JPS60111165A - Flow velocity measuring device - Google Patents

Abstract

PURPOSE:To measure exactly a velocity of flow by means of non-contact measurement, by irradiating laser light to a fluid, and measuring the velocity of flow basing on photodetecting of scattered light. CONSTITUTION:By using a laser projector 3 controlled by a laser source 1 and a scanning turning device 4, measured surfaces 6, 7 are scanned by a pair of optical beams parallel to each other along a flow direction of a fluid 5. Subsequently, scattered light in case when a fine particle contained in the fluid 5 passes through the surfaces 6, 7 is photodetected and stored by a photodetector 11 of a photoelectric converting means provided with a CCD, processed by a computer 21, and a velocity of flow of the fluid 5 is measured. According to this constitution, non-contact measurement is execued and the velocity of flow is measured exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a flow velocity measuring device that measures the flow distribution of a fluid with respect to a traveling object, a structure, or the like.

[Foreground technology] In general, when measuring the wake flow velocity distribution of the main fluid accompanying the running of a moving object such as a ship or automobile, or the wake flow velocity distribution of a fluid generated by a built structure such as a bridge or building, conventional methods One current meter was traversed over the required measurement plane to obtain the flow velocity distribution. However, with such a measurement method, the measurement time is long and the measurement time points deviate, so it is extremely difficult to obtain the flow velocity distribution at the same time point at all measurement points within the measurement plane.

Therefore, as a method to solve this problem, a method is known in which a large number of current meters are arranged within the required side surface and the wake flow velocity distribution is obtained simultaneously by these current meters. However, this method not only requires a large number of current meters, but also requires a great deal of effort and time, such as adjusting the sensitivity of each current meter individually. In particular, in this method, the current meter itself often disturbs the fluid flow.

[Object of the Invention] Here, an object of the present invention is to provide a flow velocity measuring device that can accurately measure a required flow velocity distribution within a measurement plane in a short time.

[Structure of the Invention] Therefore, the present invention includes an optical scanning means for scanning a pair of optical beams parallel to each other along the fluid flow direction in a direction perpendicular to the fluid flow direction; A photoelectric conversion means for receiving scattered light emitted when fine particles contained in a fluid pass through the pair of light beams when the pair of light beams are scanned, and detecting the scattered light as an electrical signal; and calculation processing means for calculating the flow velocity at each point within the scanning range of the light beam from the time interval of scattered light detected when a particle passes between the pair of light beams and the distance between the pair of light beams. The configuration aims to achieve the above objective.

[Example] Figure 1 shows the principle of this current velocity measuring device.

In the figure, laser light emitted from a laser light source 1 is transmitted to a laser projector 3 via an optical fiber 2.

The laser projector 3 is supported by a rotating device 4 as a light scanning means, and transmits the laser light from the laser light source 1 to the fluid 5 continuously or intermittently as a pair of parallel light beams along the flow direction of the fluid 5. irradiate the target. The rotation device 4
In this case, a pair of light beams from the laser projector 3 are directed to the fluid 5.
The laser projector 3 is rotated about an axis parallel to the flow direction of the fluid 5 so as to be scanned in a direction perpendicular to the flow direction of the fluid 5.

On the other hand, on the downstream side of the fluid 5 with respect to the measurement surfaces 6 and 7 scanned by the pair of light beams from the laser projector 3, fine particles such as dust contained in the fluid 5 pass through the pair of light beams. An image receptor 11 is disposed as a photoelectric conversion means that receives scattered light emitted from time to time and detects it as an electrical signal. The image receptor 11 collects the scattered light emitted by the particles within the measurement surfaces 6 and 7 using the condenser lens 12, and then
It is detected by the light receiving plate 13. The light-receiving plate 13 is composed of a large number of charge-coupled satin Cs (D) integrated at high density.

Each charge-coupled device CCO is disposed corresponding to each measurement site obtained by dividing the measurement surfaces 6 and 7 into a grid pattern, receives scattered light from the corresponding measurement site, and processes the received light signal with arithmetic processing means. to the computer 21 as a.

The computer 21 takes in the light reception signals from each charge coupled device CCD constituting the light reception plate 13 at regular intervals,
While sequentially storing data in the internal memory 22, the internal memory 2
The time interval between the light reception signals from the same charge-coupled device CG[ stored in 2 is calculated, and each measurement within the measurement surfaces 6 and 7 is calculated based on this time interval and the distance between the light beams inputted in advance from the keyboard 23. The flow velocity at each location is calculated and illustrated on the CRT 24, for example, the flow velocity is displayed in the form of a bar graph with respect to the coordinates of each measurement location.

Now, a pair of light beams from the laser projector 3 are directed toward the measurement surface 6.
, 7, the fluid 5
For example, when a fine particle contained therein passes between a pair of light beams separated by a distance ΔL at a speed V, the fine particle passes at a speed of ΔT−Δ
Scattered light is emitted with a time difference of L/v. Then,
Both scattered lights are connected to the same charge-coupled device CC with a time difference ΔT.
After being detected by D, the internal memory 22 of the computer 21
The received light signal from the charge-coupled device COD is stored in a time-specific storage area.

