Effects of swirler shape on swirling annular flow in a gas–liquid separator

Highlights: ► Effects of swirler shape on swirling annular flow in a separator are investigated. ► Liquid film thickness, separation performance and pressure drop are measured. ► A new swirler is proposed to effectively reduce the pressure drop. - Abstract: A downscaled model of a steam separator is used to experimentally examine the effects of swirler shape on swirling annular flow. Several swirlers having different vane angles, different hub diameters, and different number of vanes are installed in the separator. Flow patterns, the ratio of the separated liquid flow rate to the total liquid flow rate, liquid film thickness, and pressure drop are measured. An improved swirler, which has a small hub diameter, the reduced number of vanes and modified vane shape, is also designed and its performance is examined. As a result, the following conclusions are obtained. (1) The reduction of the hub diameter and the number of vanes do not lower the separator performance. (2) The decrease in vane angle deteriorates the separation performance. This is due to the decrease in the centrifugal force, i.e., the decrease in the amount of droplet deposition. (3) The improved swirler effectively reduces the pressure drop while keeping high separator performance.