CN111721966A - Flow velocity measuring method, device and equipment based on time difference method and readable storage medium - Google Patents
Flow velocity measuring method, device and equipment based on time difference method and readable storage medium Download PDFInfo
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- CN111721966A CN111721966A CN202010607259.8A CN202010607259A CN111721966A CN 111721966 A CN111721966 A CN 111721966A CN 202010607259 A CN202010607259 A CN 202010607259A CN 111721966 A CN111721966 A CN 111721966A
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- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/24—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting acoustical wave
- G01P5/245—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting acoustical wave by measuring transit time of acoustical waves
Abstract
The invention provides a flow velocity measuring method, a flow velocity measuring device, flow velocity measuring equipment and a readable storage medium based on a time difference method, wherein the method comprises the steps of respectively analyzing continuous and repeatedly acquired forward flow flight time and reverse flow flight time to obtain a forward flow flight time reference value and a reverse flow flight time reference value; and then correcting the continuously and repeatedly acquired forward flow flight time and the countercurrent flight time respectively according to the forward flow flight time reference value and the countercurrent flight time reference value, calculating to obtain a flight time difference by using the corrected forward flow flight time and the corrected countercurrent flight time, and further integrating a flow velocity calculation formula to calculate to obtain the flow velocity of the fluid. The method comprises the steps of obtaining a forward flow flight time reference value and a reverse flow flight time reference value through analysis, and then correcting forward flow flight time and reverse flow flight time, so that corrected data are closer to the real situation, the calculation precision of flow speed is improved, and the flow measurement precision is further improved.
Description
Technical Field
The invention relates to the technical field of flow measurement, in particular to a flow velocity measuring method, a flow velocity measuring device, flow velocity measuring equipment and a readable storage medium based on a time difference method.
Background
The flow measuring mode of the fluid in the channel or river channel mainly comprises a water measuring weir, a water measuring tank and the like. Wherein, the water measuring tank measures the flow state distribution in the box body through the ultrasonic probe, thereby obtaining higher flow measurement precision. The basic principle of measuring the fluid flow of the water tank is as follows: the difference between the forward propagation time and the backward propagation time of the ultrasonic wave in the fluid is related to the flow velocity of the fluid; therefore, the flow speed of the fluid to be measured can be obtained according to the time difference between the forward flow propagation and the backward flow propagation of the ultrasonic wave in the fluid; and then calculating the fluid flow rate by combining the fluid sectional area. This method of measurement of the waterbox is known as the propagation velocity difference method.
The propagation velocity difference method can be classified into a time difference method, a phase difference method, a frequency difference method, and the like. The time difference method adopts a hardware threshold value mode to calculate the flight time, namely, a comparison circuit is directly used for setting a threshold value on hardware, and when an echo signal exceeds the threshold value, the echo signal is considered to arrive. Referring to fig. 1, timing is started when the ultrasonic transmitting probe starts to transmit signals, ultrasonic waves reach the ultrasonic receiving probe after a period of time, and echo signals are sinusoidal signals with small front and rear amplitudes and large middle amplitude. The frequency of the echo signal is the frequency of the ultrasonic probe. And when the amplitude of the echo signal reaches a preset threshold value, stopping timing by the timer, wherein the timing time of the timer is the flight time of the ultrasonic wave on the propagation path.
Since the threshold value is a fixed value, the amplitude of the echo signal changes due to the fluid state of the fluid, impurities in the fluid, circuit interference, and the like, the calculated flight time is likely to deviate by 1 or more cycles. When the amplitude of the echo signal becomes large due to some influence factor, the timer may be caused to end the timing in advance, and the calculated flight time may be advanced by one or more cycles compared with the real situation. When the amplitude of the echo signal is reduced due to some influence factor, the timer may be delayed to finish timing, and the calculated flight time is delayed by one or more cycles compared with the real situation. This seriously affects the accuracy of the flow rate measurement.
Disclosure of Invention
In view of the above, the present invention provides a flow velocity measurement method, apparatus, device and readable storage medium based on a time difference method, which are intended to achieve the purpose of improving the measurement accuracy of the flow velocity.
In order to achieve the above object, the following solutions are proposed:
in a first aspect, a flow velocity measurement method based on a time difference method is provided, which includes:
acquiring n downstream flight times continuously acquired by a hardware threshold method in a current calculation period, wherein n is an integer larger than 7, and the downstream flight time is the flight time of downstream propagation of ultrasonic waves in fluid, which is sent by a first ultrasonic transmitting probe;
acquiring n countercurrent flight times continuously acquired by a hardware threshold method in a current calculation period, wherein the countercurrent flight time is the flight time of ultrasonic waves emitted by a second ultrasonic emission probe in countercurrent propagation in fluid, and the first ultrasonic emission probe and the second ultrasonic emission probe are positioned on the same height layer;
analyzing the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of the current calculation period;
correcting the n forward flow flight times based on the forward flow flight time reference value to obtain n corrected forward flow flight times;
correcting the n countercurrent flight times based on the countercurrent flight time reference value to obtain n corrected countercurrent flight times;
calculating n flight time differences based on the corrected n forward flow flight times and the corrected n reverse flow flight times;
and calculating the flow velocity of the fluid in a first height layer according to the average value of the n flight time differences, wherein the first height layer is the height layer where the first ultrasonic transmitting probe is located.
