JP2013130483A - Measuring device and measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device and a measuring method capable of measuring a flow rate or the like at a low cost.SOLUTION: The measuring device includes a processing part having a light source, a measuring part 12 to be floated on a fluid, and an optical fiber 14 disposed so as to reach the measuring part from the processing part. The measuring part has a displacement part 76 to be displaced according to the flow rate of the fluid, and the optical fiber is immersed in the fluid through the displacement part so that an immersion length in the fluid is changed according to the displacement of the displacement part. The processing part obtains the immersion length in the fluid of the optical fiber on the basis of a temperature distribution along a longitudinal direction of the optical fiber measured by introducing light from the light source to the optical fiber, and obtains the flow rate of the fluid on the basis of the obtained immersion length.

Description

  The present invention relates to a measuring apparatus and a measuring method.

  Conventionally, marine weather buoys are known.

  Marine meteorological buoys are equipped with various sensors and can observe water temperature and flow velocity.

JP 2003-14554 A JP 2003-57126 A JP-A-62-110160 JP-A-7-12655 JP-A-2-123304 JP 2002-267242 A

Fujitsu Laboratories Ltd., “Development of real-time multi-point temperature measurement technology for data centers-Contributing to energy saving in large-scale data centers by“ visualization ”of temperature distribution”, [online], April 4, 2008 Sun, Fujitsu Limited, [Search August 17, 2011], Internet <URL: //pr.fujitsu.com/jp/news/2008/04/4.html>

  However, ocean buoys were extremely expensive.

  The objective of this invention is providing the measuring apparatus and measuring method which can measure a flow velocity etc. at low cost.

  According to one aspect of the embodiment, the processing unit having a light source, a measurement unit floated on a fluid, and an optical fiber arranged to reach the measurement unit from the processing unit, the measurement unit, A displacement portion that is displaced according to a flow velocity of the fluid, and the optical fiber is supplied to the fluid via the displacement portion so that an immersion length in the fluid changes according to the displacement of the displacement portion. The immersion portion is immersed in the fluid based on the temperature distribution along the longitudinal direction of the optical fiber measured by introducing light from the light source into the optical fiber. And a flow rate of the fluid is obtained based on the obtained immersion length.

  According to another aspect of the embodiment, the processing unit having a light source, a displacement unit that is displaced according to the flow velocity of the fluid, the measurement unit floating on the fluid, and the measurement unit from the processing unit to reach the measurement unit And a measuring method using a measuring device having an optical fiber immersed in the fluid via the displacement portion so that the immersion length in the fluid changes according to the displacement of the displacement portion. And determining the immersion length of the optical fiber in the fluid based on a temperature distribution along the longitudinal direction of the optical fiber measured by introducing light from the light source into the optical fiber. And determining the flow rate of the fluid based on the immersion length.

  According to the disclosed measurement apparatus and measurement method, the optical fiber is immersed in the fluid via the displacement portion that is displaced according to the flow velocity of the fluid, so that the immersion length of the optical fiber is changed according to the fluid flow velocity. Can do. Also, based on the temperature distribution along the longitudinal direction of the optical fiber measured by introducing light into the optical fiber, the immersion length of the optical fiber in the fluid is obtained, and on the basis of the immersion length of the optical fiber in the fluid The flow rate of the fluid can be obtained. Moreover, it is possible to obtain a measuring device at a relatively low cost. Therefore, it is possible to provide a measuring device that can measure the flow velocity and the like at a low cost.

FIG. 1 is a block diagram showing a measuring apparatus according to the first embodiment. FIG. 2 is a diagram illustrating a processing unit of the measurement apparatus according to the first embodiment. FIG. 3 is a diagram illustrating an example of a spectrum of backscattered light. FIG. 4 is a diagram illustrating an example of an actual temperature distribution in the longitudinal direction of the optical fiber. FIG. 5 is a diagram illustrating an example of a time series distribution of signal intensity of Raman scattered light. FIG. 6 is a diagram showing a temperature distribution in the longitudinal direction of the optical fiber obtained based on the time-series distribution of the intensity of Raman scattered light. FIG. 7 is a diagram (part 1) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution. FIG. 8 is a diagram (part 2) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution. FIG. 9 is a diagram (part 3) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution. FIG. 10 is a perspective view showing a measuring unit of the measuring apparatus according to the first embodiment. FIG. 11 is a side view showing a measurement unit of the measurement apparatus according to the first embodiment. FIG. 12 is a plan view (part 1) illustrating a measurement unit of the measurement apparatus according to the first embodiment. FIG. 13 is a plan view (part 2) illustrating the measurement unit of the measurement apparatus according to the first embodiment. FIG. 14 is a perspective view showing the case. FIG. 15 is a perspective view partially showing the relationship between the slit portion of the case and the optical fiber. FIG. 16 is a partial perspective view showing a guide portion, a bobbin-like floating body, and a fluid flow receiving portion. FIG. 17 is a plan view and a side view showing a bobbin-like floating body. FIG. 18 is a side view and a plan view (part 1) illustrating an example of the operation of the measurement unit. FIG. 19 is a side view and a plan view (part 2) illustrating an example of the operation of the measurement unit. FIG. 20 is a side view and a plan view (part 3) illustrating an example of the operation of the measurement unit. FIG. 21 is a graph showing the relationship between the displacement of the bobbin-like floating body and the fluid flow velocity. FIG. 22 is a diagram (part 4) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution. FIG. 23 is a graph showing a transfer function. FIG. 24 is a perspective view showing a state in which a part of the optical fiber is immersed in water having a predetermined temperature. FIG. 25 is a graph showing an example of the measured temperature distribution. FIG. 26 is a flowchart showing the measurement method according to the first embodiment. FIG. 27 is a diagram illustrating an example of a temperature distribution along the longitudinal direction of the optical fiber. FIG. 28 is a diagram illustrating a part of the memory configuration of the RAM of the processing unit of the measurement apparatus according to the first embodiment. FIG. 29 is a diagram illustrating an example of a temperature distribution model. FIG. 30 is a diagram illustrating a correlation function. FIG. 31 is a perspective view showing a measurement unit of the measurement apparatus according to the second embodiment. FIG. 32 is a flowchart showing a measurement method according to the second embodiment. FIG. 33 is a diagram illustrating an example of a temperature distribution along the longitudinal direction of the optical fiber. FIG. 34 is a block diagram showing a measuring apparatus according to the third embodiment.

[First Embodiment]
A measuring apparatus and a measuring method according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a block diagram showing the measuring apparatus according to the present embodiment.

  The measurement apparatus according to the present embodiment includes, for example, a processing unit 10 disposed on the land 2, a measurement unit 12 disposed so as to float on a fluid 4 such as seawater, and an optical fiber 14 used as a probe. .

  Here, the case where the number of measurement units 12 floating on the fluid 4 is one will be described as an example. However, the number of measurement units 12 is not limited to one, and may be set as needed. obtain.

  FIG. 2 is a diagram illustrating a processing unit of the measurement apparatus according to the present embodiment.

  As shown in FIG. 2, the processing unit 10 includes a CPU (Central Processing Unit) 16, a ROM (Read-Only Memory) 18, a RAM (Random Access Memory) 20, an HDD (Hard Disk Drive) 22, and an input. A unit 24, a display unit 26, and an interface 28 are included. The processing unit 10 includes a laser light source 30, lenses 32 a and 32 b, a beam splitter 34, a wavelength separation unit 36, and a photodetector 38. The processing unit 10 can be connected to a network 40 such as a LAN (Local Area Network) or the Internet via a communication line.

  The CPU 16 governs overall control of the processing unit 10. The ROM 18 stores a boot program and the like. The RAM 20 is used as a work area for the CPU 16. A HDD (storage device, storage means) 22 stores a computer program and the like for executing predetermined processing. In addition, the HDD 22 stores measurement results and the like by the measurement apparatus according to the present embodiment. As the input unit 24, for example, a keyboard or the like is used. As the display device 26, for example, a liquid crystal display or the like is used.

  Laser light having a predetermined pulse width is output from the laser light source 30. Laser light is introduced into the optical fiber 14 from the light source side end of the optical fiber 14 through the lens 32a, the beam splitter 34, and the lens 32b.

  The optical fiber 14 has a core 42 and a clad 44 formed around the core 42.

  When laser light is introduced into the optical fiber 14, part of the laser light introduced into the optical fiber 14 is backscattered by molecules constituting the optical fiber 14 (backscattered light).

  FIG. 3 is a diagram illustrating an example of a spectrum of backscattered light.

