KR100935876B1 - Method of measuring flow velocity by ultrasonic waves and method of measuring flux by ultrasonic waves - Google Patents

Abstract

The present invention relates to an ultrasonic flow rate measuring method and an ultrasonic flow rate measuring method. The ultrasonic flow rate measuring method according to the present invention includes a preparation step of preparing a plurality of ultrasonic flow rate measuring lines in an duct, and mutually transmitting and receiving ultrasonic waves between a pair of ultrasonic vibrators of each ultrasonic flow rate measuring line, and the ultrasonic wave is a pair of ultrasonic waves. An ultrasonic flow rate measuring method comprising a main flow rate measuring step of measuring a flow rate of a fluid passing through a straight line connecting a pair of ultrasonic vibrators using a difference in time required to propagate between the vibrators, the plurality of ultrasonic flow rates When the ultrasonic wave is reflected from the inner wall of the duct and received by the downstream ultrasonic vibrator from the time when the ultrasonic wave is transmitted from the upstream ultrasonic vibrator of the pair of ultrasonic vibrators of the outermost ultrasonic flow rate measurement line disposed at the outermost portion of the measuring line. When the ultrasonic wave is sent from the first ultrasonic time and the downstream ultrasonic vibrator From this point of view, the difference in the second time required until the ultrasonic wave is reflected from the inner wall of the canal and received by the upstream ultrasonic vibrator is measured, and is surrounded by the outermost ultrasonic flow velocity measurement line and the inner wall of the canned tube. And an end flow rate measuring step of measuring the flow rate of the fluid passing through the region.

Ultrasonic, Flow Rate, Flow Rate, Flow Rate Measurement Line

Description

Method of measuring flow velocity by ultrasonic waves and method of measuring flux by ultrasonic waves

The present invention relates to an ultrasonic flow rate measuring method and an ultrasonic flow rate measuring method, and more particularly, using a plurality of ultrasonic flow rate measuring lines to measure the flow rate of the fluid flowing in the tube and through this flow rate of the fluid passing through the tube It relates to an ultrasonic flow rate measuring method and an ultrasonic flow rate measuring method for measuring.

Supply of city gas, transfer of crude oil through oil pipelines, installation of waterways for agriculture water and steel, including the provision of water supply and sewage to supply water to homes and industrial sites or to discharge the sewage generated therefrom. There are many industries that use fluids such as gas and liquids such as circulation of cooling water in chemistry and petrochemical fields. In these industries, it is very important to properly control and manage the flow rate and flow rate of fluids.

In industrial fields where fluid flow control is important, the flow rate of the fluid passing through the oil pipe is generally measured using a flow meter. The fluid flow rate can be obtained by multiplying the average velocity V of the fluid passing through the oil pipe by the oil pipe cross-sectional area. have.

In other words, the flow rate = the cross-sectional area of the oil pipe x the average flow velocity V of the fluid. Therefore, in order to accurately measure the flow rate of the fluid, the flow rate of the fluid must be accurately measured. Today, the propagation time difference method using an ultrasonic vibrator is widely used as a method for measuring the flow velocity of a fluid.

1 is a schematic cross-sectional view illustrating a method of measuring a flow rate by a propagation time difference method, FIG. 2 is a view illustrating a flow rate distribution of a fluid flowing in a flow pipe, and FIG. 3 is an ultrasonic flow rate measurement line at a central portion and an edge portion thereof. It is a duct sectional drawing in the installed state.

1 to 3, the propagation time difference method proceeds as follows. First, a pair of ultrasonic vibrators P ₁ and P ₂ are positioned downstream from the A point of the duct and the A point in the flow direction of the fluid at a predetermined angle θ with respect to the advancing direction a of the fluid. Place it at point B to face each other and then introduce fluid into the milk pipe. Of the point B from the point which transmits a ultrasonic wave from the ultrasonic transducer (P ₁₎ is installed in the point A ultrasonic transducer (P ₂₎ is installed at the time T B point to the _AB and station it takes time to receive the ultrasonic wave at point A The time T _BA taken from the time when the ultrasonic wave is transmitted from the ultrasonic vibrator P ₂ until the ultrasonic vibrator P ₁ at the point A receives the ultrasonic wave transmitted from the point B is measured. Since ultrasonic waves are influenced by the flow velocity of fluid when they are transmitted through the fluid, the measured T _AB and T _BA are different from each other, and the difference determines the flow velocity of the fluid passing through the straight line connecting the A and B points. .

