JP2013003052A - Three-dimensional velocity measuring system - Google Patents

Three-dimensional velocity measuring system Download PDF

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JP2013003052A
JP2013003052A JP2011136625A JP2011136625A JP2013003052A JP 2013003052 A JP2013003052 A JP 2013003052A JP 2011136625 A JP2011136625 A JP 2011136625A JP 2011136625 A JP2011136625 A JP 2011136625A JP 2013003052 A JP2013003052 A JP 2013003052A
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measurement
downstream
upstream
output signal
dimensional
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JP5791074B2 (en
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Taizo Kanai
大造 金井
Masahiro Furuya
正裕 古谷
Takahiro Arai
崇洋 新井
Takeetsu Shirakawa
健悦 白川
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Central Research Institute Of Electric Power Industry
一般財団法人電力中央研究所
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Abstract

A three-dimensional velocity measurement system capable of easily detecting a three-dimensional flow velocity of a measurement target such as a bubble is provided.
A sensor section having an upstream sensor section 2A disposed in the middle of a flow path 1 and a downstream sensor section 2B disposed downstream of a fluid 1 corresponding to the upstream sensor section 2A; The cross-correlation coefficient is maximized by taking the cross-correlation between the measurement signal related to the specific measurement point of the upstream sensor unit 2A and the measurement signal measured at the measurement point included in the predetermined region of the downstream sensor unit 2B. To identify the downstream measurement points where each cross-correlation coefficient is maximized by taking the cross-correlation count for each of the upstream measurement points. And an arithmetic processing unit 3 that calculates the three-dimensional flow velocity of the bubble B passing through the measurement point and reaching each downstream measurement point.
[Selection] Figure 1

Description

  The present invention relates to a three-dimensional velocity measurement system, and particularly useful for measuring the three-dimensional phase velocity of bubbles in a flow field in a gas-liquid two-phase flow state in a plant such as a nuclear reactor or a thermal power plant. is there.
  Two-phase flow analysis related to the safety evaluation of boiling water reactors is shifting from a one-dimensional to a three-dimensional model in order to accurately evaluate the coolant flow. Among them, a three-dimensional heat flow analysis code including a boiling two-phase flow needs to be verified with accurate three-dimensional two-phase flow experimental data. As a measurement system for obtaining this kind of data, a sensor unit having a wire mesh sensor is known (see Non-Patent Document 1).
  As shown in FIG. 11 (a), the wire mesh sensor crosses over a predetermined distance in the axial direction of the pipe line 01 through which the fluid flows, and within the cross section of the pipe line 01 as shown in FIG. 11 (b). The first wire electrode 02 and the second wire electrode 03 are arranged in a square lattice shape, and the first wire electrode 02 is an excitation electrode and the second wire electrode 03 is a measurement electrode. It is a sensor. The wires are close together but not in contact. Hereinafter, the intersection of the first wire electrode 02 and the second wire electrode 03 is referred to as a measurement point. Accordingly, a large number of measurement points are formed in a square lattice pattern in the plane of the wire mesh sensor.
  In such a wire mesh sensor, as shown in FIG. 12, excitation pulses (input signals) PI are sequentially applied to the input line formed by the first wire electrode 02 by switches S1, S2, S3, and S4 from the first row. . Here, the excitation pulse PI is supplied from the power supply 04 via the changeover switch SP.
  With the application of the excitation pulse PI as described above, the measurement points ([1,1], [2,1], [3,1], [4,1])... ([1,4], [2 , 4], [3, 4], [4, 4]) is measured at each measurement point ([1, 1], [2, 1], [3, 1], [4, 1]). -It changes according to the state of the fluid that short-circuits ([1,4], [2,4], [3,4], [4,4]). As a result, each measurement point ([1, 1], [2, 1], [3, 1], [4, 1])... ([1 , 4], [2, 4], [3, 4], [4, 4]), measurement signals (output signals) PO1, PO2, PO3, and PO4 are output for each row. Consider a case where the excitation pulse PI is applied to the first wire electrode 02 connected to the switch S4 by closing the switch S4. In this case, when the bubble 05 exists at the measurement point [2, 4], and the vicinity of the other measurement points [1, 4], [3,4], [4, 4] is filled with the liquid, Since the impedance at the measurement point [2, 4] is smaller than the impedance at the other measurement points [1, 4], [3,4], [4, 4], it corresponds to this measurement point [2, 4]. The measurement signal PO2 obtained through the second wire electrode 03 is detected as a lower impedance than the other measurement signals PO1, PO3, PO4. That is, the average level of the measurement signals PO1, PO3, PO4 is the measurement point ([1,1], [2,1], [3,1], [4,1]) (..., [1,4], [2, 4], [3, 4], [4, 4]) reflecting the abundance of liquid (for example, water) and gas (bubble 05) in the gas-liquid two-phase flow. As a result, each measurement point ([1,1], [2,1], [3,1], [4,1])... ( [1,4], [2,4], [3,4], [4,4]), for example, the abundance of a desired substance such as a gas-liquid ratio in a gas-liquid two-phase flow is measured by calculation. be able to.