  As shown in FIG. 3, the backscattered light includes Rayleigh scattered light, Brillouin scattered light, and Raman scattered light. Rayleigh scattered light is light having the same wavelength as incident light. Brillouin scattered light and Raman scattered light are light having a wavelength shifted from the incident wavelength.

  The Raman scattered light includes Stokes light shifted to a longer wavelength side than incident light and anti-Stokes light shifted to a shorter wavelength side than incident light. The amount of shift of Stokes light and anti-Stokes light depends on the wavelength of the laser light, the material constituting the optical fiber, etc., but is usually about 50 nm. The intensity of Stokes light and anti-Stokes light both vary with temperature, but the amount of change in Stokes light is small, and the amount of change in anti-Stokes light is large. That is, Stokes light has a small temperature dependency, and anti-Stokes light has a large temperature dependency.

  These backscattered light travels in a direction opposite to the laser light introduction direction and is emitted from the end of the optical fiber 14 on the light source side. Backscattered light emitted from the end of the optical fiber 14 on the light source side is transmitted through the lens 32 b, reflected by the beam splitter 34, and introduced into the wavelength separation unit 36.

  The wavelength separation unit 36 is provided with beam splitters 46a to 46c that transmit or reflect light according to the wavelength, and optical filters 48a to 48c that transmit only light of a specific wavelength. In addition, the wavelength separation unit 36 is provided with condensing lenses 50a to 50c for condensing the light transmitted through the optical filters 48a to 48c on the light receiving units 52a to 52c of the photodetector 38, respectively.

  The light incident on the wavelength separation unit 36 is separated into Rayleigh scattered light, Stokes light, and anti-Stokes light by the beam splitters 46a to 46c and the optical filters 48a to 48c, and input to the light receiving units 52a to 52c of the photodetector 38, respectively. The As a result, signals corresponding to the intensity of Rayleigh scattered light, Stokes light, and anti-Stokes light are output from the light receiving units 52a to 52c.

  The CPU 10 performs predetermined signal processing on the signal detected by the light detection unit 38 and obtains a temperature distribution (temperature distribution data) along the longitudinal direction of the optical fiber 14 as follows.

  As described above, since the Stokes light has a small temperature dependency and the anti-Stokes light has a large temperature dependency, it is possible to obtain the temperature at the position where the backscattering occurs based on the ratio of the two intensities.

The ratio of the Stokes light intensity Is _(Stokes) to the anti-Stokes light intensity Is _{(anti-Stokes)} is expressed by the following equation (1). In Equation (1), ω _k is the angular frequency of the optical phonon in the optical fiber, ω ₀ is the angular frequency of the incident light, h is the Planck constant, k is the Boltzmann constant, and T is Temperature.

( _{Is (anti-Stokes)} / Is _(Stokes) ) = {(ω ₀ + ω _k ) / (ω ₀ −ω _k )} ⁴ × exp (−hω _k / 2πkT) (1)
Therefore, if the intensity ratio between Stokes light and anti-Stokes light is known, the temperature at the position where the backscattering occurs can be calculated based on Equation (1).

  By the way, the backscattered light generated in the optical fiber 14 is attenuated in the process of traveling toward the light source side end of the optical fiber 14. For this reason, attenuation of light is considered in order to correctly obtain the temperature at the position where the backscattering occurs.

  FIG. 4 is a diagram illustrating an example of an actual temperature distribution in the longitudinal direction of the optical fiber. The horizontal axis in FIG. 4 indicates the distance. The vertical axis | shaft of FIG. 4 has shown temperature.

  A high temperature part, a low temperature part, and a high temperature part exist in order in a part of the path where the optical fiber 14 is installed.

  FIG. 5 is a diagram showing an example of a time series distribution of signal intensity of Raman scattered light obtained when the actual temperature distribution is as shown in FIG. The horizontal axis in FIG. 5 indicates time. The vertical axis in FIG. 5 indicates the signal intensity of the Stokes light and the anti-Stokes light detected by the photodetector 38 when pulsed laser light (laser pulse) is incident on the optical fiber 14.

  When the actual temperature distribution is as shown in FIG. 4, that is, when a high temperature portion, a low temperature portion, and a high temperature portion are sequentially present in a part of the path where the fiber 14 is laid, Stokes light and anti-Stokes light are present. The signal intensity of light exhibits a behavior as shown in FIG.

  The time shown on the horizontal axis in FIG. 5 corresponds to the distance from the end of the optical fiber on the light source side to the position where backscattering occurs.

  The decrease in signal intensity with time is due to attenuation when backscattered light travels toward the light source side end of the optical fiber 14.

Note that I ₁ in FIG. 5 indicates the intensity of the anti-Stokes light at a certain time t. Further, I ₂ in FIG. 5 indicates the intensity of Stokes light at a certain time t.

  FIG. 6 is a diagram showing a temperature distribution in the longitudinal direction of the optical fiber obtained based on the time-series distribution of the intensity of Raman scattered light. The horizontal axis in FIG. 6 indicates the distance. The vertical axis | shaft of FIG. 6 has shown temperature.

6 calculates the I ₁ / I ₂ ratio for each time based on the time series distribution of the signal intensity of Raman scattered light as shown in FIG. 5, and the horizontal axis (time) in FIG. It is obtained by converting and converting the vertical axis (signal intensity) in FIG. 5 into temperature.

Thus, by calculating the intensity ratio (I ₁ / I ₂ ) between the anti-Stokes light and the Stokes light, the temperature distribution in the length direction of the optical fiber can be obtained.

The pulse width (ON time) t ₀ of laser light emitted from the laser light source 30 is 10 nsec, the speed c of light in vacuum is 3 × 10 ⁸ m / sec, and the refractive index n of the core 44 of the optical fiber 14 is 1. Assuming 5, the pulse width W of the laser light in the optical fiber 14 is about 2 m as shown in the following formula (2).

W = t ₀ · c / n = 10 (nsec) · 3 × 10 ⁸ (m / sec) /1.5≈2 (m) (2)
Backscattered light generated when laser light is introduced into the optical fiber is detected as a signal by the photodetector 38 as described above. The CPU 16 obtains the temperature of each location based on the integrated value of the signal corresponding to the pulse width detected by the photodetector 38. Since the temperature is obtained based on the integrated value corresponding to the pulse width of the signal detected by the photodetector 38, the temperature distribution thus obtained (hereinafter referred to as “measured temperature distribution”) includes a high temperature portion, a low temperature portion, and a high temperature portion. In the vicinity of the boundary, it changes relatively slowly.

  FIG. 7 is a diagram (part 1) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution.

  FIG. 7A shows an example of an actual temperature distribution. A high temperature part, a low temperature part, and a high temperature part are located in order.

  The length L indicates the length of the portion of the optical fiber 14 located at the low temperature portion.

  When the length L of the portion located in the low temperature portion of the optical fiber 14 is not sufficiently long with respect to the pulse width W of the laser light, the measured temperature distribution is as shown in FIG. It becomes an approximately normal distribution curve.

  FIG. 8 is a diagram (part 2) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution.

  FIGS. 8A and 8B show a case where the length L of the optical fiber 14 located in the low temperature portion is shorter than the pulse width W of the laser light. In such a case, the lowest value (extreme value or minimum value) in the low temperature part of the measured temperature distribution is higher than the actual temperature.

  FIG. 8C shows a case where the length L of the optical fiber 14 located in the low temperature part is equal to the pulse width W of the laser light. In such a case, the minimum value in the low temperature part of the measured temperature distribution is equivalent to the actual temperature.

  FIG. 9 is a diagram (part 3) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution. The horizontal axis in FIG. 9 indicates the distance. The vertical axis in FIG. 9 indicates the temperature. The step-type temperature distribution in FIG. 9 shows an example of an actual temperature distribution. The temperature distribution having a substantially normal distribution in FIG. 9 indicates the measured temperature distribution. The temperature distribution indicated by the solid line in FIG. 9 indicates a case where the length L of the optical fiber 14 located in the low temperature part is 40 cm. The temperature distribution indicated by the broken line in FIG. 9 indicates a case where the length L of the optical fiber 14 located in the low temperature part is 1 m. The temperature distribution indicated by the alternate long and short dash line in FIG. 9 indicates the case where the length L of the optical fiber 14 located in the low temperature portion is 1.6 m. In FIG. 9, the temperature distribution indicated by the two-dot chain line indicates a case where the length L of the optical fiber 14 located in the low temperature portion is 2.2 m. FIG. 9 corresponds to the case where the temperature in the case described later is 25.4 ° C. and the water temperature is 20 ° C.

  As can be seen from FIG. 9, when the length of the optical fiber 14 in the low temperature part is shorter than about 2 m which is the pulse width W of the laser light, the minimum value in the low temperature part of the measured temperature distribution is lower than the actual temperature. Also gets higher.

