CN102116651A - Ultrasonic measurement method for flow velocity and flow rate of liquid of free flow open channel - Google Patents

Abstract

The invention discloses an ultrasonic measurement method for flow velocity and flow rate of liquid of a free flow open channel, relates to the technical field of measurement, and aims to solve the technical problem of low accuracy of the flow rate of the liquid in ultrasonic measurement. The ultrasonic measurement method is characterized in that: a bidirectional simultaneous measurement method is adopted to eliminate the influence of variation in propagation velocity of ultrasonic wave in different liquids on error of measurement accuracy; and the measurement method comprises the following steps of: 1) simultaneously measuring Ti1 and Ti2 of each acoustic path; 2) calculating linear average flow velocity on each acoustic path; and 3) integrating the flow velocity of each acoustic path on a measurement section to acquire the flow rate of the liquid which passes through the measurement section. The invention has the characteristics that: the measurement accuracy can be improved; and the ultrasonic measurement method is suitable for measurement in the different liquids.

Description

There is not the ultrasonic wave measuring method of pressing open channel liquid flow velocity and flow

Technical field

The present invention relates to measuring technique, particularly relate to the ultrasonic wave measuring method that a kind of nothing that can improve measuring accuracy is pressed open channel liquid flow velocity and fluid flow.

Background technology

The method of measuring fluid flow is a lot, is common a kind of method with ultrasonic measurement.But because the flow of liquid and carrier related, common ultrasonic wave measuring method precision is relatively poor.As, concerning nothings such as rivers and canals were pressed open channel, not only the flowing velocity of water was not identical on each position, cross section, and its height of water level is also in constantly changing.Therefore, simple according to acoustic velocity the variation in liquid measure the flow of liquid, the data of its measurement and actual conditions have bigger error, must be according to the different mining of liquid-carrier characteristics with different improving one's methods.

Summary of the invention

At the defective that exists in the above-mentioned prior art, technical matters to be solved by this invention provides a kind of measuring accuracy that can improve, and the nothing that is suitable for measuring in different liquids is pressed the ultrasonic wave measuring method of open channel liquid flow velocity and flow.

In order to solve the problems of the technologies described above, the ultrasonic wave measuring method of a kind of liquid flow velocity provided by the present invention, it is characterized in that the mode that described measuring method adopts two-way simultaneous to measure is with the variation of eliminating ultrasound wave velocity of propagation in the different liquids influence to measuring accuracy; Select forward and backward 2 points on the both sides of liquid flow direction axis, along liquid flow direction touch earlier for preceding point, after touch for the back point, two ultrasonic emitting receiving traps are installed respectively on forward and backward 2, its forward and backward 2 spacing is L, the liquid flow flow velocity is V, and the angle of forward and backward 2 lines and liquid flow direction is θ, 90 °＞θ＞0 °; T ₂For ultrasound wave is propagated the time of being experienced along liquid flow direction, both ultrasound wave was put the time of back point in the past, was called the forward-propagating time; T ₁For the contrary direction of liquid flow is propagated the time of being experienced, both ultrasound wave from after put preceding point time, be called the reverse travel-time;

The step of measuring method:

1) measures T1, T2 simultaneously;

2) the speed V of calculating liquid flow: its computing formula is: $v=\frac{L}{2\mathrm{COS\θ}}(\frac{1}{T_2}-\frac{1}{T_1}).$

Use the measuring method of liquid flow velocity of the present invention,, adopt at least four pairs of ultrasound wave two-way integration measuring methods, thereby improve the measuring accuracy of pressing the open channel fluid flow not having to there not being the method for pressing the open channel fluid flow to measure; If the up and down measurement plane of at least four ultrasound wave sound travels parallel with liquid flow direction, each measurement plane is as described in the method for measuring liquid flow velocity, select forward and backward 2 points on the both sides of liquid flow direction axis, along liquid flow direction touch earlier for preceding point, after touch for the back point, two ultrasonic emitting receiving traps are installed respectively on forward and backward 2, and its forward and backward 2 spacing is L _i, the liquid flow flow velocity is V _i, C is that ultrasound wave is in sound's velocity in liquid; The angle of 2 lines and liquid flow direction is θ _i90 °＞θ _i＞0 °

For ultrasound wave is propagated the time of being experienced along liquid flow direction, both ultrasound wave was put the time of back point in the past, was called the forward-propagating time;

For the contrary direction of liquid flow is propagated the time of being experienced, both ultrasound wave from after put preceding point time, be called the reverse travel-time; Consider that the accuracy requirement of general open channel flow rate is relatively low and measure cost,, increase a ultrasound wave again and vertically be installed at the bottom of the canal measuring liquid level except adopting four pairs of ultrasound wave two-way integrations measure,

