Research on detection method of large diameter pitot tube type differential pressure flowmeter

To solve the technical problem that the instrument coefficient of the large-diameter pitot tube type differential pressure flowmeter cannot be detected, a flowmeter detection method based on the similarity principle is proposed in this paper. The flow field similar to the original one in large-diameter pipeline is constructed in the small-diameter test pipeline, and the test machine with equal proportion to the original tested flowmeter is made. The instrument coefficient obtained by the testing machine under the small-diameter pipeline is used as the instrument coefficient of the original tested flowmeter. Through theoretical analysis and experimental verification, the instrument coefficient difference between the original flowmeter and the testing machine is only 0.054%. At the same time, through theoretical analysis and experimental research, it is proved that the accuracy of the proposed detection method is affected by the pipeline boundary turbulence. The smaller the pipeline diameter is, the greater the turbulence influence will be, and the lower the detection accuracy is.