JP2012137417A - Two-dimensional ultrasonic anemometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve measuring accuracy by minimizing an influence of a strut on air velocity.SOLUTION: A two-dimensional ultrasonic anemometer according to the present invention comprises three ultrasonic elements 1, 2, and 3; a holding surface 4 for holding the ultrasonic elements 1, 2, and 3 so as to make the center of ultrasonic elements respectively match with the three vertices of a regular triangle; a reflection plate 5 disposed oppositely to the holding surface 4; and a strut 7 projecting out from the holding surface 4 and supporting the reflection plate 5 so as to oppose to the holding surface 4. The strut 7 is disposed at an outer position than the ultrasonic elements 1, 2, and 3 when viewed from the center of the holding surface 4, and a position on each vertical line extending from each side of the regular triangle made by uniting the center of the three ultrasonic elements 1, 2, nd 3 through each vertex of the regular triangle opposed to the side.

Description

  The present invention relates to a two-dimensional ultrasonic anemometer that measures a two-dimensional component of wind speed using ultrasonic waves.

  Today, ultrasonic anemometers are beginning to be used in places where it is required to accurately detect and control air flow as wind.

  This ultrasonic anemometer prepares a pair of ultrasonic transducers, the time required for propagation of ultrasonic waves on the propagation path from one ultrasonic transducer to the other ultrasonic transducer, and vice versa. The component of the wind speed along the path is detected from the difference from the propagation time of the ultrasonic wave on the propagation path.

  In particular, when only the orthogonal biaxial component of the wind speed in the horizontal plane is to be measured, as shown in FIG. 5, two pairs of ultrasonic transducers are arranged so that the ultrasonic waves are orthogonal to each other on two slightly shifted planes. Two-dimensional anemometers are known. Since this two-dimensional anemometer requires a total of four transducers, for the purpose of reducing the size and cost of the apparatus, as shown in FIG. A reflection-type ultrasonic anemometer including a holding surface 4 that holds 2 and 3 and a reflecting plate 5 disposed to face the holding surface 4 has been proposed (see Patent Document 1). FIG. 6 shows the configuration of the ultrasonic anemometer described in Patent Document 1, (A) is a front view, and (B) is a plan view. In these drawings, the propagation path of ultrasonic waves is conceptually represented by a two-dot chain line.

  In the reflection-type ultrasonic anemometer of FIG. 6, first, a part of the ultrasonic wave radiated from the first transducer 1 is reflected by the reflecting plate 5, and a part of this reflected wave is further reflected by the second transducer. Is received by the device 2. In this way, the ultrasonic wave propagates obliquely in the vertical direction. Next, a part of the ultrasonic wave radiated from the second transducer 2 is reflected by the reflecting plate 5, and a further part of this reflected wave is received by the first transducer 1. Similarly, ultrasonic waves are transmitted and received between the second transducer 3 and the third transducer 3 in the diagonally up and down direction with the reflector 5, and the third transducer 3 and the first transducer Even between the transducer 1 and the reflector 5, ultrasonic waves are transmitted and received obliquely in the vertical direction.

  Since the required propagation time of the ultrasonic wave on each propagation path is affected by the wind speed, the value varies depending on a certain propagation direction (forward direction) and the opposite propagation direction (reverse direction). The component of the wind speed projected on the propagation path is detected from the difference in propagation time in both the forward and reverse directions. However, since the propagation path in the vertical direction propagates upward and is reflected and propagates downward, the influence of the vertical component of the wind speed on the propagation time cancels each other on the upward propagation path and the downward propagation path. Hold on. Therefore, with this type of reflection type, the vertical component of the wind speed is not detected, and only the horizontal component (the wind speed component on the line connecting the transducers) is to be detected.

  In the reflective ultrasonic anemometer of FIG. 6, three ultrasonic propagation paths are formed between three ultrasonic transducers. Since the wind flow is often instantaneous or non-uniform, in order to reduce the measurement error of the wind speed, out of two horizontal components of the wind speed on the three ultrasonic propagation paths The wind speed is calculated by averaging the wind speed components.

JP 10-132839 A

  As described above, the reflection type two-dimensional ultrasonic anemometer in which the apparatus is reduced in size and cost is required to have a support column that supports the reflection plate facing the holding surface of the ultrasonic element. Conventionally, as shown in FIG. 6, three support columns are arranged for the purpose of stabilizing the facing state between the holding surface 4 of the ultrasonic element and the reflecting plate 5.

