JP2014134494A - Flow rate measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate measurement device which does not need position adjustment using calibration when performing measurement and has a probe reduced in size.SOLUTION: The flow rate measurement device includes: a plurality of cameras 40, 41 arranged at different angles; and a laser beam emitting part 28 for emitting a laser beam LB1 to a space SP to be photographed of a flow field S to be photographed by the plurality of cameras 40, 41. Both of the laser beam emitting part 28 and the plurality of cameras 40, 41 are fixed to a probe 26 arranged at the tip portion of the device. The plurality of cameras 40, 41 are arranged in a direction Z perpendicular to the emission direction X of the laser beam LB1 in such a manner that the photographing lenses 42, 43 of the cameras 40, 41 are directed to a side opposite to the space SP to be photographed with the emission direction X of the laser beam LB1 as a center. The plurality of cameras 40, 41 photograph the space SP to be photographed via reflection mirrors 50, 51 arranged in front of the photographing lenses 42, 43 and fixed to the probe 26.

Description

  The present invention relates to a flow velocity measuring apparatus capable of measuring three component velocities based on images obtained by imaging with a plurality of cameras.

Conventionally, a flow field mixed with particles such as tracer particles is irradiated with a laser beam, and images of a required space including the irradiated particles are taken with a plurality of cameras with a slight time difference, thereby the flow field. Devices for measuring the flow rate of are known. For example, a three-dimensional three-dimensional space in which a three-dimensional space such as a conical shape made of laser light is formed in the required space, is imaged with a plurality of cameras, and a three-dimensional three-speed component is measured using a predetermined analysis algorithm. Ingredient (3 dimensional
3 components) is known. In addition, a sheet-like laser beam is formed in the required space, and each of the two cameras captures the sheet-like surface direction with a minute time difference, using a predetermined analysis algorithm, the surface direction. And a two-dimensional three-component (2 dimensional)
3 components) is known.

For example, the flow velocity measuring device 1 of FIG. 9 is a so-called streo PIV (Particle Image Velocity) adopting this two-dimensional three-component method (see Patent Document 1), and the device 1 forms a sheet-like laser sheet light LS. Sheet light forming section 3 and two cameras 2A and 2B. Then, the two cameras 2A and 2B take two particles in the laser sheet light LS at the same time and with a minute time difference from different directions, and the particle pattern of the total four images obtained and two The velocity component in the XY direction in the plane of the laser sheet light LS and the velocity component in the Z direction orthogonal to the laser sheet light LS are measured from the angle difference between the cameras.
At this time, if the relative positions of the two cameras 2A and 2B and the laser sheet light LS shift, accurate measurement becomes impossible. Therefore, the two cameras 2A and 2B and the sheet light forming unit 3 are connected to the guide rails 4 and 4. 5 and positioning is performed in advance by placing a calibration plate as a calibration plate at the time of measurement.

In addition, as shown in FIG. 10, there is also a flow velocity measuring device 6 that captures a particle image accurately and quickly without performing calibration and position adjustment during measurement (see Patent Document 2). .
In this measuring device 6, the laser oscillation device 8 and the two cameras 9A and 9B are fixed to the housing 7 in advance, and the housing 7 Separately, a probe 10 is provided.
A prism 11 is disposed at the tip of the probe 10, and the laser light LB emitted from the laser oscillation device 8 on the housing 7 side is changed in the direction X by the prism 11 to form the laser sheet light LS. It has become. On the other hand, the two cameras 9A and 9B are arranged toward the housing 7 along the changed irradiation direction X. From the two cameras 9A and 9B, the bore scopes 12A and 12B face the probe 10. Are stretched and fixed in the same manner in the irradiation direction X. The two lenses 13A and 13B, which are also arranged along the irradiation direction X, are fixed to the distal ends of the borescopes 12A and 12B with an angle difference. In this way, the position of each member is fixed in advance to eliminate the need for position adjustment before measurement, and only the probe 10 on which the cameras 9A, 9B, etc. are not arranged is inserted into the flow field to be measured, and the lens lens 13A , 13B and the borescopes 12A, 12B, the two cameras 9A, 9B image the particles in the laser sheet light LS.

JP 2011-17600 A JP 2010-243197 A

By the way, as in the apparatus 1 of FIG. 9, the camera 2A, 2B and the sheet light forming unit 3 are installed on the guide rails 4 and 5 and the position is adjusted by calibration. However, it is difficult to measure a narrow space such as under the vehicle body, and there is also a troublesome position adjustment using calibration at the time of measurement.
In this respect, the apparatus 6 of FIG. 10 has each member fixed in advance, so that it is not necessary to perform position adjustment using calibration, and the probe 10 in which the cameras 9A and 9B and the laser oscillation apparatus 8 are not arranged is provided. It is provided separately from the housing 7, thereby enabling measurement by inserting the probe 10 even in a small space. However, the apparatus 9 shown in FIG. 10 arranges the borescopes 12A and 12B and the lenses 13A and 13B with the same direction and the same interval as the two cameras 9A and 9B arranged along the irradiation direction X. For this reason, even if the cameras 9A and 9B are not accommodated in the probe 10, the probe 10 must eventually be large. For example, the dimension in the irradiation direction X of the probe 10 must be not less than the distance L1 between the camera 9B and the laser oscillation device 8, and there is a limit to the space in which the probe 10 can be inserted.

