The phase-isolation technology of multiphase flow in-pipe is widely used in scientific research and engineering area. Based on the application of the phase-isolation technology on single-phase flow measurement

the mechanism of radial differential pressure used in multiphase flow measurement was studied by taking oil-water two-phase flow as an example

and the experimental verification was carried out. The theoretical analysis showed that the radial differential pressure between the pipe wall and pipe center of a cross section downstream of the swirler has a functional relationship between the mass flowrate and oil cut. Once measuring the radial differential pressure between the pipe wall and pipe center of a cross section downstream of the swirler

the mass flowrate and oil cut can be determined if either of the two parameters was known. The experimental results showed that the relative error of oil cut was less than 8.02% for the cross section of 0.075 m or 0.115 m downstream of the swirler

and mass flowrate was less than 1.44%

which provides a theoretical basis for further study of the two-parameter measurement of multiphase flow.