  However, when the column receives wind, turbulence occurs in the lee of the column. The present inventors simulated how the turbulence by the support column affects the wind speed.

  FIG. 7 shows the result of simulating how the struts disturb the wind speed. This simulation is to obtain how the wind speed changes in the lee of the support when a wind of 5 m / s is blown from one direction within a square of 200 mm × 100 mm onto the support of φ4 mm. According to this condition, a wind speed range of 4.25 m / s or less was found downstream of the column, a wind speed range of 4.75 m / s or less was created around this, and a wind speed range of 5 m / s or less was created around this range. That is, a range in which the wind speed is reduced by approximately 1% or more, a range in which the wind speed is reduced by 0.5% or more, and a range in which the wind speed is reduced by 0 to 0.5% were created by the support (FIG. 8). These ranges showed similar results even when the measured wind speed was increased.

  As described above, it has been found from the simulation results that the turbulence of the wind due to the support column disturbs the distribution of the original wind speed to be measured, which may affect accurate wind speed measurement.

  In the case of the reflection type ultrasonic anemometer of FIG. 6, the measurement accuracy of the wind speed is increased by averaging the wind speed components in the two orthogonal directions in the horizontal plane of the three ultrasonic propagation paths. The measurement accuracy increases so as not to affect the wind speed detection on the ultrasonic propagation path. However, due to the configuration of the reflection-type ultrasonic anemometer of FIG. 6, the turbulence of the wind due to each of the columns always reaches one or two ultrasonic propagation paths. In order to improve the measurement accuracy in consideration of this, it is desirable to minimize the phenomenon in which the wind turbulence caused by the struts reaches the two ultrasonic propagation paths.

  However, in the reflection type ultrasonic anemometer described in Patent Document 1, the influence of the strut on the wind speed is not known at all, and no measures for improving the strut to minimize the above-described phenomenon are taken. As will be described in detail later, it has also been found that when the columns are arranged as shown in FIG. 6, the range of wind turbulence caused by each column on the two ultrasonic propagation paths is relatively large.

  Accordingly, an object of the present invention is to provide a reflection type ultrasonic anemometer in which the measurement accuracy is further improved by minimizing the influence of the support on the wind speed in view of the actual situation of the background art.

  The two-dimensional ultrasonic anemometer according to the present invention holds three ultrasonic elements and holds these ultrasonic elements so that the center of each ultrasonic element coincides with each of the three vertices of an equilateral triangle. A reflecting plate disposed opposite to the holding surface, and three support columns protruding from the holding surface and supporting the reflecting plate so as to face the holding surface.

  Further, the support column is located outside the ultrasonic element when viewed from the center of the holding surface, and is formed from an equilateral triangle facing each side from each side of the equilateral triangle formed by connecting the centers of the three ultrasonic elements. It is arranged at a position on each vertical line extending through each vertex.

  According to the present invention, it is possible to further improve the measurement accuracy by minimizing the influence of the column on the wind speed.

The figure which showed the structure of the reflection type ultrasonic anemometer by one Example of this invention. FIG. 2 is a diagram in which ultrasonic propagation paths in the three ultrasonic transducers of FIG. 1 are projected on a horizontal plane, and is a diagram for explaining a method for calculating orthogonal biaxial components of wind speed in the horizontal plane. FIG. 3 is a diagram in which ultrasonic propagation paths between the three ultrasonic transducers and the reflector shown in FIG. 2 are projected on the transducer holding surface, and the ultrasonic propagation paths (two-dot chain lines in the figure). ) And the relationship between the measurement wind speed turbulence region (shaded portion in the figure) by one strut. The figure which showed the structure of the reflection type ultrasonic anemometer by the other Example of this invention. The perspective view which shows the conventional ultrasonic anemometer. The figure which shows the structure of the reflection type ultrasonic anemometer described in patent document 1. FIG. The figure which shows the result of having simulated a mode that a support | pillar disturbs a wind speed. The figure which showed the range which a support | pillar disturbs a wind speed based on the simulation result of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same components as those in the conventional apparatus shown in FIG.

