CN100545589C - Be used to measure the method and the special-purpose acoustic resistance flowmeter thereof of fluid flow - Google Patents

Be used to measure the method and the special-purpose acoustic resistance flowmeter thereof of fluid flow Download PDF

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CN100545589C
CN100545589C CNB2005100127427A CN200510012742A CN100545589C CN 100545589 C CN100545589 C CN 100545589C CN B2005100127427 A CNB2005100127427 A CN B2005100127427A CN 200510012742 A CN200510012742 A CN 200510012742A CN 100545589 C CN100545589 C CN 100545589C
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acoustic resistance
resistance
fluid
acoustic
signal
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CN1758031A (en
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岳中琰
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Abstract

The present invention relates to a kind of method and special-purpose acoustic resistance flowmeter thereof that is used to measure fluid flow, the method of measurement fluid flow of the present invention realizes by following step: when the acoustic resistance sensor is launched sound wave in fluid, the acoustic impedance of fluid to emission's sound wave received in sense, and the acoustic impedance signal is converted into the acoustic resistance signal, the acoustic resistance signal is converted to voltage signal through metering circuit, and the processing of voltage signal process prime amplifier, phase sensitive detection and filtrator is transferred to indicator and carries out the flow indication.Special-purpose acoustic resistance flowmeter of the present invention comprises oscillator, analog switch, sampling pulse generator, acoustic resistance sensor, prime amplifier, phase-sensitive detection circuit, wave filter and indicator.The present invention relates to the mass flow measurement that surveying instrument is fit to fluid, it is simple in structure, and measurement result is accurate, and easy to use.

Description

Be used to measure the method and the special-purpose acoustic resistance flowmeter thereof of fluid flow
Technical field
The present invention relates to a kind of acoustic resistance flowmeter that utilizes the measuring method of acoustic measurement fluid mass flow and relate to a kind of this method special use.
Background technology
The measurement of fluid mass flow is the measurement project that often runs in modern industry production and the trade activity.The method that the measurement of mass rate is adopted at present has the direct method of measurement and the indirect method of measurement.The surveying instrument that belongs to the direct method of measurement mainly contains two kinds: a kind of is differential pressure type quality flow meter, and a kind of is the Ge Liaolilishi flowmeter.The common feature of these two kinds of driect type mass flowmeter is all to have mechanical moving element, complex structure, thereby hindered its widespread usage in commercial production.
Belonging to indirect method, to carry out the measurement of mass rate be the volumetric flow rate that is gone out fluid by a volume flow measurement, and measure the density of fluid in real time by another densitometer, calculate the mass rate of fluid then, owing to the density of fluid is that the variation of the factor such as temperature, pressure along with fluid changes, so measuring system is also complicated, realizes that difficulty is bigger.
Summary of the invention
The object of the present invention is to provide a kind of measurement of the acoustic resistance by convection cell to realize the measuring method and the special-purpose acoustic resistance flowmeter thereof of measurement fluid mass flow of the direct measurement of fluid flow, surveying instrument is simple in structure, and it is can effectively reduce measuring error when the pipeline caliber changes, and easy to use when measuring.
For achieving the above object, the present invention realizes by following technological means.
Be used to measure the method for fluid flow, this method may further comprise the steps:
(a) the acoustic resistance sensor along with the speed forward of rate of flow of fluid v and with velocity reversal's emission sound wave of rate of flow of fluid v;
(b) in emission sound wave process, the forward acoustic resistance signal S of fluid to the forward sound wave received in the sense of acoustic resistance sensor R1With reverse acoustic resistance signal S R2, and with forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Be converted to forward acoustic resistance signal and reverse acoustic resistance signal, and obtain the difference DELTA R of forward acoustic resistance signal and reverse acoustic resistance signal S
(c) with resistance signal Δ R SConvert voltage signal U to by metering circuit C:
When metering circuit by a forward acoustic resistance sensor and a reverse acoustic resistance sensor series connection and and the series circuit resistance that equates of two other resistance be connected in parallel on the voltage two ends when forming the half bridge measurement circuit, the bridge excitation electric current adopts AC constant-current source I, rate of flow of fluid is v, when v=0, and u c=0; When v ≠ 0,
u c=2I s* Δ R SBy Δ R S=Δ S RK Z, as can be known:
u c＝2I s*ΔS RK Z ΔS R＝u c/(2I sK Z)
Wherein, K ZThe acoustic resistance of-acoustic resistance sensor and the conversion coefficient of acoustic resistance;
Δ S RWhen-streaming flow medium is static relatively to the acoustic resistance increment of sound source acoustic emission;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
When metering circuit is made up of two forward acoustic resistance sensors and two negative sense acoustic resistance sensors, and four sensor performance parameters are all identical, and when four acoustic resistance sensor strings were formed the full-bridge type metering circuit together, the bridge excitation power supply adopted AC constant-current source I, R S1, R S1 'Be respectively the acoustic resistance that fluid produces two forward acoustic resistance sensors; R S2, R S2 'Be respectively the acoustic resistance that fluid produces two reverse acoustic resistance sensors.The electric current that flows through two acoustic resistance sensors in the series circuit is all steady excitation alternating current I S, and I S=I/2.When rate of flow of fluid v=0, R S1=R S2=R S1 '=R S2 ', output quantity u then c=0; When rate of flow of fluid was v (v ≠ 0), four transducer acoustic resistances changed, and its variable quantity is
ΔR S1＝ΔR S1’＝-ΔR S2＝-ΔR S2’＝ΔR S
According to the electric bridge characteristic, then output quantity is:
u c＝4I SΔR S＝4I SΔS RK Z?ΔS R＝u c/(4K ZI S)
In the formula, K ZThe conversion coefficient of-acoustic resistance and acoustic resistance.
