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针对倾斜板熔体处理晶粒细化与半固态成形原理,研究了倾斜板熔体处理过程边界层分布,建立了熔体传热和冷却速率的计算模型.计算结果表明,随着斜板倾角和熔体初始流动速度的增大,熔体在倾斜板上从层流向紊流的转变时间减少;温度边界层厚度随着熔体初始流动速度的增加而减小,斜板倾角对温度边界层厚度的影响较小;温度边界层厚度和速度边界层厚度都随熔体流动距离的增加而增大,在层流区,温度边界层厚度远大于速度边界层厚度,而在紊流区,温度边界层厚度与速度边界层厚度重合;倾斜板上熔体冷却速率与熔体厚度成反比,初始流速小于1m/s时,熔体的冷却速率沿着倾斜板长度方向逐渐增大,初始流速为1m/s时,熔体的冷却速率沿倾斜板长度方向基本不变,当初始流速大于1m/s时,熔体冷却速率沿倾斜板长度方向逐渐减小;倾斜板上熔体冷却速率在100—1000 K/s之间,属于亚快速凝固范畴.
Aiming at the principle of grain refinement and semi-solid forming of tilting plate melt, the boundary layer distribution in the process of tilting plate melt processing was studied and the calculation model of heat transfer and cooling rate was established. The calculation results show that with the tilting angle And the initial melt flow rate increases, the melt transition time from laminar to turbulent flow on the inclined plate decreases. The temperature boundary layer thickness decreases with the increase of initial melt flow velocity. The inclination angle of inclined plate to the temperature boundary layer The thickness of the temperature boundary layer and the thickness of the velocity boundary layer both increase with the increase of the melt flow distance. In the laminar flow area, the thickness of the temperature boundary layer is much larger than the thickness of the velocity boundary layer, while in the turbulence area, The boundary layer thickness coincides with the velocity boundary layer thickness. The melt cooling rate on the inclined plate is inversely proportional to the melt thickness. When the initial velocity is less than 1 m / s, the cooling rate increases along the length of the inclined plate. The initial velocity is 1m / s, the cooling rate of the melt is basically the same along the length of the inclined plate. When the initial flow rate is more than 1m / s, the melt cooling rate decreases along the length of the inclined plate. The cooling rate of the melt on the inclined plate is 100 -1000 K / s Between, belong to the sub-rapid solidification category.