JPH0429065A - Running water speed measuring method - Google Patents

Abstract

PURPOSE:To easily, accurately, and continuously measure running water and to improve the durability of apparatus by observing the process of movement to the water surface of a rising bubble group continuously generated from the water bottom by a video camera from the side face of the flow direction of running water. CONSTITUTION:A bubble S continuously generated from a bubble generator 2 on a water bottom 1 successively rises and reaches the water surface to disappear. When water in a channel does not run, the bubble S rises along an approximately perpendicu lar line P; but when it runs. The bubble S rises while drawing a certain arc by synthe sis of the rising speed and the speed of running water. Since there are several layers different in speed of running water actually. The angle of rise of the bubble 3 is changed, and the bubble draws a relatively slow curve as the whole. That is, speeds of running water v1 to v3 in layers are equal to delta1/t1, delta2-delta1/t2-t1, and delta3-delta2/t3-t2 respective ly when times t1, t2, and (t) of floating to upper ends delta1, delta2, and delta of respective layers from the bubble generation point are obtained in accordance with a floating time curve or the like, and an average speed in all layers is obtained by v delta/t. Thus, running water is easily, accurately, and continuously measured, and the damage of apparatus is reduced.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a method for measuring the velocity of flowing water in rivers and ports.
The purpose is to ensure the accuracy of measurement data and to improve the durability of measurement equipment.

(Prior Art) Conventionally, a propeller-type current meter has been used to measure the average flow velocity of water in a river, particularly in a waterway cross section.

This method calculates the flow velocity by multiplying the propeller rotation speed of the current meter by a certain constant based on the fact that the water flow speed is proportional to the propeller rotation speed.

Ultrasonic current meters are also known. This method utilizes the fact that the transmission speed of ultrasonic waves increases in the direction of water flow and decreases in the reverse direction, and detects the amount of change in the transmitting frequency and receiving frequency using the so-called Doppler method, and detects the difference in pulse transmission time. The water flow velocity is calculated based on the difference in ultrasonic transmission speed between the forward and reverse directions of water flow.

Furthermore, a float measurement method is also known.

This method involves measuring the surface flow velocity of the river and converting the average flow velocity in the vertical section using a logical formula (surface float measurement), and also calculating the relationship between the speed of the rod float and the average velocity of the flowing water. There is a method (rod float type measurement) in which the value is calculated using a conversion formula and then corrected based on a correction coefficient that takes into account the length of the rod float and usage conditions (rod float method measurement). It will be done.

(Problem to be Solved by the Invention) However, when using the above-mentioned propeller type or ultrasonic current meter, it is necessary to directly expose the current meter itself or the ultrasonic sensor to flowing water, which causes drifting of pieces of driftwood, etc. It is easily damaged by objects and has a significant problem in terms of durability.

In addition, even when using the float measurement method, regular continuous measurement is not possible, and there is a risk of damage to the measurement sensor.Furthermore, as with the above measurement methods, the accuracy of the measured values is also low. This is where some problems remain.

(Means for Solving the Problems) The present invention solves various problems in the prior art described above, ensures accuracy of measured values, enables continuous measurement, and eliminates the risk of damage to equipment. It is designed to improve durability, and specifically consists of means for generating bubbles from the bottom of the water, and means for detecting bubble components within a certain range in the downstream direction from vertically above the point where the bubbles are generated. Concerning water velocity measurement method. In addition, the means for detecting the bubble component described above is such that a video camera is installed in a direction perpendicular to the flow direction of the flowing water, and the flow velocity is detected based on the rising angle of the bubble array based on the image of the bubble row. This paper relates to a method for measuring the velocity of flowing water.

Furthermore, the above-mentioned means for detecting the bubble component includes installing a plurality of ultrasonic sensors oriented in a direction perpendicular to the flow direction of the flowing water. The present invention also relates to a method for measuring the velocity of flowing water.

(Function) While bubbles are continuously generated from the water bottom, the progress of the rising bubbles toward the water surface is observed using a video camera from the side in the direction of water flow, or the flow direction of the rising bubbles is observed from the side of the waterway or at the bottom of the waterway in the direction of flow. The flow velocity is calculated based on the rising angle of the bubble array and the distance the bubble moves.

(Example) The specific content of the present invention will be explained below based on an example.

Figure 1 shows a side view perpendicular to the flow direction of the river, where 1 shows the bottom of the water and 2 shows the bubble generator installed on the bottom of the water.

Fig. 2 is a plan view of the state shown in Fig. 1, and shows that air bubbles are generated in any range from the vertical line P of the bubble generator 2 in the flow direction (downstream position). A video camera VTR was installed as a component detection means, and an illumination device was installed almost parallel to the video camera VTR so as to make a certain range downstream from the vertical line P of the bubble generator 2 described above as a photographing and irradiation area. There is.

The video camera VTR 1 or lighting device described above can be easily attached to a base pole or the like installed in a river. The bubble generator 2 is equipped with a nozzle that adjusts the size and amount of bubbles that generate bubble components within a range that can be detected by the detection device, and sprays the nozzle onto the bottom of the river at a location where the flow rate is relatively large, such as the center of the river. The nozzle is stably fixed in an exposed state, and a gas tube is connected to the nozzle to connect it to an electrically operated air pump (not shown) or the like.

In the above-mentioned embodiment, a case was explained in which a video camera VTR and a lighting device were used as the bubble component detection means, but the invention is not limited to this. A plurality of ultrasonic sensors may be installed to measure the rising position and direction of the bubble.