Optionally, the analyzing the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of the current calculation period specifically includes:
classifying the n forward flow flight times and the n reverse flow flight times according to time to obtain at least one forward flow flight time set and at least one reverse flow flight time set;
judging whether a first downstream flight time set exists or not, wherein the first downstream flight time set is a downstream flight time set of which the number of the downstream flight times is greater than n/2, if so, taking the average value of all the downstream flight times of the first downstream flight time set as the downstream flight time reference value of the current calculation period, and if not, calculating the previous calculation period to obtain the downstream flight time reference value as the downstream flight time reference value of the current calculation period;
and judging whether a first countercurrent flight time set exists or not, wherein the first countercurrent flight time set is an countercurrent flight time set of which the number of the countercurrent flight times is more than n/2, if so, taking the average value of all the countercurrent flight times of the first countercurrent flight time set as a countercurrent flight time reference value, and if not, calculating the previous calculation period to obtain the countercurrent flight time reference value as the countercurrent flight time reference value of the current calculation period.
Optionally, the classifying the n forward flow flight times and the n reverse flow flight times according to time size to obtain at least one forward flow flight time set and at least one reverse flow flight time set specifically includes:
and classifying the n forward flow flight times and the n reverse flow flight times respectively by adopting a K nearest neighbor classification algorithm according to the time, so as to obtain at least one forward flow flight time set and at least one reverse flow flight time set.
Optionally, after the step of calculating the flow velocity of the fluid in the first altitude layer according to the average value of the n time-of-flight differences, the method further includes:
and judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the second height layer is greater than a preset first height layer fluid flow rate threshold value or not, if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period, and the second height layer is a height layer adjacent to and lower than the first height layer.
Optionally, after the step of calculating the flow velocity of the fluid in the first altitude layer according to the average value of the n time-of-flight differences, the method further includes:
and judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the third height layer is greater than a preset first height layer fluid flow rate threshold value or not, if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period, and the third height layer is a height layer which is adjacent to and higher than the first height layer.
In a second aspect, there is provided a flow velocity measuring apparatus based on a time difference method, including:
the downstream flight time acquisition unit is used for acquiring n downstream flight times continuously acquired by a hardware threshold method in the current calculation period, wherein n is an integer larger than 7, and the downstream flight time is the flight time of downstream propagation of ultrasonic waves in fluid, which is sent by the first ultrasonic transmitting probe;
the system comprises a counter-flow flight time acquisition unit, a counter-flow flight time acquisition unit and a counter-flow flight time acquisition unit, wherein the counter-flow flight time acquisition unit is used for acquiring n counter-flow flight times continuously acquired by a hardware threshold method in a current calculation period, the counter-flow flight time is the flight time of counter-flow propagation of ultrasonic waves in fluid, the ultrasonic waves are emitted by a second ultrasonic emission probe, and the first ultrasonic emission probe and the second ultrasonic emission probe are positioned on the same height layer;
a current calculation cycle reference value determining unit, configured to analyze the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of a current calculation cycle;
a forward flow flight time correction unit, configured to correct the n forward flow flight times based on the forward flow flight time reference value, so as to obtain n corrected forward flow flight times;
the countercurrent flight time correction unit is used for correcting the n countercurrent flight times based on the countercurrent flight time reference value to obtain n corrected countercurrent flight times;
a time difference of flight calculation unit, configured to calculate n time differences of flight based on the corrected n forward flow flight times and the corrected n reverse flow flight times;
and the flow velocity calculation unit is used for calculating the flow velocity of the fluid in a first height layer according to the average value of the n flight time differences, wherein the first height layer is the height layer where the first ultrasonic transmitting probe is located.