H.Pietruske.H.-M.Prasser / Flow Measurement and Instrumentation 18 (2007) 87-94
  If the wire mesh sensors as described above are arranged at two locations above and below the fluid flow direction, the bubble velocity can also be measured by the time difference between the output signals of the two sets of wire mesh sensors. That is, it is possible to measure the bubble velocity in one direction in the mainstream direction by cross-correlation analysis between corresponding points in the upstream and downstream wire mesh sensors. However, the measurement of the bubble velocity in this case is limited to the one-dimensional evaluation in the flow direction.
  In view of the above problems, an object of the present invention is to provide a three-dimensional velocity measuring system that can easily and accurately detect a three-dimensional flow velocity of a measurement target such as bubbles.
The first aspect of the present invention for achieving the above object is as follows:
A sensor unit that sends out an output signal that is a measurement signal that reflects the impedance of the measurement target flowing through the flow path;
Computation processing means for processing the output signal and measuring the speed of the measurement object,
The sensor unit is
An upstream sensor section for sending an upstream output signal representing the impedance of the measurement object at upstream measurement points arranged at a plurality of positions in a plane in the flow of the measurement object in the flow path;
A downstream output signal representing the impedance of the measurement target at a plurality of downstream measurement points arranged in correspondence with the upstream measurement point in another surface similar to the surface on the downstream side in the fluid flow direction is transmitted. While having a downstream sensor portion to
The arithmetic processing means calculates a cross-correlation between the upstream measurement signal related to the specific upstream measurement point and the downstream output signal measured at the downstream measurement point included in a predetermined region of the downstream sensor. The downstream measurement point where the cross-correlation coefficient is maximized by taking the cross-correlation coefficient for each of the upstream measurement points and the downstream measurement point where the cross-correlation coefficient is maximized Each of the three-dimensional velocities of the three-dimensional velocity, characterized in that each of the three-dimensional velocity of the measurement object passing through the upstream measurement points and reaching the downstream measurement points is calculated. In the measurement system.
  According to this aspect, the three-dimensional trajectory that the measurement object has moved can be identified, and the measurement object that has moved from the upstream sensor unit to the downstream sensor unit based on the movement distance in the trajectory and the time required for the movement can be identified. Information on the three-dimensional moving speed can be obtained easily and accurately.
The second aspect of the present invention is:
In the three-dimensional velocity measurement system described in the first aspect,
In the three-dimensional velocity measurement system, the upstream sensor unit and the downstream sensor unit are constituted by wire mesh sensors.
  According to this aspect, it is possible to satisfactorily configure the upstream side and downstream side sensor units.
The third aspect of the present invention is:
In the three-dimensional velocity measurement system described in the first or second aspect,
The arithmetic processing means includes:
A time difference between a component corresponding to the specific upstream measurement point in the upstream output signal and a component corresponding to the downstream measurement point at which the cross-correlation coefficient in the downstream output signal is maximized;
The downstream side where the cross-correlation coefficient is maximized from the distance along the axial direction between the upstream sensor unit and the downstream sensor unit and the coordinates of the downstream measurement point corresponding to the specific upstream measurement point Based on the distance in the plane to the coordinates of the measurement point, calculate the distance between the specific upstream measurement point and the downstream measurement point where the cross-correlation coefficient is maximized,
The three-dimensional velocity measurement system is characterized in that a three-dimensional flow velocity of the measurement object is calculated based on the time difference and the distance.
  According to this aspect, the downstream measurement point where the cross-correlation coefficient is maximized from the distance along the flow direction between the upstream sensor unit and the downstream sensor unit and the downstream measurement point corresponding to the specific upstream measurement point. The distance from the specific upstream measurement point to the downstream measurement point where the cross-correlation coefficient is maximized is obtained based on the distance in the plane of the downstream sensor unit until the three-dimensional measurement target By dividing by the time difference that is the moving time, the desired three-dimensional moving speed of the measuring object can be obtained easily and accurately.
