JP5434548B2 - Flow velocity distribution measuring method and flow velocity distribution measuring apparatus - Google Patents

Description

  The present invention relates to a flow velocity distribution measuring method and a flow velocity distribution measuring apparatus for measuring a flow velocity distribution in a water channel using ultrasonic waves.

  In hydroelectric power generation, the generator output varies depending on the flow rate of water. The flow rate of water may be controlled by providing a dam or intake weir, but in small hydroelectric power generation, the water may be diverted from a natural river. In this case, the branched water channel that does not cover the upper part is called an open water channel or open channel, and has various widths from several meters to several tens of meters. Such water flow is one of the most important observation data for river planning and management in hydropower generation.

  In order to measure the flow rate of a large channel, it is necessary to acquire the water level, the cross-sectional shape of the channel, and the flow velocity distribution. Of these, measurement of the flow velocity distribution with a significant spatiotemporal change is the most important. In order to measure the flow velocity distribution over the entire cross section, it is essential to measure the flow velocity efficiently considering that the width of many first-class rivers is several tens to several hundred meters or more.

  As a flow velocity distribution measuring apparatus, a measuring apparatus using an ultrasonic sensor and its method are well known. This measuring device measures the flow velocity distribution by receiving the reflected wave that is reflected by the ultrasonic wave oscillated in the water and reflected by the suspended matter or bubbles in the water, and mainly uses the Doppler method and the cross-correlation method. Has been. In particular, ultrasonic flow velocity distribution flowmeters using the Doppler method can measure the flow velocity distribution and flow rate of liquid in a conduit even if the conduit is opaque or the fluid itself is opaque. It has an advantage that it can be applied to the measurement of the flow velocity of various opaque fluids such as liquid, mercury, and liquid metals such as sodium (for example, Patent Document 1). In the market, a flow measuring device (ADCP: Acoustic Doppler Current Profiler) using the Doppler method is widely provided and used.

JP 2000-97742 A

  The flow velocity distribution measuring apparatus using ultrasonic waves is not limited to the ultrasonic flow velocity distribution flow measuring apparatus described in Patent Document 1, and it is necessary to input the sound velocity (sound velocity value) of the liquid at the time of measurement. As a method of calculating the sound velocity value, for example, there is a method of calculating using conditions such as the temperature and pressure of the liquid and literature values such as a science chronology. However, since the sound speed value obtained by this method is a theoretical value, this value is not always a value that matches the measurement environment. In particular, when the measurement object is river water or seawater, there are more cases where such theoretical values cannot be applied because the change in the situation is remarkable.

  Therefore, as another calculation method, there is a method using a sensor for measuring sound velocity or a measurement unit. According to this, since the distance from the launch position to the sensor is known in advance, the sound velocity value can be calculated from the time when the ultrasonic wave emitted to the fluid returns to the sensor. Therefore, a value suitable for the measurement environment can be obtained. However, this method has a problem that the cost is increased because the sound speed measurement sensor and the measurement unit are used, and the measurement system is complicated.

  In view of such problems, the present invention is capable of calculating a sound velocity value suitable for a measurement environment even with a simple configuration, and capable of measuring a flow velocity distribution with higher accuracy and a flow velocity distribution measurement. The object is to provide a device.

  In order to solve the above problems, a typical configuration of a flow velocity distribution measuring method according to the present invention is a flow velocity distribution measuring method for measuring a flow velocity distribution of a fluid using ultrasonic waves, and a reflecting member that reflects ultrasonic waves. Is installed in the direction of the emission of the ultrasonic side lobe in the fluid, the ultrasonic wave is emitted into the fluid, the reflected ultrasonic wave is reflected on the reflecting member, and the reflected wave is received. The sound speed value of the fluid is calculated using the distance from the launch position to the reflecting member and the time from when the ultrasonic wave is emitted until the reflected wave is received, and the sound speed value and the main lobe of the ultrasonic wave are in the fluid. It is characterized in that a flow velocity distribution of a fluid is obtained using a reflected wave generated by reflection on a reflector.

