高温球体与水的沸腾传热特性研究

为研究高温流体与水的传热特性,采用理论分析与自由界面追踪数值技术对高温球体表面的沸腾传热过程进行研究,得到球体表面传热特性的变化规律. 分析结果表明,当球体温度不变时,蒸气膜层厚度自前滞点往后逐渐增大,膜层内温度呈非线性分布降低,速率呈抛物型分布. 当球体温度提高时蒸气膜层厚度变大,相应的蒸气速率峰值也变大,球面传热系数却变小. 数值仿真结果显示了气-液界面上不稳定性波动发展和气泡成长过程,较为真实地反映出沸腾传热的动态过程. 

Research on the Characters of Boiling Heat Transfer from High Temperature Sphere to Water

With the purpose of investigating the characteristics of heat transfer between high temperature liquid and water, the film boiling process from hot sphere surface was analyzed by an improved boiling model and free surface tracking method. The results show that, when the temperature of sphere is constant, the film thickness increases from stagnation point of particle, the temperature contribution decreases with non-linear posture and the velocity contribution is parabolic in film. With the increase of initial temperature of sphere, both the film thickness and peak value of vapor velocity raise, while the overall heat transfer coefficient decreases. Meanwhile, the numerical technique captures the evolution of instability at interface and the process of bubble growing, which reveal the dynamic process of boiling clearly.