JPH07140161A - Wind velocity sensor using surface roughness and wind vane/anemometer employing it - Google Patents

Abstract

PURPOSE:To provide a more easy-to-handle anemometer by employing a lightweight, high response, inexpensive and convenient structure. CONSTITUTION:A wind velocity sensor 1 measures the velocity of wind flow by stretching a string having outer diameter, equal to or less than 1/11 that of a columnar object, across the entire surface of the columnar object and detecting a specific vibration or noise frequency having high Strouhal umber. The sensor 1 is set perpendicularly to the direction of an impeller 2 for detecting the direction of wind thus detecting the direction and velocity of wind based on the vibration or noise frequency of the wind velocity sensor 1. Alternatively, a plurality of wind velocity sensors 8 are set radially at a constant interval on a horizontal plane and one more wind velocity sensor 7 is set vertically in the center. Wind velocity components are detected from the vibration or noise frequency of respective wind velocity sensors and then they are combined in order to calculate the wind direction and wind velocity simultaneously.

Description

Detailed Description of the Invention

[0001]

The present invention has a shape index (d / D) of 1
TECHNICAL FIELD The present invention relates to a rod-shaped wind speed sensor having a surface shape of / 11 or less and utilizing surface roughness, and an anemometer using the wind speed sensor.

[0002]

2. Description of the Related Art Propeller anemometers and ultrasonic anemometers are commonly used as anemometers. The former propeller-type anemometer is a method in which when the propeller receives wind, the propeller is rotated to rotate a built-in generator, and the electromotive force generated from the generator is converted into a wind speed value and recorded. Recently, a propeller-type anemometer using an optical sensor has also been put into practical use, and there are anemometers that have the advantage that they can be used even in places subject to strong induction near high-voltage wires.
The latter ultrasonic anemometer is equipped with sensors at regular intervals, and it is converted into wind speed by utilizing the difference in arrival time when air moves.

There is another method in which the wind speed is obtained from the generation of Karman vortices formed behind the columnar body. When a non-streamlined object is put in the wind flow, a flow vortex is generated downstream of it. This flow is called Karman vortex, and it appears stably and continuously under certain conditions. When the width of the cylinder in the flow is D and the flow velocity is V, the vortex generation frequency (pulsation) f is expressed by the following equation. f = St (V / D), where St is called the Strouhal number, which is determined by the shape of the object and the Reynolds number (Re), but can be considered to be constant in the practical range where the wind blows (Fig. 4 (B)).
Therefore, the generated frequency (pulsation) f can be detected and the flow velocity can be known with respect to the St number. In this case, the conventional St
The number is 0.18-0.2.

[0004]

However, in the propeller type anemometer, it is necessary to turn the generator, and
Since the inertial force acts on the propeller, it is displayed larger or smaller than the actual wind speed depending on the inertia of the propeller, and there is a problem in response (response). In addition, the weight is 15 to 20 kg, and there is a problem that it is difficult to handle when mounting to a high place.

On the other hand, although the ultrasonic anemometer has a better response than the propeller type, there is a problem that the price becomes high because the ultrasonic technology is fully utilized. In addition, since the distance between the sensor parts becomes a problem, it needs to be made strong, and the weight becomes heavy. Also, since it is strongly affected by jamming radio waves from fishing radio, etc., it cannot be used until it is confirmed whether there is a facility emitting such jamming radio waves at the place of use. In other words, it is restricted by the place. Further, since the frequency in the ultrasonic band is targeted, it is necessary to reduce the signal attenuation as much as possible, and a signal cable with a large outer diameter must be used.

In the case of the vortex sensor utilizing the Karman vortex, the St number is as small as 0.18 to 0.2, the frequency is low, and the noise (vibration) level is small as described above, so that it is buried in the background noise. It is difficult to determine because it has been lost. That is, since the St number is small, the frequency resolving ability is not so good.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an anemometer which is excellent in responsiveness, light in weight, inexpensive, simple and easy to handle.

