US3638488A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid velocity measuring device and method
Assignee: ALNOR INSTR CO DIV OF ILLINOIS
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Filing: 1970-08-17
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Granted: 1972-02-01
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Expires: 1990-08-17
Abstract
Abstract For the measurement of low-fluid velocities, especially velocities which are very low, a probe is oscillated in the stream of fluid in a simple harmonic motion and in a plane that is parallel to the fluid flow. The probe carries a transducer of a type whose output is some function of relative air flow over the transducer. The frequency or amplitude of the oscillation is chosen so that at some point in the cyclic movement, the velocity of the transducer relative to the fluid stream will be zero. The output of the transducer is compared with the mechanical oscillation of the probe to find the angular positions of the probe at which there is zero relative speed and these positions are related to fluid velocity in accordance with the expression Vf A omega cos theta , WHERE Vf is the velocity of the fluid medium, A is the amplitude of the vibration of the probe, omega is the angular frequency of the vibration and theta is the angular position of the probe when velocity of transducer relative to the fluid medium is zero.
Inventors
- 👤 Robert S Meijer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:58
CPC Classifications
G; G01; G01F; G01F1/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
159 words
The method of measuring the velocity of a fluid of constant velocity flowing in a vessel which comprises A. oscillating a flow responsive device in the stream of fluid in a plane parallel with the flow at a simple harmonic rate and with an amplitude and frequency which will render the velocity of the flow responsive device equal to that of the fluid at some point in the cycle of oscillation, B. ascertaining the angular position of the flow responsive device when its velocity relative to the stream of fluid is equal to zero, C. and relating velocity of the stream of fluid in accordance with the formula Vf A omega cos theta , where Vf is the velocity of the fluid medium, A is the amplitude of the oscillation, omega is the angular frequency of the oscillation and theta is the angular position of the flow responsive device when its velocity relative to the flow medium is zero.
Claim 2
Independent Claim
159 words
The method of measuring the velocity of a fluid of constant velocity flowing in a vessel which comprises A. oscillating a flow responsive device in the stream of fluid in a plane parallel with the flow at a simple harmonic rate and with an amplitude and frequency which will render the velocity of the flow responsive device equal to that of the fluid at some point in the cycle of oscillation, B. ascertaining the angular position of the flow responsive device when its velocity relative to the stream of fluid is equal to zero, C. and relating velocity of the stream of fluid in accordance with the formula Vf A omega cos theta , where Vf is the velocity of the fluid medium, A is the amplitude of the oscillation, omega is the angular frequency of the oscillation and theta is the angular position of the flow responsive device when its velocity relative to the flow medium is zero.
Claim 3
Dependent Claim
53 words
The method as claimed in claim 1 in which the angular position of the flow responsive device is obtained by deriving an electrical characteristic of the mechanical oscillation of said flow responsive device, deriving an electrical characteristic of the relative speed of the flow responsive device, and comparing the phase of the two.
Claim 4
Dependent Claim
53 words
The method as claimed in claim 2 in which the electrical characteristic of the mechanical oscillation is applied to one axis of a cathode ray tube and the electrical characteristic of relative speed is applied to the other axis of the cathode ray tube whereby to obtain a display of the phase comparison.
Claim 5
Independent Claim
107 words
The method of ascertaining the velocity of a fluid of constant velocity flowing in a vessel comprising; A. oscillating a flow responsive device in the stream of fluid in a simple harmonic motion in a plane parallel with the flow with an amplitude and frequency which will render the velocity of the flow responsive device equal to that of the fluid at some point of time during which the oscillation is occurring, B. detecting the position of the probe at the instant that the velocity of the fluid is equal to that of the probe at that moment in time, and C. converting probe position into velocity.
Claim 6
Independent Claim
107 words
The method of ascertaining the velocity of a fluid of constant velocity flowing in a vessel comprising; A. oscillating a flow responsive device in the stream of fluid in a simple harmonic motion in a plane parallel with the flow with an amplitude and frequency which will render the velocity of the flow responsive device equal to that of the fluid at some point of time during which the oscillation is occurring, B. detecting the position of the probe at the instant that the velocity of the fluid is equal to that of the probe at that moment in time, and C. converting probe position into velocity.
Claim 7
Dependent Claim
138 words
Apparatus for measuring the velocity of a fluid of constant velocity flowing in a vessel which comprises: A. a probe having a heat responsive device on one end thereof and the other end being fixed, B. means to oscillate the probe in a plane parallel with the flow at a frequency and amplitude which at some point will cause the velocity of the fluid and that of the probe to be equal, C. first means for converting the velocity of the probe relative to the fluid medium into a repetitive signal that varies with the response of said heat responsive device, D. second means for converting the oscillation of the Probe into a repetitive signal that varies with the mechanical oscillation of the probe, E. and means for comparing the signals to obtain a phase comparison between them.
Claim 8
Dependent Claim
138 words
Apparatus for measuring the velocity of a fluid of constant velocity flowing in a vessel which comprises: A. a probe having a heat responsive device on one end thereof and the other end being fixed, B. means to oscillate the probe in a plane parallel with the flow at a frequency and amplitude which at some point will cause the velocity of the fluid and that of the probe to be equal, C. first means for converting the velocity of the probe relative to the fluid medium into a repetitive signal that varies with the response of said heat responsive device, D. second means for converting the oscillation of the Probe into a repetitive signal that varies with the mechanical oscillation of the probe, E. and means for comparing the signals to obtain a phase comparison between them.
Claim 9
Dependent Claim
17 words
The apparatus as claimed in claim 5 in which means are provided for displaying the phase comparison.
Claim 10
Dependent Claim
41 words
The apparatus as claimed in claim 5 in which the first means comprises an amplifier circuit producing a signal only when the velocity of the fluid and that of the probe are equal, the relative velocity of the probe being zero.
Claim 11
Dependent Claim
45 words
The apparatus as claimed in claim 7 in which the comparison means comprise a cathode ray tube, and the signals from the first and second converting means are applied to one and the other of the X and Y axes of said cathode-ray tube respectively.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |