Experimental investigation of flow characteristics of liquid in mini-tubes

The resistance characteristics of deionized water in minitubes with three different diameters ranging from 1.0 mm to 2.0 mm are experimentally investigated. The relation of friction factor and minor loss coefficient with Reynolds number are obtained. The results show that the variations of pressure drop and local pressure drop with mean velocity of fluid in minitubes are consistent basically. The friction factor decreases with the decrease of diameter. And the values are smaller than that in convectional scale in laminar flow region and turbulence flow region. The variations of minor loss coefficient with Reynolds number in the minitubes are consistent basically. The minor loss coefficient increases with the decrease of diameter under the condition of same Reynolds number. The critical Reynolds number is 2050~2300 in the minitubes with the diameter ranging from 1.0 mm to 2.0 mm.