Gas–liquid two-phase flow rate measurement with a multi-nozzle sampling method

A small portion of total flow was sampled using a specially designed multi-nozzle sampler for flow rate metering. The splitting nozzles were evenly placed around the circumference of the pipe and a swirl vane was mounted upstream to change the asymmetry flow pattern into uniform annular flow. The sampled fluid was separated and metered by a compact separator. The total flow rate of each phase was determined according the flow rate of sample flow and the extraction ratio. [Display omitted] •A small portion of gas–liquid mixture is sampled for flow rate measurement.•A swirl vane is used to transform upstream patterns into uniform annular flow.•The extraction ratio is independent of flow patterns, gas and liquid velocities.•The error of flow rate measurement was less than 5.0%. A novel sampling device is proposed to measure the gas–liquid two-phase flow rate based on Extracting and Separating Method (ESM). A small fraction of gas–liquid mixture is extracted from the main stream and the total gas and liquid flow rate are determined according to the flow rate of sampled fluid and the extraction ratio. The extraction ratio is determined by the ratio of sample nozzle number to the total splitting nozzle number. Experiments were carried out in an air–water two-phase flow loop, and the flow patterns occurred during the experiments were wavy flow, annular flow and slug flow. It was found that the gas and liquid extraction ratio were close to the theoretical value (0.25) and independent of flow patterns, gas and liquid velocities. The error of flow rates measurements was less than ±5.0%.