Method for constructing stable annular flow inside micro-channel

The invention discloses a method for constructing a stable annular flow inside a micro-channel. A linear center plug-in is arranged inside the micro-channel, during operation, fluid forming an outer ring is input into the micro-channel at the certain flow, after the micro-channel is filled with the fluid forming the outer ring, fluid forming an inner ring is input into the micro-channel at the certain flow, and the fluid flows in the stable annular flow type inside the micro-channel; the flow of the fluid forming the inner ring is controlled to be 0.8-20 mL/min, and the flow rate of the fluidforming the inner ring to the fluid forming the outer ring is 1:(0.2-20); when the fluid forming the outer ring is a water phase, and the fluid forming the inner ring is an organic phase, the linear center plug-in is manufactured from an oleophylic material, and an outer pipe is made from a hydrophilic material; when the fluid forming the outer ring is an organic phase, and the fluid forming the inner ring is a water phas