Apparatus configured to detect a physical quantity of a flowing fluid, and a respective method
AssigneeNederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek TNO
InventorWouter Schiferli
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Abstract
Apparatus configured detect a physical quantity, for example a density, of a flowing fluid, the apparatus including: a sensor body (2) configured to extend into the flowing fluid, the sensor body comprising a fiber Bragg grating (FBG) of a fiber Bragg grating sensor (3, 7, FBG), for generating a detector signal relating to vibration of at least part (2B) of the sensor body (2); and a processing unit, configured to process the detector signal, and to determine the physical quantity based on detected vibration at a mechanical eigenfrequency of the flexible part (2B) of the sensor body (2).
Claims29
Apparatus configured to detect a physical quantity of a flowing fluid, the apparatus including:
- a sensor body configured to extend into the flowing fluid and comprising a fiber Bragg grating sensor, for generating optical detector signals relating to fluid induced vibrations of a flexible part of the sensor body, the fluid induced vibrations including both a vortex shedding frequency and a mechanical eigenfrequency;
- and
- a detector signal processing unit, configured to detect the optical detector signals and determine both the flow rate of the fluid from the vortex shedding frequency and the physical property of the fluid from the mechanical eigenfrequency, based on the vortex shedding frequency and the mechanical eigenfrequency of the flexible part being within a same frequency spectrum of the optical detector signals and a separation between the mechanical eigenfrequency and the vortex shedding frequency of at least 100 Hz.
Apparatus configured to detect a physical quantity of a flowing fluid, the apparatus including:
- a sensor body configured to extend into the flowing fluid and comprising a fiber Bragg grating sensor, for generating optical detector signals relating to vibrations of a flexible part of the sensor body, the fluid induced vibrations including both a vortex shedding frequency and an actual eigenfrequency;
- and
- a processing unit, the processing unit having or being associated with a memory, configured for storing an initial eigenfrequency f0 of the sensor body part, corresponding to a natural eigenfrequency of the sensor body part in vacuum, the processing unit being configured to utilize the optical detector signals for detecting the vortex shedding frequency and the actual eigenfrequency of the flexible part of the sensor body, for determining a deviation of the detected actual eigenfrequency of the flexible part of the sensor body from the stored initial eigenfrequency of the flexible part,
- wherein the apparatus is configured such that the vortex shedding frequency and the mechanical eigenfrequency are within a same frequency spectrum of the optical detector signals and a separation between the vortex shedding frequency and the mechanical eigenfrequency is at least 100 Hz.
A method of detecting a physical quantity of a flowing fluid, the method comprising inducing vibrations of a flexible part of a sensor body at both a first frequency, corresponding to a vortex shedding frequency, and an eigenfrequency the method further comprising detecting optical detector signals relating to both the vortex shedding frequency and mechanical eigenfrequency, and determining both the flow rate of the fluid from the vortex shedding frequency and the physical quantity of the fluid from the mechanical eigenfrequency, wherein the mechanical eigenfrequency and the vortex shedding frequency of the flexible part are within a same frequency spectrum of the optical detector signals and a separation between the mechanical eigenfrequency and the vortex shedding frequency is at least 100 Hz.
Dependencies are inferred from the claim text.