Δ S R-forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Acoustic resistance is poor;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
(d) with voltage signal U CConvert the mass rate q of fluid to m,
Work as u c=2I s* Δ S RK ZBe Δ S R=u c/ (2I sK Z) time,
According to q m=ρ vA=Δ S RA=u cA/ (2I sK Z)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
Work as u c=4I SΔ R S=4I SΔ S RK ZBe Δ S R=u c/ (4K ZI S) time,
According to q m=ρ vA=Δ S RA=u c/ (4K ZI S)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
Be used to measure the method for fluid flow, this method can also be made up of following steps:
(a) the acoustic resistance sensor along with the speed forward of rate of flow of fluid v and with velocity reversal's emission sound wave of rate of flow of fluid v;
(b) in emission sound wave process, the forward acoustic resistance signal S of fluid to the forward sound wave received in the sense of acoustic resistance sensor R1With reverse acoustic resistance signal S R2, and with forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Be converted to forward acoustic resistance signal and reverse acoustic resistance signal, and obtain the difference DELTA R of forward acoustic resistance signal and reverse acoustic resistance signal S
(c) with resistance signal Δ R SConvert voltage signal U to by metering circuit C:
When metering circuit is connected in parallel on the half bridge measurement circuit of forming at the voltage two ends by the series circuit resistance that a forward acoustic resistance sensor (1) and a reverse acoustic resistance sensor (2) are connected also and two other resistance equates, the bridge excitation electric current adopts AC constant-current source I, rate of flow of fluid is v, when v=0, u c=0; When v ≠ 0,
u c=2I s* Δ R SBy Δ R S=Δ S RK Z, as can be known:
u c＝2I s*ΔS RK Z?ΔS R＝u c/(2I sK Z)
Wherein, K ZThe acoustic resistance of-acoustic resistance sensor and the conversion coefficient of acoustic resistance;
Δ S RWhen-streaming flow medium is static relatively to the acoustic resistance increment of sound source acoustic emission;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
When metering circuit is made up of two forward acoustic resistance sensors and two negative sense acoustic resistance sensors, and four sensor performance parameters are all identical, and when four acoustic resistance sensor strings were formed the full-bridge type metering circuit together, the bridge excitation power supply adopted AC constant-current source I, R S1, R S1 'Be respectively the acoustic resistance that fluid produces two forward acoustic resistance sensors; R S2, R S2 'Be respectively the acoustic resistance that fluid produces two reverse acoustic resistance sensors.The electric current that flows through two acoustic resistance sensors in the series circuit is all steady excitation alternating current I S, and I S=I/2.When rate of flow of fluid v=0, R S1=R S2=R S1=R S2 ', output quantity u then c=0; When rate of flow of fluid was v (v ≠ 0), four transducer acoustic resistances changed, and its variable quantity is
ΔR S1＝ΔR S1’＝-ΔR S2＝-ΔR S2’＝ΔR S
According to the electric bridge characteristic, then output quantity is:
u c＝4I SΔR S＝4I SΔS RK Z ΔS R＝u c/(4K Z?I S)
In the formula, K ZThe conversion coefficient of-acoustic resistance and acoustic resistance.
Δ S R-forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Acoustic resistance is poor;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
(d) with voltage signal U CConvert the mass rate q of fluid to m,
Work as u c=2I s* Δ S RK ZBe Δ S R=u c/ (2I sK Z) time,
According to q m=ρ vA=Δ S RA=u cA/ (2I sK Z)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
Work as u c=4I SΔ R S=4I SΔ S RK ZBe Δ S R=u c/ (4K ZI S) time,
According to q m=ρ vA=Δ S RA=u c/ (4K ZI S)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
(e) be t through emission certain hour in fluid 1Sound wave after, through certain hour t 2Interruption, promptly to launch the cycle of sound wave in fluid be T to the acoustic resistance sensor,
T=t 1+ t 2And
t 1≥2L/c
t 2＞t 1
L-measuring section length; The c-velocity of sound;
(f) repeating step (a) is to (e).
Be used to measure the acoustic resistance flowmeter of the method special use of fluid flow, comprise oscillator, constant-current circuit, can along with the forward acoustic resistance sensor of rate of flow of fluid forward direction transmission sound wave and can along with the back emitted sound wave of rate of flow of fluid with the corresponding to reverse acoustic resistance sensor of forward acoustic resistance sensor performance parameter, by just, the metering circuit that reverse acoustic resistance sensor is formed, prime amplifier, phase-sensitive detection circuit, wave filter, emitter follower and indicator, the output terminal of oscillator links to each other with the constant-current circuit input end, just described, oppositely the acoustic resistance sensor is cascaded and forms the bridge-type metering circuit, the output terminal of constant-current circuit links to each other with the input end of metering circuit and phase-sensitive detection circuit simultaneously, the voltage output end of metering circuit links to each other with the input end of prime amplifier, the signal output part of prime amplifier links to each other with the signal input part of phase-sensitive detection circuit, the signal output part of phase-sensitive detection circuit links to each other with the signal input part of wave filter, and the signal output part of wave filter links to each other with the signal input part of indicator.
