Method and device for measuring flow of large-diameter pipeline

The invention discloses a flow measurement method and device for a large-diameter pipeline, and relates to the technical field of flow measurement. The target ultrasonic water meter comprises a first ultrasonic speed measurement group and a second ultrasonic speed measurement group; ultrasonic waves emitted by the first ultrasonic speed measurement group pass through a pipeline center line; ultrasonic waves emitted by the second ultrasonic speed measurement group do not pass through the pipeline center line, and the distance between the ultrasonic wave route and the pipeline center line is a first distance; the method is applied to target ultrasonic water meters. In flow metering, the characteristic that the closer to the middle line of a pipeline, the faster the flow speed is in a flow model of fluid is considered, the speed and the initial average flow speed of a certain stationary layer of the fluid can be measured by arranging ultrasonic speed measurement sets in different emission directions, and a speci