# US 5,347,873 A · Double wing vortex flowmeter with strouhal number corrector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,347,873 A - Document ID: US5347873A - Status: Granted - Kind: A - Application number: 08/119,312 - Filed: 1993-09-09 - Granted: 1994-09-20 - Earliest claimed: 1993-04-09 - Assignees: Badger Meter, Inc. - Inventors: William H. Vander Heyden - Web page: https://patentgrep.com/patent/US5347873A ## CPC - G01F 1/3266: {by sensing mechanical vibrations} - G01F 1/325: Means for detecting quantities used as proxy variables for swirl - G01F 1/3287: {circuits therefor} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME ## Abstract A vortex flowmeter includes a body having a flow passage, a vortex generator that generates a standing transverse wave in the flow passage, and first wing and second wings in the passage downstream of the generator. A circuit that utilizes sensors in the two wings is provided for first determining an operational phase difference, .DELTA..phi..sub.m between the signals representing movement of the first and second wings. A microprocessor then determines a corrected vortex frequency, .sup.f corr, in response to a ratio of a predetermined calibration phase difference .DELTA..phi..sub.c to the measured phase difference .DELTA..phi..sub.m. ## Claims ### Claim 1 A vortex flowmeter comprising: a body having a passage for flow of a fluid therethrough in a longitudinal direction; a vortex generator positioned in the passage for transmitting vortices downstream; a first vortex sensor located at a first sensor position downstream of the vortex generator, the first vortex sensor producing a first signal of the vortex frequency, f.sub.m, in response to passage of vortices through the first sensor position; a second vortex sensor located at a second sensor position downstream of the vortex generator, the second vortex sensor producing a second signal of the vortex frequency, f.sub.m, in response to passage of vortices through the second sensor position, said second signal being phase delayed from said first signal; means for determining a measured phase difference .DELTA..phi..sub.m between the first signal and the second signal; and means for comparing the measured phase difference .DELTA..phi..sub.m to a calibration phase difference .DELTA..phi..sub.c representing the phase difference between the first sensor position and the second sensor position wing under pre-operational, calibration conditions; means for determining a corrected vortex frequency, f.sub.corr, of said flow meter during operation in response to a ratio of the predetermined calibration phase difference .DELTA..phi..sub.c to the measured phase difference .DELTA..phi..sub.m. ### Claim 2 (depends on 1) The vortex flow meter of claim 1, wherein the first vortex sensor is located in the passage in a first wing downstream of the vortex generator; and wherein the second vortex sensor is located in the passage in a second wing downstream of the vortex generator. ### Claim 3 (depends on 2) The vortex flowmeter of claim 2, wherein the sensors are piezoelectric transducers. ### Claim 4 (depends on 2) The vortex flowmeter of claim 2, wherein the means for determining the measured phase difference, .DELTA..phi..sub.m, comprises a circuit for comparing the signals from the first and second vortex sensors located in the first and second wings, respectively. ### Claim 5 (depends on 1) The vortex flowmeter of claim 1, further comprising means for determining a fluid velocity V.sub.m in accordance with the following relation: ##EQU13## where .DELTA..phi..sub.m is the determined phase difference, .DELTA..phi..sub.c is a calibrated phase difference between the first and second wings as determined before operating the flowmeter, f.sub.m is the vortex frequency, D is a characteristic length associated with the vortex generator as determined before operating the flowmeter, and N.sub.si is the initial Strouhal Number as determined before operating the flowmeter. ### Claim 6 (depends on 1) The flowmeter of claim 1 wherein the calibration phase difference .DELTA..phi..sub.c is predetermined to be 180.degree.. ### Claim 7 A method of determining a fluid velocity V.sub.m of fluid flowing through a flow passage comprising: using a vortex generator with a characteristic dimension D to generate rows of vortices in the flow passage to form a standing transverse wave flow pattern; detecting the vortices at one position in the flow passage; detecting the vortices at a second position in the flow passage located downstream from the first position; producing a first signal of a vortex frequency, f.sub.m, in response to detecting the vortices at the first detection position; producing a second signal of a vortex frequency, f.sub.m, in response to detecting the vortices at the second detection position; determining a phase difference .DELTA..phi..sub.m between the first and second signals; determining measured fluid velocity V.sub.m by obtaining a corrected vortex frequency, f.sub.corr, by multiplying the vortex frequency, f.sub.m, by the ratio of the predetermined calibration phase difference .DELTA..phi..sub.c to the measured phase difference .DELTA..phi..sub.m. ### Claim 8 (depends on 7) The method of claim 7, wherein the fluid velocity V.sub.m is further obtained by multiplying the correction frequency, f.sub.corr, by the ratio of ##EQU14## where D is the characteristic diameter of the vortex generator as determined before operation, and N.sub.si is the initial Strouhal Number as determined before operation. ### Claim 9 (depends on 7) The method of claim 7, wherein the second position is located downstream from the first position a distance that is an odd multiple of half of a wavelength of the standing transverse wave. ### Claim 10 (depends on 7) A method as recited in claim 7 wherein the phase difference .DELTA..phi..sub.m is determined by: continuously transmitting the generated signals to a circuit; and analyzing the continuously transmitted signals in the circuit.