  On the other hand, when the length of the optical fiber 14 in the low temperature part is equal to or greater than the pulse width W of the laser light, the minimum value in the low temperature part of the measured temperature distribution is equivalent to the actual temperature.

  FIG. 10 is a perspective view illustrating a measurement unit of the measurement apparatus according to the present embodiment. FIG. 11 is a side view showing the measurement unit of the measurement apparatus according to the present embodiment. FIG. 12 is a plan view (part 1) illustrating the measurement unit of the measurement apparatus according to the present embodiment. FIG. 13 is a plan view (part 2) illustrating the measurement unit of the measurement apparatus according to the present embodiment.

  As shown in FIG. 10, floating bodies (buoys) 56 a to 56 d are arranged at the four corners of the base (base) 54 of the measurement unit 12. The floating bodies 56a to 56d are for imparting buoyancy to the base 54 of the measurement unit 12 and floating the measurement unit 12 in the fluid.

  The front side of the paper surface in FIG. 10 is the front side of the measurement unit 12, and the back side of the paper surface in FIG. 10 is the rear side of the measurement unit 12.

  The two floating bodies 56c and 56d on the rear side of the base 54 are connected to each other by a frame member (joint) 58a. As shown in FIG. 12, both ends of the frame member 58a are fixed to the sides of the floating bodies 56c and 56d, respectively.

  The two floating bodies 56c and 56d on the rear side of the base 54 are connected to each other by a frame member (joint) 58b. Both ends of the frame member 58b are fixed to the upper portions of the floating bodies 56c and 56d, respectively. The frame member 58b not only connects the two rear floating bodies 56c and 56d to each other but also hooks band-shaped members 90a and 90b described later.

  The right front floating body 56a and the right rear floating body 56c are connected to each other by a frame member (joint) 58c. Both ends of the frame member 58c are fixed to the sides of the floating bodies 56a and 56c, respectively.

  The left front floating body 56b and the left rear floating body 56d are connected to each other by a frame member (joint) 58d. Both ends of the frame member 58d are fixed to the sides of the floating bodies 56b and 56d, respectively.

  For example, cylindrical members are used as the frame members 58a to 58d. As a material for the frame members 58a to 58d, for example, fiber reinforced plastics (FRP) are used. The diameter of the frame members 58a to 58d is, for example, about 60 mm. The thickness of the frame members 58a to 58d is, for example, about 2 mm. The length of the frame members 58a to 58d is, for example, about 1200 mm.

  The floating bodies 56a to 56d are formed of, for example, a hollow body. The outer shapes of the floating bodies 56a to 56d are, for example, substantially cylindrical. The diameter of the floating bodies 56a to 56d is, for example, about 300 mm. The height of the front floating bodies 56a and 56b is about 200 mm, for example. The height of the rear floating bodies 56c and 56d is, for example, about 160 mm. The thickness of the floating bodies 56a to 56d is, for example, about 2 mm. A weight (not shown) for adjusting buoyancy may be incorporated in the floating bodies 56a to 56d. The floating bodies 56a to 56d are fixed to the seabed (not shown) or the like using a chain 60 or the like. As a material of the floating bodies 56a to 56d, for example, polyethylene or the like can be used.

  The means used for fixing the floating bodies 56a to 56d to the seabed or the like is not limited to the chain 60. For example, the floating bodies 56a to 56d may be fixed to the seabed using a rope or the like.

  The floating bodies 56a to 56d and the frame members 58a to 58d are fixed using, for example, a fixing member (fixing element) such as a bolt (not shown).

  Columnar members (spacers) 62a to 62d are attached to the upper parts of the floating bodies 56a to 56d, respectively. The columnar members 62a to 62d are formed of a hollow body. The height of the columnar members 62a and 62b attached on the two front floating bodies 56a and 56b is set higher than the height of the columnar members 62c and 62d attached on the two rear floating bodies 56c and 56d. . The columnar members 62a to 62d are fixed to the floating bodies 56a to 56d using a fixing member (fixing element) such as a bolt (not shown), for example. The diameter of the columnar members 62a to 62d is, for example, about 100 mm. The height of the front columnar members 62a and 62b is, for example, about 100 mm. The height of the columnar members 62c and 62d on the rear side is about 20 mm, for example. The thickness of the columnar members 62a to 62d is, for example, about 2 mm.

  A frame member (pedestal) 64a is disposed on the two front floating bodies 56a and 56b to which the columnar members 62a and 62b are respectively attached. Both ends of the frame member 64a are connected to the floating bodies 56a and 56b via columnar members 62a and 62b, respectively.

  A frame member (pedestal) 64b is arranged on the two rear floating bodies 56c and 56d to which the columnar members 62c and 62d are attached. Both ends of the frame member 64b are connected to floating bodies 56c and 56d via columnar members 62c and 62d, respectively.

  As a material of the frame members 64a and 64b, for example, stainless steel or the like is used. The outer dimensions of the frame members 64a and 64b are, for example, about 100 mm × 1.2 m × 2 mm. The frame members 64a and 64b and the columnar members 62a to 62d are fixed using, for example, a fixing member (fixing element) such as a bolt (not shown).

  Thus, the base 54 of the measurement unit 12 is formed by appropriately combining the frame members 58a to 58d, 64a and 64b, the floating bodies 56a to 56d, and the like.

  A case (heat insulation case) 66 is attached to the base 54 of the measurement unit 12.

  FIG. 14 is a perspective view showing the case. FIG. 15 is a perspective view partially showing the relationship between the slit portion of the case and the optical fiber.

  The case 66 is for blocking the outside air and forming a portion where the temperature is greatly different from the temperature of the fluid 4. A slit (not shown) for passing the optical fiber 14 is formed on the side of the case 66. Further, two slits 68 a and 68 b for passing the optical fiber 14 are formed in parallel on the bottom surface (bottom portion) of the case 66. The slits 68a and 68b are used for introducing the optical fiber 14 from the outside of the case 66 to the inside while securing the sealing property (heat retention) of the case 66, or for drawing the optical fiber 14 from the inside of the case 66 to the outside. Is. The longitudinal direction of the slits 68 a and 68 b formed on the bottom surface of the case 66 coincides with, for example, the longitudinal direction of the case 66. The outer dimension of the case 66 is, for example, about 2000 mm × 500 mm × 120 mm. The length of the slits 68a and 68b formed on the bottom surface of the case 66 is, for example, about 190 mm. As a material of the case 66, for example, polyethylene or the like is used. The thickness of the case 66 is about 2 mm, for example. For example, urethane or rubber is used as the material of the members 70a and 70b where the slits 68a and 68b are formed.

  The bottom of the rear side of the case 66 is fixed on the frame member 64b. The case 66 is fixed using, for example, a fixing member (fixing element) such as a bolt (not shown).

  A portion of the case 66 located below the frame member 64a is fixed to the lower surface side of the frame member 64a. Thus, the case 66 is supported so as to be suspended from the frame member 64a. The case 66 and the frame member 64a are fixed using, for example, a fixing member (fixing element) such as a bolt (not shown).

  Guide portions (floating bobbin guides, guide mechanisms) 72 a and 72 b are provided on both sides of the bottom portion of the case 66 so as to extend along the longitudinal direction of the case 66. The guide portions 72 a and 72 b are for displacing the bobbin-like floating body 76 along the longitudinal direction of the case 66. As the material of the guide portions 72a and 72b, for example, polyethylene or the like is used. The guide portions 72a and 72b and the case 66 are integrally molded, for example. The diameters of the guide portions 72a and 72b are, for example, about 60 mm. The length of the guide parts 72a and 72b is, for example, about 2000 mm.

  FIG. 16 is a partial perspective view showing a guide portion, a bobbin-like floating body, and a fluid flow receiving portion.

  As shown in FIG. 16, grooves 74a and 74b are formed in the guide portions 72a and 72b along the longitudinal direction of the guide portions 72a and 72b. The grooves 74 a and 74 b are for displacing the bobbin-like floating body 76 along the longitudinal direction of the case 66. The width of the grooves 74a and 74b is, for example, about 15 mm. The depth of the grooves 74a and 74b is, for example, about 20 mm.

  A bobbin-like floating body (floating bobbin) 76 is disposed below the case 66.

  FIG. 17 is a plan view and a side view showing a bobbin-like floating body. FIG. 17A is a plan view, and FIG. 17B is a side view.