  According to the above configuration, the sound velocity value is calculated by the reflected wave generated by the reflection of the side lobe, which is a sub-polar of the ultrasonic wave, on the reflecting member, and the main lobe, which is the main pole of the ultrasonic wave, is reflected by a reflector such as a bubble. The sound velocity value can be used when calculating the flow velocity from the reflected wave generated by the above. Thereby, even if it is a simple structure, the sound speed value according to the measurement environment can be calculated, and it is possible to measure a more accurate flow velocity distribution.

  The signal obtained by receiving the reflected wave is superimposed for a predetermined time, the signal amplified by the superposition is detected as a standing wave, and the value obtained by dividing the standing wave by the predetermined time is used when obtaining the flow velocity distribution of the fluid. The signal may be corrected by subtracting from the signal, and the fluid flow velocity distribution may be obtained using the corrected signal.

  The signal of the reflected wave generated by the reflection of the ultrasonic side lobe described above on the reflecting member is useful for calculating the sound velocity value, but becomes noise in calculating the flow velocity distribution. However, according to the above configuration, the signal using the reflected wave of the side lobe is removed from the signal used when determining the fluid flow velocity distribution by the correction using the standing wave, and the fluid flow velocity distribution using the corrected signal. Can be requested.

  It is preferable to correct the obtained flow velocity distribution by complementing the negative peak at which the flow velocity decreases in the obtained flow velocity distribution waveform with an approximation function excluding values before and after the peak. Thereby, the flow velocity distribution can be corrected without superimposing signals. Therefore, it is possible to improve data accuracy while reducing the time and load required for data processing.

  In order to solve the above problems, a typical configuration of a flow velocity distribution measuring apparatus according to the present invention is a flow velocity distribution measuring apparatus that measures the flow velocity distribution of a fluid using ultrasonic waves, and emits ultrasonic waves into the fluid. Receiving the reflected wave generated by the reflection of the ultrasonic wave to the reflection member or the reflector in the fluid, and the reflection member provided in the emission direction of the side lobe of the ultrasonic wave in the fluid to reflect the ultrasonic wave The reflected wave receiving unit, the distance from the ultrasonic wave emitting unit to the reflecting member, and the time from when the ultrasonic wave emitting unit emits the ultrasonic wave until the reflected wave receiving unit receives the reflected wave, A sound velocity calculation unit that calculates a sound velocity value, a velocity distribution calculation unit that obtains a fluid flow velocity distribution using the sound velocity value and a reflected wave that is generated when the ultrasonic main lobe is reflected by a reflector in the fluid. It is characterized by that.

  The components corresponding to the technical idea in the above-described flow velocity distribution measuring method and the description thereof can be applied to the flow velocity distribution measuring apparatus.

  The shape of the reflection member may be a plate shape or a rod shape. With such a configuration, ultrasonic waves are easily reflected, and the flow of the fluid is not hindered, so that measurement of the flow velocity distribution of the fluid is not hindered.

  The reflection member may be installed in a posture along the fluid flow direction. Thereby, since the flow direction of the fluid is the same as the installation direction of the reflection member, the reflection member does not hinder the flow of the fluid. Therefore, the fluid flow is stabilized, and a more accurate flow velocity distribution can be obtained.

  According to the present invention, it is possible to calculate a sound velocity value in accordance with a measurement environment even with a simple configuration, and to measure a flow velocity distribution with higher accuracy.

It is a figure which shows schematic structure of the flow-velocity distribution measuring apparatus concerning this embodiment. It is a functional block diagram which shows the function structure of the flow-velocity distribution measuring apparatus concerning this embodiment. It is a schematic diagram explaining the detail of a reflected wave It is a waveform diagram of a reflected wave signal and a waveform diagram of a measured flow velocity distribution. It is a flowchart explaining the flow-velocity distribution measuring method concerning this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  A flow velocity distribution measuring method and a flow velocity distribution measuring apparatus according to the present embodiment measure a flow velocity distribution of a fluid in a water channel, and measure a flow velocity distribution in a water channel for intake of hydroelectric power generation as a representative example. In the following description, in order to facilitate understanding, the flow velocity distribution measuring apparatus according to the present embodiment will be described in detail, and then the flow velocity distribution measuring method using the flow velocity distribution measuring apparatus will be described in detail.

