JPH0599941A - Ultrasonic current meter - Google Patents

Abstract

PURPOSE:To measure the flow velocity of liquid at an arbitrary position in a pipe and to detect the distribution of the flow velocity in a space furthermore. CONSTITUTION:A pulse laser oscillator 4 oscillates high-output-power pulse laser light 5 in order to generate ultrasonic waves in liquid 2 in a pipe 1. A stop-down lens 6 condenses the pulse laser light 5 and focuses the light at a focal point 12 in the liquid 2. A lens driving device 7 drives the stop-down lens 6 and changes the position of the focal point 12. A position detector 8 detects the position of the stop-down lens 6. These parts are provided. Furthermore, a downstream-side ultrasonic sensor 91 and an upstream-side ultrasonic sensor 92 are provided on the walls of the pipe 1 at the downstream side and the upstream side of the focal point 12 so as to detect the ultrasonic waves. A signal processing device 10 computes the flow velocity of the liquid 2 based on the signals from both ultrasonic sensors 91 and 92 and the signal from the position detector 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ultrasonic velocity meter.

[0002]

2. Description of the Related Art A conventional ultrasonic velocity meter for measuring the flow velocity of a liquid flowing in a pipe is shown in FIG.
An ultrasonic sensor 15 ₁ for transmitting ultrasonic waves in the downstream direction, a downstream ultrasonic sensor 9 ₁ for reception, and an ultrasonic sensor for transmitting ultrasonic waves in the upstream direction are provided outside the conduit 1 through which the liquid 2 flows. 15 ₂ and upstream ultrasonic sensor 9 for reception
₂ are arranged so as to face each other and intersect the path of the ultrasonic wave, and the ultrasonic sensor 15 for transmission is provided.
₁ and 15 ₂ are driven by the pulse oscillator 14, and the signals from the ultrasonic sensors 9 ₁ and 9 ₂ for reception are supplied to the trigger output device 1.
1 is processed by the signal processing device 10 synchronized with the pulse oscillator 14. The ultrasonic sensor 15 ₁
The downstream ultrasonic wave 13 ₁ oscillated from the ultrasonic wave and the upstream ultrasonic wave 13 ₂ oscillated from the ultrasonic sensor 15 ₂ have different propagation velocities due to the flow of the liquid 2, and as a result, the ultrasonic wave 1 1
The time required for 3 ₁ and 13 ₂ to propagate from the transmission side to the reception side differs between the downstream direction and the upstream direction, so the flow velocity of the liquid 2 can be obtained from the difference in the propagation time of the ultrasonic waves in the downstream direction and the upstream direction.

However, in such a device, since the ultrasonic sensors 15 ₁ and 15 ₂ for transmission and the ultrasonic sensors 9 ₁ and 9 ₂ for reception are arranged outside the pipe line 1, the liquid 2 The flow velocity is obtained as the average flow velocity in the pipeline 1,
Therefore, there is a problem that the flow velocity at an arbitrary position in the conduit 1 and the spatial flow velocity distribution cannot be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of such circumstances, and it is possible to measure the flow velocity of a liquid at an arbitrary position in a pipeline, and to accurately detect a spatial flow velocity distribution. An object of the present invention is to provide an ultrasonic velocimeter that can be used.

[0005]

To this end, the present invention is directed to a pulse laser oscillator that oscillates a high-power pulse laser beam for generating ultrasonic waves in a liquid in a conduit, and a pulse laser beam that is focused. A lens capable of focusing in the liquid, a lens driving device that drives the lens to change the position of the focus of the pulsed laser light, a position detector that detects the position of the lens, and a downstream of the focus of the pulsed laser light. Pair of ultrasonic sensors which are respectively disposed on the upstream side and upstream side pipeline walls to detect ultrasonic waves, and signal processing for calculating the liquid flow velocity from the signals of the pair of ultrasonic sensors and the signal of the position detector. And a device.

[0006]

In the ultrasonic velocity meter of the present invention, when a high-power pulse laser is focused and incident on a liquid, molecular motion is rapidly excited by a high magnetic action in the vicinity of the focus in the liquid, and Since the liquid in the vicinity rapidly expands and induces pulsed ultrasonic waves, the ultrasonic waves are generated as a point sound source from the focus position of the focused pulsed laser light,
Therefore, the flow velocity at this focus position is measured by the ultrasonic sensor.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the ultrasonic velocity meter of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of the velocity meter of the present invention, FIG. 2 is an explanatory diagram showing the procedure of velocity measurement by the velocity meter, and FIG. 4 is an explanatory view of a propagation state of ultrasonic waves in FIG. 4, FIG. 4 is an explanatory view showing a measuring procedure of a flow velocity distribution in a one-dimensional space, and FIG. 5 is an explanatory view showing a measuring procedure of a flow velocity distribution in a two-dimensional space.

In FIG. 1, a liquid 2 circulates in a pipeline 1, and a window 3 is provided at an appropriate position in the pipeline 1. A high-power pulse laser oscillator 4 is provided outside the window 3,
It is arranged so as to oscillate the pulsed laser light 5 orthogonal to the window surface. A narrowing lens 6 is arranged on the optical path of the pulsed laser light 5 between the window 3 and the pulse laser oscillator 4, and a lens driving device 7 is connected to the narrowing lens 6, and a position detector 8 is provided there. Is attached.