  The bobbin-like floating body 76 is formed of a hollow body, and has a cylindrical portion 78 and plate-like portions 80 a and 80 b formed at both ends of the cylindrical portion 78. The cylindrical portion 78 and the plate-like portions 80a and 80b are integrally formed, for example. Two concave portions (grooves) 82 a and 82 b are formed in the cylindrical portion 78 along the outer periphery of the cylindrical portion 78. The recesses 82a and 82b are for guiding the optical fiber 14 drawn out from the case 66, and for preventing the optical fiber 14 from moving in the longitudinal direction of the cylindrical portion 78. . The plate-like portions 80a and 80b are respectively engaged with the grooves 74 and 74b of the guide portions 72a and 72b, and are formed into bobbin shapes along the longitudinal direction of the case 66, that is, along the longitudinal direction of the slits 68a and 68b. This is for displacing the floating body 76. The bobbin-like floating body 76 preferably does not rotate when displaced along the longitudinal direction of the slits 68a and 68b. For this reason, the planar shape of the plate-like portions 80a and 80b is substantially rectangular. A bobbin-like floating body 76 may have a built-in weight for adjusting buoyancy. The diameter of the cylindrical portion 78 is, for example, about 80 mm. The length of the cylindrical portion 78 is, for example, about 300 mm. The dimensions of the plate-like portions 80a and 80b are about 200 mm × 120 mm × 10 mm. Fillets are applied to the corners of the plate-like portions 80a and 80b. The fillet radius is, for example, about 30 mm.

  The planar shape of the plate-like portions 80a and 80b is not limited to a substantially rectangular shape. For example, the planar shape of the plate-like portions 80a and 80b may be substantially elliptical.

  A fluid receiving portion (sea current receiving portion, water flow receiving portion) 84 is attached to the bobbin-like floating body 76. The fluid flow receiving portion 84 is for receiving a force corresponding to the flow velocity from the fluid and displacing the bobbin-like floating body 76 according to the flow velocity of the fluid. The fluid receiving portion 84 includes a fluid receiving member (sea current receiving member, water receiving member) 86 for receiving a force corresponding to the flow velocity, and a support member 88 for supporting the fluid receiving member 86. Yes. The shape of the support member 88 is, for example, a square shape. A side portion of the fluid flow receiving member 86 is fixed to the support member 88. The fluid flow receiving member 86 is formed of, for example, a sheet in which a plurality of holes 89 are formed. As a material for such a sheet, for example, nylon or the like is used.

  For example, the following two specific examples of the dimensions of the fluid receiving member 86 are conceivable.

  In the first specific example, the dimension of the fluid receiving member 86 is, for example, about 450 mm × 400 mm × 0.3 mm.

  In the second specific example, the dimension of the fluid receiving member 86 is, for example, about 1000 mm × 1000 mm × 0.3 mm.

  The support member 88 is made of a material having higher rigidity than the fluid receiving member 86. As a material of the support member 88, for example, stainless steel or the like is used. The bobbin-like floating body 76 and the fluid flow receiving portion 84 are fixed using, for example, a fixing member (fixing element) such as a bolt (not shown).

  The fluid receiving member 86 is not limited to a member in which the hole 89 is formed. For example, a net-like member may be used as the fluid flow receiving member 86.

  Band-shaped members 90a and 90b are attached to the bobbin-like floating body 76 (see FIG. 13). These band-shaped members 90a and 90b are arranged in parallel to each other along the longitudinal direction of the slits 68a and 68b of the case 66. The sheet-like members 90a and 90b are hooked on the frame member 56b (see FIG. 11). Front ends of the band-shaped members 90 a and 90 b are attached to a cylindrical portion 78 of the bobbin-like floating body 76. A weight (balancer) 92 is attached to the rear end of the belt-shaped member. The weight 92 is formed in a cylindrical shape. The front end portion of the right band-shaped member 90 a is fixed to the right side of the cylindrical portion 78 of the bobbin-like floating body 76. The front end of the left band-shaped member 90 b is fixed to the left side of the cylindrical portion 78 of the bobbin-like floating body 76. The rear end portion of the right band-shaped member 90 a is attached to the right portion of the weight 92. The rear end of the left band-shaped member 90 b is attached to the left portion of the weight 92.

  Both ends of the bobbin-like floating body 76 are supported by the base 54 via elastic bodies 94a and 94b, respectively. More specifically, both ends of the bobbin-like floating body 76 are supported by the front floating bodies 56a and 56b via elastic bodies 94a and 94b, respectively. For example, rubber or the like can be used as the elastic bodies 94a and 94b. Examples of such rubber include silicone rubber and natural rubber to which carbon is added.

  The elastic bodies 94a and 94b are not limited to rubber. For example, a spring or the like may be used as the elastic bodies 94a and 94b.

  The optical fiber (optical fiber cable) 14 is laid so as to reach the measurement unit 12 from the processing unit 10 (see FIG. 1).

  The optical fiber 14 reaching the measuring unit 12 is wound around a winding member 96 disposed at a predetermined position of the measuring unit 12, and further wound around the winding member 98, and a slit (not shown) on the side of the case 66 is provided. Through the case 66. The optical fiber 14 introduced into the case 66 is wound around the winding member 100 disposed in the case 66. A portion of the optical fiber 14 wound around the winding member 100 in the case 66 is used as a portion for measuring the temperature in the case 66. The length of the portion of the optical fiber 14 that is wound around the winding member 100 is preferably set to be sufficiently longer than the pulse width W of the laser light so as to reliably measure the temperature in the case 66. Here, the length of the portion of the optical fiber 14 wound around the winding member 100 is, for example, about 4 m.

  After the optical fiber 14 is wound around the winding member 100 as described above, the optical fiber 14 is pulled out of the case 66 through a slit (not shown) formed in the side portion of the case 66, and a predetermined portion of the measurement unit 12 is drawn. It is wound around the winding member 102 arranged on the head. A portion of the optical fiber 14 wound around the winding member 102 is used as a portion for measuring the temperature of air (atmosphere) outside the case 66. The length of the portion of the optical fiber 14 that is wound around the winding member 102 is preferably set sufficiently longer than the pulse width W of the laser light so as to reliably measure the temperature of the air outside the case 66. Here, the length of the portion of the optical fiber 14 that is wound around the winding member 102 is, for example, about 4 m, similarly to the winding member 100.

  After the optical fiber 14 is wound around the winding member 102 as described above, the optical fiber 14 is introduced into the case 66 through a slit (not shown) formed in the side portion of the case 66 and is arranged in the case 66. It is wound around the winding member 104. The length of the portion of the optical fiber 14 that is wound around the winding member 104 corresponds to the portion that measures the temperature of the high-temperature portion described above with reference to FIGS. 6 and 7. Therefore, the length of the portion of the optical fiber 14 wound around the winding member 104 is preferably set sufficiently longer than the pulse width W of the laser light. Here, the length of the portion of the optical fiber 14 wound around the winding member 104 is, for example, about 4 m.

  After the optical fiber 14 is wound around the winding member 104 again as described above, the optical fiber 14 is drawn out of the case 66 through the slit 68 a formed in the case 66. The optical fiber 14 drawn out to the outside of the case 66 through the slit 68 a is wound around a winding member (target) 106 to which a weight (tip weight) (not shown) is attached, and through the slit 68 b formed in the case 66. Introduced inside the case 66. The optical fiber 14 introduced into the case 66 is wound around a winding member 108 disposed in the case 66. The length of the portion of the optical fiber 14 that is wound around the winding member 106 corresponds to the portion that measures the temperature of the low temperature portion described above with reference to FIGS. 6 and 7. Therefore, the length of the portion of the optical fiber 14 that is wound around the winding member 106 is preferably set sufficiently longer than the pulse width W of the laser light. Here, the length of the portion of the optical fiber 14 wound around the winding member 106 is, for example, about 4 m. The length of the portion of the optical fiber 14 that is wound around the winding member 108 corresponds to the portion that measures the temperature of the high temperature portion described above with reference to FIGS. 6 and 7. Therefore, the length of the portion of the optical fiber 14 wound around the winding member 108 is preferably set sufficiently longer than the pulse width W of the laser light. Here, the length of the portion of the optical fiber 14 that is wound around the winding member 108 is, for example, about 4 m, similarly to the winding member 104.

  After the optical fiber 14 is wound around the winding member 108 as described above, the optical fiber 14 is drawn out of the case 66 through a slit (not shown) formed in the side portion of the case 66. The optical fiber 14 drawn out of the case 66 is wound around the winding member 98, and further wound around the winding member 96, and is laid so as to reach other measurement units as necessary.

  When no other measurement unit is provided, the end of the optical fiber 14 may be located on the measurement unit 12.

  The winding member 106 to which the weight is attached is immersed in the fluid 4 together with the optical fiber 14. At this time, the optical fiber 14 is arranged so as to pass through the bobbin-like floating body 76. More specifically, the optical fiber 14 is disposed so as to engage with the concave portions 82a and 82b of the bobbin-like floating body 76.