  FIG. 1 shows the configuration of a reflective ultrasonic anemometer according to an embodiment of the present invention, in which (A) is a front view and (B) is a plan view.

  As shown in FIG. 1B, three ultrasonic transducers (ultrasound elements such as electroacoustic transducers) 1, 2, 3 are provided on the holding surface 4 which is the front end surface of the cylindrical holding body 6. Are arranged so that the respective centers 1a, 2a, 3a coincide with the three vertices of an equilateral triangle indicated by a two-dot chain line.

  As shown in FIG. 1A, three support columns 7 protrude upward from the peripheral portion of the holding surface 4, and a reflecting plate 5 having substantially the same diameter as the holding surface 4 is held at each tip. ing. The reflecting plate 5 is supported by three support columns 7 so as to face each other in parallel with the holding surface 4. In addition, when a blowing wind etc. are worried, measures, such as cutting out the part which is not used for reflection of a sound wave among the reflecting plates 5, may be taken.

  Each support column 7 is located outside the ultrasonic transducers 1, 2, 3 as viewed from the center of the holding surface 4, and is disposed at a fixed vicinity of each of the ultrasonic transducers 1, 2, 3. ing. In particular, the support column 7 extends from each side of the equilateral triangle formed by connecting the centers 1a, 2a, 3a of the ultrasonic transducers 1, 2, 3 through each vertex of the equilateral triangle facing the side. Are arranged at positions on a vertical line (total of three; shown by a one-dot chain line).

  Each transducer is connected to the operation processing unit of the anemometer body by a cable (not shown) extending through the inside of the holding body 6.

  According to the said structure, an ultrasonic wave is transmitted / received between the reflectors R in the diagonal up-down direction between the transmitter / receivers 1 and 2 adjacent. In the same manner, an ultrasonic wave propagation path in an oblique vertical direction is formed between the adjacent transducers 2 and 3 and between the transducers 3 and 1 and the reflecting plate 5. In such a reflection-type ultrasonic anemometer, the wind velocity component on the line connecting the ultrasonic transducers is detected as described in the background art section.

  When an oblique and vertical ultrasonic wave propagation path between the holding surface 4 and the reflecting plate 5 is projected on a horizontal plane, these ultrasonic wave propagation paths (two-dot chain lines in the figure) are transmitted and received as shown in FIG. It coincides with the three sides of the equilateral triangle with the centers 1a, 2a, 3a of the wavers 1, 2, 3 as the three vertices, respectively.

  Here, the horizontal component of the wind speed detected by the transducer pair (1, 2) is A, the horizontal component of the wind speed detected by the transducer pair (2, 3) is B, and the transducer pair. The horizontal component of the wind speed detected by (3, 1) is defined as C. Further, in the horizontal plane, an x axis and a y axis that are orthogonal to each other are defined as shown in the figure.

  If the x-axis and y-axis components of the calculated wind speed V, wind speed B, and wind speed C are (Vx, Vy), (Bx, By), and (Cx, Cy), respectively, To establish.

Vx = A = −Bx = −Cx (1)
Vy = By = −Cy (2)
However, since the wind speeds A, B, and C are not the same wind speed, the expressions (1) and (2) are not necessarily satisfied from the instantaneous and spatial distribution of the wind speed or from the measurement error.

  Therefore, as an example, a wind speed component averaged by simply averaging the wind speed components on each side of the formulas (1) and (2) is defined as the following formula.

Vx = (A−Bx−Cx) / 3 (3)
Vy = (By-Cy) / 2 (4)
Furthermore, Bx = Bcos 60 ° = B / 2, Cx = Ccos 60 ° = C / 2, By = Bcos 30 ° = (√3 / 2) B, Cy = Ccos 30 ° Substituting = (√3 / 2) C into the formulas (1) and (2), the following formula is obtained.

Vx = (2A-B-C) / 6 (5)
Vy = (BC) (√3 / 4) (6)
Based on the wind velocity components A, B, and C detected by the three combinations of the three ultrasonic transducers, the orthogonal biaxial components Vx and Vy of the wind velocity in the plane are calculated according to the equations (5) and (6). Is done.

  Thus, by detecting the wind speeds A, B, C in the horizontal plane in the three ultrasonic propagation paths, and averaging the X-axis direction component and the Y-axis direction component of these wind speeds A, B, C, respectively, Measurement error can be reduced.