  An object of the present invention is to solve the above-described problems, and an object of the present invention is to provide a flow velocity measuring device in which position adjustment using calibration at the time of measurement is unnecessary and the probe is miniaturized.

  According to the first aspect of the present invention, there is provided a plurality of cameras arranged at different angles, and a laser beam irradiation that irradiates laser beam onto an imaging space of a flow field imaged by the plurality of cameras. And a plurality of images obtained by imaging, and a three-component flow velocity orthogonal to each other in the imaging space is measured, and the laser beam irradiation unit And the plurality of cameras are fixed to a probe arranged at the tip, and the plurality of cameras are opposite to the imaged space side with the direction in which each imaging lens emits the laser light as a center. The imaging space is arranged through a reflecting mirror arranged in a direction orthogonal to the direction of irradiating the laser beam and facing the side, and in front of the imaging lens and fixed to the probe. To image It is achieved by the flow rate measuring device.

According to the configuration of the first aspect, the plurality of cameras are arranged along a direction orthogonal to the direction of irradiating the laser light toward the imaging space. For this reason, about the said irradiation direction, a probe can be made small compared with arranging a some camera along the irradiation direction of a laser beam.
In this regard, when a plurality of cameras are arranged along the direction orthogonal to the irradiation direction in this way, the plurality of cameras are arranged in the direction orthogonal to the irradiation direction, so that the outer shape of the probe becomes large. . In particular, in order to accurately measure the flow velocity, it is necessary to perform imaging so as to increase the amount of movement of particles in the imaging space, and it is preferable to place the camera at an angle with respect to the imaging space, If it does so, the distance of a laser beam irradiation part and a camera will become large, and a probe external shape will become large about the direction orthogonal to the said irradiation direction.
However, in the present invention, each of the plurality of cameras is arranged such that each imaging lens faces the opposite side of the imaging space side with the laser light irradiation direction as the center, and through a reflecting mirror in front of the imaging lens. Thus, the imaged space is imaged. Therefore, the probe dimensions can be set in the direction perpendicular to the laser light irradiation direction (that is, the camera arrangement direction) by the amount that the body part can be moved to the laser light irradiation part side without substantially changing the position of the imaging lens of the camera. Can be small. In addition, even if the imaging lens is directed to the opposite side in this way, the camera can capture an image with a required angle through the reflector so as to increase the amount of movement of the particles in the imaging space, and the flow rate can be accurately Measurement becomes possible.
And since all of the above laser beam irradiation unit, the plurality of cameras, and the reflecting mirror are fixed to the probe and the relative positional relationship with each other is determined in advance, the position adjustment using calibration is in use. Is also unnecessary.
As described above, according to the present invention, the outer shape of the probe can be reduced in both the direction in which the laser beam is irradiated from the laser beam irradiation unit and the direction orthogonal to the irradiation direction while enabling accurate flow velocity measurement. .

Preferably, a laser oscillation unit for oscillating the laser beam is provided separately from the laser beam irradiation unit, and the laser oscillation unit is not fixed to the probe and is a flexible optical fiber cable. The light emitted from the optical fiber cable is incident on the laser light irradiation unit.
Then, since the laser oscillation unit for oscillating the laser beam is not fixed to the probe, the probe can be made smaller accordingly.
And even if the laser beam irradiation unit and the laser oscillation unit are separated as described above, the laser beam can be incident on the laser beam irradiation unit via the optical fiber cable. Can be easily inserted into a flow field having a complicated shape.
Further, when the outgoing light from the optical fiber cable is incident on the laser light irradiation section, the outgoing light spreads at a predetermined angle. Therefore, the laser light can be irradiated in a plane or a three-dimensional form by using this spread, and the planar or three-dimensional form can be irradiated. It becomes easy to form the imaged space expanded in a shape.

  Preferably, the laser light irradiation unit and the plurality of cameras are arranged in this order toward the imaging space in a direction in which the laser light is irradiated from the laser light irradiation unit. To do. For this reason, the imaged space can be formed near the probe. That is, in order to measure the flow velocity of the three components, the imaged space requires a space having a required expansion, and therefore the required imaged space cannot be formed unless it is separated from the laser light irradiation unit to some extent. Thus, the laser beam irradiation unit can be fixed at a position farthest from the imaging space of the probe, and the imaging space with the spread can be brought as close to the probe as possible. If the space to be imaged can be brought close to the probe, even a small flow field can be dealt with, and furthermore, a high-accuracy measurement can be performed by taking a large imaging angle through the reflection mirror of the camera.

Preferably, the probe has a wall surface portion for hermetically housing the plurality of cameras and the reflecting mirror inside thereof, and the probe is interposed between the reflecting mirror and the imaging space. A transparent or translucent window is disposed so as to constitute a part of the wall surface, and the window is a filter that transmits only the wavelength of the laser beam.
Then, since the plurality of cameras and the reflecting mirror are hermetically sealed in the probe, it is possible to perform measurement with high accuracy without attaching unnecessary objects such as dust and water droplets to them. Even if the internal space of the probe is sealed in this way, a transparent or translucent window portion is arranged between the reflecting mirror and the imaged space so as to constitute a part of the wall surface portion. Therefore, the imaging space can be imaged through this window portion.
Furthermore, since this window is a filter that transmits only the wavelength of the laser beam, the camera does not pick up extra light, and more accurate measurement is possible.