Therefore, the laser projector 3 is rotated by the rotation device 4,
A pair of light beams from the laser projector 3 are transmitted to the measurement surface 6,
7, the internal memory 22 of the computer 21 sequentially stores signals from the charge-coupled device C[lD that receives the scattered light from the measurement surfaces 6 and 7 at regular intervals. .

Therefore, the signal from the same charge-coupled device CfD is read from the data stored in the internal memory 22, and the time difference ΔT between the two signals is calculated. Distance Δ between light beams
From L, the flow velocity V at each measurement site on the measurement surface 6.7 is expressed as V
=ΔL/ΔT, and the flow velocity at each measurement site is graphically displayed.

Therefore, according to this embodiment, a pair of parallel light beams are scanned along the flow direction of the fluid 5 in a direction perpendicular to the flow direction of the fluid 5, and by this scanning, fine particles contained in the fluid 5 are removed. Scattered light emitted when passing through a pair of light beams is received by an image receiver 11, and the time interval ΔT of the scattered light detected by this image receiver 11 when a particle passes between the pair of light beams and the pair of light beams The computer 21 calculates the flow velocity at each measurement site on the measurement surface 6.7 from the distance ΔL and displays them on a monitor screen, so the flow velocity distribution within the measurement surface 6.7 can be measured in a short time. can do.

In particular, in this embodiment, the fluid 5 is irradiated with a laser beam and the scattered light is received for measurement, that is, the measurement is performed without contacting the fluid 5, which is different from the conventional method. In this way, there is no risk that the current meter itself will disturb the flow, and more accurate flow speed data can be obtained.

Because it has such advantages, the measuring device of this embodiment can measure the wake flow velocity distribution of fluid accompanying the running of ships, automobiles, etc.
Alternatively, it is suitable for measuring the downstream flow velocity distribution of fluid generated by structures such as bridges and buildings. For example, when measuring the wake velocity distribution of a ship, as shown in Figure 2,
A laser projector 3 is attached to the stern 32 of the ship via the rotation device 4.
The image receptor 11 is installed on the downstream side of the measurement surfaces 6 and 7 scanned by the pair of laser beams from the laser projector 3.
If it is supported via the support arm 33, the wake velocity distribution of the propeller 34 of the hull 31 can be measured accurately and in a short time. In this case, the image receptor 11 may be installed inside the hull 31 toward the stern 32, as shown by the broken line in FIG.

In the above embodiment, a pair of light beams are irradiated onto the fluid 5 by one laser light source 1, but the laser light sources 1 are provided separately. Further, as the optical scanning means, a laser beam from the laser light source 11 may be scanned onto the fluid 5 by, for example, rotating a reflecting mirror.

Further, the means for receiving the scattered light on the measurement surfaces 6 and 7 and converting it into an electrical signal is not limited to the image receiver 11 described in the above embodiment, but in short, the means for receiving the scattered light on the measurement surfaces 6 and 7 and converting it into an electrical signal is not limited to the image receiver 11 described in the above embodiment.
Any format may be used as long as it can detect the scattered light from each of the measurement sites 7 as a signal at a position corresponding to each measurement site.

Furthermore, a more accurate flow velocity distribution can be obtained by scanning the measurement units 6 and 7 with the light beam several times and statistically processing the flow velocity data group obtained at each measurement site.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a current meter 11 device that can accurately measure the flow velocity distribution within a predetermined range in a short time.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the measurement principle of the current velocity measuring device of the present invention, and FIG. 2 is a perspective view of the measuring device installed on a ship. 5... Rotating device as traveling scanning means, 5... Fluid, 11... Image receptor as photoelectric conversion means, CCD...
- Charge 6 combining element, 21... Computer as arithmetic processing means. Agent: Patent attorney Minoru Kinoshita (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] (1) A light scanning means for scanning a pair of light beams parallel to each other along the fluid flow direction in a direction perpendicular to the fluid flow direction, and a scanning speed of the pair of light beams by the light scanning means. When the particles contained in the fluid pass through a pair of light beams, a photoelectric conversion means that receives the scattered light emitted and detects it as an electric signal, and a lever photoelectric conversion means converts the particles. The flow velocity at each point within the scanning range of the light beam is calculated from the time interval of the scattered light detected when the light beam passes between a pair of beams and the distance between the pair of light beams. A flow velocity measuring device characterized by comprising: a means for measuring flow velocity; (2) A flow velocity measuring device according to claim 1, characterized in that the light beam is a laser beam. Total 3) In claim 1 or 2, A direct measurement device characterized in that the photoelectric conversion means is constituted by an image receptor in which charge-coupled devices are arranged at a high density.