On the other hand, when the fluid flows in the milk pipe is affected by friction with the inner wall of the milk pipe, as shown in Figure 2, the flow rate of the fluid from the center of the milk pipe toward the edge of the milk pipe falls. Therefore, in order to find the average flow velocity of the whole fluid passing through the duct, the flow velocity should be measured at various points of the duct. In particular, since the edge portion of the milk pipe is directly affected by the friction generated between the fluid and the inner wall of the milk pipe, as shown in FIG. Therefore, there is a need to measure the flow velocity at a more dense interval at the edge of the milk pipe compared to the center of the milk pipe.

However, it is not easy to install a plurality of flow rate measuring lines at close intervals at the edge of the conduit due to spatial constraints. As shown in FIG. 3, when the ultrasonic flow rate measuring line is installed at the center of the milk pipe, the length l ₁ of the insertion hole into which the ultrasonic vibrator is inserted is almost the same as the wall thickness of the milk pipe, In case of installing the ultrasonic flow rate measurement line, the length of the insertion hole (l ₂ ) becomes much longer than the wall thickness of the tube. Therefore, the construction difficulty occurs. Therefore, the ultrasonic flow rate measurement line is densely arranged at the edge of the tube. There is a limit to the installation. In addition, in the installation of the ultrasonic flow rate measurement line, the ultrasonic flow rate measurement that can be provided in the duct due to the fact that the two ultrasonic vibrators are disposed to face each other and the cost increases when installing a plurality of ultrasonic vibrators, etc. There was a limit to the number of lines. Therefore, there was a limitation in accurately measuring the flow velocity of the fluid flowing through the edge of the conduit, and as a result, there was a problem in that the accuracy in measuring the flow rate of the fluid obtained by the product of the average flow velocity of the conduit and the cross section of the conduit.

The present invention has been made to solve the above problems, an object of the present invention is to measure the flow rate of the fluid passing through the edge region of the duct without additional ultrasonic flow rate measuring line in the duct, based on this It is to provide an ultrasonic flow rate measuring method that can accurately measure the average flow rate of the fluid flowing in the tube. It is also an object of the present invention to provide an ultrasonic flow rate measuring method capable of accurately measuring the flow rate of the fluid flowing in the duct.

In order to achieve the above object, the ultrasonic flow rate measuring method according to the present invention is an ultrasonic flow rate measurement consisting of a pair of ultrasonic vibrators respectively installed on the upstream side and the downstream side of the flow tube in the flow direction of the fluid flowing along the flow pipe. A preparation step of providing a plurality of lines spaced apart from each other, and the time required for transmitting and receiving ultrasonic waves between a pair of ultrasonic vibrators of each ultrasonic flow rate measurement line and propagating the ultrasonic waves between the pair of ultrasonic vibrators In the ultrasonic flow rate measuring method comprising the main flow rate measuring step of measuring the flow rate of the fluid passing through a straight line connecting the pair of ultrasonic vibrator using the difference of, the ultrasonic flow rate of the plurality of ultrasonic flow rate measurement line The outermost ultrasonic wave disposed at one end along the arrangement direction of the measuring line A first time required from the time when the ultrasonic wave is transmitted from the upstream ultrasonic vibrator of the pair of ultrasonic vibrators until the ultrasonic wave is reflected from the inner wall of the duct and received by the downstream ultrasonic vibrator; The outermost ultrasonic flow rate measurement line is measured by measuring a difference in the second time required from the time when the ultrasonic wave is transmitted from the side ultrasonic vibrator until the ultrasonic wave is reflected from the inner wall of the canal and received by the upstream ultrasonic wave vibrator. And an end flow rate measuring step of measuring a flow rate of the fluid passing through an area surrounded by the inner wall of the oil pipe reflected by the ultrasonic waves.

In addition, the ultrasonic flow rate measuring method according to the present invention to achieve the above object in the ultrasonic flow rate measuring method for calculating the flow rate of the fluid flowing in the oil pipe based on the flow rate of the fluid flowing in the milk pipe and the cross-sectional area of the milk pipe. The flow rate is characterized in that the flow rate obtained by the above-described ultrasonic flow rate measurement method.