  The mass of the weight 92 attached to the rear end portions of the band-shaped members 90a and 90b is set so as to be balanced when no fluid flows.

  FIG. 18 is a side view and a plan view (part 1) illustrating an example of the operation of the measurement unit. FIG. 18A is a side view, and FIG. 18B is a plan view.

  FIG. 18 shows a case where no fluid flow occurs. As shown in FIG. 18, when no fluid flows, the bobbin-like floating body (displacement part) 76 is located at the reference position. That is, when no fluid flow occurs, the displacement of the bobbin-like fluid 76 becomes zero.

  FIG. 19 is a side view and a plan view (part 2) illustrating an example of the operation of the measurement unit. FIG. 19A is a side view, and FIG. 19B is a plan view.

  FIG. 19 shows a case where a fluid flow is generated from the front side to the rear side of the measurement unit 12. As shown in FIG. 19, when a fluid flow is generated from the front side to the rear side of the measurement unit 12, the bobbin-like floating body 76 is arranged on the rear side of the measurement unit 12 according to the fluid flow rate. It is displaced to.

  FIG. 20 is a side view and a plan view (part 3) illustrating an example of the operation of the measurement unit. FIG. 20A is a side view, and FIG. 20B is a plan view.

  FIG. 20 shows a case where a fluid flow is generated from the rear side to the front side of the measurement unit 12. As shown in FIG. 20, when a fluid flow is generated from the rear side to the front side of the measurement unit 12, the bobbin-like floating body 76 moves to the front side of the measurement unit 12 according to the flow rate of the fluid. Displace.

  Thus, the bobbin-like floating body (displacement part) 76 is displaced according to the flow velocity of the fluid.

  FIG. 21 is a graph showing the relationship between the displacement of the bobbin-like floating body and the fluid flow velocity. FIG. 21A corresponds to the case where the dimension of the fluid receiving member 86 is the first specific example, that is, about 450 mm × 400 mm × 0.3 mm, for example. FIG. 21B corresponds to the case where the dimension of the fluid receiving member 86 is the second specific example, that is, about 1000 mm × 1000 mm × 0.3 mm, for example.

  As shown in FIGS. 21A and 21B, the bobbin-like floating body 76 is displaced according to the flow velocity of the fluid.

  Further, the displacement of the bobbin-like floating body 76 increases according to the area of the fluid flow receiving member 86.

  The relationship between the displacement of the bobbin-like floating body 76 and the fluid flow velocity may be obtained by actual measurement, or may be calculated by simulation or the like. Further, as will be described later, the relationship between the displacement of the bobbin-like floating body (displacement portion) 76 and the flow velocity of the fluid can be obtained by calculation.

  The bobbin-like floating body 76 is displaced according to the flow rate of the fluid as described above. When the bobbin-like floating body 76 is displaced, the immersion length of the optical fiber 14 immersed in the fluid changes. Therefore, the immersion length of the optical fiber 14 changes according to the flow rate of the fluid.

  Since the immersion length of the optical fiber 14 changes according to the displacement of the bobbin-like floating body 76, if the relationship between the displacement of the bobbin-like floating body 76 and the fluid flow velocity is obtained in advance, the immersion length of the optical fiber 14 is determined. Thus, the flow rate of the fluid can be obtained.

  The measuring apparatus according to the present embodiment can determine the fluid flow velocity based on the immersion length of the optical fiber 14.

  When the immersion length of the optical fiber 14 in the fluid is equal to the pulse width W of the laser light, the measured temperature distribution is, for example, a distribution as shown in FIG. That is, the minimum value in the measured temperature distribution is equivalent to the temperature of the fluid, but the length L of the low temperature portion, that is, the length (immersion length) L of the portion where the optical fiber 14 is immersed in the fluid is shown in FIG. It is difficult to obtain uniquely from the measured temperature distribution as shown in FIG.

  FIG. 22 is a diagram (part 4) illustrating an example of a relationship between an actual temperature distribution and a measured temperature distribution.

  If the immersion length of the optical fiber 14 in the fluid is set sufficiently long with respect to the pulse width W of the laser light, the measured temperature distribution as shown in FIG. 22 is obtained. It is difficult to uniquely determine the length L, that is, the immersion length L of the optical fiber 14.

  Therefore, in the present embodiment, the transfer function is obtained in advance, and the immersion length of the optical fiber 14 is obtained by performing processing as described later.

  FIG. 23 is a graph showing a transfer function.

  Such a transfer function can be obtained as follows.

  FIG. 24 is a perspective view showing a state in which a part of the optical fiber is immersed in water having a predetermined temperature.

  As shown in FIG. 24, water 112 having a predetermined temperature is put into the container 110.

  Then, a part of the optical fiber 14 is immersed in the water 112.

  The actual temperature distribution along the longitudinal direction of the optical fiber 14 can be obtained from the temperature of the water 112 in which the optical fiber 14 is immersed and the temperature in the air.

  Then, the optical fiber 14 is connected to the processing unit 10 of the measuring apparatus according to the present embodiment, pulsed laser light is introduced into the optical fiber 14, and the temperature distribution along the longitudinal direction of the optical fiber 14 as described above. (Measurement temperature distribution) is obtained.

  FIG. 25 is a graph showing an example of the measured temperature distribution. The horizontal axis in FIG. 25 indicates the distance, and the vertical axis in FIG. 25 indicates the temperature. FIG. 25 is a measured temperature distribution obtained with the optical fiber 14 set as shown in FIG.

  The temperature distribution obtained by convolving the transfer function with the actual temperature distribution is theoretically the same temperature distribution as the measured temperature distribution. Accordingly, it is possible to obtain a transfer function based on the actual temperature distribution and the measured temperature distribution.

  Next, the measurement method according to the present embodiment will be described.

  FIG. 26 is a flowchart showing the measurement method according to the present embodiment.

  First, a laser beam is emitted in a pulse form from the laser light source 30 in accordance with a command from the CPU 16. Laser light emitted from the laser light source 30 is introduced into the optical fiber 14 via the lenses 32a and 32b, the beam splitter 34, and the like. When laser light is introduced into the optical fiber 14, the laser light is backscattered by molecules in the optical fiber 14. The backscattered light travels toward the light source side end of the optical fiber 14 and is emitted from the light source side end of the optical fiber 14. Then, it is reflected by the beam splitter 34 and enters the photodetector 38 through the wavelength filter 36. The CPU 16 obtains the temperature distribution (measured temperature distribution) along the longitudinal direction of the optical fiber 14 as described above based on the backscattered light detected by the photodetector 38 (step S1).

  FIG. 27 is a diagram illustrating an example of a temperature distribution along the longitudinal direction of the optical fiber. The horizontal axis in FIG. 27 indicates the distance (position), and the vertical axis in FIG. 27 indicates the temperature. The solid line in FIG. 27 shows an example of the actual temperature distribution, and the broken line in FIG. 27 shows an example of the measured temperature distribution. Moreover, the code | symbol 96,98,100,102,104,106,108 in FIG. 27 has shown each winding member.

  Next, the CPU 16 determines the temperature of the air inside the case 66 (in-case temperature), the temperature of the air outside the case 66 (air temperature), and the temperature of the fluid (seawater) based on the measured temperature distribution (fluid). Temperature) is obtained (step S2). The temperature at the location where the winding member 100 is located is used as the case internal temperature (internal case reference temperature). Moreover, the temperature of the location where the winding member 102 is located is used as an air temperature (air reference temperature). Further, the temperature at the location where the winding member 106 is located is used as the fluid temperature (fluid reference temperature).

  Next, CPU16 sets the value of immersion length L in the temperature distribution model (temperature distribution model function) mentioned later to the maximum immersion length Lmax (step S3). The maximum immersion length Lmax is an immersion length when the optical fiber 14 immersed using the winding member 106 with a weight is immersed in the maximum length. The value of the set immersion length L is stored in an immersion length memory (see FIG. 28) provided in the RAM 20.

  FIG. 28 is a diagram showing a part of the memory configuration of the RAM of the processing unit of the measuring apparatus according to the present embodiment.

  Next, the CPU 16 creates a temperature distribution model (temperature distribution model function) based on the in-case temperature, the fluid temperature, and the set immersion length L (step S4).

  FIG. 29 is a diagram illustrating an example of a temperature distribution model.

  Next, a calculation result is obtained by convolving a transfer function with the created temperature distribution model (step S5). Such a transfer function is obtained in advance as described above with reference to FIGS.

