Bending Vibration of a Heated Rod in Quenching Process

加热棒淬火过程中的弯曲振动

• 批准号: 61550147
• 负责人: HIHARA Eiji
• 金额: $ 1.28万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61550147/
• 关键词: Reflooding; Quench; Bending Vibration; Interfacial Waves; Thermal Stress; 熱応力

When a vertical heated rod is cooled by subcooled water flowing upward, bending vibration of the rod has been observed under certain conditions. This vibration is caused by the distorted distribution of quench front around the rod and the resultant thermal stress. But the mechanism of the periodical distortion of quench front and the contribution of subcooling of the water temperature to the vibration are not understood. In this study, paying attention to the thermally stratified layers in the cooling water, the relation between the bending vibration and the gravity waves on the interface separating two layers with different temperatures was investigated.The formation of the thermally stratified layers in the water was hydrodynamically investigated. From a numerical simulation, circulation flow is induced above the quench front by the steam flow of film boiling, and heat transmitted from the rod to the water is confined in the circulation flow. Consequently, the temperature of the upper region becomes saturated, and that of the lower region is kept subcooled. The interface usually locates near the quench front.Frequency of the gravity waves on the interface of two layers in a concentric annular conduit was theoretically analyzed. To confirm the hypothesis that the waves on the interface induce the distorted distribution of quench front, various experiments were performed. Influences of the water temperature, water flow rate, and initial rod temperature on the frequencies were measured. The calculated frequencies of gravity waves reasonably agree with those of bending vibration. The marginal boundaries of the onset of bending vibration were obtained experimentally.

当竖直加热棒被向上流动的过冷水冷却时，在一定条件下观察到了棒的弯曲振动。这种振动是由淬火锋在棒周围的畸变分布和由此产生的热应力引起的。但对淬火锋周期性畸变的机理及水温过冷度对振动的贡献尚不清楚。本研究针对冷却水中的热分层现象，研究了不同温度两层分离界面上的弯曲振动与重力波的关系，并对水中热分层的形成进行了流体动力学研究。数值模拟结果表明，膜态沸腾的蒸汽流在激冷前沿上方产生了循环流动，从棒到水的热传递被限制在循环流动中。因此，上部区域的温度变得饱和，而下部区域的温度保持过冷。对同心环形管道中两层界面上重力波的频率进行了理论分析。为了证实界面上的波引起失超前沿分布畸变的假设，进行了各种实验。测量了水的温度、水的流量和初始棒温度对频率的影响。计算的重力波频率与弯曲振动频率基本一致。实验得到了弯曲振动发生的边界条件。