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在压力22.5~28MPa,质量流速600~1000kg·m-2·s-1,工质比焓800~3100 kJ·kg-1范围内,对超临界水在四头内螺纹管内的流动阻力特性进行了试验研究,得到了不同工况下内螺纹管流动阻力的变化规律,分析了压力、质量流速和工质比焓变化对内螺纹管摩擦阻力系数的影响。试验结果表明:超临界压力下质量流速对摩擦阻力压降有很大影响,但对摩擦阻力系数的影响很小;在拟临界区域摩擦阻力系数有阶跃式增长现象,且这种阶跃增长现象随着压力的增加而减弱。整理试验数据得到超临界水的内螺纹管摩擦阻力系数经验关联式,与试验值相比误差小于15%,为设计具有良好水动力特性的超临界锅炉提供可靠依据。
The flow resistance characteristics of the supercritical water in the four-headed female pipe were investigated under the conditions of pressure of 22.5-28 MPa, mass flow rate of 600-1000 kg · m-2 · s-1 and specific enthalpy of 800-3,700 kJ · kg-1 The experimental results show that the variation of flow resistance of the female pipe under different working conditions and the influence of pressure, mass flow rate and specific enthalpy of the working fluid on the frictional resistance coefficient of the female pipe are analyzed. The experimental results show that the mass flow velocity has a great influence on the pressure drop of frictional resistance under supercritical pressure, but it has little effect on the frictional resistance coefficient. The frictional drag coefficient increases in a stepwise manner in the pseudo-critical zone, Phenomena diminish with increasing pressure. Finishing the test data, the empirical correlation of the frictional resistance coefficient of the internally threaded tube of the supercritical water is obtained. The error is less than 15% compared with the experimental value, which provides a reliable basis for the design of the supercritical boiler with good hydrodynamic characteristics.