The fourth aspect of the present invention is:
In the three-dimensional velocity measurement system according to any one of the first to third aspects,
The arithmetic processing means discriminates the upstream output signal and the downstream output signal for each predetermined frequency band, and generates a plurality of the upstream output signal and the downstream output signal for each of a plurality of frequency bands; ,
A three-dimensional velocity measurement system comprising: an arithmetic processing unit that processes the upstream output signal and the downstream output signal for each frequency band generated by the preprocessing unit. .
  According to this aspect, by extracting the output signal of the sensor unit for each predetermined frequency band, it is caused by the diameter of the measurement object, that is, for example, the three-dimensional bubble according to the type of bubble ranging from a small bubble to a large bubble Speed information can be obtained. As a result, it is possible to easily and accurately grasp the characteristic behavior that differs for each bubble diameter. By the way, in the two-phase flow at a high void ratio, large bubbles having a large diameter of several tens of centimeters and small bubbles of about several millimeters are mixed and have complex multidimensionality. This is because large bubbles and small bubbles behave differently due to different degrees of influence of buoyancy, drag, etc. depending on the size of the bubbles. According to this aspect, for example, large bubbles and small bubbles 3D velocity information that can be obtained for each diameter of the measurement object's behavior in a complex multidimensional fluid can be used in a measurement object that contains a mixture of fluids. Is possible.
According to a fifth aspect of the present invention,
In the three-dimensional velocity measurement system according to any one of the first to third aspects,
The arithmetic processing means calculates the measurement object based on time series data of the upstream output signal and the downstream output signal within a predetermined range within the plane within a predetermined time and a distance between the upstream sensor unit and the downstream sensor unit. A preprocessing unit that discriminates each volume and generates a plurality of the upstream output signals and the downstream output signals for each of a plurality of volumes;
The three-dimensional velocity measurement system includes an arithmetic processing unit that processes the upstream output signal and the downstream output signal for each volume generated by the preprocessing unit.
  According to this aspect, by extracting the output signal of the sensor unit for each volume of the measurement target, it is caused by the volume of the measurement target, that is, for example, the three-dimensional bubble according to the type of the bubble from the small bubble to the large bubble Speed information can be obtained. As a result, it is possible to easily and accurately grasp the characteristic behavior that differs for each volume of bubbles.
The sixth aspect of the present invention is:
In the three-dimensional velocity measurement system described in the fourth aspect,
In the three-dimensional velocity measurement system, the pre-processing unit performs wavelet analysis of the upstream output signal and the downstream output signal.
  According to this aspect, it is possible to easily and accurately obtain information on the three-dimensional movement speed for each diameter of the measurement target by wavelet analysis of the output signal of the sensor unit.
The seventh aspect of the present invention is
In the three-dimensional velocity measurement system according to any one of the fourth to sixth aspects,
The pre-processing unit is configured to send the upstream output signal and the downstream output signal to the arithmetic processing unit based on a measurement target having a relative speed difference with the liquid phase of 2 to 5 cm / sec. It is in the three-dimensional velocity measurement system.
  According to this aspect, the three-dimensional velocity of the measurement object obtained by the arithmetic processing unit can be regarded as the three-dimensional velocity of the liquid phase, and the three-dimensional velocity of the liquid phase can be substantially detected. By the way, in the prior art, in order to measure the liquid phase velocity, a tracer is introduced into the fluid, and the movement of the tracer is tracked by, for example, PIV (Particle Image Velocimetry) using laser light and imaging means. Although necessary, according to this aspect, it is possible to easily measure the substantial three-dimensional flow velocity of the liquid phase by detecting the speed of the measurement target such as a predetermined small bubble. Incidentally, in this case, when the sampling frequency in the sensor unit is 1 kHz, the measurement object that can be regarded as a substantially liquid phase is a bubble or the like that is discriminated in a frequency band similar to this sampling frequency. If so, the diameter is about 1 mm.
The eighth aspect of the present invention is
In the three-dimensional velocity measurement system according to any one of the first to seventh aspects,
The arithmetic processing means detects a moving direction of each measurement target in the plane based on the in-plane direction component of the three-dimensional flow velocity of each measurement target, and displays the behavior of the measurement target within a predetermined time on the display unit. The three-dimensional velocity measurement system is characterized by being visualized and displayed.
  According to this aspect, it is possible to visualize and visually recognize the behavior of the measurement target, such as bubbles in a plane orthogonal to the flow direction, that is, the state of turning.
