JP3560279B2 - Method and apparatus for visualizing flow - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a method and an apparatus for visualizing a flow for visualizing various flows and observing and studying the behavior and the like.
[0002]
[Prior art]
A conventional technique for visualizing the flow is shown in FIGS. In FIG. 4, a laser beam LO emitted in a pulse form from a laser 1 is shaped into a sheet shape in a lens group 2 and is incident on a measurement field 3. One end 4E of a tube 4 connected to a cylinder 6 of nitric oxide (NO) is located in the measuring field 3, and an electromagnetic valve 5 acting as an ON-OFF valve is interposed in the tube 4. .
[0003]
"Combustion Science and Technology (1996) Vols. 116-117", pp. 541 to 566, "Combustion Science and Technology" (1996), Vol. 116-117, "Design and Optimization of Combustion System". -Based Non-Contact Diagnostic Tools Using a Laser (New Non-Invasive Laser Diagnostic Tools for Design and Optimization of Technology, Appl. Andresen, M. Malobabic, A. Schmidt). A nitric oxide emits laser induced fluorescence the laser light is irradiated, the laser-induced fluorescence, visualization is possible by capturing a camera having sensitivity in the ultraviolet region. Therefore, if nitrogen oxide is mixed into the flow to be visualized and observed and irradiated with laser light, it acts as a tracer by laser-induced fluorescence, and if it is photographed by a camera 7 having sensitivity in the ultraviolet region, the flow of the flow can be reduced. Visualization is realized. Then, in order to effectively generate laser-induced fluorescence using nitric oxide as a tracer, the ON-OFF timing of the solenoid valve 5 is synchronized with the emission (irradiation) timing of the pulse laser emitted or emitted from the laser 1. Is controlled.
[0004]
Such visualization of the flow is very effective for observing or measuring the flow field in general, and is particularly effective for observing and measuring the combustion field.
[0005]
However, since the tube 4 directly connected to the nitric oxide cylinder is directly inserted into the measuring field 3, the moment the solenoid valve 5 is opened, as shown particularly clearly in FIG. Nitric oxide (GL in FIG. 5) to which the head is added due to the pressure is ejected into the measurement field 3. In other words, the nitric oxide GL is spouted into the measuring field 3 with an initial velocity that cannot be ignored.
[0006]
Then, as a result of the emission of nitric oxide GL, the flow to be visualized represented by the streamline t in FIGS. 4 and 5 is disturbed near the tip 4E of the tube 4, and is visualized by laser-induced fluorescence. Even so, the observation or measurement of the flow field is not correct.
[0007]
[Problems to be solved by the invention]
The present invention has been proposed in view of the prior art as described above, and when a tracer is added, a method for visualizing a flow such that a flow field can be prevented from being disturbed thereby. It is intended to provide equipment.
[0008]
[Means for Solving the Problems]
According to the method of visualizing the flow of the present invention, a tracer supply step of supplying a tracer to a measurement site, a laser irradiation step of irradiating a sheet-shaped laser beam, and a laser-induced irradiation of the tracer with the laser beam Observing the state of emitting fluorescence, wherein the tracer supplying step includes a porous member or a metal net for reducing the flow velocity due to a high pressure loss immediately before the tracer is supplied to the measurement site. The head held by the tracer passing therethrough is lost due to the pressure loss.
[0009]
Further, according to the apparatus for visualizing the flow of the present invention, it has a laser irradiation mechanism for irradiating laser light shaped into a sheet, and a tracer supply mechanism for supplying a tracer to a measurement site, and the tracer supply mechanism includes: A tracer supply passage for supplying the tracer to the measurement site, and a porous member or a metal net provided at the tip of the tracer supply passage for reducing the flow velocity due to a high pressure loss.
[0010]
In practicing the present invention, the tracer is preferably, for example, nitric oxide.
[0011]
According to the present invention having such a configuration, a tracer (for example, nitric oxide) supplied from a supply source such as a cylinder via the tracer supply mechanism can reduce the pressure loss immediately before being supplied to the measurement site. It passes through a structure that slows down the flow velocity at higher altitudes. At that time, for example, the head added to the tracer due to the pressure in the cylinder, etc., disappears when passing through a structure that reduces the flow velocity due to a high pressure loss and cancels the high pressure loss. I do.
[0012]
Therefore, the tracer supplied into the measurement field through the porous member or the metal net for reducing the flow velocity due to the high pressure loss can hardly have a flow velocity by itself. This prevents the flow to be visualized and measured from being disturbed by the jet flow of the tracer.
[0013]
As a result, when the sheet-like laser light is irradiated, the tracer emits laser-induced fluorescence, and the flow is visualized by photographing it with a means such as a camera having sensitivity in an ultraviolet region.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show an apparatus for visualizing a flow according to a first embodiment of the present invention. In FIG. 1, an apparatus for visualizing a flow according to a first embodiment of the present invention, which is denoted by reference numeral 10 in its entirety, includes a laser 11 that emits a laser beam LO in a pulse shape and a laser beam LO that is emitted from the laser 11 in a sheet form. And a lens group 12 for shaping into a pulsed laser beam having a shape. The laser beam LS shaped into a sheet by the lens group 12 is incident on a measurement field 13.
[0015]
