JPS5950945B2 - Probe for 3-directional measurement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a probe used when measuring wind speed (or flow speed) using ultrasonic waves.

The reason why ultrasonic waves are used to measure wind speed and flow velocity (hereinafter simply referred to as wind speed) is that the propagation speed of the ultrasonic waves changes depending on whether there is wind or when there is no wind, and the direction of propagation of the ultrasonic waves is the same. If there is a vector component of wind speed in the direction, the apparent ultrasonic propagation speed becomes faster, but if there is a vector component of wind speed in the opposite direction to the ultrasonic propagation direction, the apparent ultrasonic propagation becomes faster. This is because since the speed is slow, the value of the wind speed can be calculated by measuring the ultrasonic propagation time for both and calculating based on the measurement results.

In actual measurements, wind speed components in two directions, the X-axis direction and the Y-axis direction, may be determined as necessary, or wind speed components may be determined in three directions, the Z-axis (vertical) in addition to the X-axis and Y-axis. Measure the ingredients.

For each axis, a probe is constructed with ultrasonic transducers arranged so that it can be controlled under two conditions: when the wind components match and when the wind components are opposite to the propagation direction of the ultrasonic waves. However, when measuring in the two directions of the X and Y axes, use separate probes for the X-axis measurement and Y-axis measurement.
The same applies to 3-direction measurements.

Therefore, the first method that has been conventionally used is, as shown in FIG. 1, when measuring the wind speed component VX in the They are separated by a certain distance 1, their axes are aligned with the X-axis, they are lined up in parallel, and ultrasonic waves are transmitted from A to B, and in the opposite direction from C to D, and the ultrasonic waves propagate. Measure time.

When an ultrasonic wave is sent from A to B, the ultrasonic propagation direction and the direction of the wind speed component match, so the ultrasonic propagation time from A to B is J = 42... ...(1) However, C: Sound propagation velocity Vx: Wind velocity component Next, when ultrasonic waves are sent from C to D, the direction of ultrasonic F wave propagation and the direction of the wind velocity component are opposite, so from C to D Ultrasonic propagation time up to.

From (1) and (2), therefore, in equation (3), l is a constant and known value, so t1 and T2
If you measure , the wind speed can be found through numerical calculation.

Figure 2 shows the procedure for arranging the probe when measuring the wind speed in the three axes x, Y, and Z using this method. The direction perpendicular to both is the Z axis, and the ultrasonic transducers are installed facing each other at a certain distance on the axis of each probe (as shown in the figure).
(see mark). And for each axis, x+, x-, y+
As shown by the arrows y1, z+, and z-, the ultrasonic propagation time in both forward and reverse directions is measured to determine the wind speed. However, generally speaking, wind often blows horizontally, so
In the 0° range, the X-axis or Y-axis may coincide with or be very close to each other, and in this case, the effect of wind is generated on the plane of the ultrasonic transducer, and there is no wind in the ultrasonic propagation path. It is desirable to prevent the occurrence of turbulence, as this will result in a figure that is different from the true figure of the wind that is being measured.

Furthermore, as the wind speed increases, the influence of turbulence increases, and as a result, the upper limit of the wind speed measurable range becomes lower.

The method of installing the probes parallel to the horizontal plane has the above-mentioned drawbacks, so in order to avoid this drawback, in the second method, as shown in FIG. 3, the probes of ultrasonic transducers A and B are
A probe is used in which the axes of the probes C and D are arranged so that they intersect with each other at an appropriate angle.

In this case, as in Fig. 1, we send an ultrasonic wave from A to B and from C to D, measure its propagation time, and calculate the wind speed component Vx in the Y-axis direction, which becomes ( The difference from formula 3) is that a coefficient K is included, but this coefficient is determined by the shape of the probe.

Figure 4 shows an example of measuring wind speed in three axes using this crossing method.As you can see, the difference from Figure 2 is that the Ultrasonic transducers are arranged so as to cross the axis at an angle.

The measurement procedure is the same as in the case of FIG.

Since the direction of the axis connecting the ultrasonic transmitter and θ receiver installed opposite to the x-axis and Y-axis is inclined, most of the natural wind is horizontal, and there is little vertical wind. Taking this into consideration, it is clear that wind blows along the axis of the ultrasonic transducer is extremely rare, and therefore it is extremely unlikely that wind turbulence will occur on the ultrasonic propagation path. can be avoided.

However, in this method, the ultrasonic transducer is not used for both transmission and reception, so different ultrasonic propagation paths must be used for measurements in both forward and reverse directions.However, it is necessary to ensure that the two path lengths 1 are strictly equal. It is difficult to measure this, and as a result of this variation, the zero point of measurement shifts, and errors become a problem when precision is required.

In view of the current situation described above, the present invention aims to minimize the disadvantage of placing the probe on the target axis of graduation, that is, the occurrence of wind disturbance caused by the ultrasonic transducer in the ultrasonic propagation path. At the same time, it is intended to expand the measurable range, and to eliminate fluctuations in the zero point due to deviations in the interval 1 between the ultrasonic transmitter and receiver. In other words, by tilting the probe with respect to the measurement target axis, disturbances caused by the ultrasonic transducer can be avoided as much as possible on the ultrasonic propagation path, and the same ultrasonic propagation path can be used for correct measurement. Measurements are taken in both opposite directions, and consideration is given to eliminating zero-point fluctuations in measurements that occur due to discrepancies in the distance 1 between the ultrasonic transducers.

Examples will be described below.

FIG. 5 shows the arrangement of probes for measuring wind speed in three axial directions according to the embodiment of the present invention. A transducer will be installed.

However, such ultrasonic transducers are constructed in a dual-purpose system that performs both transmitting and receiving functions, and measure the ultrasonic propagation time in both forward and reverse directions in the same path. There is. The three sets of probes are intersected with each other at an appropriate angle in the horizontal plane (the figure shows an example of dividing the probe into three equal angles of 120 degrees), and at an appropriate angle with respect to the vertical plane (the figure shows an example of 45 degrees). ).

By measuring the ultrasonic propagation time for each of the three sets of probes, the wind speed in the axial direction of each probe can be determined, but as it is currently impossible to display the desired wind speeds in the x, Y, and Z axes, It must be converted into Y and Z axis values.

This conversion can be performed by using the results of numerical calculations performed and analyzed by geometric coordinate transformation, so if the arrangement of the probes is determined, the method of conversion can be determined in advance.

In the case of the figure, if we omit the intermediate calculation process and just summarize the results, we can see that when wind speed is measured using the probe according to the present invention, the occurrence of wind turbulence in the ultrasonic propagation system is greatly reduced. This has great practical effects, such as eliminating fluctuations in the measurement zero point caused by differences in the length of the ultrasonic propagation path.

[Brief explanation of the drawing]

Figure 1 shows a conventional example in which ultrasonic transducers are installed facing each other along the measurement target axis.

Claims (1)

[Claims] 1 Three sets of probes used in a device that uses ultrasonic waves to measure wind speed (or flow speed) in three directions relative to the X-axis, Y-axis in a horizontal plane, and Z-axis perpendicular to the two axes, each probe having a Ultrasonic transducers for transmitting and receiving are installed facing each other at a certain distance apart, and the axis of each probe that connects the facing ultrasonic transducers is It is characterized by intersecting through the midpoint of the axis so as to maintain an appropriately determined angle in the horizontal plane on which the transducer is placed, and being inclined with respect to the vertical plane by an appropriately determined angle. Probe for measuring direction.