  Furthermore, the present invention can minimize the influence of each column 7 on the original wind speed by installing each column 7 at a specific position. The conventional reflective ultrasonic anemometer of FIG. The measurement accuracy can be further increased compared to the above.

  In order to obtain this effect, when each column 7 is installed at a position outside the ultrasonic transducers 1, 2, 3 as viewed from the center of the holding surface 4, each column 7 is connected to the ultrasonic transducer 1. , 2, and 3, each of which is located in the vicinity of each of the ultrasonic transducers 1, 2, and 3, and is connected to the centers 1 a, 2 a, and 3 a, and the equilateral triangle that faces the corresponding side from each side of the equilateral triangle Are arranged at positions on a vertical line (total of three) extending through each vertex.

  Here, the effect of each column 7 on the wind speed to be measured will be described by comparing the position of the column 7 according to the present invention and the case according to the prior art.

  FIG. 3 is a diagram in which the ultrasonic propagation path between the three ultrasonic transducers 1, 2, 3 and the reflector 5 shown in FIG. 2 is projected into the transducer holding surface 4. This shows the relationship between the ultrasonic propagation path (two-dot chain line in the figure) and the region of the measurement wind speed turbulence (shaded area in the figure) by the support.

  In (A1), (B1), (A2), and (B2) in FIG. 3, only one ultrasonic wave is transmitted to and received by the first ultrasonic wave transmitter 1 by one strut 7. A state (hereinafter, abbreviated as a two-pass influence state) in which a range (see FIG. 8) that disturbs the wind speed V [m / s] is shown. For convenience, these drawings show only a range in which the wind speed is reduced by 0.5% or more due to the influence of the column 7.

  According to the arrangement of struts according to the prior art (see FIG. 6B), the wind direction when the above-mentioned two-path influence state occurs closest to the second ultrasonic transducer 2 is as shown in FIG. The wind direction when the two-path influence state occurs closest to the first ultrasonic transducer 1 is as shown in (B1) of FIG. From the simulation results shown in (A1) and (B1) of FIG. 3, the range of the wind direction in which the two-pass influence state occurs is 29.37 ° as shown in (C1) of FIG. The same applies to the two ultrasonic propagation paths transmitted and received by the third ultrasonic transducer 3. As a result, in the case of the column arrangement according to the conventional technique, the range of the wind direction in which the disturbance of the wind by the column always reaches the two ultrasonic propagation paths is about 58 ° (29.37 ° + 29.37 °) per column. became. Since there are three columns 7, the total wind direction range is taken into consideration, which is about 174 ° (= about 58 ° × 3).

  It has been found that the above-mentioned two-pass influence state occurs in this conventional technique in a wind direction range of about 174 ° with respect to the entire wind direction range (360 °) in the horizontal plane. The smaller the wind direction range in which the two-pass influence state occurs, the smaller the probability that a measurement error will occur. Then, when the arrangement position of the three support columns 7 that can keep the two-pass influence state to a minimum is tried and errored, the present inventors have reached the support configuration of the present invention.

  According to the strut arrangement of the present invention (see FIG. 1B), the wind direction when the above-mentioned two-path influence state occurs closest to the second ultrasonic transducer 2 is shown in FIG. The wind direction when the two-path influence state occurs closest to the third ultrasonic transducer 3 is as shown in FIG. 3 (B2). From the simulation results shown in (A2) and (B2) of FIG. 3, the range of the wind direction in which the above-mentioned two-path influence state occurs is 22.52 ° as shown in (C2) of FIG. As a result, in the case of the support arrangement according to the present invention, the range of the wind direction in which the disturbance of the wind by the support is always applied to the two ultrasonic propagation paths is about 22 ° per support. Since there are three columns 7, the total wind direction range is taken into consideration, which is about 66 ° (= about 22 ° × 3).

  When the struts are arranged as in the present invention, the wind direction range in which the above-mentioned two-pass influence state occurs is minimized, so that the measurement error is smaller than in the conventional technique in the entire wind direction range in the horizontal plane.