Optionally, the unit for determining the reference value of the current calculation cycle specifically includes:
the classification unit is used for classifying the n forward flow flight times and the n reverse flow flight times according to time to obtain at least one forward flow flight time set and at least one reverse flow flight time set;
a forward flow flight time reference value determining unit, configured to determine whether a first forward flow flight time set exists, where the first forward flow flight time set is a forward flow flight time set with a forward flow flight time number greater than n/2, if the first forward flow flight time set exists, an average value of all forward flow flight times in the first forward flow flight time set is used as a forward flow flight time reference value in a current calculation period, and if the first forward flow flight time set does not exist, a forward flow flight time reference value obtained by calculating in a previous calculation period is used as a forward flow flight time reference value in the current calculation period;
and the counter-flow flight time reference value determining unit is used for judging whether a first counter-flow flight time set exists or not, the first counter-flow flight time set is a counter-flow flight time set of which the number of counter-flow flight times is greater than n/2, if so, the average value of all counter-flow flight times of the first counter-flow flight time set is used as a counter-flow flight time reference value, and if not, the counter-flow flight time reference value obtained by calculating in the previous calculation period is used as the counter-flow flight time reference value of the current calculation period.
Optionally, the classifying unit is specifically configured to classify the n forward flow flight times and the n reverse flow flight times respectively by using a K nearest neighbor classification algorithm according to time, so as to obtain at least one forward flow flight time set and at least one reverse flow flight time set.
Optionally, the flow rate measuring device based on the time difference method further includes:
and the flow rate correction unit is used for judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the second height layer is larger than a preset first height layer fluid flow rate threshold value or not, if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period, and the second height layer is a height layer which is adjacent to and lower than the first height layer.
Optionally, the flow rate measuring device based on the time difference method further includes:
and the flow velocity correction unit is used for judging whether the difference value between the flow velocity of the fluid in the first height layer and the flow velocity of the fluid in the third height layer is larger than a preset first height layer fluid flow velocity threshold value or not, if so, taking the flow velocity of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow velocity of the fluid in the first height layer in the current calculation period, and the third height layer is a height layer which is adjacent to and higher than the first height layer.
In a third aspect, a readable storage medium is provided, on which a program is stored, which when executed by a processor, implements the steps of any one of the time difference method-based flow rate measurement methods according to the first aspect.
In a fourth aspect, there is provided a flow rate measuring device based on time difference method, comprising a memory for storing a program and a processor, wherein the processor is configured to execute the program to implement the steps of any one of the flow rate measuring methods based on time difference method according to the first aspect.
Compared with the prior art, the technical scheme of the invention has the following advantages:
the flow velocity measuring method, the flow velocity measuring device, the flow velocity measuring equipment and the readable storage medium based on the time difference method have the advantages that the method comprises the steps of respectively analyzing the continuous and multiple collected downstream flight time and the continuous and multiple collected upstream flight time to obtain a downstream flight time reference value and a upstream flight time reference value; and then correcting the continuously and repeatedly acquired forward flow flight time and the countercurrent flight time respectively according to the forward flow flight time reference value and the countercurrent flight time reference value, calculating to obtain a flight time difference by using the corrected forward flow flight time and the corrected countercurrent flight time, and further integrating a flow velocity calculation formula to calculate to obtain the flow velocity of the fluid. The method comprises the steps of obtaining a forward flow flight time reference value and a reverse flow flight time reference value through analysis, and then correcting forward flow flight time and reverse flow flight time, so that corrected data are closer to the real situation, the calculation precision of flow speed is improved, and the flow measurement precision is further improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of a time-difference method hardware threshold timing;
fig. 2 is a schematic diagram of a flow velocity measuring apparatus based on a time difference method according to an embodiment of the present invention;
fig. 3 is a flowchart of a flow velocity measurement method based on a time difference method according to an embodiment of the present invention;
FIG. 4 is a schematic illustration of water depth versus flow velocity in a channel or canal;
fig. 5 is a schematic diagram of a flow rate measuring device based on a time difference method according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 2, a flow rate measuring device based on a time difference method is provided for an embodiment of the present invention. The device comprises a power supply unit, a control and calculation unit and a plurality of analog front-end units. The power supply unit is used for converting an input power supply into an analog signal power supply, a digital signal power supply and a high-voltage power supply required by the ultrasonic transmitting probe and the ultrasonic receiving probe. Each analog front end unit is respectively connected with an ultrasonic transmitting probe and an ultrasonic receiving probe. The analog front end unit is used for providing a transmitting signal for the ultrasonic transmitting probe according to requirements and carrying out processing such as filtering and amplification on an echo signal received by the ultrasonic receiving probe. The control and calculation unit is used for performing power control, logic control of system functions, calculation of flight time, processing of flight time difference, processing of flow velocity and flow rate and the like. The control and calculation unit comprises a timer, a communication interface for interacting with other equipment and the like.
Control and computing Unit memory and a processor, which in some embodiments may be a CPU (Central Processing Unit), or an ASIC (Application specific Integrated Circuit), or one or more integrated circuits configured to implement embodiments of the present invention, etc.