The step of measuring method:

1) measures the T of each sound travel simultaneously _I1, T _I2

2) calculate line mean flow rate on each sound travel:

$\mathrm{vi}=\frac{\mathrm{Li}}{2\mathrm{COS\θi}}(\frac{1}{{\mathrm{Ti}}_2}-\frac{1}{{\mathrm{Ti}}_1})$

3) flow velocity on each sound travel is carried out integration to useful area, can obtain flow by the measurement section,

Flow rate calculation formula: Q=QT+QM+QB

Wherein: Q=canal cross section total flow;

QT=channel top layer flow;

Each laminar flow amount in the middle of the QM=channel;

QB=lowest tier of channels flow;

Described QT, QM and QB are tried to achieve by following various calculating respectively again:

$\mathrm{QT}=\frac{1}{4}(1+k_T)V_4\·(H-h_4)\·(W_4+W_T)\·\·\·\left(3\right)$

$\mathrm{QM}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{1}{4}(V_i+V_{i+1})\·(W_i+W_{i+1})\·(h_{i+1}-h_i)\·\·\·..\left(4\right)$

$\mathrm{QB}=\frac{1}{4}(1+k_b)V_1\·(h_1-h_b)(W_1+W_b)\·\·\·\left(5\right)$

Wherein: V ₄=step 2) calculates the flow velocity (four tones of standard Chinese pronunciation Lu Eryan) of the superiors' work sound travel of gained in;

V _i=step 2) flow velocity that the i sound travel of calculating gained records in;

V ₁=step 2) flow velocity that the orlop work sound travel of calculating gained records in;

The current water level of H=;

k _t=channel surface current speed coefficient;

k _b=canal underflow speed coefficient;

h ₄=the superiors work sound travel elevation (four tones of standard Chinese pronunciation Lu Eryan);

h _i=the i sound travel elevation;

h ₁=orlop work sound travel elevation;

h ₀Elevation at the bottom of the=canal

W ₄The width of the channel (four tones of standard Chinese pronunciation Lu Eryan) at=the superiors work sound travel place;

W _TThe width of=ditch water flow surface layer;

W ₁The width of the channel at=orlop work sound travel place;

W _b=canal bottom width degree.

Utilize nothing provided by the invention to press the ultrasonic wave measuring method of open channel liquid flow velocity and fluid flow, because the mode that adopts two-way simultaneous to carry out ultrasonic measurement, with the variation of eliminating ultrasound wave velocity of propagation in different liquids the error that influences, improve and do not have the flow measurement precision of pressing open channel measuring accuracy.

Description of drawings

Fig. 1 is the synoptic diagram of the ultrasonic wave measuring method of embodiment of the invention liquid flow velocity;

Fig. 2 does not have the synoptic diagram of the measuring method of pressing the open channel fluid flow for the embodiment of the invention;

Wherein,

Fig. 2 a is the diagrammatic cross-section vertical with liquid flow direction;

Fig. 2 b is the velocity flow profile synoptic diagram on the section vertical with liquid flow direction.

Embodiment

Below in conjunction with description of drawings embodiments of the invention are described in further detail, but present embodiment is not limited to the present invention, every employing similarity method of the present invention and similar variation thereof all should be listed protection scope of the present invention in.

A kind of method that improves ultrasonic measurement fluid flow precision that the embodiment of the invention provided is characterized in adopting the two-way simultaneous mensuration to eliminate the influence of the variation of ultrasound wave velocity of propagation in different liquids to measuring accuracy.

The ultimate principle of ultrasonic measurement is that liquid flow causes ultrasound wave to change in the time of specifying distance to propagate, and goes out the speed of liquid flow according to the change calculations of time.Because the speed difference propagated in different liquid of ultrasound wave is different as the speed in water and in the oil, different its velocity of propagation of the proportion of oil are also different, so brought than mistake to measurement.