The apparatus 10 has a cylinder 16 of nitric oxide (NO), and the cylinder 16 is connected to a tube 14 (a tracer supply passage for supplying a tracer to a measurement site). The distal end of the tube 14 is located at the measurement site 13, and an electromagnetic valve 15 acting as an ON-OFF valve is interposed in a region between the distal end and the cylinder 16.
Here, the laser 11 and the lens group 12 constitute a “laser irradiating mechanism for irradiating laser light shaped into a sheet”, and the tube 14, the solenoid valve 15, and the nitric oxide cylinder 16 “ Tracer supply mechanism ".
[0016]
Nitric oxide emits laser-induced fluorescence as described above and acts as a so-called tracer. The ON / OFF timing of the electromagnetic valve 15 is controlled so as to be synchronized with the emission (irradiation) timing of the pulse laser emitted or emitted from the laser 11.
Reference numeral 17 denotes a camera for recording a state in which the sheet-like laser beam LS is irradiated and nitric oxide as a tracer emits induced fluorescence.
[0017]
The configuration up to this point is substantially the same as that of the prior art, but in the embodiments of FIGS. 1 and 2, the end of the tube 14 (the end on the measurement field side) is particularly provided as clearly shown in FIG. The porous member 20 is attached as a "structure for reducing the flow velocity due to a high pressure loss".
[0018]
Nitrogen monoxide supplied from the cylinder 16 blows out from the tip of the tube 14 into the measurement site 13 when the solenoid valve 15 is in the “open (or ON)” state. The head added to the nitric oxide (to be blown into 13) disappears due to pressure loss as it passes through porous member 20.
Therefore, nitric oxide (indicated by GL in FIG. 2) supplied into the measurement field 13 through the porous member 20 has almost no flow velocity itself. Therefore, the flow to be visualized and measured (the flow having the streamline indicated by the symbol t in FIG. 2) is not disturbed by the flow of nitric oxide.
Then, when the sheet-like laser light LS is irradiated, the nitric oxide emits laser-induced fluorescence, which is photographed by the camera 17 (observation means for performing an observation step), and the flow is visualized.
[0019]
Here, in the embodiment of FIGS. 1 and 2, the porous member 20 is attached to the distal end of the tube 14, but a metal net having a relatively fine mesh may be provided on the tube 14 instead. . Also in this case, the "metal mesh with relatively fine eyes" should be measured by visualizing and measuring the loss of the head held by nitric oxide as a "structure that reduces the flow velocity due to high pressure loss". This has the effect of preventing the flow from being disturbed by the ejection of the nitric oxide.
[0020]
FIG. 3 shows a flow visualization device according to a second embodiment of the present invention. An apparatus for visualizing the flow indicated by reference numeral 30 has a configuration substantially similar to that of the first embodiment shown in FIGS. 1 and 2 except that a laser 31 for emitting (irradiating) a laser beam LO is provided. , An OPO system having a dye laser or an optical parametric oscillator (hereinafter abbreviated as “OPO”).
[0021]
When the laser 31 is a dye laser or an OPO system, the laser 31 performs the functions of “excitation” and “oscillation by selecting a wavelength”. The vibrational energy level of nitrogen can be used. For example, by using a transition in which the vibration energy level around 226 nm is relatively low, the flow is not limited to a high-temperature region such as in a flame, and can be measured at room temperature or room temperature at a relatively low temperature. Visualization becomes possible. Therefore, it is very effective for observation and measurement of a flow field.
[0022]
It should be noted that the illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
[0023]
【The invention's effect】
The functions and effects of the present invention are listed below.
[0024]
(1) The flow to be visualized and measured is prevented from being disturbed by the flow of nitric oxide supplied to the measurement site.
(2) Nitric oxide emits laser-induced fluorescence, and flow visualization is preferably performed.
(3) There is no need to significantly modify the conventional flow visualization device.
[Brief description of the drawings]
FIG. 1 is a block diagram of a first embodiment of the present invention.
FIG. 2 is an enlarged view of an arrow F2 part in FIG. 1;
FIG. 3 is a block diagram of a second embodiment of the present invention.
FIG. 4 is a block diagram of a conventional apparatus for visualizing a flow.
FIG. 5 is an enlarged view of a portion indicated by an arrow F5 in FIG. 4;
[Explanation of symbols]
10, 30: Device for visualizing the flow LO: Laser light 1, 11, 31: Laser LS: Sheet-like pulsed laser light 2, 12: Lens group 3, 13: Measurement field 4, 14, Tube 5, 15: Electromagnetic Valves 6, 16: Nitric oxide cylinder 7, 17: Camera 20: Porous member

Claims (2)

A tracer supply step of supplying the tracer to the measurement site, a laser irradiation step of irradiating a sheet-shaped laser light, and a step of observing a state in which the tracer is irradiated with the laser light and emits laser-induced fluorescence. In the tracer supplying step, immediately before the tracer is supplied to the measurement site, the head held by the tracer passes through a porous member or a metal net for reducing the flow velocity due to a high pressure loss and reduces the flow rate. A method of visualizing flows characterized by disappearing due to loss. A laser irradiation mechanism for irradiating the sheet-shaped laser beam; and a tracer supply mechanism for supplying the tracer to the measurement place. The tracer supply mechanism includes a tracer supply passage for supplying the tracer to the measurement place, An apparatus for visualizing a flow, comprising: a porous member or a metal net provided at a tip of a tracer supply passage for reducing a flow velocity due to a high pressure loss.

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