According to the ultrasonic flow velocity measuring method of the present invention, not only the flow velocity at the point where the ultrasonic flow velocity measurement line is installed, but also the flow velocity in the edge region of the flow pipe can be measured. In particular, the edge region of the duct is so variable that it is necessary to be measured in order to calculate an accurate average flow rate in the duct, but it is difficult to measure the flow rate by a conventional method because it is not easy to install an ultrasonic flow rate measurement line. . However, according to the present invention, it is possible to additionally measure the flow velocity of the duct region, and as a result, it is possible to measure the average flow velocity of the fluid more accurately than in the prior art.

In addition, according to the ultrasonic flow rate measuring method of the present invention, since the flow rate of the fluid is measured using the average flow velocity of the fluid more accurately than the conventional, it is possible to measure the flow rate of the fluid more accurately than the conventional.

Hereinafter, an ultrasonic flow rate measuring method and an ultrasonic flow rate measuring method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

4 is a step-by-step flowchart for explaining the ultrasonic flow rate measuring method and the ultrasonic flow rate measuring method according to an embodiment of the present invention, Figure 5 is a schematic perspective view for explaining the preparation step shown in Figure 4, Figure 6 4 is a schematic projection view of the projection line I of FIG. 5 viewed in the fluid direction to explain the preparation step and the main flow velocity measurement step shown in FIG. 4.

4 to 6, the ultrasonic flow rate measuring method M100 according to the present embodiment includes a preparation step M101, a main flow rate measuring step M102, an end flow rate measuring step M103, and an end flow rate setting. A step M104 and an average flow rate calculation step M105 are included.

In the preparation step (M101), a plurality of ultrasonic flow rate measuring lines consisting of two ultrasonic vibrators are installed in the oil pipe 11 having a radius R and made of steel. First, a first ultrasonic flow rate measuring line including two ultrasonic vibrators 1A and 1B is disposed on the center line of the projection surface as shown in FIG. 5, but one ultrasonic vibrator 1A is located upstream of the fluid direction. It installs in the side and the other ultrasonic vibrator 1B is installed in the downstream side. Accordingly, the two ultrasonic vibrators 1A and 1B are disposed to face each other, and as shown in FIG. 5, the straight line connecting the two ultrasonic vibrators 1A and 1B and the moving direction a of the fluid have a predetermined angle ( θ). Thereafter, the second ultrasonic flow rate measuring line and the third ultrasonic flow rate measuring line are respectively located at a position perpendicular to the first ultrasonic flow rate measuring line, that is, R / 3 and 2R / 3 to the right along the diameter direction of the milk pipe. It is installed in parallel with the first ultrasonic flow rate measurement line. In the same manner, the fourth ultrasonic flow rate measuring line and the fifth ultrasonic flow rate measuring line are respectively installed at points spaced apart by R / 3 and 2R / 3 to the left along the direction perpendicular to the first ultrasonic flow rate measuring line, respectively. Subsequently, when each ultrasonic vibrator included in the first to fifth ultrasonic flow velocity measuring lines is connected to a controller (not shown) to receive and transmit ultrasonic waves, the preparation step M101 is completed. On the other hand, the preparation step (M101) in the present embodiment can be carried out by installing the ultrasonic flow rate measurement line directly on the oil pipe 11 as described above, but the duct is provided with a plurality of ultrasonic flow rate measurement lines in the above configuration. Also by providing a can be replaced by the preparation step (M101) in the present embodiment. In addition, through the so-called 'construction of water', it is possible to replace the preparation step (M101) by installing the ultrasonic flow rate measurement line without blocking the flow of the fluid in the existing pipe.

In the main flow rate measuring step (M102), the fluid flows into the inside of the oil pipe 11 prepared through the preparation step (M101), and then, using a so-called propagation time difference method, a pair of ultrasonic waves included in each ultrasonic flow rate measuring line is connected. Measure the flow velocity of the fluid passing through the straight lines K1 to K5. It will be described in detail below.