(Flow velocity distribution measuring device)
FIG. 1 is a diagram showing a schematic configuration of a flow velocity distribution measuring apparatus according to the present embodiment. As shown in FIG. 1, the fluid 104 flows in the direction of the white arrow in the water channel 100 that is the measurement target of the flow velocity distribution measurement by the flow velocity distribution measuring apparatus. Is included. As a result, it is possible to receive the reflected wave generated when the ultrasonic wave 260 is reflected by the bubble 106 and measure the flow velocity distribution of the fluid 104. The bubble 106 can be generated by disposing a bubble generator (not shown) in the water channel 100 on the upstream side of the flow velocity distribution measuring device 200, for example.

  As shown in FIG. 1, the flow velocity distribution measuring device (hereinafter referred to as a measuring device 200) according to the present embodiment is mainly composed of a measuring terminal 210, a probe 250, and a reflecting member 270. The measurement terminal 210 and the probe 250 are connected via a cable 202 by wire. Both the probe 250 and the reflecting member 270 are fixed to a fixing jig 272.

  FIG. 2 is a block diagram showing a functional configuration of the flow velocity distribution measuring apparatus 200 according to the present embodiment. A measurement terminal 210 shown in FIG. 2 includes a control unit 212, a storage unit 224, a display unit 226, and an input unit 228. The measurement terminal 210 controls input of an ultrasonic wave 260 by a probe 250 described later, The reflected wave received by the probe 250 is calculated.

  The control unit 212 manages and controls the entire measuring apparatus 200 using a semiconductor integrated circuit including a central processing unit (CPU). In this embodiment, the control unit 212 also functions as a pulsar 214, a receiver 216, an A / D conversion unit 218, a sound speed calculation unit 220, and a flow velocity distribution calculation unit 222.

  The pulser 214 transmits an electrical signal (current) corresponding to the waveform of the ultrasonic wave to the ultrasonic wave emitting unit 252 via the cable 202. The electrical signal is transmitted at a predetermined frequency and interval for driving the ultrasonic emitter 252. The receiver 216 amplifies an analog signal generated when the reflected wave receiving unit 254 receives the reflected wave of the ultrasonic wave 260. The A / D converter 218 converts the reflected wave as an analog signal amplified by the receiver 216 into a digital signal.

  The sound speed calculation unit 220 calculates the distance from the ultrasonic wave emitting unit 252 to the reflecting member 270 and the time from when the ultrasonic wave emitting unit 252 emits the ultrasonic wave 260 until the reflected wave receiving unit 254 receives the reflected wave. To calculate the sound velocity value of the fluid. Details of the calculation of the sound speed value by the sound speed calculation unit 220 will be described later.

  The flow velocity distribution calculation unit 222 uses the sound velocity value calculated by the sound velocity calculation unit 220 and the reflected wave that is generated when the main lobe 260a of the ultrasonic wave 260 is reflected by the bubble 106 (the reflector in the fluid) in the fluid 104. To obtain the flow velocity distribution. In the present embodiment, the flow velocity distribution calculation unit 222 also corrects a signal obtained by receiving the reflected wave, that is, a signal used when obtaining the flow velocity distribution and the flow velocity distribution. The calculation and correction of the flow velocity distribution by the flow velocity distribution calculation unit 222 will be described later.

  The storage unit 224 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD (Hard Disk Drive), and the like, and stores a program processed by the control unit 212. The display unit 226 includes a liquid crystal display, EL (Electro Luminescence), PDP (Plasma Display Panel), and the like, and can display a GUI (Graphical User Interface) of an application stored in the storage unit 224.