As shown in Figure 1: select forward and backward P2, P1 at 2 on the both sides of liquid flow direction axis, along liquid flow direction touch earlier for preceding some P2, after touch be back point P1, on forward and backward P2, P1, two ultrasonic emitting receiving traps are installed at 2 respectively, the spacing of its forward and backward 2 P1, P2 is L, the liquid flow flow velocity is V, and C is that ultrasound wave is in sound's velocity in liquid; The angle of 2 lines of P1, P2 and liquid flow direction is θ, 90 °＞θ＞0 °; T ₂For ultrasound wave is propagated the time of being experienced along liquid flow direction, both ultrasound wave was put the time of P2 to back point P1 in the past, was called the forward-propagating time.T ₁For the contrary direction of liquid flow is propagated the time of being experienced, both the time of ultrasound wave, be called the reverse travel-time from back point P1 to preceding some P2.Just, reverse travel-time can be expressed as:

$T_2=\frac{L}{C+\mathrm{VCOS\θ}}$ $T_1=\frac{L}{C-\mathrm{VCOS\θ}}$

Wherein: the V=fluid velocity

The L=sound travel is long

The angle of the θ=sound wave path and the flow direction

The C=velocity of sound

Measure T1, T2 simultaneously, then can obtain the speed of liquid flow by above-mentioned two formulas:

$v=\frac{L}{2\mathrm{COS\θ}}(\frac{1}{T_2}-\frac{1}{T_1})\·\·\·.\left(1\right)$

Above-mentioned formula has shown the liquid flow velocity of measurement and the velocity of propagation of ultrasound wave in liquid, and it doesn't matter.So just eliminated of the influence of the velocity of propagation of ultrasound wave in liquid to measuring accuracy.

Use the method for above-mentioned measurement liquid flow velocity, one embodiment of the invention are the measuring methods of pressing the fluid flow in the open channel to not having, and adopt four pairs of ultrasound wave two-way integration measuring methods, thereby improve the measuring accuracy of pressing the fluid flow in the open channel to not having.

As shown in Figure 2, for do not have pressing open channel, to distribute be uneven to the fluidised form at different elevations place in the water, and liquid level also has certain variation, and especially the variation of liquid level has a strong impact on measuring accuracy.If the up and down measurement plane of four ultrasound wave sound travels parallel with liquid flow direction, each measurement plane is as described in the method for measuring liquid flow velocity, select forward and backward 2 points on the both sides of liquid flow direction axis, along liquid flow direction touch earlier for preceding point, after touch for the back point, two ultrasonic emitting receiving traps are installed respectively on forward and backward 2, and its forward and backward 2 spacing is L _i, the liquid flow flow velocity is V _i, C is that ultrasound wave is in sound's velocity in liquid; The angle of 2 lines and liquid flow direction is θ _i

For ultrasound wave is propagated the time of being experienced along liquid flow direction, both ultrasound wave was put the time of back point in the past, was called the forward-propagating time. For the contrary direction of liquid flow is propagated the time of being experienced, both ultrasound wave from after put preceding point time, be called the reverse travel-time.Consider that the accuracy requirement of general open channel flow rate is relatively low and measure cost,, increase a ultrasound wave again and vertically be installed at the bottom of the canal measuring liquid level except adopting four pairs of ultrasound wave two-way integrations measure,

Measure the T of each sound travel at first simultaneously _I1, T _I2Calculate the line mean flow rate on each sound travel then:

$\mathrm{vi}=\frac{\mathrm{Li}}{2\mathrm{COS\θi}}(\frac{1}{{\mathrm{Ti}}_2}-\frac{1}{{\mathrm{Ti}}_1})\·\·\·.(1*)$

With the flow velocity that records useful area is carried out integration then, can obtain the flow (if accuracy requirement then adopt eight pairs of sound travels to measure) by measuring section.

Flow rate calculation formula: Q=QT+QM+QB ... (2)

Wherein: Q=canal cross section total flow;

QT=channel top layer flow;

Each laminar flow amount in the middle of the QM=channel;

QB=lowest tier of channels flow;

As shown in Figure 2, QT, QM and QB are tried to achieve by following various calculating respectively again:

$\mathrm{QT}=\frac{1}{4}(1+k_T)V_4\·(H-h_4)\·(W_4+W_T)\·\·\·\left(3\right)$

$\mathrm{QM}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{1}{4}(V_i+V_{i+1})\·(W_i+W_{i+1})\·(h_{i+1}-h_i)\·\·\·..\left(4\right)$

$\mathrm{QB}=\frac{1}{4}(1+k_b)V_1\·(h_1-h_b)(W_1+W_b)\·\·\·\left(5\right)$

Wherein: V ₄The flow velocity (four tones of standard Chinese pronunciation Lu Eryan) that=the superiors work sound travel records;

V _iThe flow velocity that=the i sound travel records;

V ₁The flow velocity that=orlop work sound travel records;

The current water level of H=;

k _t=channel surface current speed coefficient;

k _b=canal underflow speed coefficient;

h ₄=the superiors work sound travel elevation (four tones of standard Chinese pronunciation Lu Eryan);

h _i=the i sound travel elevation;

h ₁=orlop work sound travel elevation;

h ₀Elevation at the bottom of the=canal

W ₄The width of the channel (four tones of standard Chinese pronunciation Lu Eryan) at=the superiors work sound travel place;

W _TThe width of=ditch water flow surface layer;

W ₁The width of the channel at=orlop work sound travel place;

W _b=canal bottom width degree.