First, the ultrasonic wave is transmitted from the upstream ultrasonic vibrator 1A of the first ultrasonic flow rate measurement line, and the ultrasonic wave vibrator 1A from the downstream ultrasonic vibrator 1B receives the ultrasonic wave transmitted from the upstream ultrasonic vibrator 1A. ), The time T ₁₂ taken from the time point at which the ultrasonic wave is transmitted until the downstream side ultrasonic vibrator 1B receives the ultrasonic wave transmitted from the upstream side ultrasonic vibrator 1A is measured. On the contrary, the ultrasonic wave is transmitted from the downstream ultrasonic vibrator 1B, and the ultrasonic wave vibrator 1B is received from the upstream ultrasonic vibrator 1A, and the ultrasonic wave is transmitted from the downstream ultrasonic vibrator 1B. The time T ₂₁ taken until the upstream ultrasonic vibrator 1A receives the ultrasonic wave transmitted from the downstream ultrasonic vibrator 1B is measured. At this time, the sound velocity propagated by the ultrasonic wave from the ultrasonic vibrator under the condition that the fluid does not move is called C, and the flow rate of the fluid passing on the straight line K1 connecting the two ultrasonic vibrators 1A and 1B. If V ₁ , and the distance between two ultrasonic vibrators 1A and 1B is L, T ₁₂ and T ₂₁ are as follows.

,

,

In other words, the time T _{12 when} the ultrasonic wave is emitted in the forward direction with respect to the advancing direction of the fluid is shorter than the time T ₂₁ when the ultrasonic wave is emitted in the reverse direction with respect to the advancing direction of the fluid. If we find the time difference ΔT,

항은 무시할 수 있을 정도로 작은 양이다. 따라서, V₁은

으로 구하여지며, 이 식에 T₂₁ - T₁₂ 즉 ΔT를 대입하면 두 초음파 진동자(1A, 1B)를 연결한 직선(K1) 상을 통과하는 유체의 유속 V₁을 구할 수 있다. 마찬가지로, 나머지 초음파 유속측정회선들을 사용하여 상술한 과정을 반복함으로써 직선(K2~K5) 상을 통과하는 유체의 유속 V₂ ~ V₅ 를 측정한다.here

The term is negligibly small. Therefore, V ₁ is

Is given by this formula T ₂₁ -Substituting T ₁₂ or ΔT, the flow velocity V ₁ of the fluid passing on the straight line K1 connecting the two ultrasonic vibrators 1A and 1B can be obtained. Similarly, the flow rates V ₂ to V ₅ of the fluid passing through the straight lines K2 to K5 are measured by repeating the above process using the remaining ultrasonic flow rate measuring lines.

In the end velocity measurement step (M103), the outermost ultrasonic velocity measurement line, i.e., the third and fifth ultrasonic velocity measurement lines, disposed at both ends of the five ultrasonic velocity measurement lines in the arrangement direction of the ultrasonic velocity measurement line, that is, in the horizontal direction. Use the flow rate measurement line to measure the flow rate of the fluid through the edge of the duct. Hereinafter, the total reflection phenomenon used in the end velocity measurement step will be described with reference to the accompanying drawings, and then the process of the end velocity measurement step will be described in detail.

FIG. 7 is a conceptual diagram illustrating Snell's law, and FIG. 8 is a schematic projection view of the projection line I of FIG. 5 in the fluid direction to explain the end velocity measurement step and the end velocity setting step shown in FIG. 4. to be.

Snell's law, which represents the relationship between the angle of incidence and the angle of refraction when light rays or radio waves enter and pass through the interface of different media, is expressed by the following equation.

C ₁ / C ₂ = sinθ ₁ / sinθ ₂ = n ₂ / n ₁

In this case, C ₁ and C ₂ are the speeds of propagation propagating in the medium 1 and the medium 2, θ ₁ and θ ₂ is the angle of incidence and the angle of refraction, n ₁ and n ₂ Is the refractive index of medium 1 and medium 2.

According to Snell's law, the refractive index of the medium and the propagation speed of the propagation in the medium are proportional to each other, and as shown in FIG. 7, the radio wave is incident from the medium having a small refractive index n ₁ to the medium having a large refractive index n ₂ . In this case, the reflection angle θ ₂ is larger than the incident angle θ ₁ . In addition, as the incident angle θ ₁ of the radio wave increases, the reflection angle θ ₂ also becomes larger and larger, and the incident angle at the instant when the reflection angle becomes 90 ° is referred to as the critical angle θ _c . When the incident angle θ ₁ is greater than or equal to the critical angle θ _c , total reflection occurs at the interface of the medium, and as shown by the dashed-dotted line in FIG. 7, the radio waves are reflected at the same angle as the incident angle at the interface of the medium. When the critical angle (θ _c ) in which total reflection occurs is represented by the propagation speed of the propagation in the medium, θ _c = arcsin (C ₁ / C ₂ ). For example, the transmission speed of ultrasonic waves in the steel tube material of the present embodiment is about 5900m / s, and the ultrasonic transmission speed of the fluid flowing in the milk pipe, in particular water is about 1480m / s. Therefore, when ultrasonic waves are transmitted from the water to the steel direction, the critical angle θ _c becomes arcsin (1480/5900) ≒ 14.53 °.