Preferably, the laser beam irradiation unit includes a sheet beam forming unit for converting the laser beam into a sheet-like laser sheet beam, and the laser beam from the sheet beam forming unit is bent to perform the flow. A bending optical unit for irradiating the laser sheet light on the field, and all of the plurality of cameras are on the side of the sheet light forming unit from an imaginary line connecting the bending optical unit and the laser sheet light. The bending optical part is exposed to the outside of the wall surface part.
Then, since it has a sheet light forming unit that can generate a sheet-like laser sheet light, it forms a sheet-like laser sheet light in a space close to the object in the flow field, and makes an angle difference with respect to the thin sheet-like space. If the images are taken by a plurality of cameras, the flow velocity of the three components can be measured from the angle difference using a known analysis algorithm, so that the flow velocity of a narrow flow field can also be measured.
Since the plurality of cameras are arranged on one side of the virtual line connecting the bending optical part and the laser sheet light, the plurality of cameras are compared with the case where the cameras are arranged on both sides with the virtual line in between. The size in the direction of arrangement can be reduced. In addition, when a plurality of cameras are arranged only on one side of the virtual line, the area connecting the reflecting mirror and the laser sheet light in front of the cameras is less likely to be blocked by the object.
Furthermore, since the bending optical part is exposed to the outside of the wall surface part, when the laser light irradiated from the bending optical part spreads in a surface shape to form laser sheet light, the wall surface part blocks the surface expansion. Can be prevented. Therefore, the probe can be made small with respect to the dimension of the component having a planar spread.
As described above, it is possible to reduce the area of the imaged space, reduce the possibility that the imaging area is blocked by an object, and further reduce the size of the probe to measure the flow velocity of a smaller flow field. it can.

  Preferably, the laser light irradiation unit includes a conical light forming unit for forming conical laser light in the imaging space. Accordingly, the three-dimensional imaging space is imaged by a plurality of cameras, and the velocity component (that is, the three-dimensional imaging) of the entire stereoscopic imaging space is obtained by a known analysis algorithm using three-dimensional particle tracking, tomography, or the like. 3 components) can be measured.

  As described above, according to the present invention, it is possible to provide a flow velocity measuring device in which position adjustment using calibration at the time of measurement is unnecessary and the probe is downsized.

1 is a schematic diagram of a flow velocity measuring device according to an embodiment of the present invention. The schematic front view which looked at the flow-velocity measuring apparatus of FIG. 1 from the F direction (front) of FIG. FIG. 3 is a schematic AA sectional view of FIG. 2. The schematic sectional drawing at the time of cut | disconnecting the periphery of the laser beam irradiation part of FIG. 1 in the position of BB of FIG. FIG. 5A is a cross-sectional view of the vicinity of a laser beam irradiation unit according to a first modification of the present embodiment, FIG. 5A is a cross-sectional view in the same direction as FIG. 3, and FIG. Figure. Schematic of the flow velocity measuring apparatus which concerns on the 2nd modification of embodiment of this invention. Schematic of the flow velocity measuring apparatus which concerns on the 3rd modification of embodiment of this invention. FIG. 8A is a cross-sectional view of the vicinity of the laser light irradiation unit of the flow velocity measuring device of FIG. 7, FIG. 8A is a cross-sectional view in the same direction as FIG. 3, and FIG. The figure which measures the flow velocity around the body of a car with the conventional flow velocity measuring device. Schematic of the flow velocity measuring apparatus which has the conventional probe.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these embodiments. Moreover, the same code | symbol attached | subjected in each figure has the same structure.

[Overview of flow velocity measuring device]
First, an outline of the flow velocity measuring device will be described with reference to FIGS. 1 and 2.
FIG. 1 is a flow velocity measuring device 20 according to an embodiment of the present invention, and FIG. 2 is a front view of the flow velocity measuring device 20 as viewed from the direction F in FIG. In FIG. 2, transparent or translucent windows that will be described later are indicated by parallel diagonal lines.
The flow velocity measuring device (hereinafter referred to as “the present device”) 20 in these figures is used to measure the flow velocity of the flow field S in a narrow space such as a car engine room, under the car floor, or a place between building models in an urban model wind tunnel test. It is preferably used to measure.

  In other words, this apparatus 20 is an apparatus for measuring the flow velocity of two-dimensional three components, and irradiates the flow field S mixed with tracer particles with the laser beam LB1 to form a sheet-like laser in the imaging space. The sheet light SP is formed, the scattered light applied to the particles in the laser sheet light SP is photographed by the two cameras 40 and 41, and the surface direction XY and the out-of-plane direction Z of the laser sheet light SP are measured. It is like that. Therefore, since the laser sheet light SP is sheet-like and does not require a thickness, it is suitable for measuring the flow velocity of the flow field S (see FIG. 3) that is narrow in width or close to the object plane AT.

  The apparatus 20 includes a housing 22 and a probe 26 connected to the housing 22 via a tube 24. In the present embodiment, only the cameras 40 and 41 and the laser beam irradiation unit 28 are arranged as a relatively large device and the size is reduced. Thus, only the miniaturized probe 26 is inserted into the narrow flow field S so that the flow velocity can be measured.

