边长为 60cm，通道的边长为 20cm，混凝土的导热系数为 k =1.4 W /(m K )。假定烟囱内表面的温度为 100℃，烟囱外表面暴露在空气中，空气的温度为 30℃，换热系数为 h=20 W /(m 2 K )。计算烟囱截面内的稳态温度场。 设置计算类型 Main Menu: Preferences… →select Thermal → OK 选择单元类型 Main Menu: Preprocessor →Element Type→Add/Edit/Delete →Add →select Thermal Solid Quad 4node55 →OK (back to Element Types window) → Options… →select K3: Plane →OK→Close (the ElementType window) 定义材料参数 Main Menu: Preprocessor →Material Props →Material Models →Thermal →Conductivity →Isotropic→input KXX:1.4 → OK → Thermal →Convection or film Coefficient for Material Number 1 → T1:20 → OK 生成几何模型 生成特征点 Main Menu: Preprocessor →Modeling →Create →Keypoints →In Active CS →依次输入 6 个点的坐标：input:1(0.1, 0, 0), 2(0.3, 0, 0), 3(0.3, 0.3, 0), 4(0, 0.3, 0), 5(0, 0.1, 0), 6(0.1, 0.1, 0)→OK 生成截面 Main Menu: Preprocessor →Modeling →Create →Areas →Arbitrary →Through KPS →依次连接 6 个特征点: 1(0.1, 0, 0), 2(0.3, 0, 0), 3(0.3, 0.3, 0), 4(0, 0.3, 0), 5(0, 0.1, 0), 6(0.1, 0.1, 0)→OK 网格划分 Main Menu: Preprocessor →Meshing →Mesh Tool→(Size Controls) lines: Set →分别拾取左边 2竖直边:OK→input NDIV: 10 和5 →Apply→拾取右条竖直边NDIV: 15 →； Set →拾取上直边:OK→input NDIV:15 →Apply→分别拾取下边的两条横直边:OK →input NDIV: 10 和 5 →OK →(back to the mesh toolwindow)Mesh: Areas, Shape: Quad, Free → Mesh → Close( the Mesh Tool window) 网格划分 模型施加热约束 分别给两条对称边施加热流量 0 (对称边界)的约束Main Menu: Solution →Define Loads →Apply →Thermal → Heat Flux → On Lines → 拾取(对称边)左边, Heat Flux: 0 → Apply → 拾取(对称边)下边，Heat Flux: 0 →OK 模型施加热约束 给内部边界加已知烟囱内表面的温度为 100℃Main Menu: Solution →Define Loads →Apply →Thermal →Temperature →On Lines → 分别拾取内部两边, 选 TEMP → TEMP Value:100 →OK 模型施加热约束 给外部热对流边界加换热系数和外界温度 30℃(heat film coefficients with associated ambienttemperatures)Main Menu: Solution →Define Loads →Apply →Thermal →Convection → On Lines → 分别拾取外部两边, 输入：Film Coeffecient:20, Bulk Temperature:30 →OK 分析计算 Main Menu: Solution →Solve →Current LS →OK(to close the solve Current Load Step window) →OK 结果显示 Main Menu: General Postproc →Plot Results → C