On the other hand, the ultrasonic wave transmitted from the ultrasonic vibrator is not only propagated in the linear direction but is spread at a predetermined angle (direction angle) and propagates in the fluid. Therefore, as illustrated in FIG. 8, the ultrasonic waves transmitted from the upstream ultrasonic vibrator 3A of the third ultrasonic flow rate measurement line also propagate toward the inner wall of the milk pipe, and the upstream ultrasonic vibrator 3A and the downstream ultrasonic vibrator ( The ultrasonic wave incident to the center point of the 3B), that is, the first reflection point H ₁ , is reflected by the inner wall of the canal and received by the downstream ultrasonic vibrator 3B. For reference, in order for the ultrasonic wave to be totally reflected at the first reflection point H ₁ , the ultrasonic wave passes through the incident angle θ _i , that is, the first reflection point H ₁ , and is in contact with the first reflection point H ₁ . The first incident angle formed between the vertical straight line, that is, the diameter line T, and the straight line connecting the ultrasonic vibrator 3A and the first reflecting point H ₁ should be greater than or equal to the critical angle θ _c , that is, 14.53 °. do. When the first incident angle θ _i in the present embodiment is calculated using the geometry shown in FIG. 8, the first incident angle θ _i is arctan (5 ^0.5 ) ≒ 65.9 °. That is, since the first incident angle θ _i of the ultrasonic waves is much larger than the critical angle θ _c , it can be seen that the ultrasonic waves transmitted from the upstream ultrasonic vibrator 3A are totally reflected at the first reflection point H ₁ . Therefore, the ultrasonic wave transmitted from the upstream ultrasonic vibrator 3A is received by the downstream ultrasonic vibrator 3B while maintaining almost the same intensity.

On the contrary, the ultrasonic wave transmitted from the downstream ultrasonic vibrator 3B of the third ultrasonic flow rate measurement line also propagates toward the inner wall of the milk pipe, wherein the center point of the upstream ultrasonic vibrator 3A and the downstream ultrasonic vibrator 3B, i.e., The ultrasonic wave incident on the second reflection point H ₂ is received by the upstream ultrasonic vibrator 3A after being reflected from the inner wall of the milk pipe. As shown in FIG. 8, since the first reflection point H ₁ and the second reflection point H ₂ coincide with each other, the second incidence angle is the same as the first incidence angle, and thus, in the downstream ultrasonic vibrator 3B. The transmitted ultrasound is also totally reflected at the second reflection point (H ₂ ).

On the other hand, since the fifth ultrasonic flow rate measurement line is disposed symmetrically with the third ultrasonic flow rate measurement line with respect to the center O of the conduit, the upstream and downstream ultrasonic vibrators 5A and 5B of the fifth ultrasonic flow rate measurement line. Ultrasonic waves transmitted and received between are also totally reflected at the first reflection point H ₃ and the second reflection point H ₄ .

That is, the ultrasonic waves received and transmitted between the third ultrasonic flow rate measuring line and the fifth ultrasonic flow rate measuring line are totally reflected at the inner wall of the flow tube, and thus the process of the end velocity measuring step M104 will be described.

First, when an ultrasonic wave is transmitted from the ultrasonic vibrator 3A upstream of the third ultrasonic flow rate measurement line, the ultrasonic wave propagates at a predetermined direction angle and is totally reflected at the first reflection point H ₁ , and then the third ultrasonic flow rate measurement line. To the downstream ultrasonic vibrator 3B. At this time, the first time required from the time when the ultrasonic wave is transmitted from the upstream ultrasonic vibrator 3A until the ultrasonic wave is reflected at the first reflection point H ₁ and received by the downstream ultrasonic vibrator 3B is determined. Measure On the contrary, when the ultrasonic wave is transmitted from the downstream ultrasonic vibrator 3B, the ultrasonic wave is reflected by the second reflection point H ₂ and then received by the upstream ultrasonic vibrator 3A, at which time the downstream ultrasonic vibrator 3B From the time point at which the ultrasonic waves were transmitted, the second time required for the ultrasonic waves to be reflected by the _second reflecting point H ₂ and received by the upstream ultrasonic vibrator 3A is measured. Subsequently, by using the difference between the first time required and the second time required and the propagation time difference method described above, the flow rate V ₆ of the fluid passing on the path G through which the ultrasonic waves proceed can be obtained. However, as shown in FIG. 8, the ultrasonic wave proceeds across an area surrounded by the ultrasonic flow velocity measurement line and the inner wall of the duct, in which the ultrasonic wave is reflected, that is, the right edge region P ₁ of the duct shown by hatching. It is evenly affected by the fluid passing through the edge region at the flow rate. Therefore, the flow velocity of the fluid passing on the traveling path G of the ultrasonic wave may be set to the flow rate of the fluid passing through the edge region of the duct. Then, if the same process is repeated using the fifth ultrasonic flow rate measuring line, the flow rate V ₇ of the fluid passing through the left edge region P ₂ of the milk pipe can be obtained.