[Configuration other than probe]
Next, the configuration of the apparatus 20 other than the probe 26 will be described.
1 is provided with a laser oscillation unit 30, a laser power source 31, a camera power source 32, a controller 33, a computer 34, and a cooling device 35. In the figure, these devices or devices 30 to 35 are collectively arranged in the housing 22, but the present invention is not limited to this and may not be integrated in the housing 22.
The laser oscillating unit 30 is a device that oscillates laser light, and the oscillated laser light is irradiated through the tube 24 and the probe 26 so as to be planar laser light LB1 toward the imaging space of the flow field S. The The laser beam LB1 of the present embodiment is a double pulse laser, and for example, a YAG laser having a wavelength of 532 nm can be used.
The laser power source 31 supplies power to the laser oscillation unit 30 and energizes in accordance with the pulse width of the pulse laser.

The camera power supply 32 is electrically connected to the plurality of cameras 40 and 41 in the probe 26, supplies power, and transmits and receives signals to and from the cameras 40 and 41. The camera power source 32 and the laser power source 31 are connected to the controller 33.
The controller 33 synchronizes the camera power supply 32 and the laser power supply 31 to synchronize the timing of oscillating the laser beam from the laser oscillation unit 30 and the timing of photographing with the cameras 40 and 41. The controller 33 is connected to a computer 34 and transmits image data captured by the cameras 40 and 41 to the computer 34.
The computer 34 calculates the flow velocity of the flow field S using a known analysis algorithm (see, for example, Japanese Patent Application Laid-Open No. 2004-20385) based on the received plurality of pieces of image data. That is, data of two images (scattered light images in the laser sheet light SP, etc.) and two cameras sent from two cameras 40 and 41 having an angle difference from each other with a minute time difference. From the angular difference between 40 and 41, the moving function of the particles in the vector XY in the plane direction of the laser sheet light SP and the vector Z orthogonal thereto is calculated using a mapping function.

The tube 24 is a flexible tube, and even if the flow field S has a complicated shape, the probe 26 attached to the tip of the flow field S can be inserted into the flow field S while being twisted. That is, the tube 24 is a hollow cable, and is a so-called composite cable in which a plurality of flexible cables or tubes C1 to C4 are inserted. In FIG. 1, C1 is a cooling tube, C2 is an optical fiber cable, and C3 and C4 are power and signal cables for the cameras 40 and 41, respectively. These cables or tubes C1 to C4 are inserted into the probe 26 and fixed in the probe 26.
As described above, the flexible tube 24 can be used because a plurality of cameras 40 and 41 are accommodated in the probe 26 so that the positional relationship between the housing 22 and the probe 26 is not limited. It is. In the present apparatus 20, even if the cameras 40 and 41 are accommodated in the probe 26, the probe 26 is downsized. Hereinafter, the probe 26 will be described with reference to FIGS. 3 and 4.

[About the probe]
3 is a schematic cross-sectional view taken along the line AA in FIG. 2, and FIG. 4 is a schematic partial cross-sectional view when the laser beam irradiation unit 28 and its periphery are cut at the position BB in FIG. In FIG. 3, a part of the laser beam irradiation unit 28 and the like are further cut out. Further, in FIG. 3, the cables C3 and C4 are partially omitted so as not to complicate the drawing.
The probe 26 disposed at the distal end of this apparatus fixes a plurality of cameras 40 and 41, a laser beam irradiation unit 28, and an optical fiber cable C2 to a substantially rectangular housing.
The cameras 40 and 41 image the scattered light that hits the particles of the laser sheet light SP. In the figure, two cameras are provided, and they are fixed to the inner bottom 29e with an angle difference. Note that a digital COMS camera, a CCD camera, or the like can be used as the cameras 40 and 41. In this embodiment, a CCD camera is used.

The laser beam irradiation unit 28 bends the sheet light forming unit 28a, which is an optical system for generating the sheet-shaped laser sheet light SP, and the laser beam from the sheet light forming unit 28a, toward the imaging space. It comprises a bending optical part 28b for irradiating the laser beam LB1.
As shown in FIGS. 3 and 4, the sheet light forming portion 28 a and the bending optical portion 28 b are connected so as to be arranged along the Z direction with a screw 13 or the like, and have a generally cylindrical shape (FIG. 1). reference). Specifically, the sheet light forming unit 28a includes an optical system lens 60 and a lens holder 62 that holds the optical system lens 60, and the bending optical unit 28b changes the irradiation direction for changing the irradiation direction. And a direction changing portion holding body 68 for holding the irradiation direction changing portion 66. And the lens holding body 62 and the direction change part holding body 68 are connected so that attachment or detachment is possible.

Such a laser beam irradiation unit 28 is fixed so that the sheet light forming unit 28 a is inserted into the internal space AC of the probe 26 and is detachable from the probe 26.
That is, as shown in FIG. 1, the probe 26 has a substantially rectangular shape as a whole, and a through hole 59 is formed in the wall surface portion 29c on the distal end side as shown in FIGS. The sheet light forming portion 28 a is inserted into the through hole 59. The lens holder 62 has an outer peripheral side surface corresponding to the inner surface of the through hole 59, and the outer peripheral side surface of the lens holder 62 and the inner surface of the through hole 59 are in close contact with each other with a waterproof O-ring 64 interposed therebetween. ing.
The bending optical part 28b protrudes from the wall surface part 29c on the distal end side and is exposed to the outside. This makes it possible to emit the laser beam LB1 with a large divergence angle in the Y direction and form the laser sheet beam SP near the probe 26 even with the probe 26 having a small height H in FIG. Yes. Further, even if the flow field S has a complicated shape, the laser sheet light SP can be formed by inserting the bent optical portion 28b protruding therefrom.