The memory includes at least one type of readable storage medium. The readable storage medium may be an NVM (non-volatile memory) such as flash memory, hard disk, multimedia card, card-type memory, etc. The readable storage medium may also be a high-speed RAM (random access memory) memory.
A memory for storing a computer program, the processor being capable of calling the computer program stored in the memory, the computer program being for performing the steps of the time-difference based flow rate measurement method provided by the embodiments of the present invention. The flow velocity measuring method based on the time difference method provided by the invention is described in detail below. Referring to fig. 3, a flow rate measuring method based on a time difference method according to an embodiment of the present invention may include the following steps:
s31: and acquiring n forward flow flight times continuously acquired by using a hardware threshold method in the current calculation period.
n is an integer greater than 7, and the downstream flight time is the flight time of the downstream propagation of the ultrasonic wave emitted by the first ultrasonic transmitting probe in the fluid. The calculation period is greater than the total time for continuously acquiring n downstream flight times by using a hardware threshold method.
S32: and acquiring n counter-flow flight times continuously acquired by using a hardware threshold method in the current calculation period.
The upstream flight time is the flight time of the ultrasonic wave emitted by the second ultrasonic transmitting probe in upstream propagation in the fluid. The first ultrasonic transmitting probe and the second ultrasonic transmitting probe are positioned on the same height layer. The forward flow flight time and the reverse flow flight time are collected simultaneously.
S33: and analyzing the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of the current calculation period.
And analyzing the n downstream flight times to obtain a downstream flight time reference value of the current calculation period. The n forward flow flight times acquired in one calculation period should have a small difference, so that when more forward flow flight times are in a certain smaller interval, the forward flow flight time in the interval is determined to be more accurate, and the average value of all forward flow flight times in the interval is used as the forward flow flight time reference value. If the n forward flow flight time distributions are relatively dispersed, a forward flow flight time reference value can be obtained by calculating the previous calculation period and is used as the forward flow flight time reference value of the current calculation period. In the same way, the countercurrent flight time reference value can be obtained.
In a specific embodiment, the method for analyzing n forward flow flight times and n reverse flow flight times to obtain the forward flow flight time reference value and the reverse flow flight time reference value of the current calculation period specifically includes the following steps:
(1) and classifying the n forward flow flight times and the n reverse flow flight times according to the time to obtain at least one forward flow flight time set and at least one reverse flow flight time set.
Specifically, n forward flow flight times and n reverse flow flight times can be classified respectively according to the time by using a K nearest neighbor classification algorithm, so as to obtain at least one forward flow flight time set and at least one reverse flow flight time set.
(2) Judging whether a first downstream flight time set exists or not, if so, taking the average value of all downstream flight times of the first downstream flight time set as the downstream flight time reference value of the current calculation period, and if not, calculating the previous calculation period to obtain the downstream flight time reference value as the downstream flight time reference value of the current calculation period;
the first forward flow flight time set is a forward flow flight time set with the forward flow flight time number larger than n/2.
(3) And judging whether a first countercurrent flight time set exists or not, if so, taking the average value of all countercurrent flight times of the first countercurrent flight time set as a countercurrent flight time reference value, and if not, calculating a previous calculation period to obtain an countercurrent flight time reference value as the countercurrent flight time reference value of the current calculation period.
The first set of counterflow flight times is a set of counterflow flight times with a number of counterflow flight times greater than n/2,
s34: and correcting the n forward flow flight times based on the forward flow flight time reference value to obtain the n corrected forward flow flight times.
And for the downstream flight time of which the difference value with the reference value of the downstream flight time is not more than half of the ultrasonic period value in the n downstream flight times, no correction is needed. And for the downstream flight time of which the difference value with the downstream flight time reference value is more than half of the ultrasonic period value in the n downstream flight times, adding and subtracting a plurality of ultrasonic period values to the downstream flight time, so that the difference value of the corrected downstream flight time and the downstream flight time reference value is not more than half of the ultrasonic period value. The ultrasonic period value is a preset fixed value, and the value is the reciprocal of the frequency of the ultrasonic transmitting probe.
S35: and correcting the n countercurrent flight times based on the countercurrent flight time reference value to obtain the n corrected countercurrent flight times.
Step S35 is the same principle as step S36. And in the n countercurrent flight times, the difference value between the reference value of the countercurrent flight time and the countercurrent flight time is not more than half of the ultrasonic period value, and no correction is needed. And for the n countercurrent flight times, if the difference value between the countercurrent flight time and the reference value of the countercurrent flight time is greater than half of the period value of the ultrasonic wave, adding and subtracting a plurality of ultrasonic wave period values to the countercurrent flight time, so that the difference value between the corrected countercurrent flight time and the reference value of the countercurrent flight time is not greater than half of the period value of the ultrasonic wave.
S36: and calculating to obtain n flight time differences based on the corrected n downstream flight times and the corrected n upstream flight times.