  Next, a correlation function (autocorrelation function) between the calculation result obtained by convolving the transfer function with the temperature distribution model and the temperature distribution (measured temperature distribution) obtained based on the backscattered light is obtained (step S6). ).

  Next, it is determined whether or not the obtained peak value of the correlation function is a past maximum (step S7). Here, the past maximum means the maximum in the flow velocity measurement process performed this time, and does not include the previously performed flow velocity measurement process.

  FIG. 30 is a diagram illustrating a correlation function (autocorrelation function). The horizontal axis in FIG. 30 indicates the position in the length direction of the optical fiber, and the vertical axis in FIG. 30 indicates the magnitude of the correlation function, that is, how much matching is shown as the reference waveform.

  The solid line in FIG. 30 shows a case where the created temperature distribution model approximates the actual temperature distribution. On the other hand, the broken line in FIG. 30 shows a case where the created temperature distribution model is significantly different from the actual temperature distribution.

  As shown in FIG. 30, the peak value of the correlation function increases as the created temperature distribution model approximates the actual temperature distribution.

  In other words, the higher the correlation function peak value, the closer the temperature distribution model and the actual temperature distribution.

  When the peak value of the obtained correlation function is the maximum in the past, the peak value and the immersion length L in the temperature distribution model are stored in, for example, a correlation function peak value memory provided in the RAM 20 (see FIG. 28). (Step S8).

  Next, it is determined whether or not the number of times the loop processing has been performed is equal to or greater than a predetermined number of loops (step S9). If the number of times the loop processing has been performed is equal to or less than the predetermined number of loops, a predetermined length ΔL is subtracted from the immersion length L stored in the immersion length memory (see FIG. 28) (step S10).

  Thereafter, the loop processing from step S4 to step S10 is repeatedly performed until the predetermined number of loops is completed. That is, the temperature distribution model (temperature distribution model function) in which the value of the immersion length L is changed is sequentially created, and the above processing is sequentially performed.

  The immersion length L stored in the correlation function peak value memory (see FIG. 28) is the immersion length L in the temperature distribution model when the correlation function reaches the maximum in the past. Since the temperature distribution model when the correlation function is the maximum in the past is the closest to the actual temperature distribution, the immersion length in the temperature distribution model when the correlation function is the maximum in the past is estimated as the actual immersion length (step S11).

  Next, the flow velocity is obtained based on the immersion length as follows (step S12).

  That is, first, the displacement of the displacement portion 76 is obtained based on the immersion length L obtained as described above.

When the immersion length of the optical fiber 14 when the position of the displacement portion 76 is the reference position is L ₀ and the displacement of the displacement portion 76 is X, the displacement X of the displacement portion 76 is expressed by the following equation (3). Is done.

X = (L−L ₀ ) / 2 (3)
Next, the fluid flow velocity is obtained based on the relationship between the displacement of the displacement portion 76 and the fluid flow velocity obtained in advance (see FIG. 21) and the displacement of the displacement portion 76 obtained as described above. A table indicating the relationship between the displacement of the displacement unit 76 and the fluid flow velocity is stored in a table (not shown) provided in the RAM 20, for example.

  Thus, the flow rate of the fluid can be obtained based on the immersion length of the optical fiber 14.

  Even if the relationship between the displacement of the displacement portion 76 and the fluid flow velocity is not acquired in advance, the fluid flow velocity can be obtained based on the displacement of the displacement portion 76 as follows.

When the fluid flow rate is Q (m ³ / sec), the flow coefficient is A, the area of the fluid receiving member 86 is S, and the flow velocity is v ₁ , the following equation (4) is established.

Q = A × S × v ₁
When the pressure applied to the fluid receiving member 86 by the fluid is P and the fluid density is σ (N / m ² ), the following equation (5) is established.

P = 0.5 × σ × v ₁ ² (5)
When the force generated by the fluid flow is F ₁ (N), the following equation (6) is established.

F ₁ = P × S (6)
The force received when the elastic bodies 94a and 94b are extended is F ₂ (N), the spring constant of the elastic bodies 94a and 94b is K (N / m), and the displacement of the displacement portion 76 is δ (m). When the lengths of the elastic bodies 94 and 94b are L _en (m), the following equation (7) is established.

F ₂ = 2 × K × {δ ² + L _en ² } ^0.5 −L _en } × δ ÷ {δ ² + L _en ² } ^0.5 (7)
Since F ₁ and F ₂ are balanced, the following equation (8) is established.

F ₁ = F ₂ (8)
The following formula (9) is established by formula (6) and formula (8).

P × S = F ₂ (9)
The following formula (10) is established by formula (5) and formula (9).

0.5 × σ × v ₁ ² × S = F ₂ (10)
When the equation (10) is transformed, the following equation (11) is obtained.

v ₁ = {F ₂ ÷ (0.5 × σ × S)} ^0.5 (11)
Since the value of F ₂ can be obtained by Expression (7), v ₁ can be obtained.

  When the dimension of the fluid receiving member 86 is the first specific example, that is, for example, about 450 mm × 400 mm × 0.3 mm, the values of the above parameters are, for example, as follows.

For example, the area S of the fluid flow receiving member 86 is 0.18 (m ² ), for example. The fluid density σ is 1.03 (kg / m ³ ) in the case of seawater, for example. The spring constant K of the elastic bodies 94a and 94b is, for example, 3.5 (N / m). The length of the elastic member 94a, 94b _{L en} is, for example, 0.4 (m). Further, the flow coefficient A is, for example, 1.

  When the dimension of the fluid receiving member 86 is the second specific example, that is, for example, about 1000 mm × 1000 mm × 0.3 mm, the values of the above parameters are, for example, as follows.

For example, the area S of the fluid flow receiving member 86 is, for example, 1 (m ² ).

The fluid density σ, the spring constant K of the elastic bodies 94a and 94b, the length L _en of the elastic bodies 94a and 94b, and the flow coefficient A are the same as in the case of the specific example 1.

  As described above, the flow velocity of the fluid can be obtained by calculation based on the displacement of the displacement portion 76.

  As described above, according to the present embodiment, the optical fiber 14 is immersed in the fluid via the displacement portion 76 that is displaced according to the flow velocity of the fluid. Therefore, the immersion length of the optical fiber 14 is changed according to the fluid flow velocity. Can be made. In addition, according to the present embodiment, the immersion length of the optical fiber 14 in the fluid is obtained based on the temperature distribution along the longitudinal direction of the optical fiber 14 measured by introducing light into the optical fiber 14. Based on the immersion length of the fiber 14 in the fluid, the fluid flow rate can be determined. Moreover, according to the present embodiment, it is possible to obtain a measuring device at a relatively low cost. Therefore, according to the present embodiment, it is possible to provide a measuring device that can measure the flow velocity and the like at low cost.

  Further, according to the present embodiment, the portions on both sides of the optical fiber 14 immersed in the fluid are located in the case 66, and the temperature in the case 66 is different from the temperature of the fluid. For example, the temperature in the case 66 is sufficiently higher than the temperature of the fluid due to the irradiation of sunlight. For this reason, according to this embodiment, the immersion length of the optical fiber 14 in the fluid can be obtained more reliably, and as a result, the flow velocity of the fluid can be obtained more reliably.

  Further, according to the present embodiment, the temperature distribution in the longitudinal direction of the optical fiber 14 is measured based on the backscattered light generated when the optical fiber 14 is used as a probe and light is introduced into the optical fiber 14. For this reason, according to the present embodiment, it is possible to measure the flow velocity and the like without supplying power to the measurement unit 12 floated on the fluid.

  Further, according to the present embodiment, not only the fluid flow velocity but also the fluid temperature, the air temperature, and the like can be obtained based on the temperature distribution in the longitudinal direction of the optical fiber 14.

[Second Embodiment]
A measuring apparatus and a measuring method according to the second embodiment will be described with reference to FIGS. The same components as those of the measurement apparatus and the measurement method according to the first embodiment shown in FIGS. 1 to 30 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  The measuring apparatus and the measuring method according to the present embodiment measure the temperature of the fluid at a location different from the location where the immersion length of the optical fiber 14 changes.

  First, the measuring apparatus according to the present embodiment will be described.

  FIG. 31 is a perspective view showing a measuring unit of the measuring apparatus according to the present embodiment.

  As shown in FIG. 31, in the measurement unit of the measurement apparatus according to the present embodiment, the optical fiber 14 drawn out from the case 66 and wound around the winding member 102 is wound around the winding member 114 to which a weight (not shown) is attached. It is wound. The optical fiber 14 is further wound around the winding member 102 and introduced into the case 66. The winding member 114 is immersed in the fluid together with the optical fiber 14.