  For the irradiation direction changing unit 66 of the bending optical unit 28b, a prism, a cube mirror, or the like for changing the direction of the laser beam from the optical lens 60 can be used. In this embodiment, the laser beam is bent by 90 degrees. A right angle prism is used. Specifically, the irradiation direction changing unit 66 is a rectangular parallelepiped prism in which the inclined surfaces of the two right-angle prisms 66a and 66b are combined, and this is held by the direction changing unit holding body 68 which is a case. doing. Further, as shown in FIG. 4, the direction changing portion holding body 68 includes a flat plate-like portion 55 that can come into contact with the tip surface FF of the right-angle prism 66a on the tip side in a planar shape, and the flat plate-like portion 55. And a screw 57 that can be pushed toward the right-angle prism 66a side. Accordingly, the right-angle prisms 66a and 66b are pushed in by turning the screw 57 to perform fine adjustment, and the pushed-in right-angle prism 66b crushes the O-ring 65, and the optical system lens 60 and the irradiation direction changing unit. Intrusion of dust, water droplets, and the like with respect to 66 is prevented.

  The probe 26 has a wall surface portion 29 that seals the internal space AC, and as shown in FIGS. 1 and 2 so that maintenance of the cameras 40 and 41 and the laser beam irradiation unit 28 in the internal space AC is possible. Further, the front wall surface portion 29a and the flat wall surface portion 29b are detachable with screws 37 or the like.

Here, as shown in FIG. 3, the two cameras 40 and 41 are arranged along the out-of-plane direction Z of the laser sheet light SP orthogonal to the direction X in which the laser light LB1 is irradiated from the laser light irradiation unit 28. Has been. For this reason, by arranging the cameras 40 and 41 having the largest outer shape among the probes 26, the probe 26 is in a direction orthogonal to the arrangement direction Z of the cameras 40 and 41 (that is, the direction in which the laser beam LB1 is irradiated). ) The dimension D of X can be reduced.
Specifically, both of the two cameras 40 and 41 are cameras in the arrangement direction Z with respect to an imaginary line (substantially the same as the irradiation direction of the laser light LB1) connecting the bending optical unit 28b and the laser sheet light SP. 40 and the sheet light forming part 28a are arranged on the sheet light forming part 28a side so that a region Wa overlaps with the sheet light forming part 28a.

The cameras 40 and 41 are arranged so that the imaging lenses 42 and 43 face the opposite side to the laser sheet light SP side with the irradiation direction X of the laser light LB1 as the center. The laser sheet light SP is imaged through the flat reflecting mirrors 50 and 51 which are the front and fixed to the probe 26. Accordingly, the probe 26 is arranged in the arrangement direction Z of the cameras 40 and 41 by the amount that the body portions 45 and 46 can be moved to the laser beam LB1 side without substantially changing the fixing positions of the imaging lenses 42 and 43 of the cameras 40 and 41. The dimension W can be reduced.
That is, since it is preferable to take an image with a large angle with respect to the laser sheet light SP in order to accurately grasp the amount of movement of the particles, the center CN of the laser sheet light SP (the convergence point of the laser light in the Z direction). And the imaging directions of the cameras 40 and 41 cannot be reduced, and the body portions 45 and 46 are swung to the laser beam LB1 side while maintaining the different intersection angles θ1 and θ2. . The crossing angle θ2 between the imaging direction through the reflecting mirror 51 of the camera 40 and the laser sheet light SP is 35 degrees, and the crossing angle θ1 between the imaging direction through the reflecting mirror 50 of the camera 41 and the laser sheet light SP is 45. Degree.
In this way, the probe 26 can be reduced in both the dimension D and the dimension W.

Specifically, the main surfaces of the thin plate-like reflecting mirrors 50 and 51 are arranged along the irradiation direction LB1. The imaging lens 42 far from the laser beam LB1 is directed to the opposite side of the laser beam LB1 so that the angle θ3 with respect to the irradiation direction X of the laser beam LB1 is about 45 degrees. Further, the imaging lens 43 close to the laser beam LB1 is directed to the opposite side of the laser beam LB1 so that the angle θ4 with respect to the irradiation direction X of the laser beam LB1 is about 35 degrees.
The reflecting mirrors 50 and 51 are total reflection mirrors, and the reflecting mirror 50 is bonded to the inner wall 29d of the probe 26 with an adhesive such as an epoxy resin and fixed with a bolt 39. The reflecting mirror 51 disposed between the camera 40 and the camera 41 is inserted into the groove of the base portion 38 whose longitudinal section joined to the inner bottom 29e of the probe 26 is U-shaped and fixed by the bolt 17. Yes.

  In addition, in the cameras 40 and 41, the imaging lenses 42 and 43 and the body portions 45 and 46 are separated, and the light collected by the imaging lenses 42 and 43 is imaged on the body portions 45 and 46 to generate electrical signals. An image sensor (CCD sensor in the present embodiment) 52 that converts the image sensor 52 and a substrate 53 on which the image sensor 52 and a capacitor are mounted. The cameras 40 and 41 have a so-called Scheimpflug function, and the imaging lenses 42 and 43 are fixed to the probe 26, whereas the body portions 45 and 46 are in the R direction in FIG. In this way, the optical axis of the imaging lenses 42 and 43 and the optical axis of the imaging element 52 can be tilted. Therefore, even with the laser sheet light SP having a predetermined length in the irradiation direction X, the cameras 40 and 41 can be focused.