In the end flow rate setting step M104, the flow velocity V ₆ and V ₇ measured in the end flow rate measurement step M103 is surrounded by the outermost ultrasonic flow rate measurement line and the inner wall of the tube in which ultrasonic waves are reflected, that is, the edge region of the tube. It is included in (P ₁ , P ₂ ) and is set to the flow rate of the fluid passing on the straight line parallel to the outermost ultrasonic flow rate measurement line. In particular, in the present embodiment, the flow velocity (V ₆ , V ₇ ) measured in the end flow velocity measurement step (M103) is parallel to the outermost ultrasonic flow rate measurement line and passes a straight line passing through the center of the edge region (P ₁ , P ₂ ). Set the flow rate of the fluid to pass through. That is, as shown in FIG. 8, among the flow rates measured in the end flow rate measurement step M103, the flow rate V ₆ measured using the third ultrasonic flow rate measurement line is converted into the right edge region ( It went by the center of the P ₁₎ of claim 3 related to ultrasonic flow rate measurement line and parallel to a straight line (K ₆₎ set at a flow rate of fluid passing through the phase, and the fifth ultrasonic flow velocity measured by using the measuring line velocity (V ₇₎ ( It is set to the flow velocity of the fluid passing through the center of the left edge region P ₂ of 11) and passing on the straight line K ₇ parallel to the fifth ultrasonic flow velocity measurement line. Meanwhile, in the present embodiment, the flow velocity measured in the end velocity measurement step is set to the flow velocity of the fluid passing through the center of the edge region of the tube and passing in a straight line parallel to the outermost ultrasonic flow rate measurement line, but this is the shape of the tube or the inner wall of the tube. The position may be changed to an optimized point through experimentation as it may vary depending on the influence of friction.

FIG. 9 is a schematic diagram for explaining an effect of measuring a flow rate using the ultrasonic flow rate measuring method shown in FIG. 4 and the ultrasonic flow rate measuring method shown in FIG. 4, and FIG. 10 is an ultrasonic flow rate measuring method shown in FIG. 4. This graph illustrates the effect of measuring the flow rate using the method.

Hereinafter, the average flow rate calculation step M105 and the ultrasonic flow rate measurement method M200 will be described with reference to FIGS. 9 and 10.

In the average flow rate calculation step (M105), five flow rates V ₁ to V ₅ measured in the main flow rate measurement step (M102) And, using the two flow rates V ₆ ~ V ₇ obtained in the end flow rate measurement step (M103) to calculate the average flow rate V of the fluid flowing in the oil pipe (11). That is, the average flow rate calculation step M105 includes seven flow rates V ₁ to V ₇ obtained through the main flow rate measurement step M102 and the end flow rate measurement step M103. Multiply each weighting factor by 2, add them up, and divide the sum by 7.

[∑ (flow rate V _i × weighting factor)] ÷ 7 = mean velocity V

The multiplication by multiplying the weighting factor is called the weighting factor method, which is a known method. The weighting coefficient is dependent on the shape of the canal and the position of the ultrasonic vibrators installed in the canal, which can be determined in consideration of the repeated shape or the geometric shape of the canal cross section. As a known arrangement of the ultrasonic vibrators and a weighting factor accordingly, weighting factors such as a "Gaussian" shape, a "Shevysef" shape, and a "Taylor" shape are known and the description thereof will be omitted.

