FIELD: physics.
SUBSTANCE: subassembly has a channel for fluid medium and a flow metre. The flow metre (1) has at least one vortex former (2) passing into the channel (C). Each vortex former (2) is configured to generate Karman vortices (V) in the fluid medium flowing through the channel (C) during operation. Each vortex former (2) is provided, integrally, with a first fibre Bragg grating (FBG) sensor (3, 7, FBG). Frequency (fk) of the Karman vortex for vortices (V) generated by the vortex former (2) is detected using a fibre Bragg grating (FBG) sensor signal associated with the corresponding first fibre Bragg grating (FBG) of that vortex former (2). The method of measuring flow rate of fluid medium comprises steps for providing at least one vortex former (2) in a channel (C), providing the vortex former (2) with a fibre (7) having at least one first fibre Bragg grating (FBG). The grating is configured to reflect an optical signal with a defined wavelength depending on the tension value of the grating. Measurements of pressure of the fluid medium arising as a result of Karman vortices (V) leads to variable tension to which the corresponding fibre Bragg grating (FBG) is subjected. The optical signal is transmitted to the fibre (7). The optical signal reflected by the first fibre Bragg grating (FBG) of the vortex former (2) is determined and the detected optical signal is processed in order to determine flow rate of the fluid medium from changes in the detected signal.
EFFECT: more accurate measurement of flow rate in a relatively wide range.
18 cl, 8 dwg