The longitudinal direction of the laser light irradiation unit 28 including the sheet light forming unit 28a and the bending optical unit 28b is arranged along the arrangement direction Z of the plurality of cameras 40 and 41, and from the sheet light forming unit 28a to the camera arrangement direction Z. The laser beam emitted along is bent at a right angle by the irradiation direction changing unit 66 to form the laser sheet beam SP in the flow field S.
Then, with respect to the irradiation direction X of the laser beam LB1 from the probe 26, the laser beam irradiation unit 28 and the plurality of cameras 40 and 41 are arranged in this order toward the imaging space. As a result, the laser sheet light SP that is difficult to form a space that expands in the Y direction in the vicinity of the probe 26 is brought as close to the probe 26 as possible. If the laser sheet light SP can be brought close to the probe 26, even a small flow field S can be dealt with. Further, the imaging direction of the cameras 40 and 41 through the reflecting mirrors 50 and 51 and the laser sheet light SP can be handled. By making the crossing angles θ1 and θ2 large, it is possible to perform accurate measurement.

Furthermore, the laser beam irradiation unit 28 uses an optical fiber to reduce the size of the sheet light forming unit 28a. That is, since the optical fiber has an incident angle and receives light, the outgoing light LB2 from the optical fiber cable C2 is emitted with a predetermined divergence angle (conical shape), and this divergence angle is irradiated in the plane of the laser sheet light SP. It is used in a direction Y (see also FIG. 1) orthogonal to the direction X. The numerical aperture (NA) of the optical fiber may be determined in consideration of the size of the laser sheet light SP and the distance from the probe 26.
Specifically, the emitted light LB2 from the optical fiber cable C2 enters the convex cylindrical lens 60 of the sheet light forming unit 28a. The convex cylindrical lens 60 has an optical center disposed along the optical axis direction of the outgoing light LB2, and converges the outgoing light LB2 in the XZ direction as shown in FIG. 3, while the XY direction as shown in FIG. The emitted light LB2 is irradiated on the irradiation direction changing unit 66 as it is without being converged. In this way, in this embodiment, even if the number of lenses of the sheet light forming portion 28a is reduced, the laser beam LB1 can be irradiated to the flow field with spreading in a planar shape. Accordingly, the sheet light forming portion 28a can be reduced in size.
Further, the laser beam irradiation unit 28 irradiates the laser beam LB1 using the emitted light LB2 of the optical fiber cable C2 fixed to the probe 26. For this reason, the irradiation position is difficult to shift, and the relative positions of the cameras 40 and 41 and the laser sheet light SP can be accurately matched.

  In addition, the laser beam irradiation part of this invention is not restricted to the aspect mentioned above, For example, it is sectional drawing of the periphery of the laser beam irradiation part 28-1 which concerns on the 1st modification of this embodiment in FIG. As shown, a concave cylindrical lens 70 may be provided between the convex cylindrical lens 60 and the irradiation direction changing unit 66 so as to arrange the optical center along the optical axis direction of the emitted light LB2. Accordingly, the laser beam LB1 is further expanded as much as possible in the direction Y orthogonal to the irradiation direction X in the surface direction of the laser sheet light SP by the concave cylindrical lens 70, and the laser sheet light SP is probed. 26.

  The probe 26 is transparent or translucent so as to constitute a part of the wall surface portion 29a between at least the reflecting mirrors 50 and 51 and the space to be imaged (that is, the space where the laser sheet light SP is formed). A window portion 15 having a property is arranged (see FIGS. 1 and 2). Thereby, even if the cameras 40 and 41 are accommodated in the inner space AC, the scattered light of the outer laser sheet light SP can be imaged. In addition, the window part 15 of this embodiment is one piece, and is arrange | positioned in all the center area | regions except the peripheral part of the wall surface part 29a. The window 15 is a filter that transmits only the wavelength of the laser beam LB1. In the present embodiment, since the wavelength of the laser beam LB1 is 532 nm, it is a band-pass filter or the like that transmits only this wavelength. Therefore, the cameras 40 and 41 can measure with high accuracy without imaging extra light.

As shown in FIGS. 1 and 3, a cooling tube C <b> 1 connected to the cooling device 35 is inserted into the probe 26 through the inside of the tube 24, and heat is dissipated in the internal space AC of the probe 26. It is supposed to be. The air that has exited from the cooling tube C1 passes back through the internal space AC and back into the tube 24. At this time, it is preferable to insert the air as far as possible so that the air passes through the interior space AC.
Further, the optical fiber cable C2 is fixed in the probe 26 via a pedestal 77. At this time, the pedestal 77 is formed with a long elongated hole 78 along the Z direction, and a bolt 79 is inserted into the elongated hole 78. It is inserted and fixed. In this way, the optical fiber cable C2 can be finely adjusted in the position in the Z direction.