And the difference value between the corrected forward flow flight time and the corresponding corrected reverse flow flight time is the flight time difference. For example, the continuously collected n forward flow flight times are Tu _1, Tu _2, …, Tu _ n; continuously collecting n countercurrent flight times which are Td _1, Td _2, … and Td _ n; the corrected n downstream flight times are Tu _1 ', Tu _2 ', … and Tu _ n '; the corrected n countercurrent flight times are Td _1 ', Td _2 ', … and Td _ n '; the resulting n time-of-flight differences are dT _1, dT _2, …, dT _ n. Wherein dT _ i ═ Tu _ i '-Td _ i', i takes on values from 1 to n.
S37: and calculating the flow velocity of the fluid in the first height layer according to the average value of the n time-of-flight differences.
The first height layer is a height layer of the first ultrasonic transmission probe. According to the average value of the time difference of flight, the flow velocity of the fluid can be calculated by using the existing flow velocity calculation formula, which is not described in detail herein.
It should be noted that one of the flow velocity measurement methods based on the time difference method shown in fig. 3 is a method of measuring the flow velocity of water in a certain height layer, and the calculation of the instantaneous flow rate needs to be performed in combination with the flow velocity and the cross-sectional area of water in each height layer. The cumulative flow rate is integrated with the instantaneous flow rate.
Referring to fig. 4, the flow rates at different water depths in a channel or canal are shown. It can be seen from the figure that the flow velocity changes at different water depth positions have continuity, and the change rate is gentle. Based on the method, when the flow velocity of different water depths is calculated, a threshold value can be set, so that the reasonability and the reliability of the measured flow velocity are ensured, and the flow velocity calculation errors caused by flight time calculation errors and the like are eliminated. Specifically, after the step of calculating the flow velocity of the fluid in the first height layer according to the average value of the n time differences of flight, the method may further include: and judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the second height layer is greater than a preset first height layer fluid flow rate threshold value or not, and if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period. The second height layer is a lower height layer adjacent to the first height layer. If the first height level is the lowest height level, the rationality of the flow velocity of the water flow in the height level is not determined.
After the step of calculating the flow velocity of the fluid in the first height layer according to the average value of the n time-of-flight differences, the method may further include: and judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the third height layer is greater than a preset first height layer fluid flow rate threshold value or not, and if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period. The third height layer is adjacent to and higher than the first height layer, and if the first height layer is the highest height layer, the reasonability of the flow speed of the water flow of the height layer is not judged.
The flow velocity measurement method based on the time difference method provided by the present invention is exemplified below.
Example 1, 9 forward flow flight times were continuously collected { 487.91; 487.91, respectively; 488.9, respectively; 487.93, respectively; 487.91, respectively; 487.89, respectively; 486.93, respectively; 487.92, respectively; 487.92, classifying the 9 forward flow flight times by adopting a K nearest neighbor classification algorithm, and obtaining classification results which are the following three forward flow flight time sets:
forward flow time-of-flight set 1: { 487.91; 487.91, respectively; 487.93, respectively; 487.91, respectively; 487.89, respectively; 487.92, respectively; 487.92 };
forward flow time-of-flight set 2: {488.9 };
forward flow time-of-flight set 3: {486.93}.
The number of the forward flow flight times in the forward flow flight time set 1 exceeds 9/2, so that the average value of all the forward flow flight times in the forward flow flight time set 1 is determined as a forward flow flight time reference value Tub，Tub(487.91+487.91+487.93+487.91+487.89+487.92+ 487.92)/7-487.91, wherein Tu isbThe value of the two-digit decimal is rounded and retained.
The ultrasonic period value is 1, and the difference between the forward flight time 488.9 and the forward flight time 487.91 in the forward flight time set 2 is larger than 1/2, so that 488.9 is corrected, that is, 488.9-1 is 487.9, and the corrected forward flight time 487.9 is obtained.
Similarly, the difference between the forward flight times 486.93 and 487.91 in the forward flight time set 3 is greater than 1/2, so that 486.93 is corrected, that is, 486.93+1 is 487.93, and the corrected forward flight time 487.93 is obtained.
Thus, the corrected 9 forward flow flight times are { 487.91; 487.91, respectively; 487.9, respectively; 487.93, respectively; 487.91, respectively; 487.89, respectively; 487.93, respectively; 487.92, respectively; 487.92}
While collecting smooth flight time, collecting the flight time of the countercurrent, wherein the 9 countercurrent flight times corresponding to the 9 forward flow flight times are as follows: { 488.23; 488.22, respectively; 488.30, respectively; 489.28, respectively; 488.23, respectively; 488.24, respectively; 489.23, respectively; 488.27, respectively; 487.22, classifying the 9 countercurrent flight times by adopting a K nearest neighbor classification algorithm, and obtaining classification results which are the following three countercurrent flight time sets:
set of countercurrent flight times 1: { 488.23; 488.22, respectively; 488.30, respectively; 488.23, respectively; 488.24, respectively; 488.27 };
set of upstream flight times 2: { 489.28; 489.23 };
set of countercurrent flight times 3: {487.22}.