Further, a downstream ultrasonic sensor 9 ₁ is arranged at a downstream position on the side opposite to the window 3 of the conduit 1, and an upstream ultrasonic sensor 9 ₂ is arranged at an upstream position. The output ends of ₁ and 9 ₂ are connected to the signal processing device 10, and the output end of the position detector 8 is connected to the signal processing device 10, and the trigger output device 11 is connected to the signal processing device 10. It is connected to the pulse laser oscillator 4.

In such a device, the pulsed laser light 5 oscillated from the high-powered pulsed laser oscillator 4 is condensed by the squeezing lens 6 and is incident on the liquid 2 in the conduit 1 through the window 3 so that the liquid 2 Focus on 12 with.
The position of the focal point 12 can be changed by the lens driving device 7, and the position of the focal point 12 is measured by the position detector 8 each time. The ultrasonic waves 13 generated from the focal point 12 are detected by the downstream ultrasonic sensor 9 ₁ and the upstream ultrasonic sensor 9 ₂ , and the signals detected by both ultrasonic sensors 9 ₁ and 9 ₂ are the focal points from the position detector 8. The position information of 12 is sent to the signal processing device 10 synchronized with the pulse laser oscillator 4 by the trigger output device 11 and processed.

The procedure of measuring the flow velocity by the ultrasonic wave 13 will be described in detail with reference to FIG. 2. The ultrasonic wave 13 generated as a point sound source at the focus of the pulsed laser light 5 is an ultrasonic wave 13 ₁ , which is directed to the downstream side and an ultrasonic wave to the upstream side, respectively. Assuming that the downstream ultrasonic sensor 9 ₁ and the upstream ultrasonic sensor 9 ₂ are equidistant from the focal point 12 as they propagate as ultrasonic waves 13 _2, as shown in FIG. The propagation time t ₁ of 13 ₁ is smaller than the propagation time t ₂ of the ultrasonic wave 13 ₂ to the upstream side. Therefore, the distance between the focal point 12 and the wall of the conduit 1 is h, and the focal point 12 is
If the distance between the leg from the pipe to the wall of the conduit 1 and each of the ultrasonic sensors 9 ₁ , 9 ₂ is L, the flow velocity V of the liquid 2 can be obtained by the following equation (1). Calculated by 10. V = (1 / t ₁ −1 / t ₂ ) ・ (h ₂ + L ² ) / L ・ ・ ・ (1)

It should be noted that the generation position of the ultrasonic wave 13, that is, the focal point 1
Since the position of 2 can be determined by the position of the aperture lens 6, the flow velocity distribution in a one-dimensional space on the incident center line of the pulse laser beam 5 can be obtained by moving the aperture lens 6 up and down as shown in FIG. Further, as shown in FIG. 5, when the incident direction of the pulsed laser light 5 is changed, a flow velocity distribution in a two-dimensional space can be obtained.

[0013]

In summary, according to the present invention, a pulse laser oscillator that oscillates a high-power pulse laser beam for generating an ultrasonic wave in a liquid in a conduit, and a pulse laser beam that is focused in the liquid , A lens drive device that drives the lens to change the position of the focus of the pulsed laser light, a position detector that detects the position of the lens, downstream and upstream of the focus of the pulsed laser light. A pair of ultrasonic sensors each disposed on the side wall of the pipe for detecting ultrasonic waves, and a signal processing device for calculating the flow velocity of the liquid from the signals of the pair of ultrasonic sensors and the signal of the position detector. Since the present invention provides an ultrasonic velocity meter capable of measuring the flow velocity of a liquid at an arbitrary position in a pipe, and further capable of accurately detecting a spatial flow velocity distribution, the present invention is extremely useful industrially. Than it is.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of an ultrasonic velocity meter of the present invention.

FIG. 2 is an explanatory diagram showing a procedure for measuring a flow velocity by the same velocity meter.

FIG. 3 is an explanatory diagram of an ultrasonic wave propagation state in the above.

FIG. 4 is an explanatory diagram showing a procedure for measuring a flow velocity distribution in a one-dimensional space.

FIG. 5 is an explanatory diagram showing a procedure for measuring a flow velocity distribution in a two-dimensional space.

FIG. 6 is a schematic diagram of a conventional ultrasonic velocity meter.

[Explanation of symbols]

1 Pipeline 2 Liquid 3 Window 4 Pulsed Laser Oscillator 5 Pulsed Laser Light 6 Focusing Lens 7 Lens Driving Device 8 Position Detector 9 ₁ Downstream Ultrasonic Sensor 9 ₂ Upstream Ultrasonic Sensor 10 Signal Processing Device 11 Trigger Output Device 12 Focus 13, 13 ₁ , 13 ₂ Ultrasound

Claims (1)

[Claims] 1. A pulse laser oscillator that oscillates a high-power pulse laser beam for generating ultrasonic waves in a liquid in a duct, and a lens that focuses the pulse laser beam and focuses it in the liquid. A lens driving device that drives the lens to change the focus position of the pulsed laser light,
A position detector for detecting the position of the lens, a pair of ultrasonic sensors arranged on the downstream and upstream pipe walls of the focus of the pulsed laser light to detect ultrasonic waves, respectively, and
An ultrasonic velocity meter, comprising: a signal processing device that calculates the flow velocity of a liquid from the signal of a pair of ultrasonic sensors and the signal of a position detector.