  Of course, as the position of each support column 7 is moved outward from the ultrasonic transducers 1, 2, and 3 with respect to the center of the holding surface 4, the turbulence of the wind speed due to the support column 7 becomes less likely to reach the ultrasonic propagation path. As a matter of course, according to the present invention, even when it is difficult to move the support column 7 away from the ultrasonic wave propagation path for downsizing the anemometer, it is possible to obtain more reliable measurement accuracy than the conventional apparatus. Can do.

(Other examples)
In the above embodiment, when the three columns 7 are installed at positions outside the ultrasonic transducers 1, 2, 3 when viewed from the center of the holding surface 4, The position of the column 7 that reduces the influence on the measurement accuracy is shown. The position of the support for achieving such an object is not limited to the above embodiment.

  FIG. 4 is a plan view showing the configuration of a reflective ultrasonic anemometer according to another embodiment of the present invention. As shown in this figure, three ultrasonic transducers (ultrasound elements such as electroacoustic transducers) 1, 2, and 3 are respectively provided on the holding surface 4 which is the tip surface of the cylindrical holding body 6. Are arranged so that the centers 1a, 2a, and 3a of each of them coincide with the three vertices of an equilateral triangle indicated by a two-dot chain line.

  In this embodiment, one support column 7 having high hardness such as stainless steel, molybdenum or tungsten protrudes upward from the central portion 4a of the holding surface 4 and is substantially the same as the holding surface 4 at its tip. A reflector having a diameter (not shown) is held. The reflecting plate 5 is supported by a single column 7 so as to face the holding surface 4 in parallel.

  In this case, from the simulation result, the range of the wind direction in which the turbulence by the support always reaches the two ultrasonic wave propagation paths is about 30 ° per support. Since there are three struts 7, the total wind direction range is taken into consideration, which is about 90 ° (= about 30 ° × 3). Therefore, also in the support | pillar arrangement | positioning of a present Example, the measurement error of a wind speed can be made smaller than the prior art of FIG. 6 in the whole wind direction range in a horizontal surface.

  However, it is more desirable that the three columns 7 of the reflecting plate 5 are equally provided as in the embodiment shown in FIG. Since the facing state of the holding surface 4 and the reflecting plate 5 of the ultrasonic element is stable, the reflecting plate 5 vibrates due to the wind, or the facing position relationship with the holding surface 4 changes due to the reflecting plate 5 being blown by the wind. This is because there is no concern of disturbing the wind speed measurement.

  In each of the embodiments described above, a configuration is shown in which the transducers 1, 2, and 3 are arranged on the holding surface 4 with the normals set at the centers of the ultrasonic transducers kept parallel to each other. . However, it is arranged so that each transducer is radiated toward the center of the reflecting plate 5 by arranging the normals standing at the center of each transducer to be slightly inclined so as to cross each other forward. It is also possible to adopt a configuration that does this.

  Further, in each of the above-described embodiments, the case where the surface of the reflector 5 on the side of the transducers 1, 2, 3 is illustrated as being parallel to the holding surface 4, but is convex in a direction away from the holding surface 4. A curved reflecting plate 5 may be formed. When the reflection plate 5 is formed in this way, even if an ultrasonic wave sent from one transducer to another transducer is blown by the wind, depending on the inclination angle of the sound wave reflection surface portion of the reflection plate 5 It becomes easy to enter other transducers and reception efficiency increases.

1, 2, 3 Ultrasonic transducer 4 Holding surface 5 Reflecting plate 6 Holding body 7 Support column

Claims (3)

Three ultrasonic elements,
A holding surface that holds the three ultrasonic elements such that the center of each ultrasonic element coincides with each of the three vertices of an equilateral triangle;
A reflector disposed opposite the holding surface;
Three struts that protrude from the holding surface and support the reflector opposite to the holding surface;
The support column is located outside the ultrasonic element when viewed from the center of the holding surface, and is a positive face facing the side from each side of an equilateral triangle formed by connecting the centers of the three ultrasonic elements. A two-dimensional ultrasonic anemometer, wherein the two-dimensional ultrasonic anemometer is arranged at a position on each vertical line extending through each vertex of a triangle.   2. The two-dimensional ultrasonic anemometer according to claim 1, wherein each of the support columns is disposed at a fixed position from the ultrasonic element.   2. The two-dimensional ultrasonic anemometer according to claim 1, wherein the reflector is configured to bend in a convex shape in a direction away from the holding surface.

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