The number of the reverse flow flight times in the reverse flow flight time set 1 exceeds 9/2, so the average value of all the reverse flow flight times in the reverse flow flight time set 1 is determined as a reverse flow flight time reference value Tdb，TdbWhere (488.23+488.22+488.30+488.23+488.24+488.27)/6 is 488.25, it should be noted that Td isbThe value of the two-digit decimal is rounded and retained.
The ultrasonic period value is 1, and the difference values of the backflow flight times 489.28, 489.23 and 488.25 in the backflow flight time set 2 are both larger than 1/2, so that 489.28 is corrected, namely 489.28-1 is 488.28, and the corrected backflow flight time 488.28 is obtained; 489.23 was corrected to 489.23-1 ═ 488.23, yielding a corrected backflow flight time 488.23.
Similarly, the difference between the upstream flight times 487.22 and 488.25 in the upstream flight time set 3 is greater than 1/2, so that the corrected downstream flight time 488.22 is obtained by correcting 487.22, i.e., 487.22+1 equals 488.22.
Thus, the corrected 9 upstream flight times were { 488.23; 488.22, respectively; 488.30, respectively; 488.28, respectively; 488.23, respectively; 488.24, respectively; 488.23, respectively; 488.27, respectively; 488.22}.
The upstream flight time minus the corresponding downstream flight time yields 9 time differences in flight: dt ═ 488.23-487.91; 488.22-487.91; 488.30-487.9; 488.28-487.93; 488.23-487.91; 488.24-487.89; 488.23-487.93; 488.27-487.92; 488.22-487.92 ═ 0.32; 0.31; 0.40; 0.35; 0.32 of; 0.35; 0.30; 0.35; 0.30}
And calculating the average value of the 9 flight time differences to further calculate the flow velocity, and calculating the instantaneous flow and the accumulated flow by the flow velocity.
Example 2, 9 forward flow flight times were continuously collected as { 485.93; 485.91, respectively; 486.94, respectively; 487.96, respectively; 485.93, respectively; 488.95, respectively; 487.97, respectively; 487.95, respectively; 485.92, classifying the 9 forward flow flight times by adopting a K nearest neighbor classification algorithm, and obtaining classification results which are four forward flow flight time sets as follows:
forward flow time-of-flight set 1: { 485.93; 485.91, respectively; 485.93, respectively; 485.92 };
forward flow time-of-flight set 2: {486.94 };
forward flow time-of-flight set 3: { 487.96; 487.97, respectively; 487.95 };
forward flow time-of-flight set 4: {488.95}.
Since the number of the downstream flight times in each downstream flight time set does not exceed 9/2, the smooth flight time reference value calculated in the previous calculation period is used as the downstream flight time reference value of the current calculation period. If the previous calculation period is the calculation process of example 1, the downstream time of flight reference value Tu of the current calculation periodb＝487.91。
{ 485.93; 485.91, respectively; 485.93, respectively; 485.92, the difference between each forward flight time and 487.91 is greater than 1/2, and the difference between { 485.93; 485.91, respectively; 485.93, respectively; 485.92, adding 2 to each forward flow flight time to obtain corrected forward flow flight time { 487.93; 487.91, respectively; 487.93, respectively; 487.92}.
{486.94} forward flow flight times 486.94 and 487.91 were all greater than 1/2, and a corrected forward flow flight time 487.94 was obtained by adding 1 to 486.94.
{ 487.96; 487.97, respectively; 487.95 the difference between each of the free time of flight and 487.91 is no greater than 1/2 and therefore no processing is required.
{488.95} forward flow time of flight 488.95 differs from 487.91 by more than 1/2, and 488.95 is subtracted by 1 to give corrected forward flow time of flight 487.95.
The corrected 9 forward flow flight times are thus: { 487.93; 487.91, respectively; 487.94, respectively; 487.96, respectively; 487.93, respectively; 487.95, respectively; 487.97, respectively; 487.95, respectively; 487.92}.
The procedure for correcting the upstream flight time is similar to that for correcting the downstream flight time, and the description thereof is omitted here.
While, for purposes of simplicity of explanation, the foregoing method embodiments have been described as a series of acts or combination of acts, it will be appreciated by those skilled in the art that the present invention is not limited by the illustrated ordering of acts, as some steps may occur in other orders or concurrently with other steps in accordance with the invention.
