热分层弯管热波动及其削弱机理研究

Investigations of thermal fluctuation and its weaken mechanism in elbow pipe with thermal stratification

热分层弯管中的热波动容易诱发热疲劳,越来越受到核电工程与技术的关注。对弯管内热分层的流动与传热机理进行研究,建立数学模型,运用FLUENT软件,对有/无防涡器条件下T型弯管内流体的温度波动过程进行了大涡模拟,获得了弯管处无量纲温度波动曲线和无量纲均方根温度。数值模拟结果表明,加入防涡器后,由于管内湍流减弱,防涡器下方弯管处温度波动减弱,热波动受到抑制。

Thermal fluctuation in bent pipes with thermal stratification tends to induce thermal fatigue, so it increasingly attracts the attention of nuclear engineering and technology.This work focuses on a research of the flow and heat transfer mechanism of thermal stratification in bent pipes,establishes the mathematical model.The temperature fluctuation of fluid is simulated by large eddy simulations on FLUENT platform for the cases with and without vortex breaker.The dimensionless temperature fluctuation graph and RMS dimensionless temperature of an elbow pipe were obtained.The numerical results show that,due to the weaken of turbulence in the pipe,temperature fluctuation of the elbow-pipe below the vortex breaker is declined with the consideration of vortex breaker,and thermal fluctuation is suppressed.