半周加热光管内超临界水传热特性的数值模拟

Numerical Analysis on Heat Transfer Characteristics of Supercritical Water Flowing in Smooth Tube With Semi-Circumference Heating

采用SSTκ-ω湍流模型,对半周加热光管内超临界水的传热特性进行了数值模拟研究。计算结果表明,半周加热光管内,壁温沿周向呈抛物线型分布,加热侧中点壁温达到峰值,绝热侧中点壁温度达到谷值。半周加热条件下,壁温峰值比全周加热条件下的高,但发生传热恶化时的临界热流密度更高.上升流中,浮升力与流向一致,使边界层内工质流速增加,进而减小湍流强度,削弱传热;下降流中,浮升力与流向相反,强化了传热。

Heat transfer of supercritical water flowing in smooth tube with semi-circumference heating was numerically studied with SST k-ω turbulent model. Results showed that the eireum- ferencial wall temperature distribution was parabolic. It reached the peak at the middle of heating side and downed to the minimum at the middle of adiabatic side. The maximum value of wall temperature with semi-circumference heating was higher than that with uniform heating. However, the critical heat flux for heat transfer deterioration was increased when semi-circumference heating was adopted. Heat transfer was impaired in upward flow and enhanced in downward flow. It was due to different directions of buoyancy force. In upward flow, the direction of buoyancy force was consistent with that of fluid velocity, which accelerated the fluid in the boundary layer and weakened the turbulent intensity. Conversely, the fluid was decelerated and the turbulent intensity was improved.