水平光管内超临界水在大比热容区内的传热与交混特性数值模拟研究

对超临界压力水在管径为32 mm 3 mm、长度为8 m的水平光管内的流动和传热特性进行数值模拟研究。探讨不同压力、流量、热负荷下管内换热系数的变化特征;重点分析超临界水的交混特性,对比分析流动通道内二次流动的特性及演变规律,进而对二次流动的变化规律给出合理的解释;利用无量纲的Gr/Re2和Gr/Re2.7对交混特性中自然对流与强制对流的相对大小进行定量描述,以解释超临界水在水平管内的流动与换热特征。

Numerical Simulation of Heat Transfer and Mixing Characteristics of Supercritical Pressure Water in Horizontal Tubes in Large Specific Heat Region

Numerical simulation of the flow and heat transfer of supercritical pressure water in horizon-tal smooth tubes has been carried out.The diameter of the tube was Φ32 mm,and the length of the tube was 8000mm.Variation of heat transfer coefficients along the tube was obtained at pressures of 26MPa and 34MPa,respectively,and the evolution characteristics of the secondary flows in the tube were analyzed.The local parameters,such as the inner-wall temperature and the specific heat were adopted in the present study to reasonably explain the variation of the secondary flows of the supercritical pressure fluid in heated tubes.Acomparison of the natural convection to that of the force convection was made through dimensionless num-bers Gr/Re2 and Gr/Re2.7,and the characteristics of flow and heat transfer in horizontal tubes was well ex-plained.