The ultrasonic flow rate measuring method M200 includes the ultrasonic flow rate measuring method M100 and the flow rate calculating step M201 which have been previously examined as shown in FIG. 4. That is, the preparation step (M101), the main flow rate measuring step (M102), the end flow rate measuring step (M103), the end flow rate setting step (M104), the average flow rate calculation step (M105) and the flow rate calculation step (M201) It includes. The remaining steps except for the flow rate calculation step M201 are the same as those of the ultrasonic flow rate measuring method M100 previously discussed, and thus description thereof will be omitted and only the flow rate calculation step M201 will be described.

In the flow rate calculation step M201, the flow rate of the fluid flowing in the oil pipe 11 is calculated using the flow velocity of the fluid and the cross-sectional area of the oil pipe 11 through which the fluid flows. In this way, the flow rate is calculated by multiplying the cross-sectional area of the entire oil pipe 11 by the average flow velocity of the fluid flowing in the oil pipe 11, and measured at each point of the oil pipe 11 in which the flow rate measuring line is arranged. There is a method of calculating the sum of the flow rate and the area of the oil pipe 11 in a predetermined range around the point and summing for the whole oil pipe 11. It will be described in detail below.

In the method of calculating the flow rate using the average flow rate, the flow rate is calculated by multiplying the average flow rate V obtained in the average flow rate calculation step M105 of the ultrasonic flow rate measuring method M100 discussed above with the cross-sectional area of the oil pipe 11.

In other words, the flow rate = average flow rate V x cross-sectional area of the oil pipe is calculated.

And the method of measuring the flow rate using the respective flow rate measured in the ultrasonic flow rate measurement line with reference to Figure 9 as follows.

The shaded portion in FIG. 9 is for clarifying the division of the first range A ₁ to the seventh range A ₇ . Referring to FIG. 9, the cross-sectional area of the first range A ₁ centered on the first ultrasonic flow rate measurement line, that is, S ₁ And the flow rate of the fluid passing through the first range (A ₁ ) by multiplying the flow rate V ₁ measured in the first ultrasonic flow rate measurement line, the second range if the same process is repeated for the remaining ultrasonic flow rate measurement line. The flow rate of the fluid passing through the (A ₂ ) to the seventh range (A ₇ ) can be calculated. At this time, the cross-sectional area of the first range A ₁ to the seventh range A ₇ multiplied by each flow rate is determined by the weighting factor in the method for calculating the flow rate using the step called the weighting factor method described above. As corresponding, it is determined by experiment. Thereafter, the sum of the respective flow rates passing through the first range A ₁ to the seventh range A ₇ is calculated to calculate the flow rate of the fluid passing through the oil pipe 11. That is, flow rate = ∑ (V _i × S _i ), Where i is from 1 to 7.

As described above, when the flow rate of the fluid flowing through the oil pipe 11 is measured by using the ultrasonic flow rate measuring method M100 according to the present embodiment, it is disposed on the cross section of the oil pipe 11 as shown in FIGS. 9 and 10. The flow rates V ₁ to V ₇ of the fluid passing through the seven parallel lines (K1 to K7) can be measured, and based on this, the average flow rate V of the entire fluid passing through the oil pipe 11 can be obtained. That is, while the conventional ultrasonic flow rate measuring method using the same number of ultrasonic flow rate measuring lines was able to measure only the flow rates V ₁ to V ₅ of _five points K1 to K5, the ultrasonic flow rate measurement according to the present embodiment Method (M100) is necessary to be measured in order to calculate an accurate average flow rate in the duct because the edge region (P ₁ , P ₂ ) of the duct, that is, the flow rate is severe, but it is not easy to install the ultrasonic flow rate measurement line Therefore, the flow rate of the areas P ₁ and P ₂ , which are difficult to measure the flow rate by the conventional method, can be further measured, so that the average flow rate can be measured more accurately than the conventional method.

In addition, by using the ultrasonic flow rate measuring method M200 according to the present embodiment, since the flow rate in the pipe can be measured based on the flow rate accurately measured by the ultrasonic flow rate measuring method M100, a more accurate flow rate can be measured. It becomes possible.

 Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the above-described specific preferred embodiments, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

1 is a cross-sectional view for explaining a method of measuring a flow rate by a propagation time difference method.

2 is a diagram illustrating a flow rate distribution of a fluid flowing in an oil pipe.

Figure 3 is a cross-sectional view of the ultrasonic flow rate measurement line is installed in the center and the edge portion of the duct.

4 is a step-by-step flowchart for explaining an ultrasonic flow rate measuring method and ultrasonic flow rate measuring method according to an embodiment of the present invention.

5 is a perspective view for explaining a preparation step shown in FIG.