  The reason why the optical fiber 14 is wound around the winding member 114 and immersed in the fluid is to measure the temperature of the fluid by the portion of the optical fiber 14 wound around the winding member 114. In order to reliably measure the temperature of the fluid, the length of the optical fiber 14 that is wound around the winding member 114 is set to be sufficiently longer than the pulse length W of the laser light.

  In the present embodiment, the temperature at the location where the winding member 114 is located is used as the fluid temperature (fluid reference temperature).

  In the present embodiment, the length of the optical fiber 14 wound around the winding member 106 and immersed in the fluid is set shorter than the pulse length W of the laser light. That is, the length of the optical fiber 14 immersed in the fluid via the displacement portion 76 is set to be shorter than the pulse length W of the laser light. In the present embodiment, the length of the optical fiber 14 immersed in the fluid via the displacement portion 76 is set to be shorter than the pulse length W of the laser light because the immersion length is obtained by a measurement method as described later. is there. Here, the length of the portion of the optical fiber 14 wound around the winding member 106 is, for example, about 1 m.

  Next, the measurement method according to the present embodiment will be described.

  FIG. 32 is a flowchart showing the measurement method according to the present embodiment.

  First, similarly to Step S1 in the measurement method according to the first embodiment, a temperature distribution (measurement temperature distribution) along the longitudinal direction of the optical fiber 14 is obtained (Step S21).

  FIG. 33 is a diagram illustrating an example of a temperature distribution along the longitudinal direction of the optical fiber. The horizontal axis in FIG. 33 indicates distance (position), and the vertical axis in FIG. 33 indicates temperature. A solid line in FIG. 33 shows an example of an actual temperature distribution, and a broken line in FIG. 33 shows an example of a measured temperature distribution. 33, reference numerals 96, 98, 100, 102, 114, 104, 106, and 108 indicate the respective winding members.

  Next, the CPU 16 determines the temperature of the air inside the case 66 (in-case temperature), the temperature of the air outside the case 66 (air temperature), and the temperature of the fluid (seawater) based on the measured temperature distribution (fluid). Temperature) is obtained (step S22). The temperature at the location where the winding member 100 is located is used as the case internal temperature (internal case reference temperature). Moreover, the temperature of the location where the winding member 102 is located is used as an air temperature (air reference temperature). Moreover, the temperature of the location where the winding member 114 is located is used as the fluid temperature (fluid reference temperature).

  Next, CPU16 sets the value of immersion length L in the temperature distribution model (temperature distribution model function) mentioned later to the maximum immersion length Lmax (step S23). The maximum immersion length Lmax is an immersion length when the optical fiber 14 immersed using the winding member 106 with a weight is immersed in the maximum length. The value of the set immersion length L is stored in an immersion length memory (see FIG. 28) provided in the RAM 20.

  Next, the CPU 16 creates a temperature distribution model (temperature distribution model function) based on the in-case temperature, the fluid temperature, and the set immersion length L (step S24).

  Next, a calculation result is obtained by convolving a transfer function with the created temperature distribution model (step S25). Such a transfer function is obtained in advance as described above with reference to FIGS.

  Next, it is determined whether or not the fluid temperature in the calculation result matches the fluid temperature in the measured temperature distribution (step S26). Specifically, it is determined whether or not the fluid temperature at the location where the winding member 106 is located in the calculation result is equal to the fluid temperature at the location where the winding member 106 is located in the measured temperature distribution. When the fluid temperature in the calculation result approximates the fluid temperature in the measured temperature distribution, it can be determined that the temperature distribution model approximates the actual temperature distribution. If the fluid temperature in the calculation result and the fluid temperature in the measured temperature distribution are not equivalent, a predetermined length ΔL is subtracted from the immersion length L stored in the immersion length memory (see FIG. 28) (step S27). The loop processing from step S24 to step S27 is repeatedly performed until the fluid temperature in the result is equal to the fluid temperature in the measured temperature distribution. That is, the temperature distribution model (temperature distribution model function) in which the value of the immersion length L is changed is sequentially created, and the above processing is sequentially performed.

  The temperature distribution model when the fluid temperature in the calculation result is equal to the fluid temperature in the measured temperature distribution is a temperature distribution model approximated to the actual temperature distribution. Therefore, the immersion length in the temperature distribution model is estimated as the actual immersion length (step S28).

  Next, similarly to step S12 of the measuring apparatus according to the first embodiment, the flow velocity is obtained based on the immersion length (step S29).

  Thus, also in the present embodiment, the fluid flow velocity and the like can be obtained reliably.

[Third Embodiment]
A measuring apparatus and a measuring method according to the third embodiment will be described with reference to FIG. FIG. 34 is a block diagram showing the measuring apparatus according to the present embodiment. The same components as those of the measurement apparatus and the measurement method according to the first or second embodiment shown in FIGS. 1 to 33 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  The measuring apparatus according to the present embodiment is provided with measuring units arranged in a plurality of different directions, and obtains the fluid flow velocity based on the fluid flow velocity components in the plurality of directions.

As shown in FIG. 34, the optical fiber 14 is laid so as to reach the first measurement unit 12 ₍₁₎ from the processing unit 10, and the optical fiber 14 further reaches the _second measurement unit 12 ₍₂₎ . Are laid like so.

As the first measurement unit 12 ₍₁₎ and the second measurement unit 12 ₍₂₎ , any of the measurement units 12 and 12a of the measurement apparatus according to the first or second embodiment described above is used.

The front-rear direction of the first measurement unit 12 ₍₁₎ is set to the first direction. Accordingly, the displacement unit 76 of the first measurement unit 12 ₍₁₎ is displaced in the first direction according to the flow velocity component of the fluid in the first direction.

The front-rear direction of the second measurement unit 12 ₍₂₎ is set to the second direction. Therefore, the displacement part 76 of the second measurement unit 12 ₍₂₎ is displaced in the second direction according to the flow velocity component of the fluid in the second direction.

The processing unit 10 obtains the flow velocity component of the fluid in the first direction based on the immersion length obtained using the first measurement unit 12 ₍₁₎ , and obtains it using the second measurement unit 12 _(2). The flow velocity component of the fluid in the second direction is obtained based on the immersion length to be performed. Then, the flow velocity of the fluid is obtained based on the flow velocity component of the fluid in the first direction and the flow velocity component of the fluid in the second direction.

Thus, according to the present embodiment, the measurement units 12 ₍₁₎ and 12 ₍₂₎ are arranged so as to be directed to a plurality of different directions, respectively, and the flow velocity of the fluid is based on the flow velocity components of the fluid in the plurality of directions. Ask for. Therefore, according to the present embodiment, the flow velocity of the fluid can be obtained more accurately.

[Modified Embodiment]
The present invention is not limited to the above embodiment, and various modifications are possible.

  For example, in the first or second embodiment, the case where one measuring unit 12, 12a is arranged has been described as an example, but the number of measuring units 12, 12a is not limited to one. A plurality of measurement units 12 and 12a may be arranged to measure the flow velocity of the fluid at each location.

In the third embodiment, the case where a pair of measurement units 12 ₍₁₎ and 12 ₍₂₎ is provided has been described as an example. However, a plurality of pairs of measurement units 12 ₍₁₎ and 12 ₍₂₎ are provided. Also good.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1)
A processing unit having a light source;
A measuring part floating in the fluid;
An optical fiber arranged to reach the measurement unit from the processing unit,
The measurement unit has a displacement unit that is displaced according to the flow rate of the fluid,
The optical fiber is immersed in the fluid via the displacement portion so that the immersion length in the fluid changes according to the displacement of the displacement portion,
The processing unit obtains the immersion length of the optical fiber in the fluid based on a temperature distribution along the longitudinal direction of the optical fiber measured by introducing light from the light source into the optical fiber. A measuring device characterized in that a flow velocity of the fluid is obtained based on the obtained immersion length.

(Appendix 2)
In the measuring apparatus according to attachment 1,
The processing unit measures the temperature distribution along a longitudinal direction of the optical fiber based on light backscattered in the optical fiber when light is introduced from the light source into the optical fiber. A measuring device.

(Appendix 3)
In the measuring apparatus according to appendix 1 or 2,
The processing unit also obtains the temperature of the fluid based on the temperature distribution.

(Appendix 4)
In the measuring apparatus according to any one of appendices 1 to 3,
The measurement unit further includes a case,
The measuring apparatus, wherein both portions of the optical fiber immersed in the fluid are located in the case.

(Appendix 5)
In the measuring apparatus according to appendix 4,
The case has a slit formed along the direction in which the displacement portion is displaced,
The measuring apparatus, wherein the optical fiber is arranged to pass through the slit.