  The input unit 228 includes a plurality of keys (switches) such as a keyboard, a cross key, and a joystick, a mouse, and the like, and receives a user operation input. For example, the distance from the ultrasound emitting unit 252 to the reflecting member 270 can be input by the input unit 228.

  The probe 250 is attached to a fixed jig 272, and a tip is disposed in the fluid 104 while being inclined with respect to the flow of the fluid 104, and the ultrasonic wave 260 is emitted into the fluid 104 and transmitted through the fluid 104. Receive the reflected wave. The probe 250 includes an ultrasonic wave emitting unit 252 and a reflected wave receiving unit 254.

  The ultrasonic wave emitting unit 252 emits an ultrasonic wave 260 into the fluid 104. Referring to FIG. 1 again, the ultrasonic wave 260 emitted from the ultrasonic wave emitting unit 252 mainly passes through the fluid 104 as a main lobe 260a and a side lobe 260b. Specifically, the main lobe 260a (also referred to as a main pole) has directivity in the central axis direction of the probe 250 that emits the ultrasonic wave 260, and goes straight from the probe 250 in the direction of the solid arrow. It is a strong wave. The side lobe 260b (also referred to as a sub-pole) is a broken line from the probe 250 in a conical shape so as to surround the main lobe 260a in an outer direction that forms a constant angle θ with the straight direction of the main lobe 260a. A weak wave radiated in the direction of the arrow.

  Although only one side lobe 260b is drawn on each side in the figure, a plurality of side lobes are actually generated at different angles. The strength of the side lobes decreases as the angle θ increases. In the present embodiment, any of a plurality of side lobes may be used. In consideration of the intensity, the one close to the main lobe 260a is preferable, but if it is too close, the irregular reflection of the ultrasonic wave emitted from the main lobe 260a may be reflected on the reflecting member 270. Therefore, the side lobe 260b to be used can be appropriately selected in consideration of the inclination angle of the probe 250 with respect to the fixing jig 272, the size (dimension) of the reflecting member 270, and the strength of the side lobe.

  The reflected wave receiving unit 254 receives a reflected wave that is generated when the ultrasonic wave 260 is reflected by the reflecting member 270 or the bubble 106 (a reflector in the fluid). Although details will be described later, in the present embodiment, the flow velocity distribution is measured using the reflected wave of the main lobe 260a received by the reflected wave receiving unit 254, and the sound velocity value is calculated using the reflected wave of the side lobe 260b. .

  The reflecting member 270 (see FIG. 1) is a member that reflects the ultrasonic wave 260 provided in the emitting direction of the side lobe 260b of the ultrasonic wave 260 in the fluid while being fixed to the fixing jig 272. The reflecting member 270 is provided at a position that is within the passage region of the side lobe 260b and outside the passage region of the main lobe 260a. Accordingly, it is possible to appropriately calculate only the side lobe 260b without reflecting the main lobe 260a, and to calculate the sound speed value.

  The shape of the reflecting member 270 may be a plate shape or a rod shape. Thereby, reflection of the side lobe 260b (ultrasonic wave 260) becomes easy. Further, since the flow of the fluid 104 is not hindered, measurement of the flow velocity distribution is not hindered. The reflecting member 270 may be installed in a posture along the flow direction of the fluid 104. Thereby, since the flow direction of the fluid 104 and the installation direction of the reflection member 270 become the same, the reflection member 270 does not obstruct the flow of the fluid 104. Therefore, the flow of the fluid 104 is stabilized, and a more accurate flow velocity distribution can be obtained.

(Processing by the sound velocity calculation unit 220 and the flow velocity distribution calculation unit 222)
Next, calculation of the sound velocity value by the sound velocity calculation unit 220 and calculation and correction of the flow velocity distribution by the flow velocity distribution calculation unit 222 will be described. FIG. 3 is a schematic diagram illustrating details of the reflected wave. As described above, when the ultrasonic wave 260 is emitted into the fluid 104 from the ultrasonic wave emitting unit 252 of the probe 250, the ultrasonic wave 260 passes through the fluid 104 as the main lobe 260a and the side lobe 260b ( (See FIG. 1).

