CN102116777A - Ultrasonic wave measuring method for liquid flowing speed and flow of pressure pipeline - Google Patents

Abstract

The invention discloses an ultrasonic wave measuring method for the liquid flowing speed and the flow of a pressure pipeline, relating to the technical field of measurement, and solving the technical problem of low precision for measuring liquid flow by ultrasonic wave. The ultrasonic wave measuring method is characterized in that error influence on measurement precision because the transmission rate of ultrasonic wave in different liquids changes is eliminated with a bidirectional simultaneous measurement method. The measuring method comprises the following steps of: (1) simultaneously measuring the Ti1 and the Ti2 of each sound path; (2) calculating the line mean velocity of each sound path; and (3) carrying out integration to a measured cross section by the flow rate on each sound path to obtain the flow of the measured cross section. The measurement precision can be improved with the measuring method, and the measuring method is suitable for measuring different liquids.

Description

The ultrasonic wave measuring method of pressure conduit liquid flow velocity and flow

Technical field

The present invention relates to measuring technique, particularly relate to and a kind ofly can improve the pressure conduit liquid flow velocity of measuring accuracy and the ultrasonic wave measuring method of 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 pressure conduit, the flowing velocity of liquid is not identical on each position, its cross section.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, the pressure conduit liquid flow velocity that is suitable for measuring and the ultrasonic wave measuring method of fluid flow in different liquids.

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 eight pairs of ultrasound wave two-way integration measuring methods, thereby improve measuring accuracy the pressure conduit fluid flow to the method that the pressure conduit fluid flow is measured; If the up and down measurement plane of at least eight 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, 90 °＞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; 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 measuring section, can obtain flow by the measurement section,, the flow integral formula is:

$Q=\frac{D^2}{2}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{W}_i{V}_i$

Wherein: the D=pipe diameter;

N=measures the sound travel number on the section;

W _iThe weighting coefficient of=the i sound travel;

V _i=step 2) the line mean flow rate on the i sound travel of calculating gained.

Utilize the ultrasonic wave measuring method of pressure conduit liquid flow velocity provided by the invention 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 the different liquids error that influences to measuring accuracy, improving has the flow measurement precision of pressing pipe.

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 is the synoptic diagram of the measuring method of embodiment of the invention pressure conduit fluid flow;

Wherein,

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

Fig. 2 b is a stereographic map;

Fig. 3 is the synoptic diagram of explanation flow integral principle in the measuring method of embodiment of the invention pressure conduit fluid flow;

Wherein,

Fig. 3 a is the diagrammatic cross-section vertical with liquid flow direction;

Fig. 3 b is flow integral principle figure.

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; 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 to the pressure conduit fluid flow, adopt eight pairs of ultrasound wave two-way integration measuring methods, thereby improve the measuring accuracy to the pressure conduit fluid flow.

As shown in Figure 2, for the bigger pipe of diameter, fluidised form is complicated and changeable; The liquid of the pressure conduit accuracy requirement height that generally charges adopts both arrangements of eight sound travels of eight pairs of ultrasound wave bidirectional measurements in order to improve measuring accuracy.If the up and down measurement plane of eight 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.Measure the T of each sound travel at first simultaneously _I1, T _I2Calculate the line mean flow rate on each sound travel then:

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

Again the flow velocity on each sound travel is carried out integration to measuring section, can obtain flow by the measurement section,, the flow integral formula is:

$Q=\frac{D^2}{2}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{W}_i{V}_i\·\·\·\left(2\right)$

Wherein: the D=pipe diameter;

N=measures the sound travel number on the section;

W _iThe weighting coefficient of=the i sound travel;

V _iLine mean flow rate on=the i sound travel;

V in the above-mentioned formula (2) _iBe exactly the V of formula (1*) _i, at diverse location many a plurality of V that sensor measurement is gone out are arranged exactly _i, available formula (1) calculates V _i

(succinct for picture, eight pairs of ultrasound waves of horizontal direction have only been drawn four pairs among the figure) as shown in Figure 3, the principle of flow integration:

Flow=sectional area * mean flow rate.

The sectional area of pipe=π r ²=π (d/2) ²π is that circular constant, r are radius of circle, d circular diameter

Mean flow rate=(K1V1+K2V2+ ... + KnVn)/n.Wherein k is the weighting coefficient of diverse location.

Flow=π (d/2) ²* (K1V1+K2V2+ ... + KnVn)/n. is for convenience of calculation, (pi/2 n) calculated with weighting coefficient k just obtain new weighting coefficient W, so all obtains flow integral formula (2) above.

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:

2. method of the pressure conduit fluid flow being measured according to the measuring method of the described liquid flow velocity of claim 1, if the up and down measurement plane of at least eight 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 _i

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;

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:

3) flow velocity on each sound travel is carried out integration to measuring section, can obtain by measuring the flow of section, the flow integral formula is:

Wherein: the D=pipe diameter;

N=measures the sound travel number on the section;

W _iThe weighting coefficient of=the i sound travel;

V _i=step 2) the line mean flow rate on the i sound travel of calculating gained.

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