  According to the present invention, it is possible to identify a three-dimensional trajectory that the measurement object has moved, and based on the movement distance in the trajectory and the time required for the movement, the measurement object that has moved from the upstream sensor unit to the downstream sensor unit. Information on the three-dimensional moving speed can be obtained easily and accurately. As a result, the time resolution can be drastically improved as compared with the prior art in which the upstream and downstream sensor units measure the velocity in one dimension in the mainstream direction by cross-correlation analysis between corresponding points. Conventionally, the multi-dimensionality of two-phase flow that changes in a short time cannot be accurately evaluated, but in the present invention, multi-point cross-correlation analysis enables cross-correlation analysis with a small number of frames, with high temporal resolution. This is because a multidimensional phase velocity vector can be obtained.
  Furthermore, by performing preprocessing such as wavelet analysis, it is possible to accurately analyze the characteristic behavior of each measurement object having a different diameter and volume. In particular, it is possible to easily detect a substantial liquid phase speed regardless of the PIV method using a tracer by regarding the speed of the measurement object as the liquid phase speed.
It is a block diagram which shows the whole three-dimensional velocity measuring system which concerns on embodiment of this invention. It is a flowchart which shows the outline | summary of the whole signal processing in the said embodiment. It is explanatory drawing which shows notionally the measurement principle in the said embodiment. It is a flowchart which shows the procedure of the concrete signal processing in the said embodiment. It is explanatory drawing for demonstrating the problem in the measurement which concerns on a prior art. It is explanatory drawing which shows the 1st Example which is the other modification of this invention. It is explanatory drawing which shows the 2nd Example which is the other modification of this invention. It is explanatory drawing which shows the 3rd Example which is the other modification of this invention. It is explanatory drawing which shows the 4th Example which is the other modification of this invention. It is explanatory drawing which shows the 5th Example which is the other modification of this invention. It is explanatory drawing which shows a wire mesh sensor. It is explanatory drawing which shows notionally the wire mesh sensor also including a measurement principle.
  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
  It is a block diagram which shows the whole three-dimensional velocity measuring system which concerns on embodiment of this invention. As shown in the figure, the three-dimensional velocity measurement system according to the present embodiment includes an upstream sensor unit 2A disposed at at least two locations on the upstream side and the downstream side of the flow path 1 through which the fluid containing the bubbles B flows. , 2B, an arithmetic processing device 3 that performs predetermined arithmetic processing on an output signal that is a measurement signal sent from the sensor unit 2, and an output that has undergone predetermined arithmetic processing by the arithmetic processing device 3 And a monitor device 4 for visualizing predetermined information related to the gas-liquid two-phase flow represented by the signal.
  Here, in the case of this embodiment, the sensor unit 2 in this embodiment is configured by a wire mesh sensor (hereinafter also referred to as WMS) shown in FIG. Therefore, a large number of upstream measurement points and downstream measurement points are arranged in a matrix in each plane. The measurement object is bubbles in a gas-liquid two-phase flow.
  The arithmetic processing device 3 includes a storage unit 5, a preprocessing unit 6, and an arithmetic processing unit 7. The storage unit 5 is an output signal of the sensor unit 2, and an upstream output signal and a downstream output that reflect the impedance of the fluid at the upstream measurement point and the downstream measurement point of the upstream sensor unit 2A and the downstream sensor unit 2B. Store the signal once. The preprocessing unit 6 reads the upstream output signal and the downstream output signal stored in the storage unit 5 and performs predetermined preprocessing. In this embodiment, the entire wavelet analysis of the upstream output signal and the downstream output signal is performed by performing wavelet transform of the output signal from each measurement point. Thereby, N types of signals of scale 1 to scale N, which are discriminated for each bubble diameter, are obtained as signals having a higher frequency for smaller bubbles and a lower frequency for larger bubbles. Here, the scale represents a sampling cycle, scale 1 is a signal having a cycle of 1 msec when the sampling frequency is 1 kHz, and scale N is a signal having a cycle of N (N is a natural number) msec. is doing.
  The arithmetic processing unit 7 first includes an upstream measurement signal related to a specific upstream measurement point of the upstream sensor unit 2A, and downstream output signals at a plurality of downstream measurement points included in a predetermined region of the downstream sensor unit 2B. The downstream measurement point where the cross-correlation coefficient is maximized is specified by taking the cross-correlation. Then, by performing the same correlation process for each of the upstream measurement points, the downstream measurement points where the cross-correlation coefficients are maximized are specified, and the three-dimensional flow velocity of the bubble B is calculated. The specific contents of such calculation will be described later in detail as a signal processing technique relating to the upstream output signal and the downstream output signal. Such signal processing is performed on each signal of each scale 1 to N after wavelet analysis. That is, it is performed for a part or all of arbitrarily selected upstream output signals and downstream output signals representing each of predetermined small bubbles to large bubbles.