This is used for measuring the acoustic resistance flowmeter of the method special use of fluid flow, and forward and reverse acoustic resistance sensor respectively is one, and also is provided with the resistance R that two resistances equate in described bridge-type metering circuit 1And R 2, R 1, R 2Be cascaded, and form the semibridge system metering circuits with two forward and reverse sensors that are in series and be connected the output terminal of constant-current circuit.
This is used for measuring the acoustic resistance flowmeter of the method special use of fluid flow, positive and negative acoustic resistance sensor can also respectively be two, and four sensor performance parameters are identical, the output terminal that these four acoustic resistance sensors link together and form the full-bridge type metering circuit and be connected constant-current circuit.
This is used for measuring the acoustic resistance flowmeter of the method special use of fluid flow, can also be connected with analog switch between the input end of the input end of the output terminal of constant-current circuit and metering circuit and phase-sensitive detector (PSD), the signal input part of analog switch is connected with a sampling pulse generator.
This acoustic resistance flowmeter oscillator that is used for measuring the method special use of fluid flow is made up of oscillatory circuit, follower, and in the oscillatory circuit, the positive pole of power supply is by pull-up resistor R 3With triode BG 1Collector link to each other divider resistance R 1And R 2Series connection, and R 1And R 2Tie point and triode BG 1Base stage link to each other resistance R 4With capacitor C 1Parallel connection, and with triode BG 1Emitter series connection, the resonant capacitance C2 back of connect with C3 is in parallel with the electric coil L of deluding of resonance, and an end and triode BG 1Collector link to each other triode BG 1Emitter and capacitor C 2And C 3Tie point link to each other; The triode BG of follower 2Collector link to each other base stage and pull-up resistor R with positive source 3With triode BG 1The tie point of collector links to each other, and emitter passes through resistance R 5Ground connection; Field effect transistor T in the described constant-current circuit (8) 1Grid by biasing resistor R 18Extremely link to each other with positive source, drain electrode is by coupling capacitance C 4Be connected in triode BG 2And resistance R 5Contact, source electrode and current sampling resistor R 6Link to each other isolated amplifier IC 1Two input ends be connected to current sampling resistor R 6Two ends, its output terminal is by commutation diode D 1With feedback resistance R 8Link to each other, and with biasing resistor R 18Form a loop; The bridge-type metering circuit that described metering circuit (13) is made up of acoustic resistance sensor (1) (2), it is as the input end and the sampling resistor R of continuous current 6Output terminal link to each other; Amplifier IC in the prime amplifier (4) 2Negative input end and positive input respectively by electricity group R 11, coupling capacitance C 8And resistance R 12Link to each other feedback resistance R with two output terminals of metering circuit (13) 14Be connected in amplifier IC 2Negative input end and output terminal; The field effect transistor T of described phase-sensitive detection circuit (5) 3Grid and sampling resistor R 6Output terminal link to each other drain electrode and amplifier IC 2Output terminal link to each other, source electrode is by pull-up resistor R 15Ground connection; In the wave filter (6), capacitor C 9By filter resistance R 16The source electrode of field effect transistor T3 links to each other; The base stage and the resistance R of emitter follower (9) 16Output terminal link to each other, collector links to each other with the positive pole of power supply, emitter while and pull-up resistor R 17Link to each other with the input end of indicator (7).
In the acoustic resistance flowmeter of the method special use of this measurement fluid flow, sampling pulse generator (9) mainly is made up of multivibrator, and multivibrator is by two Sheffer stroke gate G 1, G 2With two adjustable resistance R 9, R 10And two capacitor C 6, C 7Form R 9, R 10, be parallel to Sheffer stroke gate G respectively 1, G 2Output and input end, coupling capacitance C 6, C 7Be connected to the output terminal of a Sheffer stroke gate and the input end of another Sheffer stroke gate, field effect transistor T in the described analog switch (8) 2Drain electrode and sampling resistor R 6Output terminal link to each other grid and Sheffer stroke gate G 2Output terminal link to each other the input end of source electrode and measuring bridge, field effect transistor T 3Grid link to each other.
When adopting a pair of forward and reverse acoustic resistance sensor, RS 1And RS 2Be respectively the acoustic resistance of described forward and reverse acoustic resistance sensor, one of them acoustic resistance and resistance R 1Tie point and resistance R 6Output terminal link to each other the tie point of two acoustic resistances and two resistance R 1, R 2Tie point constitute two output terminals of voltage.
When adopting two pairs of forward and reverse acoustic resistance sensors, RS 1, RS 1 ', RS 2, RS 2 'Be respectively the acoustic resistance of described forward and reverse acoustic resistance sensor (1) (1 ') (2) (2 '), the wherein tie point of a pair of forward and reverse acoustic resistance and resistance R 6Output terminal link to each other, the forward acoustic resistance of this centering and the tie point of the reverse acoustic resistance of another one be two output terminals of the reverse acoustic resistance of centering and another one forward acoustic resistance formation voltage therewith.