FIG. 6 is a schematic projection view of the projection line I of FIG. 5 in a fluid direction to explain the preparation step and the main flow rate measurement step shown in FIG. 4.

7 is a conceptual diagram illustrating Snell's law.

FIG. 8 is a schematic projection view of the projection line I of FIG. 5 in the fluid advancing direction in order to explain the end velocity measurement step and the end velocity setting step shown in FIG. 4.

FIG. 9 is a cross-sectional view for describing an effect of measuring a flow rate using the ultrasonic flow rate measuring method shown in FIG. 4 and an ultrasonic flow rate measuring method shown in FIG. 4.

FIG. 10 is a graph for explaining an effect of measuring a flow rate using the ultrasonic flow rate measuring method shown in FIG. 4.

<Description of the symbols for the main parts of the drawings>

200 ... Ultrasonic flow measurement method 201 ... Flow calculation step

100.Ultrasonic flow rate measurement method 101 ... Preparation step

102.Main flow rate measurement step 103.Step flow rate measurement step

104 ... Step flow rate setting step 105 ... Average flow rate calculation step

11 ... related

Claims (5)

A preparation step of providing a plurality of ultrasonic flow rate measuring lines, each of which is provided with a pair of ultrasonic vibrators respectively installed on the upstream side and the downstream side of the flow tube in an advancing direction of the fluid flowing along the flow pipe; The pair of ultrasonic vibrators using the difference in the time required for the ultrasonic wave to be transmitted and received between the pair of ultrasonic vibrators of each ultrasonic flow rate measurement line, and the ultrasonic wave is propagated between the pair of ultrasonic vibrators. In the ultrasonic flow rate measuring method comprising a main flow rate measuring step of measuring the flow rate of the fluid passing through a straight line connecting the, From the time point at which the ultrasonic wave is transmitted from the upstream ultrasonic vibrator of the pair of ultrasonic vibrators of the outermost ultrasonic flow rate measuring line arranged at one end of the plurality of ultrasonic flow rate measuring lines along the arrangement direction of the ultrasonic flow rate measuring line. The first time required to be reflected by the inner wall of the milk pipe and received by the downstream ultrasonic vibrator, and from the time when the ultrasonic wave is transmitted from the downstream ultrasonic vibrator, the ultrasonic waves are reflected from the inner wall of the milk pipe and then upstream. An end for measuring the flow rate of the fluid passing through the area surrounded by the inner wall of the outermost ultrasonic flow rate measurement line and the ultrasonic pipe is reflected by measuring the difference in the second time required until received by the side ultrasonic vibrator Ultrasonic flow rate measuring method further comprising the flow rate measuring step. The method of claim 1, The flow velocity measured in the end velocity measurement step is set to a flow velocity of a fluid passing in a straight line parallel to the outermost ultrasonic flow velocity measurement line in an area surrounded by the outermost ultrasonic flow velocity measurement line and the inner wall of the oil pipe in which the ultrasonic waves are reflected. Ultrasonic flow rate measuring method further comprising an end flow rate setting step. The method of claim 2, The end flow rate setting step includes setting the flow rate measured in the end flow rate measuring step to a flow rate of a fluid passing through a straight line parallel to the outermost ultrasonic flow rate measurement line passing through the center of the region. Way. The method of claim 1, The velocity at which the ultrasonic waves propagate in the inner wall of the fluid and the canal is C ₁ and C ₂ , respectively. In this case, a straight line connecting the first reflection point that is reflected from the upstream ultrasonic vibrator and the ultrasonic wave transmitted from the upstream ultrasonic vibrator among the inner wall of the duct passes through the first reflection point and passes to the first reflection point. A straight line connecting the first incident angle formed between a straight line perpendicular to the plane of contact and a second reflection point at which the ultrasonic wave transmitted from the downstream ultrasonic vibrator is reflected from the downstream ultrasonic vibrator and the inner wall of the tube; The second incident angles formed between straight lines passing through the reflection point and perpendicular to the plane of the second reflection point are all

Ultrasonic flow rate measuring method, characterized in that above. In the ultrasonic flow rate measuring method for calculating the flow rate of the fluid flowing in the oil pipe based on the flow rate of the fluid flowing in the oil pipe and the cross-sectional area of the oil pipe, The said flow rate is the ultrasonic flow rate measuring method characterized by the flow rate measured by the ultrasonic flow rate measuring method as described in any one of Claims 1-4.

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