论文部分内容阅读
针对消失模铸造过程中泡沫密度、涂层透气性以及泡沫降解温度问题,提出了热传递、泡沫降解和气体扩散的二维模型。考虑了泡沫和熔融金属间的辐射和热传导,对金属表面和泡沫表面进行了追踪,计算了气隙体积和压力;结合能量守恒和几何相关性,定义了在金属填充过程中消退的泡沫表面;将间隙中的气体流动看成楔形流,并将层状不可压缩楔形流的努塞尔特数用于该过程。为了将模型应用于实例,使用算法对具有自由边界的熔融金属流动进行了仿真。仿真结果显示,新二维模型在铸造过程中,泡沫密度、涂层透气性以及泡沫降解温度越大,压力就会越大,导致金属充模时间更长。
Aiming at the foam density, the permeability of the coating and the foam degradation temperature during the process of lost foam casting, a two-dimensional model of heat transfer, foam degradation and gas diffusion was proposed. Considering the radiation and heat conduction between the foam and the molten metal, the metal surface and the foam surface are traced, the air gap volume and pressure are calculated, and the foam surface which is dissipated during the metal filling process is defined according to the conservation of energy and the geometric correlation. The flow of gas in the gap is considered a wedge flow and the Nusselt number of the laminar incompressible wedge flow is used for this process. In order to apply the model to the examples, an algorithm was used to simulate the flow of molten metal with free boundaries. The simulation results show that in the new two-dimensional model, the larger the foam density, the permeability of the coating and the degradation temperature of the foam during casting, the greater the pressure and the longer the filling time of the metal.