The present invention adopts that the increment to the acoustic resistance that sound source showed carries out the measurement of the flow of fluid stream therein when measuring mobile fluid it is static relatively, this flowmeter structure is simple, easy to use, measure and be not subjected to the hydrodynamic pressure influence of temperature variation, owing to adopt the pulse producer convection cell to carry out the intermittent transmission sound wave, thereby carrying out intermittence measures, make when measuring the pipeline caliber and change, can eliminate because the reflection wave of and non-measuring tube disconnected caliber variation place generation disconnected at measuring tube to the influence of sound wave, makes measurement result more accurate.
Description of drawings
Below in conjunction with accompanying drawing embodiment of the present invention is described in further detail.
Fig. 1 is the circuit theory diagrams of the acoustic resistance flowmeter of special use of the present invention;
Fig. 2 measures the flow chart of the method for fluid flow for the present invention;
Arrangement figure when Fig. 3 is two for acoustic resistance sensor of the present invention in measuring pipeline section;
Metering circuit figure when Fig. 4 is two for acoustic resistance sensor of the present invention;
Fig. 5 measures the arrangement figure in the pipeline section again when being four for acoustic resistance sensor of the present invention;
Metering circuit figure when Fig. 6 is four for acoustic resistance sensor of the present invention;
Principle key diagram when Fig. 7 adopts the intermittent transmission sound wave for the present invention;
Oscillogram when Fig. 8 adopts the intermittent transmission sound wave for the present invention.
Embodiment
One, the present invention is used to measure the embodiment of the method for fluid flow:
Embodiment one:
A, choose with a pair of performance parameter identical forward and reverse acoustic resistance sensor or two pairs of forward and reverse sensors that performance parameter is identical, by the acoustic resistance sensor along with the speed forward of rate of flow of fluid v and with velocity reversal's emission sound wave of rate of flow of fluid v;
B, in emission sound wave process, the forward acoustic resistance signal S of fluid to the forward sound wave received in the sense of acoustic resistance sensor R1With reverse acoustic resistance signal S R2, and with forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Be converted to forward acoustic resistance signal and reverse acoustic resistance signal, and obtain the difference DELTA R of forward acoustic resistance signal and reverse acoustic resistance signal S
C, according to Fig. 4 and metering circuit figure shown in Figure 6, with resistance signal Δ R SConvert voltage signal U to by metering circuit (13) C:
When metering circuit (13) is connected in parallel on the half-bridge change-over circuit of forming at the voltage two ends by the series circuit resistance that a forward acoustic resistance sensor (1) and a reverse acoustic resistance sensor (2) are connected also and two other resistance equates, the bridge excitation power supply adopts AC constant-current source I, rate of flow of fluid is v, when v=0, u c=0; When v ≠ 0,
u c=2I s* Δ R SBy Δ R S=Δ S RK Z, as can be known:
u c＝2I s*ΔS RK ZΔS R＝u c/(2I sK Z)
Wherein, K ZThe acoustic resistance of-acoustic resistance sensor and the conversion coefficient of acoustic resistance;
Δ S RWhen-streaming flow medium is static relatively to the acoustic resistance increment of sound source acoustic emission;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
When metering circuit (13) is made up of two forward acoustic resistance sensors (1) (1 ') and two reverse acoustic resistance sensors (2) (2 '), and four sensor performance parameters are all identical, when sensor (1) (2) series connection and the full-bridge type metering circuit formed with the sensor (1 ') (2 ') that is cascaded, the bridge excitation power supply adopts AC constant-current source I, R S1, R S1 'Be respectively the acoustic resistance that fluid acoustic resistance two forward acoustic resistance sensors produce; R S2, R S2 'Be respectively the acoustic resistance that fluid produces two reverse acoustic resistance sensors.The electric current that flows through two acoustic resistance sensors in the series circuit is all steady excitation alternating current I S, and I S=I/2.When rate of flow of fluid v=0, R S1=R S2=R S1 '=R S2 ', output quantity u then c=0; When rate of flow of fluid was v (v ≠ 0), four transducer acoustic resistances changed, and its variable quantity is
ΔR S1＝ΔR S1’＝-ΔR S2＝-ΔR S2’＝ΔR S
According to the electric bridge characteristic, then output quantity is:
u c＝4I SΔR S＝4I SΔS RK Z ΔS R＝u c/(4K ZI S)
In the formula, K ZThe conversion coefficient of-acoustic resistance and acoustic resistance.
