Experimental investigation of phase split of gas–liquid two-phase flow through small holes at the pipe wall

•A device was proposed for gas–liquid phase split at small holes on the pipe wall.•The correlations of the gas and liquid extraction ratio were derived.•Four samplers with different arrangement of sampling holes were studied.•Effect of swirl vane on phase split was investigated. An experimental and analytical study on phase split of gas–liquid two-phase flow through small holes at the main pipe wall has been performed in this paper. The inner pipe diameter of the test section is 40mm and the diameter of sampling hole is 2.5mm. Experiments were conducted in an air–water two-phase flow loop and four types of sampler with different arrangement of sampling-holes were tested. Stratified-wavy, annular and slug flows were observed. Experimental results show that phase splitting behavior is significantly influenced by the number and positions of the sampling-holes and the superficial velocities of the gas and liquid. If a swirl vane is mounted at the upstream of the four-hole sampler, an interesting phenomenon that the liquid extraction ratio maintains constant and is independent of the inlet flow patterns can be observed.