JPS5939711B2 - Flow velocity and direction measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that uses sound waves to measure the flow velocity and direction of fluid, and its purpose is to measure gas, wind, and ocean currents using a small sensor with no mechanically moving parts. To provide a flow rate and direction measurement device such as the following.

In the present invention, receivers are placed upstream and downstream, and a sound wave transmitter is placed at the same distance from the receivers, so that when there is a flow in the fluid, the time taken for the sound waves to reach each receiver is This is an application of the principle of measuring the presence or absence of a flow and the flow velocity by using different factors. Four receivers are placed at the vertices of a square, and the difference between two receivers on the diagonal is measured. Two sets of outputs are obtained, and the detection signals are provided as a horizontal axis signal and a vertical axis signal to an oscilloscope, and the oscilloscope measures not only the flow velocity but also the direction of the flow.

Embodiments of the present invention will be described below based on the drawings.

Fig. 1 is a principle diagram explaining the basic principle of the present invention, where A is a sonic wave transmitter, B and C are receivers installed at the same distance from the transmitter A, and AMPI and AMP2 are amplifiers. , PS is a phase shifter, and PM is a phase meter.

Now, considering a basic case, if we match the direction of fluid flow with line BC, and set BC = 2tCm] and /BAC = 2θ, when the flow velocity is υ (m/s), the flow on line AB is The sound speed decreases against the flow by the minute velocity υsinθ. Further, the sound speed from A to C increases by the minute velocity υ sin θ of the flow.

Since the distance from A to B is / sin θ, the propagation time tl of sound from A to B is tl::″m), where C is the speed of sound when the fluid flow is 0, Cm/s.゜c-υsinθ, and the propagation time from A to C is 2=-'sinθ C+υsinθ, so the time difference dt to reach B and C is dt=1-
2 If the flow velocity υ is sufficiently small compared to the sound velocity C, the time difference dt is proportional to the flow velocity υ.

When this time difference dt is expressed as a phase difference, the phase difference is 2πfdt, where f is the frequency of the sound wave. Measuring the phase difference is more accurate and easier than measuring the time difference, and it is also possible to measure the range from a minimum of 1° to 1800 degrees with an accuracy of 1°.

It is also possible to measure the phase difference by a simple method instead of the expensive phase meter PM, and FIG. 2 shows this.

In other words, if the outputs of receivers B and C are adjusted to be equal and the vector difference between the two is taken, within a range of valences where the phase difference is a certain value, it is regarded as a straight line starting from O, so the magnitude of the combined vector is The flow rate is easy.

Figure 3 shows an embodiment of the present invention, in which four receivers are placed at the four vertices of a square, transmitters are placed at the intersections of the diagonals of the square, and two receivers are placed on the diagonals of the square. Calculate the phase difference (time difference) of the two receivers, add this to the horizontal axis of the oscilloscope, and add the phase difference of the other two diagonal receivers to the vertical axis of the oscilloscope. For example, wind speed and direction are measured from the amplitude and angle of the combined bright spot.
Now, if the time of sound reaching the four receivers BCDE from transmitter A is t, ~ t4, the wind direction is φ, and the wind speed is υ, then each minute of the wind speed υ on the AB, AC, AD, and AE lines The force is υ
cosφ, υsinφ, -υlowφ, -υsinφ, and due to the flow, the sound speeds on the AB, AC, AD, and AE lines are respectively, and from time t1 to t4, AB=AC=ADoA
If E=t, then the arrival time difference dt1 between B, D and C, E. If dt2 is C〉υ, then the phase difference at frequency f is 2πfdt1, 2πfdt2
becomes.

- ν▼X! bZV! ■ T then 4th
If these two phase difference signals are synchronously detected by detectors SD1 and SD2 at the reference transmission frequency as shown in the figure, υcos
Since a direct current component proportional to φ and υ sin φ can be taken out, if this is added to the horizontal and vertical axes of the oscilloscope, the position of the bright spot moves by υ in the direction of φ from the center point.

The wind speed and direction can be determined from the amount of movement.

To explain this using FIG. 5, B in FIG.
If the D line is the X axis and the CE line is the Y axis, the X axis and the Y axis are orthogonal, and the phase difference component proportional to the X axis direction component υcosφ of the wind speed υ and the Y axis component υsinφ is 2πfdt1, 2π
Since it is obtained by fdt2, it is clear that the wind direction intersects the X axis at an angle φ, and its magnitude is υ. As described above, the device according to the present invention uses a sensor with no mechanically moving parts, and since small transmitters and receivers are currently being developed, it is possible to detect the flow velocity and flow of highly durable gases and ocean currents. This is a huge contribution to industry as it can provide a device for measuring the direction of.

[Brief explanation of the drawing]

1 and 2 are block diagrams for explaining the principle of the present invention, FIG. 3 is a diagram showing the arrangement of a transmitter and a receiver in an embodiment of the present invention, and FIG. 4 is a block diagram for explaining the principle of the present invention. is a block diagram, and FIG. 5 is a diagram showing wind speed and phase difference. A...Transmitter, B-E...Receiver, A
MP1, AMP2...Amplifier, PS...
・Phase shifter, PM... Phase shifter.

Claims (1)

[Scope of Claims] 1. Four wave receivers are placed at the vertices of a square, and a sound wave transmitter is placed at a position equidistant from each of the wave receivers, and a sound wave transmitter is placed on one diagonal of the square. The amplitude and time difference (phase difference) of the received waves of the two receivers are extracted and added as the horizontal axis signal of the oscilloscope, and the amplitude and time difference of the other two receivers on the diagonal are added to the oscilloscope. A flow velocity and direction measuring device characterized by measuring flow velocity and flow direction by the deflection of a bright spot of an oscilloscope in addition to the vertical axis signal of the oscilloscope. 2. The flow velocity and direction measuring device according to claim 1, wherein all four receivers have equal sensitivity.