重型燃机透平导向叶片的缩松形成机理

Analysis of Formation Mechanism of Shrinkage Porosities in Heavy-duty Gas Turbine Guide Vane

以重型燃机导向叶片为研究对象,采用精铸试验与数值模拟计算相结合的方法,分析了叶片的温度场分布。同时,以半定量的理论计算,阐述了缩松的形成过程。结果表明,缩松的形成与凝固阶段收缩体量密切相关,而收缩量与温度梯度、壁厚、糊状区宽度等密切相关。增大各方向温度梯度可以有效减小收缩体量,消除缩松。同时,也可以减缓铸件在型芯、型壳侧的过热。

The temperature field distribution of the guide vane of heavy-duty gas turbine was analyzed by combining with precision casting experiment and numerical calculation.In addition,the forming process of shrinkage porosities was expounded by semi-quantitative theoretical calculation.The results reveal that the shrinkage porosities are closely related to the shrinkage volume in solidification stage,and the shrinkage volume is closely related to temperature gradient,wall thickness and mushy-zone width.Through increasing the temperature gradient in all directions,the shrinkage volume can be reduced to be eliminated.Meanwhile,it can also slow down the overheating of the casting on the core and shell side.