中文摘要：

推导了湿蒸汽在等截面直管道稳定流动的动量方程，结合能量方程和连续性方程，给出管道各截面湿蒸汽参数的计算方法。得到管道入口为干饱和蒸汽和湿蒸汽时管道各截面的蒸汽参数，并分析阻力对蒸汽参数的影响。结果表明：由于存在阻力使湿蒸汽的压力降低、温度降低、比容增大、流速增大、焓值降低；干度沿流动方向的变化规律主要与入口干度和入口压力有关。以1000MW核电汽轮机为例，在额定工况下，除主蒸汽干度将逐渐减小外，其它蒸汽管道内湿蒸汽在流动过程中干度都将逐渐增大。

英文摘要：

Momentum equation was derived when wet steam flows through a straight pipeline with a constant cross section . Combined with energy equation and the continuity equation , a calculating method of steam parameters varying along the straight pipeline was given .Steam parameters was obtained when the inlet was dry saturated steam and wet saturated steam . The influence of the resistance to the steam parameters was analyzed .The results show that friction pressure loss lead to the decrease of temperature ,the increase of specific volume ,the increase of velocity and the decrease of enthalpy .The change rule of dryness varying along the pipeline mainly related with the inlet dryness and inlet pressure .Taking a 1 000 MW nuclear steam turbine as example,main steam dryness will gradually decrease,while the dryness in other steam pipeline will gradually increase under the rated operating conditions .