Δ S R-forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Acoustic resistance is poor;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
D, with voltage signal U CConvert the mass rate q of fluid to m,
Work as u c=2I s* Δ S RK ZBe Δ S R=u c/ (2I sK Z) time,
According to q m=ρ vA=Δ S RA=u cA/ (2I sK Z)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
Work as u c=4I SΔ R S=4I SΔ S RK ZBe Δ S R=u c/ (4 K ZI S) time,
According to q m=ρ vA=Δ S RA=u c/ (4 K ZI S)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
Embodiment two:
A, choose with a pair of performance parameter identical positive and negative acoustic resistance sensor or two pairs of positive and negative sensors that performance parameter is identical, by the acoustic resistance sensor along with the speed forward of rate of flow of fluid v and with velocity reversal's emission sound wave of rate of flow of fluid v;
B, in emission sound wave process, the forward acoustic resistance signal S of fluid to the forward sound wave received in the sense of acoustic resistance sensor R1With reverse acoustic resistance signal S R2, and with forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Be converted to forward acoustic resistance signal and reverse acoustic resistance signal, and obtain the difference DELTA R of forward acoustic resistance signal and reverse acoustic resistance signal S
C, according to Fig. 4 and metering circuit figure shown in Figure 6, with resistance signal Δ R SConvert voltage signal U to by metering circuit (13) C:
When metering circuit (13) was connected in parallel on the half-bridge change-over circuit of forming at the voltage two ends by the series circuit resistance that a forward acoustic resistance sensor (1) and a reverse acoustic resistance sensor (2) are connected also and two other resistance equates, rate of flow of fluid was v, when v=0, and u c=0; When v ≠ 0,
u c=2I s* Δ R SBy Δ R S=Δ S RK Z, as can be known:
u c＝2I s*ΔS RK Z ΔS R＝u c/(2I sK Z)
Wherein, K ZThe acoustic resistance of-acoustic resistance sensor and the conversion coefficient of acoustic resistance;
Δ S RWhen-streaming flow medium is static relatively to the acoustic resistance increment of sound source acoustic emission;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
When metering circuit (13) is made up of two forward acoustic resistance sensors (1) (1 ') and two reverse acoustic resistance sensors (2) (2 '), and four sensor performance parameters are all identical, when sensor (1) (2) series connection and the full-bridge type metering circuit formed with the sensor (1 ') (2 ') that is cascaded, the bridge excitation power supply adopts AC constant-current source I, R S1, R S1 'Be respectively the acoustic resistance that fluid acoustic resistance two forward acoustic resistance sensors produce; R S2, R S2 'Be respectively the acoustic resistance that fluid produces two reverse acoustic resistance sensors.The electric current that flows through two acoustic resistance sensors in the series circuit is all steady excitation alternating current I S, and I S=I/2.When rate of flow of fluid v=0, R S1=R S2=R S1 '=R S2 ', output quantity u then c=0; When rate of flow of fluid was v (v ≠ 0), four transducer acoustic resistances changed, and its variable quantity is
ΔR S1＝ΔR S1’＝-ΔR S2＝-ΔR S2’＝ΔR S
According to the electric bridge characteristic, then output quantity is:
u c＝4I SΔR S＝4I SΔS RK Z ΔS R＝u c/(4K ZI S)
In the formula, K ZThe conversion coefficient of-acoustic resistance and acoustic resistance.
Δ S R-forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Acoustic resistance is poor;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
D, with voltage signal U CConvert the mass rate q of fluid to m,
Work as u c=2I s* Δ S RK ZBe Δ S R=u c/ (2I sK Z) time,
According to q m=ρ vA=Δ S RA=u cA/ (2I sK Z)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
Work as u c=4I SΔ R S=4I SΔ S RK ZBe Δ S R=u c/ (4K ZI S) time,
According to q m=ρ vA=Δ S RA=u c/ (4K ZI S)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
E, according to the method for Fig. 7, intermittent transmission sound wave shown in Figure 8, be t through emission certain hour in fluid 1Sound wave after, through certain hour t 2Interruption.Be that the acoustic resistance sensor is launched sound wave in fluid cycle is T,
T=t 1+ t 2And
t 1≥2L/c
t 2＞t 1
L-measuring section length; The c-velocity of sound;
(f) repeating step (a) and (e).
Two, the present invention is used to measure the embodiment of acoustic resistance flowmeter of the method special use of fluid flow:
According to the flow chart of the method for measurement fluid flow shown in Figure 2 as can be known: acoustic resistance flowmeter comprises oscillator (3), constant-current circuit (8), can along with the forward acoustic resistance sensor (1) of the forward direction transmission sound wave of rate of flow of fluid and can along with the back emitted sound wave of rate of flow of fluid with the forward acoustic resistance sensor performance corresponding to reverse acoustic resistance sensor of parameter (2), by just, the metering circuit (13) that reverse acoustic resistance sensor (1) (2) is formed, prime amplifier (4), phase-sensitive detection circuit (5), wave filter (6), emitter follower (9) and indicator (7), the output terminal of oscillator (3) links to each other with the input end of constant-current circuit (8), just described, negative acoustic resistance sensor (1) (2) is cascaded and forms bridge-type metering circuit (13), the output terminal of constant-current circuit (8) links to each other with the input end of metering circuit (13) with phase-sensitive detection circuit (5) simultaneously, the voltage output end of metering circuit (13) links to each other with the input end of prime amplifier (4), the signal output part of prime amplifier (4) links to each other with the signal input part of phase-sensitive detection circuit (5), the signal output part of phase-sensitive detection circuit (5) links to each other with the signal input part of wave filter (6), and the signal output part of wave filter (6) links to each other with the signal input part of indicator (7).