  Then, as shown in FIG. 3A, a part of the main lobe 260a is reflected by the bubble 106 near the tip of the probe 250, and the reflected wave 262a of the main lobe 260a (hereinafter simply referred to as the reflected wave 262a). Occurs. The side lobe 260b is reflected by the reflecting member 270, and a reflected wave 262b (hereinafter simply referred to as a reflected wave 262b) of the side lobe 260b is generated. These reflected waves 262 a and 262 b reach the probe 250 and are received by the reflected wave receiving unit 254.

  At this time, the emission position of the ultrasonic wave 260, that is, the distance L from the probe 250 to the reflecting member 270 is known and is substantially constant. Therefore, when the reflected wave receiving unit 254 receives the reflected wave 262b, the time from when the ultrasonic wave 260 is emitted until the reflected wave 262b is received can be obtained. Thereby, the sound velocity value can be calculated using the distance L from the probe 250 to the reflecting member 270 and the time from when the ultrasonic wave 260 is emitted until the reflected wave 262b is received.

  The sound velocity value calculated as described above is obtained by actually emitting the ultrasonic wave 260 into the fluid 104 to be measured. Therefore, the sound velocity value is a value including environmental influences such as the water temperature and water quality of the fluid 104, that is, It is a value according to the measurement environment. For this reason, if such a sound velocity value is used, the flow velocity distribution of the fluid can be measured with high accuracy.

  In FIG. 3A, the main lobe 260a that has further traveled straight through the fluid 104 without being reflected by the bubble 106 is reflected by the bubble 106 flowing through the water channel 100 as shown in FIG. 3B, and a reflected wave 262a is generated. The reflected wave 262 a also reaches the probe 250 and is received by the reflected wave receiving unit 254. Then, by continuously receiving the reflected wave 262a of the main lobe 260a shown in FIGS. 3A and 3B, the flow velocity distribution calculation unit 222 is calculated by the reflected wave 262a and the sound velocity calculation unit 220. The flow velocity distribution can be obtained using the sound velocity value.

  In FIG. 3B as well, the main lobe 260a that travels further straight in the fluid 104 without being reflected by the bubbles 106 is reflected by the bottom surface 100a of the water channel 100 as shown in FIG. 3C, and a reflected wave 262c is generated. This reflected wave 262 c also reaches the probe 250 and is received by the reflected wave receiving unit 254.

  FIG. 4 is a waveform diagram of a reflected wave signal and a waveform diagram of a measured flow velocity distribution. When the reflected wave receiving unit 254 receives the reflected waves 262a, 262b, and 262c shown in FIGS. 3A to 3C, the waveform of the reflected wave signal has a shape as shown in FIG. Specifically, the reflected wave receiving unit 254 first receives the reflected wave 262a that the main lobe 260a reflects on the bubble 106 in the vicinity of the probe 250, and detects a weak signal. Thereafter, the reflected wave receiving unit 254 receives the reflected wave 262b reflected by the reflecting member 270 along with the reflected wave 262a, and a strong signal is detected.

  This strong signal, that is, the signal generated by the reflected wave 262b that is generated when the side lobe 260b is reflected by the reflecting member 270 is extremely useful for calculating the sound velocity value. However, since the signal by the reflected wave 262b is too strong, the signal of the reflected wave 262a received in the same time zone as the reflected wave 262b is buried in the signal by the reflected wave 262b. That is, the signal by the reflected wave 262b becomes noise in the calculation of the flow velocity distribution.

  When the flow velocity distribution is calculated using the reflected wave signal having a waveform as shown in FIG. 4A, the waveform of the flow velocity distribution has a shape as shown in FIG. 4B, and the reflecting member 270 is installed. A negative peak 264 occurs in the flow velocity portion at distance. For this reason, it becomes impossible to accurately grasp the flow velocity at that portion.

