Acoustic flowmeter and method for determining the flow in an object

Abstract

The invention relates to a method for determining the flow or the flow rate of a medium in an electrically conductive object, in particular a pipe (1) or a pipeline, through which a medium flows. At least one ultrasonic wave (16) is produced by means of a transmitting transducer (11) in the object and is injected into the medium as a longitudinal wave (8) on an inner side of the object, and an ultrasonic signal, coming at least partially from the longitudinal wave (8), is received by the receiving transducer (12), at a spatial distance from the injection point and is used to evaluate the flow or the flow rate. Said transmitting transducer (11) produces, preferably in the absence of an acoustic coupling with the surface of the object, a first variable magnetic field in an area close to the surface of the object, in particular metallic, and a first ultrasonic wave is produced in said area by means of the interaction of said variable magnetic field with a static or quasi-static magnetic field. Said transmitting transducer (11) also produces an additional variable magnetic field in the area of the object and an additional ultrasonic wave is produced in said area by means of the interaction of the variable magnetic field with a static or quasi-static magnetic field, said other ultrasonic wave is superimposed on the first ultrasonic wave such that an amplitude of a resulting wave in the direction of the receiving transducer (12) is increased and is reduced in the direction away from said receiving transducer (12). Preferably, the first and the second magnetic fields are produced by two high frequency bobbins (18, 19) of the transmitting transducer (11). The invention also relates to a device for carrying out said inventive method.

Description

technical field [0001] The invention relates to a method for determining the flow rate or flow rate of a medium in an electrically conductive object through which the medium flows, in particular in a pipe or line. Furthermore, the invention relates to an acoustic flow meter for carrying out such a method. Background technique [0002] Conventional non-intrusive flow meters must be clamped fixedly to the pipe or pipeline, so the ultrasound generated by the transmitting transducer may couple into the pipe. The fastening and subsequent operation of the device does not impair the medium transport in the pipeline, thus representing a non-invasive flow measurement. Wedge-shaped acoustic couplers are often additionally used, which are arranged between the piezoelectric element and the object and which couple the acoustic signal emitted by the transmitting transducer into the conducting wall, often using additionally using a coupling medium. . [0003] The installation and commis...

AI Technical Summary

Problems solved by technology

In addition to temperature problems, however, from time to time thorny problems may arise due to stresses in the material of the acoustic coupler, which stresses are generated by strong temperature gradients

Furthermore, the aging of the mostly gel-like coupling medium inserted between the acoustic coupler and the pipe is problematic

As the coupling medium ages, the signal quality of the ultrasonic waves generated in the object decreases

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