  FIG. 2 is a flowchart showing an outline of overall signal processing in the present embodiment. As shown in the figure, i (x-axis line segment), j (y-axis component), k (time-axis component) detected as output signal components of the upstream sensor unit 2A and the downstream sensor unit 2B at each measurement point. ) Is subjected to continuous wavelet transform (see step ST01). Here, “continuous” means that wavelet transform is performed on all frequency components. In this embodiment, continuous wavelet transform is performed, but this may of course be performed as necessary for a specific discrete frequency.
  As a result, a WMS output signal discriminated for each bubble diameter is obtained as N types of information for each bubble diameter as an i × j × k matrix (see steps ST021 to ST02N). This is represented by scales 1 to N.
  Next, as will be described in detail later, multipoint cross-correlation analysis for bubble signal extraction is performed (see step ST03), and then the three-dimensional bubble velocity is calculated for each scale 1 to N (steps ST041 to ST04N). ).
  Note that the processes of steps ST01 and ST021 to ST02N are executed by the preprocessing unit 6, and the processes of steps ST03 and ST041 to ST04N are executed by the arithmetic processing unit 7, respectively.
  The principle of the above-mentioned multipoint cross-correlation analysis and three-dimensional bubble velocity calculation processing will be described with reference to FIG. As shown in FIG. 3A, first, upstream measurement at a specific upstream measurement point (measurement point indicated by a black portion in the drawing) of the upstream sensor unit 2A (“1stWMS” in the drawing; the same applies hereinafter). Signals and downstream outputs at a plurality of downstream measurement points included in a predetermined area (“Nx × Ny area” in the figure; the same shall apply hereinafter) of the downstream sensor unit 2B (“2ndWMS” in the figure; the same shall apply hereinafter) By taking the cross-correlation with the signal, the downstream measurement point having the maximum cross-correlation coefficient is specified. In FIG. 3A, the degree of the correlation coefficient with the signal at the measurement point in 1st WMS is represented by the color shading. Here, it is considered that the bubble that has passed a specific measurement point of 1stWMS has reached the downstream measurement point that gives the maximum correlation coefficient of 2ndWMS.
Therefore, as shown in FIG. 3B, the distance vector from the specific measurement point of 1stWMS to the corresponding downstream measurement point of 2ndWMS along the flow direction (vertical direction in the figure) is set as u G, z and the distance The vector starts from u G, z , passes through the 2nd WMS plane (in the horizontal plane in the figure), reaches the downstream measurement point of the 2nd WMS that gives the maximum correlation coefficient, and the distance vector with the downstream measurement point as the end point is u In the case of G, xy , the three-dimensional distance vector u G representing the movement distance of the bubble is given as a vector sum of the distance vector u G, z and the distance vector u G, xy . Here, the distance vector u G, z is an interval along the flow direction between the 1st WMS and the 2nd WMS, and the distance vector u G, xy is between the coordinates of the start point and the end point coordinates in the xy plane which is the surface of the 2nd WMS. Given as a distance. On the other hand, the time from when a bubble reaches a downstream measurement point that gives a maximum correlation coefficient of 2ndWMS from a specific upstream measurement point of 1stWMS is separately given as information representing the time difference between the two. Therefore, the three-dimensional bubble velocity can be calculated based on the three-dimensional distance vector u G and the time difference information.
  The three-dimensional flow velocity of bubbles passing through each upstream measurement point by performing the above-described series of processing for obtaining cross-correlation at a plurality of downstream measurement points included in a predetermined region of 2ndWMS with respect to each upstream measurement point of 1stWMS Can be requested. Here, the predetermined setting in 2ndWMS can be arbitrarily expanded until the entire area of 2ndWMS is set as the target area. For example, when the downstream measurement point that gives the maximum correlation coefficient in the first cross-correlation exists at the edge of the area, and there is a possibility that there is a region where the correlation coefficient increases beyond the edge. The cross-correlation processing can be optimized by performing processing such as expanding the area and re-acquiring the cross-correlation.
  FIG. 4 is a flowchart showing a specific procedure of signal processing in the arithmetic processing unit 3 of the present embodiment. As shown in the figure, the information processing in the arithmetic processing unit 3 is divided into a wavelet analysis I performed by the preprocessing unit 6 and a multipoint cross-correlation analysis II performed by the arithmetic processing unit 7 following this. As shown in the figure, the wavelet analysis I includes i (x-axis line segment), j (y-axis component), detected as components of output signals of the upstream sensor unit 2A and the downstream sensor unit 2B at each measurement point, The process is started by reading matrix information including k (time-axis components) from the storage unit 5 (see step ST1). Wavelet transformation is performed at a measurement point at a specific coordinate position (x, y) every time 1 to k. Similar processing is performed for i = 1 to i while sequentially shifting the coordinate position of the measurement point in the x direction (see loop 1), and similar processing is performed for j = 1 to 1 while sequentially shifting the coordinate position of the measurement point in the y direction. For j (see loop 2).