According to the circuit theory diagrams of inferior acoustic resistance flowmeter shown in Figure 1 as can be known, oscillator (3) is made up of oscillatory circuit, follower, and in the oscillatory circuit, the positive pole of power supply is by pull-up resistor R 3With triode BG 1Collector link to each other divider resistance R 1And R 2Series connection, and R 1And R 2Tie point and triode BG 1Base stage link to each other resistance R 4With capacitor C 1Parallel connection, and with triode BG 1Emitter series connection, the resonant capacitance C2 back of connect with C3 is in parallel with the electric coil L of deluding of resonance, and an end and triode BG 1Collector link to each other triode BG 1Emitter and capacitor C 2And C 3Tie point link to each other; The triode BG of follower 2Collector link to each other base stage and pull-up resistor R with positive source 3With triode BG 1The tie point of collector links to each other, and emitter passes through resistance R 5Ground connection; Field effect transistor T in the described constant-current circuit (8) 1Grid by biasing resistor R 18Link to each other with positive source, drain electrode is by coupling capacitance C 4Be connected in triode BG 2And resistance R 5Contact, source electrode and current sampling resistor R 6Link to each other isolated amplifier IC 1Two input ends be connected to current sampling resistor R 6Two ends, its output terminal is by commutation diode D 1With feedback resistance R 8Link to each other, and with biasing resistor R 18Form a loop; The bridge-type metering circuit that described metering circuit (13) is made up of acoustic resistance sensor (1) (2), it is as the input end and the sampling resistor R of continuous current 6Output terminal link to each other; Amplifier IC in the prime amplifier (4) 2Negative input end and positive input respectively by electricity group R 11, coupling capacitance C 8And resistance R 12Link to each other feedback resistance R with two output terminals of metering circuit (13) 14Be connected in amplifier IC 2Negative input end and output terminal; The field effect transistor T of described phase-sensitive detection circuit (5) 3Grid and sampling resistor R 6Output terminal link to each other drain electrode and amplifier IC 2Output terminal link to each other, source electrode is by pull-up resistor R 15Ground connection; In the wave filter (6), capacitor C 9By filter resistance R 16The source electrode of field effect transistor T3 links to each other; The base stage and the resistance R of emitter follower (9) 16Output terminal link to each other, collector links to each other with the positive pole of power supply, emitter while and pull-up resistor R 17Link to each other with the input end of indicator (7).When adopting sampling pulse generator (9), sampling pulse generator (9) mainly is made up of multivibrator, and multivibrator is by two Sheffer stroke gate G 1, G 2With two adjustable resistance R 9, R 10And two capacitor C 6, C 7Form R 9, R 10, be parallel to Sheffer stroke gate G respectively 1, G 2Output and input end, coupling capacitance C 6, C 7Be connected to the output terminal of a Sheffer stroke gate and the input end of another Sheffer stroke gate, field effect transistor T in the described analog switch (8) 2Drain electrode and sampling resistor R 6Output terminal link to each other grid and Sheffer stroke gate G 2Output terminal link to each other the input end of source electrode and measuring bridge, field effect transistor T 3Grid link to each other.
According to Fig. 3, Fig. 4 as can be known, when adopting a pair of forward and reverse acoustic resistance sensor, RS 1And RS 2Be respectively the acoustic resistance of described forward and reverse acoustic resistance sensor, one of them acoustic resistance and resistance R 1Tie point and resistance R 6Output terminal link to each other the tie point of two acoustic resistances and two resistance R 1, R 2Tie point constitute two output terminals of voltage.
According to Fig. 5, Fig. 6 as can be known, when adopting two pairs of forward and reverse acoustic resistance sensors, RS 1, RS 1 ', RS 2, RS 2 'Be respectively the acoustic resistance of described forward and reverse acoustic resistance sensor (1) (1 ') (2) (2 '), the wherein tie point of a pair of forward and reverse acoustic resistance and resistance R 6Output terminal link to each other, the forward acoustic resistance of this centering and the tie point of the reverse acoustic resistance of another one be two output terminals of the reverse acoustic resistance of centering and another one forward acoustic resistance formation voltage therewith.
In use, will be just, oppositely the acoustic resistance sensor is placed in the pipe of tested pipeline or outside the pipe, oscillatory circuit by oscillator produces electric oscillation signal, electric oscillation signal produces the ac-excited signal of constant current through constant-current circuit, thereby the acoustic resistance sensor produces sound wave in the excitation metering circuit, and provide constant current source required in the metering circuit, acoustic resistance sensor in the metering circuit is experienced the acoustic impedance of fluid to sound wave in the emission sound wave, and the acoustic impedance signal is converted into the acoustic resistance signal, the acoustic resistance signal changes into voltage signal by metering circuit, voltage signal carries out the signal processing and amplifying through prime amplifier, behind the signal process phase-sensitive detection circuit after amplifying, the interchange carrier signal that carries flow information is carried out demodulation, be transformed into the d. c. voltage signal that has flow information, d. c. voltage signal is through wave filter, and filtering residual carrier signal is indicated by indicator.
When measuring tube breaks at caliber under the constant and time-limited situation, can be according to the measurement point of measuring pipeline section and the length level L between the caliber change point, according to relation between t1 and the t2 and T=t1+t2, determine the sound wave emissions period T, thereby determine to adopt the pulse control cycle of pulse producer and analog switch to carry out the intermittently cycle of measurement, at this moment, analog switch according to intermittence measurement period T control the switching that permanent source circuit transmits to metering circuit and phase-sensitive detection circuit, thereby realize intermittently measuring.