[0008]

SUMMARY OF THE INVENTION The above object of the present invention is to provide a cylindrical object having an outer peripheral surface with an outer diameter of 1 mm.
A wind velocity sensor utilizing surface roughness, characterized in that a linear body having an outer diameter of / 11 or less is formed into a twisted or spirally wound shape, and peculiar vibration or noise with a large Strouhal number is generated. The wind speed anemometer according to claim 1, wherein the wind speed sensor described in 1 is arranged at right angles to the direction of the wind direction detecting arrow blade, and the wind speed is detected from the frequency of vibration or noise emitted by the wind speed sensor. A plurality of wind speed sensors are installed at equal intervals on a horizontal plane and the wind speed sensors are arranged vertically at the center of the radiation, and the wind speed is detected from the frequency of vibration or noise emitted by each wind speed sensor. This is achieved by the wind direction anemometer characterized by detecting the wind direction from the combined value of the components.

That is, the shape index (d / D) is 1/11.
A cylindrical object having the following surface roughness is used as a wind speed sensor, and the frequency of the sound generated when the sensor receives wind is converted into the wind speed and, if necessary, detected in the wind direction and detected. The frequency of the generated vortex is higher than the frequency of vibration or noise due to the Karman vortex so far, the relationship between the frequency and the wind speed appears clearly, and the accuracy of reading the wind speed is improved.

The relationship between wind speed and vortex generation frequency is St = f.
It can be represented by D / V (1). Here, f is the vortex generation frequency (HZ), D is the outer diameter (m), and V is the wind speed (m /
s) and St are Strouhal numbers.

Generally, the St number in the case of a cylinder is (Re number 10
It becomes 0.2 to 0.18 (for ⁴ to 10 ⁶ ). In accordance with this, transmission lines are also set at around 0.2. However, when the outer diameter of the electric wire is D and the outer diameter of the wire forming the outermost layer is d, the shape index (d / D) representing the surface roughness is 1/11 or less, and the surface roughness is relatively small. In addition to this, the existence of the Strouhal number of about 0.5 to 0.7 is recognized in the electric wire (see FIGS. 4A and 4B). According to a separate confirmation of an electric wire having a shape index of 1/9, such a phenomenon is not observed. As shown in FIG. 5 (B), a large St number is recognized in the electric wire whose shape index is 1/11 or less.
In addition to the pulsation due to the generation of a large Karman vortex, a small dent on the surface of the wire (a V-shaped dent appearing on the outer side between the wires) acts as a kind of hole, and a small vortex separated by the wire causes resonance. It is presumed that this is an edge tone.
The present invention uses this property as a wind speed sensor.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a wind speed sensor. This wind speed sensor 1 cuts a predetermined length L from an electric wire formed by twisting a plurality of metal element wires, for example, aluminum wires concentrically in a plurality of layers, At least the ends of the outermost layer wires are fixed so that they do not come apart, and the outer diameter d of the wires forming the outermost layer is 1/11 or less than the outer diameter D of the wire. There is.

When the relationship between the wind speed and the vibration frequency of the generated vortices was investigated by using a wind tunnel experimental apparatus for electric wire samples having different shape indices (d / D), the surface roughness was as shown in FIG. 4 (A). A high-level frequency vibration is generated in an electric wire whose (d / D) is 1/11 or less, and the noise level of the sound emitted from such an electric wire is as shown in Fig. 5 (A). It is high, and it is distributed in the area where it can be sufficiently discriminated by a noise meter or a vibrometer.

Therefore, a wire having a shape index of 1/11 or less and having a predetermined length L is used as a sensor.
The wind speed sensor 1 is fixed upright as shown in FIG. 2 (A), and the noise and vibration meter 6 connected to the frequency analyzer downwind thereof.
Is arranged to detect high-level vibration or noise emitted from the wind speed sensor 1 through the noise vibrometer 6, analyze the frequency with an analyzer, and convert the peak value into the wind speed to detect the wind speed. it can.

FIG. 2 (B) shows another example of use of the wind speed sensor 1. The wind speed sensor 1 is mounted horizontally on the tip side of the arrow blade 2 for detecting the wind direction of the wind vane, and the wind speed sensor 1 is used.
Attach the noise vibration meter 6 to the sensor grip 5 on the leeward side of
The wind speed is detected through the noise vibrometer 6 and the wind direction can be detected by using a potentiometer built in the cylinder 3 on the pedestal 4. In this case, in order to reduce the influence of background noise, the sensor part of the noise vibration meter 6 may be built in the sensor grip part 5.