  As a result, the WMS signal component that is the upstream output signal and the downstream output signal is selected for an arbitrary scale (see step ST3).
  Multipoint cross-correlation analysis II is performed using the WMS signal component selected in step ST3 for each of the specific scales 1 to N. Therefore, i (x-axis line segment), j (y-axis component), k (time-axis component) detected as components of output signals of the upstream sensor unit 2A and the downstream sensor unit 2B at each measurement point with respect to a specific scale. ) Is read from the preprocessing unit 5 (see step ST4). Thereafter, a specific upstream output signal from the upstream sensor unit 2A for which a predetermined wavelet transform has been completed, and a downstream output signal of a measurement point shifted in the x direction and the y direction within the plane of the downstream sensor unit 2B. Based on the cross correlation between the two. Such processing is performed every time 1 to k (see step ST5). Subsequently, the maximum value of the cross-correlation coefficient at each measurement point in the predetermined area of the downstream sensor unit 2B and the time difference that gives this maximum value are stored (see step ST6). The same processing is performed for i = 1 to i while sequentially shifting the coordinate position of the downstream measurement point in the x direction (see loop 3), and the same processing is performed while sequentially shifting the coordinate position of the measurement point in the y direction. 1 to j (see loop 4).
  Thereafter, the coordinate (x, y) in the plane of the downstream sensor unit 2B having the maximum correlation coefficient and the time difference at that time are selected (see step ST7), and then the coordinate (x, y) is selected. Then, the three-dimensional bubble velocity is obtained from the interval (z) between the upstream sensor unit 2A and the downstream sensor unit 2B given in advance and the time difference (see step ST8). The same processing is performed for i = 1 to i while sequentially shifting the coordinate position of the upstream measurement point in the x direction (see loop 1), and the same processing is performed while sequentially shifting the coordinate position of the upstream measurement point in the y direction. A series of processing is ended by performing j = 1 to j (see loop 4) (see step ST9).
  If such a series of processing is performed, information on the three-dimensional movement speed of the bubble moved from the upstream sensor unit 2A to the downstream sensor unit 2B can be obtained easily and accurately. Compared with the conventional technique that performs one-dimensional bubble velocity measurement by cross-correlation analysis between points along the flow direction corresponding to a specific measurement point in the downstream sensor unit 2B, the time resolution can be dramatically improved. .
This point will be described in more detail with reference to FIG. As shown in FIG. 5 (a), a measurement point that is a point along the flow direction corresponding to a specific measurement point of the upstream sensor unit 2A (blacked portion in FIG. 5 (a)) in the downstream sensor unit 2B ( When the bubble velocity measurement is performed using the one-dimensional vector u G, z by cross-correlation analysis between the white areas in FIG. 5 (a), as shown in FIG. 5 (b) as the vector u G, z. In the case where the flow direction of the bubbles is greatly deviated in the surface (horizontal plane) of the downstream sensor unit 2B, if the measurement time is shortened, the measurement point of the downstream sensor unit 2B is deviated, so that no correlation can be obtained. Therefore, a long measurement time is set to some extent, and a one-dimensional correlation has to be taken based on the averaged signal therebetween. According to this embodiment, even if the sampling period is shortened, the downstream sensor unit of the bubble that has passed a specific measurement point of the upstream sensor unit at any one of a large number of measurement points spread in the plane of the downstream sensor unit 2B The passage of 2B can be reliably detected, and the time resolution in the measurement can be dramatically improved.
  The present embodiment is not limited to that shown in FIG. 1, and various modifications in which the shape of the flow path and the configuration of the sensor unit are changed are conceivable. These will be described as first to fifth embodiments.
<First embodiment>
FIG. 6 is an explanatory diagram showing the first embodiment. As shown in the figure, in this embodiment, a large number of downstream sensor units 2B,..., 2N are arranged in the axial direction of the flow path 1 with respect to the upstream sensor unit 2A.
  According to this embodiment, the three-dimensional behavior can be measured based on the three-dimensional flow velocity of the bubble B.