The preferred embodiment of the present invention is configured as described above, and the flow velocity can be measured even in a narrow and complicated flow field. That is, the conventional probe-type flow velocity measuring apparatus does not accommodate a relatively large camera in the probe in an attempt to reduce the size of the probe. However, when measuring three-component velocities using multiple cameras, each device and member in the probe can reflect the positional relationship of the multiple cameras as it is without inserting the camera into the probe. Since it is necessary to fix the position precisely, the result is an increase in the size of the apparatus. In this respect, the present invention is based on the idea of reverse rotation, and achieves a technique that allows a plurality of cameras 40 and 41 to be accommodated in the probe 26 as shown in FIG. The size of the probe 26 of this embodiment is about 13 cm in FIG. 1, about 10 cm in D, and about 4 cm in H, and can be remarkably reduced in size.
In addition, since all of the laser beam irradiation unit 28, the plurality of cameras 40 and 41, and the reflecting mirrors 50 and 51 are fixed to the probe 26 and their relative positional relationships are determined in advance, calibration is required during use. There is no need to adjust the position using the screen.

FIG. 6 is a schematic diagram of a flow velocity measuring device 100 according to a second modification of the embodiment of the present invention. In FIG. 6, only the area where the cameras 72 and 73 and the reflecting mirrors 74 and 75 of the probe 26-1 are fixed is cut out to visually recognize the internal space AC.
In this figure, since the part which attached | subjected the code | symbol same as the flow velocity measuring apparatus 20 of FIG. 1 thru | or FIG. 5 is the same structure, the overlapping description is abbreviate | omitted and it demonstrates centering on difference below.
The flow velocity measuring apparatus 100 according to the second modification differs from the above-described embodiment only in the arrangement of the cameras 72 and 73 and the reflecting mirrors 74 and 75 and the shape of the probe that accommodates them (camera and reflecting mirror). The structure of the member itself excluding the arrangement of (2) is the same as that shown in FIGS.

  That is, also in FIG. 6, as in the above-described embodiment, the plurality of cameras 72 and 73 are configured so that the imaging lenses 72a and 73a are in the imaging space (that is, the laser sheet light SP) with the laser beam irradiation direction LB1 as the center. Reflecting mirrors arranged in a direction Z perpendicular to the laser beam irradiation direction X and facing the opposite side of the laser beam, and fixed to the probe 26-1 in front of the imaging lenses 72a and 73a The space to be imaged is imaged through 73 and 74. Therefore, the probe 26-1 can be miniaturized in the same manner as the probe 26 shown in FIGS.

However, the probe 26-1 has one camera 72 and 73 arranged on both sides around the direction X in which the laser beam LB1 is irradiated from the laser beam irradiation unit 28 toward the imaging space. The laser beam LB1 emitted from the laser beam irradiation unit 28 is irradiated toward the imaging space through the internal space AC sandwiched between the two cameras 72 and 73 of the probe 26-1.
Further, the plurality of cameras 72 and 73 are arranged along the out-of-plane direction Z of the laser sheet light SP orthogonal to the irradiation direction X so that the imaging lenses 72a and 73a face each other. The reflecting mirrors 73 and 74 are disposed at an angle with respect to the direction Z in which the plurality of cameras 72 and 73 are arranged such that the reflecting surfaces 74a and 75a face the laser sheet light SP side. Specifically, the intersection angle θ5 between the imaging direction of the camera 72 through the reflection mirror 74 and the laser sheet light SP, and the intersection angle θ6 of the imaging direction through the reflection mirror 75 of the camera 73 and the laser sheet light SP. Are 45 degrees.
In this manner, in the probe 26-1 in FIG. 6, compared with the probe 26 in FIG. 3, since the cameras 72 and 73 are not angled with respect to the Z direction, they are along the irradiation direction X of the laser beam LB1. The dimension D1 is made small.
However, the probe 26-1 in FIG. 6 differs from the probe 26 in FIG. 3 in that the cameras 72 and 73 are arranged on both sides around the irradiation direction X of the laser beam LB1. The probe 26-1 is larger by the amount of W2.

6 is compared with the probe 26 of FIG. 3 as follows.
The probe 26-1 in FIG. 6 has a relatively elongated shape compared to the probe 26 in FIG. 3, and is suitable for measuring the flow velocity of such a flow field S.
However, the probe 26-1 in FIG. 6 has a large protrusion of W2. Further, since the laser beam LB1 is irradiated through the internal space AC of the probe 26-1, in order to emit the laser beam LB1 with a large divergence angle in the Y direction, compared with the height H of the probe 26 in FIG. The height of the probe 26-1 in FIG. 6 must be increased. For these reasons, the probe 26 of FIG. 3 can be downsized in terms of overall capacity.
Further, as shown in FIG. 6, when the probe 26-1 attempts to image the vicinity of the corner CR of the object AT in the flow field S, the corner CR becomes an obstacle to the imaging, and approaches the object AT. In some cases, the laser sheet light SP cannot be formed.
For this reason, considering that the flow velocity of the small flow field S is increased, the probe 26 of FIG. 3 is excellent overall.

FIG. 7 is a schematic diagram of a flow velocity measuring device 101 according to a third modification of the embodiment of the present invention. 8A is a cross-sectional view of the periphery of the laser light irradiation unit of the flow velocity measuring apparatus 101 in FIG. 7, FIG. 8A is a cross-sectional view in the same direction as FIG. 3, and FIG. It is sectional drawing of the same direction.
In these drawings, the portions denoted by the same reference numerals as those of the flow velocity measuring device 20 in FIGS. 1 to 5 have the same configuration, and therefore, the overlapping description will be omitted and the following description will focus on the differences.
The flow velocity measuring device 101 according to the third modification differs from the above-described embodiment in that a three-dimensional three-component (3 dimensional)
3 components).