V in above-mentioned formula (3), (4), (5) _iBe exactly the V of formula (1), at diverse location many a plurality of V that sensor measurement is gone out arranged exactly _i, available formula (1*) calculates V _i

In Fig. 2, Ch represents to survey the ultrasonic emitting receiving trap of liquid level, and Cv represents the ultrasonic emitting receiving trap of velocity measurement, and Si represents the i sound travel, and H represents liquid level.

Claims (2)

1. the ultrasonic wave measuring method of a liquid flow velocity, select forward and backward 2 points on the both sides of liquid flow direction axis, two ultrasonic emitting receiving traps are installed respectively on forward and backward 2, its forward and backward 2 spacing is L, the liquid flow flow velocity is V, the angle of forward and backward 2 lines and liquid flow direction is θ, 90 °＞θ＞0 °; T ₂Propagate the time of being experienced for ultrasound wave along liquid flow direction, be called the forward-propagating time; T ₁Propagate the time of being experienced for the contrary direction of liquid flow, be called the reverse travel-time;

It is characterized in that the step of measuring method:

1) measures T1, T2 simultaneously;

2) the speed V of calculating liquid flow: its computing formula is: $v=\frac{L}{2\mathrm{COS\θ}}(\frac{1}{T_2}-\frac{1}{T_1}).$

One kind according to the measuring method of the described liquid flow velocity of claim 1 to there not being the method for pressing the open channel fluid flow to measure, if the up and down measurement plane of at least four ultrasound wave sound travels parallel with liquid flow direction, each measurement plane is measured the method for liquid flow velocity according to claim 1, select forward and backward 2 points on the both sides of liquid flow direction axis, two ultrasonic emitting receiving traps are installed respectively on forward and backward 2, and its forward and backward 2 spacing is L _i, the liquid flow flow velocity is V _i, the angle of 2 lines and liquid flow direction is θ _i90 °＞θ _i＞0 °

Propagate the time of being experienced for ultrasound wave along liquid flow direction, be called the forward-propagating time;

Propagate the time of being experienced for the contrary direction of liquid flow, be called the reverse travel-time; Setting up a ultrasonic emitting receiving trap vertically is installed at the bottom of the canal to measure liquid level;

It is characterized in that the step of measuring method:

1) measures Ti1, the Ti2 of each sound travel simultaneously;

2) calculate line mean flow rate on each sound travel:

$\mathrm{vi}=\frac{\mathrm{Li}}{2\mathrm{COS\θi}}(\frac{1}{{\mathrm{Ti}}_2}-\frac{1}{{\mathrm{Ti}}_1})$

3) flow velocity on each sound travel is carried out integration to useful area, can obtain by measuring the flow of section, flow rate calculation formula: Q=QT+QM+QB

Wherein: Q=canal cross section total flow;

QT=channel top layer flow;

Each laminar flow amount in the middle of the QM=channel;

QB=lowest tier of channels flow;

Described QT, QM and QB are tried to achieve by following various calculating respectively again:

$\mathrm{QT}=\frac{1}{4}(1+k_T)V_4\·(H-h_4)\·(W_4+W_T)$

$\mathrm{QM}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{1}{4}(V_i+V_{i+1})\·(W_i+W_{i+1})\·(h_{i+1}-h_i)$

$\mathrm{QB}=\frac{1}{4}(1+k_b)V_1\·(h_1-h_b)(W_1+W_b)$

Wherein: V ₄=step 2) calculates the flow velocity of the superiors' work sound travel of gained in;

V _i=step 2) flow velocity that the i sound travel of calculating gained records in;

V ₁=step 2) flow velocity that the orlop work sound travel of calculating gained records in;

The current water level of H=;

k _t=channel surface current speed coefficient;

k _b=canal underflow speed coefficient;

h ₄=the superiors work sound travel elevation;

h _i=the i sound travel elevation;

h ₁=orlop work sound travel elevation;

h ₀Elevation at the bottom of the=canal

W ₄The width of the channel at=the superiors work sound travel place;

W _TThe width of=ditch water flow surface layer;

W ₁The width of the channel at=orlop work sound travel place;

W _b=canal bottom width degree.

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