钢板阵列射流冷却过程换热实验研究

Experimental study on heat transfer during jet cooling of steel plate array

基于组合式超快速冷却测试装置,研究了8.4×10~5、14.0×10~5、19.6×10~5 L·(m^2·min)^(-1)水流密度对50 mm厚AISI304奥氏体不锈钢0.1 m·s^(-1)辊式淬火过程中厚向截面冷却速度和表面换热的影响,利用导热微分方程及反传热求解方法,计算钢板表面热流密度分布。结果表明,在冷却速度增长区,水流密度通过影响温度梯度的分布进而影响冷却速度变化;在平缓区,温度梯度的改变基本不受水流密度变化的影响,而是由遗传效应主导的;8.4×10~5 L·(m^2·min)^(-1)水流密度条件下的沸腾曲线能观察到明显的膜沸腾和热流肩现象,随着水流密度增加到14.0×10~5 L·(m^2·min)^(-1)和19.6×10~5 L·(m^2·min)^(-1),实验钢板表面在射流水的冲击下无法形成稳定的沸腾蒸汽膜,较高的表面温度也使得临界热流密度值增加到无法到达的水平,沸腾过程无法出现热流肩。

Based on the combined ultra-fast cooling test equipment,the effects of different flow densities (8.4×10^5 L·m^-2·min^-1,14.0×10^5 L·m^-1·min^-1 and 19.6×10^5 L·m^-2·min^-1)on cooling rate and surface heat transfer of thick cross section of 50 mm thick AISI304 austenitic stainless steel during 0.1 m·s^-1 rolling quenching were investigated.The heat flux distribution on the surface of the steel plate was calculated by using heat conduction differential equation and inverse heat transfer method.The results show that in the growth area of cooling rate,the flow density affects the distribution of temperature gradient and then the change of cooling rate,and while in the flat area,the change of temperature gradient is not affected by the change of flow density,but is dominated by genetic effect.The obvious phenomenon of film boiling and heat flow shoulder can be observed in the boiling curve at the flow density of 8.4×10^5 L·(m^2· min)^-1.With the flow density increases to 14.0 ×10^5 L·(m^2·min)^-1 and 19.6×10^5 L·(m^2·min)^-1,a stable boiling vapor film cannot be formed on the surface of the experimental steel plate due to the impact of jet water.The higher surface temperature also increases the critical heat flux density to an unreachable level,and the heat flow shoulder can not appear in the boiling process.