<Second embodiment>
FIG. 7 is an explanatory view showing a second embodiment. As shown in the figure, the flow path in which the sensor unit is disposed may be a curved pipe (elbow pipe) 1A. Even in this case, by processing the output signals of the upstream sensor unit 2A and the downstream sensor units 2B, 2C, 2D, 2E, 2F, and 2G as described above, the upstream sensor units 2A and the downstream sensor units 2B to 2B are processed. The three-dimensional flow velocity of the bubble B at each measurement point of 2G can be obtained, and thereby the moving direction of the bubble B can be traced. Incidentally, the speed of the bubbles in this case cannot be detected by the conventional technique that processes only one-dimensional information set in the axial direction of the flow path 1A.
<Third embodiment>
FIG. 8 is an explanatory view showing a third embodiment. As shown in the figure, this example is a case where the flow path 1B has a reducer portion. Even if the plate area of the flow path 1B changes, if the area of the downstream sensor unit 2B is changed with respect to the area of the upstream sensor unit 2A, desired measurement can be performed without any problem. Specifically, the WMS mesh interval may be changed.
<Fourth embodiment>
FIG. 9 is an explanatory view showing a fourth embodiment. This figure shows a case where an orifice (obstacle) 8 exists between the upstream sensor unit 2A and the downstream sensor unit 2B. Even in this case, the desired three-dimensional flow velocity of the bubble B can be detected without any problem. Incidentally, the bubble velocity in this case cannot be detected by the conventional technique that processes only one-dimensional information related to the axial direction of the flow path 1.
<Fifth embodiment>
FIG. 10 is an explanatory diagram showing the fifth embodiment. As shown in the figure, the locus 9 of the bubble B accompanying the convection of the fluid between the upstream sensor unit 2A and the downstream sensor unit 2B can be traced as shown in the present embodiment. Incidentally, the speed of the bubbles in this case cannot be detected by the conventional technique that processes only one-dimensional information about the axial direction in the flow path 1.
  As mentioned above, although this invention was demonstrated in detail with embodiment, this invention is not limited to the said embodiment. For example, although the sensor part 2 used the wire mesh sensor, it is not necessary to restrict to this. There is no further limitation as long as it is a sensor that can send out an output signal representing the phase state of the fluid at measurement points dispersedly arranged at a plurality of positions in a plane orthogonal to the axis of the flow path 1. Further, it is not necessary to limit the measurement target to bubbles in the gas-liquid two-phase flow. In general, one or a plurality of measurement objects in a fluid in which a plurality of measurement objects having different impedances are mixed can be specified, and the three-dimensional velocity can be measured for each measurement object.
  Further, the arithmetic processing unit is also configured to identify a measurement point having the maximum cross-correlation in a predetermined region of the downstream sensor unit and process vector information between the specific measurement point of the upstream sensor unit. It should be.
  Further, the discrimination for each bubble diameter is performed using wavelet analysis. However, if the bubble diameter can be discriminated based on the frequency, the same object can be achieved by using, for example, a bandpass filter.
  On the other hand, the pre-processing unit 6 can be configured to send an output signal in a frequency band obtained by discriminating a small-diameter measurement object having a relative speed difference from the liquid phase of 2 to 5 cm / cm to the arithmetic processing unit 7. In this case, the three-dimensional velocity to be measured such as small bubbles obtained by the arithmetic processing unit 7 can be regarded as the three-dimensional velocity of the liquid phase, and the three-dimensional velocity of the liquid phase can be substantially detected.
  The size of the measurement object can also be discriminated by calculating its volume. That is, based on the time series data of the upstream output signal and the downstream output signal in a predetermined range within the plane of the flow path 1 within a predetermined time and the distance between the upstream sensor unit 2A and the downstream sensor unit 2B in the preprocessing unit. The volume of the measurement target (for example, bubble B) is obtained, and the measurement target is discriminated for each volume, and the arithmetic processing unit processes the upstream output signal and the downstream output signal for each volume generated by the preprocessing unit. It is also possible to configure so as to perform predetermined arithmetic processing. In this case, by extracting the output signal of the sensor unit for each volume of the measurement target, it is caused by the volume of the measurement target, that is, the three-dimensional velocity of the bubble according to the type of the bubble ranging from a small bubble to a large bubble, for example Information can be obtained.
  Furthermore, the arithmetic processing unit 7 detects the movement direction of each bubble in the plane based on the in-plane direction component of the three-dimensional flow velocity of each bubble, and visualizes the behavior of each bubble within a predetermined time on the monitor device 4. It may be displayed. In this case, the behavior of bubbles in a plane orthogonal to the fluid flow direction, that is, the state of swirling can be visualized and visually confirmed.