Claims (10)

1, be used to measure the method for fluid flow, this method may further comprise the steps:
(a) the acoustic resistance sensor along with the speed forward of rate of flow of fluid v and with velocity reversal's emission sound wave of rate of flow of fluid v;
(b) in emission sound wave process, the forward acoustic resistance signal S of fluid to the forward sound wave received in the sense of acoustic resistance sensor R1With reverse acoustic resistance signal S R2, and with forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Be converted to forward acoustic resistance signal and reverse acoustic resistance signal, and obtain the difference DELTA R of forward acoustic resistance signal and reverse acoustic resistance signal S
(c) with resistance signal Δ R SConvert voltage signal U to by metering circuit (13) C:
When metering circuit (13) is connected in parallel on the half bridge measurement circuit of forming at the voltage two ends (13) by the series circuit resistance that a forward acoustic resistance sensor (1) and a reverse acoustic resistance sensor (2) are connected also and two other resistance equates, the bridge excitation power supply adopts AC constant-current source I, rate of flow of fluid is v, when v=0, u c=0; When v ≠ 0,
u c=2I s* Δ R SBy Δ R S=Δ S RK Z, as can be known:
u c＝2I s*ΔS RK Z ΔS R＝u c/(2I sK Z)
Wherein, K ZThe acoustic resistance of-acoustic resistance sensor and the conversion coefficient of acoustic resistance;
Δ S RWhen-streaming flow medium is static relatively to the acoustic resistance increment of sound source acoustic emission;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
When metering circuit (13) is made up of two forward acoustic resistance sensors (1) (1 ') and two negative sense acoustic resistance sensors (2) (2 '), and four sensor performance parameters are all identical, when sensor (1) (2) series connection and the full-bridge type metering circuit (13) formed with the sensor (1 ') (2 ') that is cascaded, the bridge excitation power supply adopts AC constant-current source I, R S1, R S1 'Be respectively the acoustic resistance that fluid produces two forward acoustic resistance sensors; R S2, R S2 'Be respectively the acoustic resistance that fluid produces two reverse acoustic resistance sensors; The electric current that flows through two acoustic resistance sensors in the series circuit is all steady excitation alternating current I S, and I S=I/2; When rate of flow of fluid v=0, R S1=R S2=R S1 '=R S2 ', output quantity u then c=0 when rate of flow of fluid is v (v ≠ 0), and four transducer acoustic resistances change, and its variable quantity is
ΔR S1＝ΔR S1’＝-ΔR S2＝-ΔR S2’＝ΔR S
According to the electric bridge characteristic, then output quantity is:
u c＝4I S?ΔR S＝4I S?ΔS RK Z ΔS R＝u c/(4K Z?I S)
In the formula, K ZThe conversion coefficient of-acoustic resistance and acoustic resistance;
Δ S R-forward acoustic resistance signal S R1With reverse acoustic resistance signal S R2Acoustic resistance is poor;
I sThe electric current in-forward acoustic resistance sensor and reverse acoustic resistance sensor series connection highway section;
(d) with voltage signal U CConvert the mass rate q of fluid to m,
Work as u c=2I s* Δ S RK ZBe Δ S R=u c/ (2I sK Z) time,
According to q m=ρ vA=Δ S RA=u cA/ (2I sK Z)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending;
Work as u c=4I SΔ R S=4I SΔ S RK ZBe Δ S R=u c/ (4K ZI S) time,
According to q m=ρ vA=Δ S RA=u c/ (4K ZI S)
Wherein, the effective cross section of A-measuring section a fluid stream is long-pending.
2, the method that is used to measure the mass rate of fluid stream therein according to claim 1 is characterized in that: further be made up of following steps after step (d):
(e) be t through emission certain hour in fluid 1Sound wave after, through certain hour t 2Interruption, promptly to launch the cycle of sound wave in fluid be T to the acoustic resistance sensor,
T=-t 1+ t 2And
t 1≥2L/c
t 2＞t 1
L-measuring section length; The c-velocity of sound;
(f) repeating step (a) is to (e).
3, be used to measure the acoustic resistance flowmeter of the method special use of fluid flow, it is characterized in that: described acoustic resistance flowmeter comprises oscillator (3), constant-current circuit (8), can along with the forward acoustic resistance sensor (1) of the forward direction transmission sound wave of rate of flow of fluid and can along with the back emitted sound wave of rate of flow of fluid with the forward acoustic resistance sensor performance corresponding to reverse acoustic resistance sensor of parameter (2), by just, the metering circuit (13) that anti-acoustic resistance sensor (1) (2) is formed, prime amplifier (4), phase-sensitive detection circuit (5), wave filter (6), emitter follower (9) and indicator (7), the output terminal of oscillator (3) links to each other with the input end of constant-current circuit (8), just described, anti-acoustic resistance sensor (1) (2) is cascaded and forms bridge-type metering circuit (13), the output terminal of constant-current circuit (8) links to each other with the input end of metering circuit (13) with phase-sensitive detection circuit (5) simultaneously, the voltage output end of metering circuit (13) links to each other with the input end of prime amplifier (4), the signal output part of prime amplifier (4) links to each other with the signal input part of phase-sensitive detection circuit (5), the signal output part of phase-sensitive detection circuit (5) links to each other with the signal input part of wave filter (6), and the signal output part of wave filter (6) links to each other with the signal input part of indicator (7).
4, the acoustic resistance flowmeter that is used to measure the method special use of fluid flow according to claim 3, it is characterized in that: described positive and negative acoustic resistance sensor (1) (2) respectively is one, and also is provided with the resistance R that two resistances equate in described bridge-type metering circuit 1And R 2, R 1, R 2Be cascaded, and form semibridge system metering circuits (13) with two positive and negative sensors (1) (2) of being in series and be connected the output terminal of constant-current circuit (8).
