层流冷却传热系数对金属物料温度场的影响

Influence of heat transfer coefficient of laminar cooling on metal materials temperature field

层流冷却的冷却强度决定着金属物料微观组织结构,从而影响产品的性能,而传热系数直接影响着冷却强度的大小。本工作提出了一种获得层流冷却传热系数的方法,通过工艺分析得到其分布形式为以喷头为中心由半波正弦和直线构成的分段函数,给出了通过结构参数、运行参数和实验数据获得函数特征参数的方法。以实验台验证了该方法的准确性,同时分析了特征参数变化对金属物料温度场的影响规律。结果表明,振幅增加1W/(m^(2)·K),金属物料表面温度相对下降量在最后一个区域达到最大值,为-0.36m^(2)·K^(2)/W,断面温差最大相对变化量为0.07m^(2)·K^(2)/W;周期减小1s,金属物料表面温度相对增加量在最后一个区域达到最大值,为13.24K/s,断面温差呈现周期性变化,变化范围为-2.5~0 K/s。

The cooling intensity of laminar cooling determines the microstructure of metal materials,thus affecting the performance of the product,while the heat transfer coefficient directly affects the cooling intensity.In this work,a method for obtaining the heat transfer coefficient of laminar cooling is presented.Through the process analysis,the distribution form of the heat transfer coefficient was a piecewise function which was composed of half wave sine and straight line with the nozzle as the center.The characteristic parameters of the piecewise function can be achieved by some calculations,which involved the structural parameters,operational parameters and experimental data.The experimental bench verified the accuracy of this method.The calculation results showed that when the amplitude is increased by 1W/(m^(2)·K),the relative decline of the metal material surface temperature reached maximum in the final area,which was-0.36 m^(2)·K^(2)/W,and the maximum relative change of section temperature difference was 0.07 m^(2)·K^(2)/W.When the period decreased by 1s,the relative increment of surface temperature of metal materials reached the maximum value of 13.24 K/s in the last region,and the section temperature difference showed periodic changes with a range of-2.5~0 K/s.