The following are embodiments of the apparatus of the present invention that may be used to perform embodiments of the method of the present invention. For details which are not disclosed in the embodiments of the apparatus of the present invention, reference is made to the embodiments of the method of the present invention.
Referring to fig. 5, a flow rate measuring device based on a time difference method according to an embodiment of the present invention includes: a downstream flight time acquisition unit 51, an upstream flight time acquisition unit 52, a current calculation cycle reference value determination unit 53, a downstream flight time correction unit 54, an upstream flight time correction unit 55, a flight time difference calculation unit 56, and a flow rate calculation unit 57.
A downstream time-of-flight obtaining unit 51, configured to obtain n downstream time-of-flight continuously acquired by using a hardware threshold method in a current calculation period, where n is an integer greater than 7, and the downstream time-of-flight is a time-of-flight during which an ultrasonic wave emitted by the first ultrasonic transmitting probe propagates downstream in a fluid.
The countercurrent flight time acquiring unit 52 is configured to acquire n countercurrent flight times continuously acquired by using a hardware threshold method in a current calculation cycle, where the countercurrent flight time is a flight time of an ultrasonic wave emitted by the second ultrasonic wave emitting probe in countercurrent propagation in a fluid, and the first ultrasonic wave emitting probe and the second ultrasonic wave emitting probe are located in the same altitude layer.
And a current calculation period reference value determining unit 53, configured to analyze the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of the current calculation period.
And a forward flow flight time correction unit 54, configured to correct the n forward flow flight times based on the forward flow flight time reference value, so as to obtain n corrected forward flow flight times.
And an upstream flight time correction unit 55, configured to correct the n upstream flight times based on the upstream flight time reference value, so as to obtain n corrected upstream flight times.
And a time difference of flight calculation unit 56, configured to calculate n time differences of flight based on the n corrected forward flow flight times and the n corrected reverse flow flight times.
And a flow velocity calculating unit 57, configured to calculate a flow velocity of the fluid in a first height layer according to an average value of the n time differences of flight, where the first height layer is a height layer where the first ultrasonic transmission probe is located.
Optionally, the unit for determining the reference value of the current calculation cycle specifically includes: the device comprises a classification unit, a forward flow flight time reference value determination unit and a reverse flow flight time reference value determination unit.
And the classifying unit is used for classifying the n forward flow flight times and the n reverse flow flight times according to the time, so as to obtain at least one forward flow flight time set and at least one reverse flow flight time set.
And the downstream flight time reference value determining unit is used for judging whether a first downstream flight time set exists or not, the first downstream flight time set is a downstream flight time set of which the number of the downstream flight times is greater than n/2, if so, the average value of all the downstream flight times of the first downstream flight time set is used as the downstream flight time reference value of the current calculation period, and if not, the downstream flight time reference value obtained by calculating the previous calculation period is used as the downstream flight time reference value of the current calculation period.
And the counter-flow flight time reference value determining unit is used for judging whether a first counter-flow flight time set exists or not, the first counter-flow flight time set is a counter-flow flight time set of which the number of counter-flow flight times is greater than n/2, if so, the average value of all counter-flow flight times of the first counter-flow flight time set is used as a counter-flow flight time reference value, and if not, the counter-flow flight time reference value obtained by calculating the previous calculation period is used as the counter-flow flight time reference value of the current calculation period.
Optionally, the classifying unit is specifically configured to classify the n forward flow flight times and the n reverse flow flight times respectively by using a K nearest neighbor classification algorithm according to time, so as to obtain at least one forward flow flight time set and at least one reverse flow flight time set.
Optionally, the flow rate measuring device based on the time difference method further includes:
and the flow rate correction unit is used for judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the second height layer is larger than a preset first height layer fluid flow rate threshold value or not, if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period, and the second height layer is a height layer which is adjacent to and lower than the first height layer.
Optionally, the flow rate measuring device based on the time difference method further includes:
and the flow velocity correction unit is used for judging whether the difference value between the flow velocity of the fluid in the first height layer and the flow velocity of the fluid in the third height layer is larger than a preset first height layer fluid flow velocity threshold value or not, if so, the flow velocity of the fluid in the first height layer obtained by calculation in the previous calculation period is used as the flow velocity of the fluid in the first height layer in the current calculation period, and the third height layer is a height layer which is adjacent to and higher than the first height layer.
An embodiment of the present invention further provides a readable storage medium, where the readable storage medium may store a program adapted to be executed by a processor, where the program is configured to:
acquiring n forward flow flight times continuously acquired by a hardware threshold method in a current calculation period;
acquiring n countercurrent flight times continuously acquired by using a hardware threshold method in a current calculation period;
analyzing the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of the current calculation period;
correcting the n downstream flight times based on the downstream flight time reference value to obtain n corrected downstream flight times;
correcting the n countercurrent flight times based on the countercurrent flight time reference value to obtain n corrected countercurrent flight times;
calculating to obtain n flight time differences based on the corrected n downstream flight times and the corrected n upstream flight times;
and calculating the flow velocity of the fluid in the first height layer according to the average value of the n time-of-flight differences.