5, the acoustic resistance flowmeter that is used to measure the method special use of fluid flow according to claim 3, it is characterized in that: described positive and negative acoustic resistance sensor (1) (2) respectively is two identical sensors (1) (1 ') (2) (2 '), forward and reverse acoustic resistance sensor (1) (2) is cascaded, and forms full-bridge type metering circuit (13) with the series circuit that positive and negative sensor (1 ') (2 ') is formed and be connected the output terminal of constant-current circuit (8).
6, the acoustic resistance flowmeter that is used to measure the method special use of fluid flow according to claim 3, it is characterized in that: be serially connected with analog switch (8) between the input end of the output terminal of constant-current circuit (8) and metering circuit (13) and phase-sensitive detection circuit (5), the signal input part of analog switch (8) is connected with a sampling pulse generator (9).
7, according to the acoustic resistance flowmeter that is used to measure the method special use of fluid flow according to claim 3, it is characterized in that: described oscillator (3) is made up of oscillatory circuit, follower, and in the oscillatory circuit, the positive pole of power supply is by pull-up resistor R 3With triode BG 1Collector link to each other divider resistance R 1And R 2Series connection, and R 1And R 2Tie point and triode BG 1Base stage link to each other resistance R 4With capacitor C 1Parallel connection, and with triode BG 1Emitter series connection, the resonant capacitance C2 back of connect with C3 is in parallel with the electric coil L of deluding of resonance, and an end and triode BG 1Collector link to each other triode BG 1Emitter and capacitor C 2And C 3Tie point link to each other; The triode BG of follower 2Collector link to each other base stage and pull-up resistor R with positive source 3With triode BG 1The tie point of collector links to each other, and emitter passes through resistance R 5Ground connection; Field effect transistor T in the described constant-current circuit (8) 1Grid by biasing resistor R 18Link to each other with positive source, drain electrode is by coupling capacitance C 4Be connected in triode BG 2And resistance R 5Contact, source electrode and current sampling resistor R 6Link to each other isolated amplifier IC 1Two input ends are connected to current sampling resistor R 6Two ends, its output terminal is by commutation diode D 1With feedback resistance R 8Link to each other, and with biasing resistor R 18Form a loop; The bridge-type metering circuit that described metering circuit (13) is made up of acoustic resistance sensor (1) (2), it is as the input end and the sampling resistor R of continuous current 6Output terminal link to each other; Amplifier IC in the prime amplifier (4) 2Negative input end and positive input respectively by electricity group R 11, coupling capacitance C 8And resistance R 12Link to each other feedback resistance R with two output terminals of metering circuit (13) 14Be connected in amplifier IC 2Negative input end and output terminal; The field effect transistor T of described phase-sensitive detection circuit (5) 3Grid and sampling resistor R 6Output terminal link to each other drain electrode and amplifier IC 2Output terminal link to each other, source electrode is by pull-up resistor R 15Ground connection; In the wave filter (6), capacitor C 9By filter resistance R 16The source electrode of field effect transistor T3 links to each other; The base stage and the resistance R of emitter follower (9) 16Output terminal link to each other, collector links to each other with the positive pole of power supply, emitter while and pull-up resistor R 17Link to each other with the input end of indicator (7).
8, the acoustic resistance flowmeter that is used to measure the method special use of fluid flow according to claim 6, it is characterized in that: described sampling pulse generator (9) mainly is made up of multivibrator, and multivibrator is by two Sheffer stroke gate G 1, G 2With two adjustable resistance R 9, R 10And two capacitor C 6, C 7Form R 9, R 10, be parallel to Sheffer stroke gate G respectively 1, G 2Output and input end, coupling capacitance C 6, C 7Be connected to the output terminal of a Sheffer stroke gate and the input end of another Sheffer stroke gate, field effect transistor T in the described analog switch (8) 2Drain electrode and sampling resistor R 6Output terminal link to each other grid and Sheffer stroke gate G 2Output terminal link to each other the input end of source electrode and measuring bridge, field effect transistor T 3Grid link to each other.
9, the acoustic resistance flowmeter that is used to measure the method special use of fluid flow according to claim 4 is characterized in that: RS 1And RS 2Be respectively the acoustic resistance of described forward and reverse acoustic resistance sensor, one of them acoustic resistance and resistance R 1Tie point and resistance R 6Output terminal link to each other the tie point of two acoustic resistances and two resistance R 1, R 2Tie point constitute two output terminals of voltage.
10, the acoustic resistance flowmeter that is used to measure the method special use of fluid flow according to claim 5 is characterized in that: RS 1, RS 1 ', RS 2, RS 2 'Be respectively the acoustic resistance of described forward and reverse acoustic resistance sensor (1) (1 ') (2) (2 '), the wherein tie point of a pair of forward and reverse acoustic resistance and resistance R 6Output terminal link to each other, the forward acoustic resistance of this centering and the tie point of the reverse acoustic resistance of another one be two output terminals of the tie point formation voltage of the reverse acoustic resistance of centering and the positive acoustic resistance of another one therewith.
CNB2005100127427A 2005-08-18 2005-08-18 Be used to measure the method and the special-purpose acoustic resistance flowmeter thereof of fluid flow Expired - Fee Related CN100545589C (en)

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