  Therefore, in the present embodiment, the flow velocity distribution calculation unit 222 corrects a signal obtained by receiving the reflected wave, that is, a signal used when obtaining the flow velocity distribution. In such correction, first, the flow velocity distribution calculation unit 222 superimposes a series of signals obtained by receiving the reflected wave for a predetermined time (predetermined number of times) and divides by the number of times of superimposition. At this time, since the reflected wave 262a by the main lobe 260a is random, it approaches zero. On the other hand, since the distance from the emission position of the ultrasonic wave 260 (probe 250) to the reflecting member 270 is fixed, the signal by the reflected wave 262b of the side lobe 260b is always detected with the same intensity. Therefore, as shown in FIG. 4C, when the signals are superimposed for a predetermined time, the waveform of the reflected wave 262b becomes clear and can be detected as a substantially constant standing wave 266.

  Next, the flow velocity distribution calculation unit 222 subtracts the standing wave 266 from a signal (see FIG. 4A) used when obtaining the flow velocity distribution of the fluid. As a result, the waveform of the signal used when obtaining the flow velocity distribution of the fluid changes from the shape as shown in FIG. 4A to the shape as shown in FIG. 4D, and noise from the signal due to the reflected wave 262b is removed. The signal is corrected. Thereby, the reflected wave 262a from the bubble at the same distance as the reflecting member 270 can also be detected.

  When the flow velocity distribution is calculated using the corrected signal and sound velocity value, the waveform of the flow velocity distribution has the shape shown in FIG. 4E, and the negative peak 264 is removed. Therefore, by correcting the signal using the standing wave 266 as described above, it is possible to eliminate the influence of the reflected wave 262b of the side lobe 260b and measure the flow velocity distribution with higher accuracy.

  As described above, the signal used for obtaining the flow velocity distribution is corrected, and the calculation of the flow velocity distribution using the corrected signal has been described. Although this correction method can improve the accuracy of the flow velocity distribution, it takes time to superimpose the signal, so that the measurement time and the processing load are increased. Therefore, a correction method capable of correcting the flow velocity distribution without superimposing signals will be described next.

  In the next correction method, first, the flow velocity distribution calculation unit 222 calculates the flow velocity distribution using signals (see FIG. 4A) obtained by receiving the reflected waves 262a, 262b, and 262c. The waveform of the flow velocity distribution thus calculated has the shape shown in FIG. 4B as already described. Next, the flow velocity distribution calculation unit 222 complements the negative peak 264 in which the flow velocity decreases in the obtained flow velocity distribution waveform with an approximate function excluding values around the peak 264. As a result, the flow velocity distribution is corrected, and the waveform thereof has the shape shown in FIG. Therefore, the flow velocity distribution can be corrected without superimposing signals, and the accuracy of data can be improved while reducing the time and load required for data processing.

(Measurement method of flow velocity distribution)
Then, the flow velocity distribution measuring method using the flow velocity distribution measuring apparatus 200 mentioned above is demonstrated in detail. FIG. 5 is a flowchart for explaining the flow velocity distribution measuring method according to the present embodiment. In the flow velocity distribution measuring method according to the present embodiment, first, the fixing jig 272 to which the probe 250 and the reflecting member 270 are fixed is inserted into the water channel 100, and the probe 250 and the reflecting member 270 are installed in the fluid 104 (S302). ). At this time, it arrange | positions so that the reflection member 270 may be located in the discharge direction of the side lobe 260b of the ultrasonic wave 260. In addition, in order to further stabilize the installation of the probe 250 and the reflecting member 270, it is preferable to fix the fixing jig 272 to a structure (not shown) such as a bridge provided above the water channel 100.

  And the memory | storage part 224 memorize | stores the distance L from the probe 250 (launch position of the ultrasonic wave 260) input via the input part 228 to the reflection member 270 (S304). The distance L is a predetermined set value, and the reflecting member 270 is attached to the fixing jig 272 according to the value of the distance L. However, in order to improve calculation accuracy, the distance between the probe 250 and the reflecting member 270 may be measured after the reflecting member 270 is fixed, and the current value may be input. Further, the process of S304 is not necessarily performed after S302, and may be performed at least before S310 described later.

