1954 年 20 巻 92 号 p. 280-285
The property of the coefficient of friction for the vapour-liquid mixture, which has been used to calculate the water circulation in boiler tubes in the previous report, is inquired, referring to Lockhart's method of calculating the pressure drop for two-phase, two component flows and also to Schurig's experimental data for air-water mixture. The ratio of the coefficient of friction for mixture to that for the liquid in the mixture (when only the liquid flow in the tube), is expressed as a function of the flowing ratio of both liquids. And this value for the mixture of saturated water and saturated steam of 1∼225 ata is shown. In the approximate calculation of water circulation in natural circulation boilers which pressure is above 10 ata, 1.5∼2.0 can be used as this value.