When bubbles S are continuously generated from the bubble generator 2 at the bottom of the water, each bubble S sequentially rises toward the water surface due to buoyancy, and when it reaches the water surface, it breaks and disappears. In this case, if there is almost no flow in the waterway, the bubbles S rise vertically along the vertical line P, but the rising bubbles draw a constant arc due to the combination of the rising speed and the water flow speed. It will rise.

Therefore, the flow velocity in the waterway can be determined by measuring the flow velocity component of the bubble movement due to the above-mentioned rising velocity of the bubbles and water flow velocity.

The calculation of the flow velocity component is as follows.

In other words, a row of bubbles S floating in flowing water exhibits a curved angle that leans toward the downstream side, but in reality, there are multiple layers with different water flow velocities, and when rising through each of these layers, the rising angle is at a single rate. Each time the water passes through a layer with a different flow rate, the rising angle is changed, resulting in a relatively gentle curve as a whole. Therefore, if we measure the case where water passes through layers with different flow speeds based on the diagram in FIG. 3, we will find that from the bubble generation point S by the bubble generator 2 to the upper end of each layer where the water flow speeds are different, Sl, 2, The respective levitation times t, t2, and r up to g are determined from a separately prepared bubble levitation time curve or table.

Therefore, the flow velocity in each layer is ■I=Sl/l.

Vz = (Sz -51)/ (tz -
t+ )V3 − (s Sr)/(t
tt). The average velocity V of all layers is 'v
It is determined by #s/τ.

In addition, when the flowing water is extremely turbid, such as during heavy rain or floods, the video camera and lighting equipment should be placed above the water surface in a direction perpendicular to the flow, and directly above the vertical line P. Install it in a position where you can see it within your field of vision.
The average flow velocity V can also be determined by measuring the point at which each bubble emerges above the water surface S and breaks down. In this case, the position of each bubble bursting point is determined by digital processing of the image, and the distance from the vertical line P is determined by computer calculation.

The vertical line P mentioned above is set in advance on the image based on the camera installation position, the bubble generation point, and the water level of the waterway. Furthermore, it is also necessary to set the correction between the image and the actual position in the program in advance.

In addition, the video camera V described above is used as a means for detecting bubble components.
When using an ultrasonic sensor instead of TR, 4th to 5th
As shown in the figure, a plurality of ultrasonic sensors are attached to each sealed can on the measuring line in the water flow direction, at regular intervals on the oscillating side (13 to 10a) and the receiving side (1b to 10b). Arrange at equal intervals.

The depth of the bubble S can be determined by constantly oscillating ultrasonic waves from the oscillating side (la to 10a) to the receiving side (1b to 10b) and measuring the time it takes for each bubble to collide and be reflected and return to the sensor. can be measured.

This relationship is clearly shown in the reflection recording schematic diagram of each sensor shown in FIG.

Therefore, in this case, assuming that the water depth is 6 m, for example, the time is determined by tz = 6 m x 2/1500 m/s = 8 ms.

In the embodiment described above, a case has been described in which a plurality of ultrasonic sensors (1 to 10) are arranged at equal intervals along the flow direction on the survey line in the water flow direction, but the invention is not necessarily limited to this. (A pair of oscillation and vibration receiving sensors may be disposed opposite each other, and the reflected waves of ultrasonic waves during movement may be recorded by disposing these sensors so as to be movable in the flow direction.)

(Effects of the Invention) As described above, the present invention comprises means for generating bubbles from the bottom of the water, and means for detecting bubble components within a certain range in the downstream direction from vertically above the bubble generation point, and the present invention continuously generates bubbles from the bottom of the water. It is easy to use because it allows the flow rate of water to be measured based on the rising angle of the bubble group and the distance traveled from the vertical line of the bubble generation point by observing the movement progress of the rising bubble group toward the water surface while generating the bubble group. Moreover, accurate measurement values of flow velocity can be obtained, continuous measurement is possible, there is no fear of damage to measuring instruments, and durability can be improved.

[Brief explanation of the drawing]

Fig. 1 is a side view of an example of the measurement method according to the present invention taken perpendicularly to the flow direction of a river, and Fig. 2 shows a video camera and lighting equipment in the state shown in Fig. Fig. 3 is a side view showing the measurement conditions shown in Figs. 1 and 2; Fig. 4 is a side view when an ultrasonic sensor is used as a means of detecting bubble components; FIG. 5 is a plan view of FIG. 4, and FIG. 6 is a schematic diagram of reflection recording of each sensor when measured by the measuring method shown in FIGS. 4 and 5. ■・・・・・・Water Bottom 2・・・Bubble generator S・・・Bubble p・・・・・・Plumb line VTR ...Video camera L...Lighting device inventor Hiroshi Kurimoto Patent applicant Taisei Basic Sekkei Co., Ltd. Agent Patent attorney Yoshimura Part diagram

Claims (3)

[Claims] (1) A water velocity measurement method comprising means for generating bubbles from the bottom of the water, and means for detecting bubble components within a certain range in the downstream direction from vertically above the point where the bubbles are generated. (2) The means for detecting bubble components is to install a video camera in a direction perpendicular to the flow direction of the flowing water, and to detect the flow velocity based on the rising angle of the bubble array based on the image of the bubble array. The method for measuring flowing water velocity according to claim (1). (3) The means for detecting bubble components is to install a plurality of ultrasonic sensors oriented in a direction perpendicular to the flow direction of the flowing water, and detect the flow velocity by searching for the bubble column and detecting the bubble column rising angle or bubble movement distance. The method for measuring flowing water velocity according to claim (1).