(Appendix 6)
In the measuring apparatus according to any one of appendices 1 to 5,
The processing unit generates a plurality of temperature distribution model functions with different immersion lengths of the optical fiber in the fluid, and obtains a calculation result obtained by convolving a predetermined transfer function with the temperature distribution model function and the temperature A measurement apparatus characterized in that an immersion length of the optical fiber in the fluid is obtained based on a correlation with a distribution.

(Appendix 7)
In the measuring apparatus according to any one of appendices 1 to 5,
The processing unit generates a plurality of temperature distribution model functions having different immersion lengths of the optical fiber in the fluid, and a predetermined location in a calculation result obtained by convolving a predetermined transfer function with the temperature distribution model function A measuring device, wherein the immersion length of the optical fiber in the fluid is obtained based on the coincidence of the temperature of the fluid and the temperature of the fluid at the predetermined location in the temperature distribution.

(Appendix 8)
In the measuring apparatus according to any one of appendices 1 to 7,
A plurality of the measurement units;
A first direction in which the displacement part of the first measurement part among the plurality of measurement parts is displaced, and a direction in which the displacement part of the second measurement part among the plurality of measurement parts is displaced. And the second direction are orthogonal to each other,
The processing unit obtains a flow velocity component of the fluid in the first direction based on the immersion length of the optical fiber in the fluid in the first measurement unit, and the light in the second measurement unit. Based on the immersion length of the fiber into the fluid, the flow velocity component of the fluid in the second direction is obtained, and the flow velocity component of the fluid in the first direction and the flow velocity component of the fluid in the second direction. The flow rate of the fluid is obtained based on the following.

(Appendix 9)
In the measuring apparatus according to any one of appendices 1 to 8,
The measurement unit further includes a base body on which a floating body is arranged,
The displacement unit is supported by the base via an elastic body.

(Appendix 10)
A processing unit having a light source; a displacement unit that is displaced according to a flow rate of the fluid; and a measurement unit that floats on the fluid, and is arranged to reach the measurement unit from the processing unit. A measuring method using a measuring device having an optical fiber immersed in the fluid via the displacement part, so that the immersion length in the fluid changes accordingly,
Determining the immersion length of the optical fiber in the fluid based on a temperature distribution along the longitudinal direction of the optical fiber measured by introducing light from the light source into the optical fiber;
Determining the flow velocity of the fluid based on the determined immersion length.

(Appendix 11)
In the measurement method according to attachment 10,
In the step of determining the immersion length, the temperature distribution along the longitudinal direction of the optical fiber is measured based on light backscattered in the optical fiber when light is introduced from the light source into the optical fiber. A measuring method characterized by the above.

(Appendix 12)
In the measurement method according to appendix 10 or 11,
The measurement method further comprising the step of obtaining the temperature of the fluid based on the temperature distribution.

(Appendix 13)
In the measurement method according to any one of appendices 10 to 12,
The measurement unit further includes a case,
A part of the optical fiber that is immersed in the fluid on both sides of the part is located in the case.

(Appendix 14)
In the measurement method according to attachment 13,
The case has a slit formed along the direction in which the displacement portion is displaced,
The measurement method, wherein the optical fiber is arranged so as to pass through the slit.

(Appendix 15)
In the measurement method according to any one of appendices 10 to 14,
Generating a plurality of temperature distribution model functions with different immersion lengths of the optical fiber in the fluid;
In the step of obtaining the immersion length of the optical fiber in the fluid, the fluid of the optical fiber is based on a correlation between a calculation result obtained by convolving a predetermined transfer function with the temperature distribution model function and the temperature distribution. A measurement method characterized by obtaining a dipping length in water.

(Appendix 16)
In the measurement method according to any one of appendices 10 to 14,
Generating a plurality of temperature distribution model functions with different immersion lengths of the optical fiber in the fluid;
In the step of determining the immersion length of the optical fiber in the fluid, the temperature of the fluid at a predetermined position in the calculation result obtained by convolving a predetermined transfer function with the temperature distribution model function and the predetermined position in the temperature distribution A measurement method, wherein the immersion length of the optical fiber in the fluid is obtained based on the coincidence with the temperature of the fluid.

(Appendix 17)
In the measurement method according to any one of appendices 10 to 14,
The measurement apparatus has a plurality of the measurement units,
A first direction in which the displacement part of the first measurement part among the plurality of measurement parts is displaced, and a direction in which the displacement part of the second measurement part among the plurality of measurement parts is displaced. And the second direction are orthogonal to each other,
In the step of obtaining the flow velocity of the fluid, the flow velocity component of the fluid in the first direction is obtained based on the immersion length of the optical fiber in the fluid in the first measurement unit, and the second measurement is performed. The flow velocity component of the fluid in the second direction is determined based on the immersion length of the optical fiber in the fluid in the section, and the flow velocity component of the fluid in the first direction and the fluid velocity in the second direction A measurement method, wherein the flow velocity of the fluid is obtained based on a flow velocity component of the fluid.

2 ... Land 4 ... Fluid 10 ... Processing units 12, 12a, 12 ₍₁₎ , 12 ₍₂₎ ... Measurement unit 14 ... Optical fiber 16 ... CPU
18 ... ROM
20 ... RAM
22 ... HDD
24 ... input unit 26 ... display unit 28 ... interface 30 ... laser light sources 32a, 32b ... lens 34 ... beam splitter 36 ... wavelength splitter 38 ... photodetector 40 ... network 42 ... core 44 ... clad 46 ... beam splitters 48a-48c ... Optical filters 50a to 50c ... Condensing lenses 52a to 52c ... Light receiving part 54 ... Base bodies 56a to 56d ... Floating bodies 58a to 58d ... Frame member 60 ... Chain members 62a to 62d ... Columnar members 64a and 64b ... Frame member 66 ... Case 68a, 68b ... Slits 70a, 70b ... Members 72a, 72b ... Guide portions 74a, 74b ... Groove 76 ... Floating body, displacement portion 78 ... Cylindrical portions 80a, 80b ... Plate-like portions 82a, 82b ... Recess 84 86 ... Fluid receiving member 88 ... Support member 89 ... Hole 90 ... Band-shaped member 92 ... Weight 94a, 4b ... elastic body 96 ... winding member 98 ... winding member 100 ... wound member 102 ... wound member 104 ... wound member 106 ... wound member 108 ... wound member 110 ... vessel 112 ... Water 114 ... wound member

Claims (5)

A processing unit having a light source;
A measuring part floating in the fluid;
An optical fiber arranged to reach the measurement unit from the processing unit,
The measurement unit has a displacement unit that is displaced according to the flow rate of the fluid,
The optical fiber is immersed in the fluid via the displacement portion so that the immersion length in the fluid changes according to the displacement of the displacement portion,
The processing unit obtains the immersion length of the optical fiber in the fluid based on a temperature distribution along the longitudinal direction of the optical fiber measured by introducing light from the light source into the optical fiber. A measuring device characterized in that a flow velocity of the fluid is obtained based on the obtained immersion length. The measuring apparatus according to claim 1,
The measurement unit further includes a case,
The measuring apparatus, wherein both portions of the optical fiber immersed in the fluid are located in the case. The measuring apparatus according to claim 1 or 2,
The processing unit generates a plurality of temperature distribution model functions with different immersion lengths of the optical fiber in the fluid, and obtains a calculation result obtained by convolving a predetermined transfer function with the temperature distribution model function and the temperature A measurement apparatus characterized in that an immersion length of the optical fiber in the fluid is obtained based on a correlation with a distribution. The measuring apparatus according to any one of claims 1 to 3,
A plurality of the measurement units;
A first direction in which the displacement part of the first measurement part among the plurality of measurement parts is displaced, and a direction in which the displacement part of the second measurement part among the plurality of measurement parts is displaced. And the second direction are orthogonal to each other,
The processing unit obtains a flow velocity component of the fluid in the first direction based on the immersion length of the optical fiber in the fluid in the first measurement unit, and the light in the second measurement unit. Based on the immersion length of the fiber into the fluid, the flow velocity component of the fluid in the second direction is obtained, and the flow velocity component of the fluid in the first direction and the flow velocity component of the fluid in the second direction. The flow rate of the fluid is obtained based on the following. A processing unit having a light source; a displacement unit that is displaced according to a flow rate of the fluid; and a measurement unit that floats on the fluid, and is arranged to reach the measurement unit from the processing unit. A measuring method using a measuring device having an optical fiber immersed in the fluid via the displacement part, so that the immersion length in the fluid changes accordingly,
Determining the immersion length of the optical fiber in the fluid based on a temperature distribution along the longitudinal direction of the optical fiber measured by introducing light from the light source into the optical fiber;
Determining the flow velocity of the fluid based on the determined immersion length.

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