  Next, the pulser 214 transmits an electrical signal to the ultrasonic wave emitting unit 252 and the ultrasonic wave emitting unit 252 emits an ultrasonic wave 260 into the fluid 104 (S306). The reflected wave receiving unit 254 receives the reflected waves 262a, 262b, and 262c generated by reflecting the emitted ultrasonic wave on the bubble 106, the reflecting member 270, or the bottom surface 100a of the water channel 100 (S308). The ultrasonic wave emitting unit 252 repeats the emission of the ultrasonic wave 260 and the reflected wave reception unit 254 repeats the reception of the reflected wave until the emission of the ultrasonic wave 260 and the reception of the reflected wave reach a predetermined number of times, that is, a predetermined time (S310). ).

  The predetermined number of times can be arbitrarily determined by the user. However, when the reflected wave signal is superimposed in S316, which will be described later, it is preferable to set the number of predetermined times higher, for example, about 100 times. If the reflected wave signal is not superimposed, it is sufficient to set the predetermined number of times less, for example, about 10 times. The reason why the measurement is performed a plurality of times even when not superimposed is to improve the measurement accuracy and improve the reliability by taking the average of the calculated flow velocities.

  When the emission of the ultrasonic wave 260 and the reception of the reflected wave reach the predetermined number of times (YES in S310), the sound speed calculation unit 220 emits the ultrasonic wave 260 from the ultrasonic wave emission unit 252 and then the side lobe 260b of the ultrasonic wave 260. The sound speed value is calculated using the time until the reflected wave receiving unit 254 receives the reflected wave 262b generated by being reflected by the reflecting member 270 and the distance L (S312). In addition, what is necessary is just to refer to any one measured value among the measured values of the predetermined number of times from the emission of the ultrasonic wave to the reception of the reflected wave.

  Next, when correcting the signal obtained by receiving the reflected wave (the signal used when obtaining the flow velocity distribution) (YES in S314), the flow velocity distribution calculating unit 222 obtains the signal obtained by receiving the reflected wave a predetermined number of times. Is superimposed for a predetermined number of times (S316), and a signal amplified by the superposition is detected as a standing wave 266 (S318). Then, the flow velocity distribution calculation unit 222 corrects the signal by subtracting the standing wave 266 (S320). Thereafter, the flow velocity distribution calculation unit 222 obtains a flow velocity distribution using the corrected signal and the sound velocity value calculated by the sound velocity calculation unit 220 (S322). Thereby, the process in the flow velocity distribution measuring method is completed.

  When the signal obtained by receiving the reflected wave is not corrected (NO in S314), the flow velocity distribution calculating unit 222 obtains the flow velocity distribution using the sound velocity value and the signal obtained by receiving the reflected wave 260a as they are (S324). . Then, when correcting the obtained flow velocity distribution (YES in S326), the flow velocity distribution calculation unit 222 approximates the negative peak 264 where the flow velocity decreases from the waveform of the obtained flow velocity distribution by excluding values before and after the negative peak 264. Complemented by a function, a corrected flow velocity distribution is obtained (S328). Thereby, the process in the flow velocity distribution measuring method is completed. If the obtained flow velocity distribution is not corrected at all (NO in S326), the process is terminated as it is.

  As described above, in the flow velocity distribution measuring apparatus 200 and the flow velocity distribution measuring method according to the present embodiment, the sound velocity value is calculated by the reflected wave 262b that is generated when the side lobe 260b is reflected by the reflecting member 270, and the main lobe 260a is a bubble. The sound speed value can be used when calculating the flow velocity from the reflected wave 262a generated by reflection on a reflector such as 106. Since only the reflecting member 270 is added to calculate the sound velocity value, the simple configuration of the apparatus can be maintained, and the increase in cost and the complexity of the system can be avoided. Therefore, even with a simple configuration, it is possible to calculate the sound velocity value in accordance with the measurement environment, and it is possible to measure the flow velocity distribution with higher accuracy.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  Each procedure in the flow velocity distribution measuring method of the present specification does not necessarily have to be processed in time series in the order described in the flowchart, and may partially include processing in parallel or a subroutine.

