In718合金叶片冷却过程热-力耦合场三维数值模拟

3D Numerical Simulation on Thermal Mechanical Field of In718 Alloy Blade in Cooling Process

在确立高温叶片冷却过程辐射和对流边界换热系数的基础上,依据有限元理论对In718高温镍基合金末级叶片终锻后的冷却过程进行了热-力耦合三维数值模拟。研究了叶片冷却过程中的温度、应力和应变分布及变形规律。结果表明:初始时刻叶片表面和环境温差较大,温降较快,随着冷却过程进行,温降速度变缓;叶片形状复杂,非均匀的热传导和换热作用使等效应力和应变分布不均匀,从而产生附加内应力,榫头与叶身交接处应力最大,易于产生裂纹;叶片在冷却时发生了严重翘曲,叶尖部分的翘曲明显。

The heat transfer coefficient including radiation and convection in the blade air cooling was investigated.The thermal mechanical coupled field of In718 alloy blade in cooling process after finish forging was simulated by 3D finite element method.The effects of temperature,stress and strain and deformation after cooling were discussed.The results show that the temperature reduces fast at first stage,because of the larger difference between blade and air.Then,the temperature reduction rate decreases slowerly,in cooling process.The non-uniform temperature distribution leads to the non-uniform stress and strain so that the additional stress occurs in the blade.Furthermore,the maximum value of the stress lies in the conjunction zone between blade rabbet and body,which results in the occurrance of crack.The blade shape largely changes,on the corner of the blade edge,the deformation is larger than that of others after cooling.