  The present invention can be effectively used in the industrial field of measuring the three-dimensional phase velocity of bubbles in a flow field of a gas-liquid two-phase flow that flows through a flow path.
1, 1A, 1B Flow path 2 Sensor unit 2A Upstream sensor unit 2B Downstream sensor unit 3 Arithmetic processing device 4 Monitor device 5 Storage unit 6 Preprocessing unit 7 Arithmetic processing unit

Claims (8)

  1. A sensor unit that sends out an output signal that is a measurement signal that reflects the impedance of the measurement target flowing through the flow path;
    Computation processing means for processing the output signal and measuring the speed of the measurement object,
    The sensor unit is
    An upstream sensor section for sending an upstream output signal representing the impedance of the measurement object at upstream measurement points arranged at a plurality of positions in a plane in the flow of the measurement object in the flow path;
    A downstream output signal representing the impedance of the measurement target at a plurality of downstream measurement points arranged in correspondence with the upstream measurement point in another surface similar to the surface on the downstream side in the fluid flow direction is transmitted. While having a downstream sensor portion to
    The arithmetic processing means calculates a cross-correlation between the upstream measurement signal related to the specific upstream measurement point and the downstream output signal measured at the downstream measurement point included in a predetermined region of the downstream sensor. The downstream measurement point where the cross-correlation coefficient is maximized by taking the cross-correlation coefficient for each of the upstream measurement points and the downstream measurement point where the cross-correlation coefficient is maximized Each of the three-dimensional velocities of the three-dimensional velocity, characterized in that each of the three-dimensional velocity of the measurement object passing through the upstream measurement points and reaching the downstream measurement points is calculated. Measuring system.
  2. The three-dimensional velocity measurement system according to claim 1,
    The three-dimensional velocity measurement system, wherein the upstream sensor unit and the downstream sensor unit are constituted by wire mesh sensors.
  3. In the three-dimensional velocity measurement system according to claim 1 or 2,
    The arithmetic processing means includes:
    A time difference between a component corresponding to the specific upstream measurement point in the upstream output signal and a component corresponding to the downstream measurement point at which the cross-correlation coefficient in the downstream output signal is maximized;
    The downstream side where the cross-correlation coefficient is maximized from the distance along the axial direction between the upstream sensor unit and the downstream sensor unit and the coordinates of the downstream measurement point corresponding to the specific upstream measurement point Based on the distance in the plane to the coordinates of the measurement point, calculate the distance between the specific upstream measurement point and the downstream measurement point where the cross-correlation coefficient is maximized,
    A three-dimensional velocity measurement system that calculates a three-dimensional flow velocity of the measurement object based on the time difference and the distance.
  4. In the three-dimensional velocity measurement system according to any one of claims 1 to 3,
    The arithmetic processing means discriminates the upstream output signal and the downstream output signal for each predetermined frequency band, and generates a plurality of the upstream output signal and the downstream output signal for each of a plurality of frequency bands; ,
    A three-dimensional velocity measurement system comprising: an arithmetic processing unit that processes the upstream output signal and the downstream output signal for each frequency band generated by the preprocessing unit.
  5. In the three-dimensional velocity measurement system according to any one of claims 1 to 3,
    The arithmetic processing means calculates the measurement object based on time series data of the upstream output signal and the downstream output signal within a predetermined range within the plane within a predetermined time and a distance between the upstream sensor unit and the downstream sensor unit. A preprocessing unit that discriminates each volume and generates a plurality of the upstream output signals and the downstream output signals for each of a plurality of volumes;
    A three-dimensional velocity measurement system comprising: an arithmetic processing unit that processes the upstream output signal and the downstream output signal for each volume generated by the preprocessing unit.
  6. In the three-dimensional velocity measurement system according to claim 4,
    The three-dimensional velocity measurement system, wherein the preprocessing unit performs wavelet analysis of the upstream output signal and the downstream output signal.
  7. In the three-dimensional velocity measurement system according to any one of claims 4 to 6,
    The pre-processing unit is configured to send the upstream output signal and the downstream output signal to the arithmetic processing unit based on a measurement target having a relative speed difference with the liquid phase of 2 to 5 cm / sec. Three-dimensional velocity measurement system.
  8. In the three-dimensional velocity measurement system according to any one of claims 1 to 7,
    The arithmetic processing means detects a moving direction of each measurement target in the plane based on the in-plane direction component of the three-dimensional flow velocity of each measurement target, and displays the behavior of the measurement target within a predetermined time on the display unit. A three-dimensional velocity measurement system characterized by being visualized and displayed.
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