That is, the laser beam irradiation unit 28-2 of the flow velocity measuring apparatus 101 includes a cone light forming unit 28a-1 for forming the cone-shaped laser beam LB3 in the imaging space.
Specifically, the conical light forming portion 28a-1 has a single concave lens 80, and the laser light LB2 emitted from the optical fiber cable C2 enters the concave lens 80. The optical center of the concave lens 80 is disposed along the optical axis direction of the laser beam LB2, and the lens holding body 62 that holds the concave lens 80 has the same outer shape as that of FIG.
As a result, the laser beam LB2 emitted conically from the optical fiber cable C2 having a predetermined numerical aperture (NA) is diverged by the concave lens 80, and the diverging laser beam is bent at a right angle by the irradiation direction changing unit 66. Thus, the conical laser beam LB3 is applied to the flow field S. Accordingly, among the conical portion formed by the laser beam LB3 near the probe 26-2, the three-dimensional solid portion CU is imaged by the plurality of cameras 40 and 41, and the imaging data is transmitted to the housing 22 side. Then, using known analysis algorithms such as 3D particle tracking and tomography, 3D 3 components (3dimensional
3 components) can be measured.

The third modification is configured as described above, and the difference between the probe 26-2 and the probe 26 in FIG. 3 is that the convex cylindrical lens 60 of the laser beam irradiation unit 28 in FIG. It has only changed, and as a result, the three-dimensional three-component (3 dimensional
3 components) can be measured.
As shown in FIG. 3, the laser light irradiation unit 28 has a configuration in which the sheet light forming unit 28 a is inserted into the probe 26 and connected and fixed by the screw 13 or the like. Therefore, the laser beam irradiation unit 28 is removed from the probe 26 in FIG. 3, and the sheet light forming unit 28a and the bending optical unit 28b of the laser beam irradiation unit 28 are separated, and instead of the sheet light forming unit 28a, It is also possible to join the conical light forming portion 28a-1 in FIG. 8 to the bending optical portion 28b in FIG. 3 and insert it into the probe 26-2 in FIG.

By the way, this invention is not limited to the said embodiment, A various modified example is employable.
For example, in the embodiment described above, only two cameras have been described, but three or more cameras may be accommodated in the probe.
In addition, a cylindrical laser beam is formed in the imaging space, and two or more light field cameras are used to shoot a plurality of focal plane images having different focal lengths, thereby obtaining a volume PIV using a multi-section stereo PIV. It may be a multi-section 2D3C (2 dimensional 3 components).
Further, the number of the tubes 24 in FIG. 3 is one, but two or more tubes may be used as long as they have flexibility.

DESCRIPTION OF SYMBOLS 15 ... Window part, 20,100,101 ... Flow velocity measuring apparatus, 26 ... Probe, 28 ... Laser beam irradiation part, 28a ... Sheet light formation part, 28b ... Bending optical part , 30 ... laser oscillation unit, 40, 41 ... camera, 50, 51 ... reflecting mirror, S ... flow field, LB1, LB2 ... laser light, SP ... laser sheet light, C2: Optical fiber cable

Claims (6)

A plurality of cameras arranged at different angles, and a laser beam irradiation unit configured to irradiate laser beam to the imaging space of the flow field captured by the plurality of cameras, and obtained by imaging In the flow velocity measuring apparatus that compares the plurality of images and measures the flow velocity of the three components orthogonal to each other in the imaging space,
Both the laser beam irradiation unit and the plurality of cameras are fixed to a probe arranged at a tip part,
The plurality of cameras are arranged along a direction orthogonal to the direction of irradiating the laser light so that each imaging lens faces the side opposite to the imaged space side with the direction of irradiating the laser light as a center. The flow velocity measuring apparatus is characterized in that the imaging space is imaged through a reflecting mirror arranged in front of the imaging lens and fixed to the probe. A laser oscillation part for oscillating the laser light separately from the laser light irradiation part,
The laser oscillation unit is not fixed to the probe, but is connected to the probe via a flexible optical fiber cable,
2. The flow velocity measuring device according to claim 1, wherein light emitted from the optical fiber cable is incident on the laser light irradiation unit.   The laser light irradiation unit and the plurality of cameras are arranged in this order toward the imaging space in a direction in which the laser light is irradiated from the laser light irradiation unit. 2. The flow velocity measuring device according to 2. The probe has a wall surface portion for sealingly housing the plurality of cameras and the reflecting mirror inside thereof,
Between the reflecting mirror and the imaged space, a window part having transparency or translucency is arranged so as to constitute a part of the wall surface part,
The flow velocity measuring device according to claim 1, wherein the window portion is a filter that transmits only the wavelength of the laser beam. The laser beam irradiation unit includes a sheet beam forming unit for converting the laser beam into a sheet-like laser sheet beam, and the laser sheet from the sheet beam forming unit is bent so that the laser sheet enters the flow field. A bending optical part for irradiating light,
All of the plurality of cameras are disposed closer to the sheet light forming unit than a virtual line connecting the bending optical unit and the laser sheet light,
The flow velocity measuring device according to claim 4, wherein the bending optical part is exposed to the outside of the wall surface part.   5. The flow velocity measuring device according to claim 1, wherein the laser light irradiation unit includes a conical light forming unit for forming conical laser light in the imaging space.

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