FIG. 3 shows another example of use of the wind speed sensor. In this example, four wind speed sensors shown in FIG. 1 are used, one of them is vertically attached to the gantry 9, and the remaining three are arranged at equal intervals in the horizontal direction at a pitch of θ = 120 °. The wind speed and the wind direction are simultaneously detected by detecting the vibration or noise emitted from the sensors 7 and 8. Although not shown, noise vibrometers are arranged near the wind speed sensors 7 and 8, respectively. Needless to say. In this case, the wind direction can also be detected by using a combination of the true wind speed detected by using the vertically mounted wind speed sensor 7 and each wind speed detected by using the horizontally mounted wind speed sensor 8.

According to an experiment on a sample of an electric wire corresponding to a wind speed sensor, when the wind hits it obliquely, the noise level tends to decrease as the wind hitting angle becomes smaller, as shown in FIG. Therefore, the wind direction can be easily detected by using this tendency.

The case where the wind speed sensors 1, 7 and 8 described above are cut out from an electric wire is shown. This wind speed sensor is formed on the surface of a cylindrical object such as a pipe or a bar made of aluminum or plastic. Shape index (d
It is also possible to arrange and fix a filamentous body such as a wire rod or a cord material whose / D) is 1/11 or less like the outermost layer of the electric wire.

[0019]

According to the invention as set forth in claim 1, since high-level vibration or noise is generated by the action of wind, the response is good by using this in combination with a vibrometer or a sound level meter. An inexpensive and simple anemometer can be obtained.

According to the second and third aspects of the invention, since the special wind velocity sensor is used, it is possible to provide an anemometer which is light in weight, inexpensive, simple and easy to handle.

[Brief description of drawings]

FIG. 1 is a front view (A) and a sectional view (B) showing a shape of a wind speed sensor utilizing surface roughness of the present invention.

FIG. 2 is a perspective view (A) and (B) of an embodiment of a wind speed sensor using the surface roughness of the present invention.

FIG. 3 is a perspective view of another embodiment of the wind speed sensor using the surface roughness of the present invention.

FIG. 4 is a graph showing the shape index (d / D) of the wind speed sensor,
Relationship between wind speed (m / sec) and vibration frequency (A), R
A relational diagram of the number of e and the number of St (B).

FIG. 5: Shape index (d / D): relational diagram between noise level (dB) and wind speed (m / s) of electric wire shape of 1/11 or less (A), schematic diagram of vortex in cross section of sensor ( B).

FIG. 6 is a diagram showing the relationship between the wind speed (θ) and the noise level (dB) of the wind speed sensor according to the present invention.

[Explanation of symbols]

 d Outer diameter of the wire D Outer diameter of the wire 1 Wind speed sensor 2 Arrow blade 3 Potentiometer built-in part 4 Stand 5 Sensor grip 6 Noise vibrometer 7 Vertically mounted wind speed sensor 8 Horizontally mounted wind speed sensor 9 Mounting base

Claims (3)

[Claims] 1. A peculiarity in which the entire outer circumference of a cylindrical object is formed by twisting or spirally winding a linear body having an outer diameter of 1/11 or less of the outer diameter of the cylindrical object, and having a large Strouhal number. A wind velocity sensor using surface roughness that generates various vibration or noise frequencies. 2. The wind velocity sensor according to claim 1, wherein the wind velocity sensor is arranged at right angles to the direction of the wind direction detecting blade, and the wind velocity is detected from the vibration or noise frequency emitted by the wind velocity sensor. Total. 3. A wind speed sensor according to claim 1, wherein a plurality of wind speed sensors are installed at equal intervals on a horizontal plane, and the wind speed sensors are arranged vertically at the center of the radiation, so that vibrations generated by the respective wind speed sensors or An anemometer that detects wind speed from a noise frequency and detects the wind direction from a combined value of the wind speed components.