  INDUSTRIAL APPLICABILITY The present invention can be used as a flow velocity distribution measurement method and a flow velocity distribution measurement device that measure the flow velocity distribution in a water channel using ultrasonic waves.

DESCRIPTION OF SYMBOLS 100 ... Water channel, 100a ... Bottom surface, 104 ... Fluid, 106 ... Bubble, 200 ... Measuring device, 202 ... Cable, 210 ... Measuring terminal, 212 ... Control part, 214 ... Pulser, 216 ... Receiver, 218 ... A / D conversion part , 220 ... sound velocity calculation unit, 222 ... flow velocity distribution calculation unit, 224 ... storage unit, 226 ... display unit, 228 ... input unit, 250 ... probe, 252 ... ultrasonic wave emission unit, 254 ... reflected wave reception unit, 260 ... Ultrasonic, 260a ... Main lobe, 260b ... Side lobe, 262a, 262b, 262c ... Reflected wave, 264 ... Negative peak, 266 ... Standing wave, 270 ... Reflecting member, 272 ... Fixed jig

Claims (6)

A flow velocity distribution measuring method for measuring a flow velocity distribution of a fluid using ultrasonic waves,
A reflecting member for reflecting the ultrasonic wave is installed in a direction in which the side lobe of the ultrasonic wave is emitted in the fluid;
Firing the ultrasound into the fluid;
The reflected ultrasonic wave side lobe is reflected on the reflecting member to receive the reflected wave,
Using the distance from the ultrasonic emission position to the reflecting member and the time from when the ultrasonic wave is emitted until the reflected wave is received, the sound velocity value of the fluid is calculated,
A flow velocity distribution measuring method, wherein the flow velocity distribution of the fluid is obtained using the sound velocity value and a reflected wave generated by reflecting the ultrasonic main lobe on a reflector in the fluid. A signal obtained by receiving the reflected wave is superimposed for a predetermined time,
Detecting a signal amplified by the superposition as a standing wave;
A value obtained by dividing the standing wave by the predetermined time is subtracted from a signal used when obtaining the flow velocity distribution of the fluid to correct the signal,
The flow velocity distribution measuring method according to claim 1, wherein the flow velocity distribution of the fluid is obtained using the corrected signal.   The corrected flow velocity distribution is corrected by complementing a negative peak at which the flow velocity decreases in the waveform of the obtained flow velocity distribution with an approximate function excluding values before and after the peak. Item 2. The flow velocity distribution measuring method according to Item 1. A flow velocity distribution measuring device that measures the flow velocity distribution of a fluid using ultrasonic waves,
An ultrasonic wave emitting unit that emits the ultrasonic wave into the fluid;
A reflecting member provided in the emitting direction of the ultrasonic side lobe in the fluid and reflecting the ultrasonic wave;
A reflected wave receiving unit that receives a reflected wave generated by reflecting the ultrasonic wave on the reflecting member or the reflector in the fluid; and
Using the distance from the ultrasonic wave emitting unit to the reflecting member and the time from when the ultrasonic wave emitting unit emits the ultrasonic wave to when the reflected wave receiving unit receives the reflected wave, A sound speed calculation unit for calculating a sound speed value;
A flow velocity distribution calculation unit for obtaining a flow velocity distribution of the fluid using the sound velocity value and a reflected wave generated by reflecting a main lobe of the ultrasonic wave to a reflector in the fluid;
A flow velocity distribution measuring device comprising:   The flow velocity distribution measuring apparatus according to claim 4, wherein the shape of the reflecting member is a plate shape or a rod shape.   The flow velocity distribution measuring apparatus according to claim 5, wherein the reflection member is installed in a posture along the flow direction of the fluid.

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