The refinement function and the extension function of the program may be referred to as described above.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are mainly described as different from other embodiments, the same and similar parts in the embodiments may be referred to each other, and the features described in the embodiments in the present description may be replaced with each other or combined with each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A flow velocity measurement method based on a time difference method is characterized by comprising the following steps:
acquiring n downstream flight times continuously acquired by a hardware threshold method in a current calculation period, wherein n is an integer larger than 7, and the downstream flight time is the flight time of downstream propagation of ultrasonic waves in fluid, which is sent by a first ultrasonic transmitting probe;
acquiring n countercurrent flight times continuously acquired by a hardware threshold method in a current calculation period, wherein the countercurrent flight time is the flight time of ultrasonic waves emitted by a second ultrasonic emission probe in countercurrent propagation in fluid, and the first ultrasonic emission probe and the second ultrasonic emission probe are positioned on the same height layer;
analyzing the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of the current calculation period;
correcting the n forward flow flight times based on the forward flow flight time reference value to obtain n corrected forward flow flight times;
correcting the n countercurrent flight times based on the countercurrent flight time reference value to obtain n corrected countercurrent flight times;
calculating n flight time differences based on the corrected n forward flow flight times and the corrected n reverse flow flight times;
and calculating the flow velocity of the fluid in a first height layer according to the average value of the n flight time differences, wherein the first height layer is the height layer where the first ultrasonic transmitting probe is located.
2. The method for measuring flow velocity based on the time difference method according to claim 1, wherein the analyzing the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of a current calculation period specifically comprises:
classifying the n forward flow flight times and the n reverse flow flight times according to time to obtain at least one forward flow flight time set and at least one reverse flow flight time set;
judging whether a first downstream flight time set exists or not, wherein the first downstream flight time set is a downstream flight time set of which the number of the downstream flight times is greater than n/2, if so, taking the average value of all the downstream flight times of the first downstream flight time set as the downstream flight time reference value of the current calculation period, and if not, calculating the previous calculation period to obtain the downstream flight time reference value as the downstream flight time reference value of the current calculation period;
and judging whether a first countercurrent flight time set exists or not, wherein the first countercurrent flight time set is an countercurrent flight time set of which the number of the countercurrent flight times is more than n/2, if so, taking the average value of all the countercurrent flight times of the first countercurrent flight time set as a countercurrent flight time reference value, and if not, calculating the previous calculation period to obtain the countercurrent flight time reference value as the countercurrent flight time reference value of the current calculation period.
3. The method for measuring flow velocity based on the time difference method according to claim 2, wherein the classifying the n forward flow flight times and the n reverse flow flight times according to time size to obtain at least one forward flow flight time set and at least one reverse flow flight time set comprises:
and classifying the n forward flow flight times and the n reverse flow flight times respectively by adopting a K nearest neighbor classification algorithm according to the time, so as to obtain at least one forward flow flight time set and at least one reverse flow flight time set.
4. The method of claim 1, further comprising, after the step of calculating the flow velocity of the fluid in the first altitude layer according to the average of the n time-of-flight differences:
and judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the second height layer is greater than a preset first height layer fluid flow rate threshold value or not, if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period, and the second height layer is a height layer adjacent to and lower than the first height layer.
5. The method of claim 1, further comprising, after the step of calculating the flow velocity of the fluid in the first altitude layer according to the average of the n time-of-flight differences:
and judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the third height layer is greater than a preset first height layer fluid flow rate threshold value or not, if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period, and the third height layer is a height layer which is adjacent to and higher than the first height layer.
6. A flow velocity measuring apparatus based on a time difference method, comprising:
the downstream flight time acquisition unit is used for acquiring n downstream flight times continuously acquired by a hardware threshold method in the current calculation period, wherein n is an integer larger than 7, and the downstream flight time is the flight time of downstream propagation of ultrasonic waves in fluid, which is sent by the first ultrasonic transmitting probe;
the system comprises a counter-flow flight time acquisition unit, a counter-flow flight time acquisition unit and a counter-flow flight time acquisition unit, wherein the counter-flow flight time acquisition unit is used for acquiring n counter-flow flight times continuously acquired by a hardware threshold method in a current calculation period, the counter-flow flight time is the flight time of counter-flow propagation of ultrasonic waves in fluid, the ultrasonic waves are emitted by a second ultrasonic emission probe, and the first ultrasonic emission probe and the second ultrasonic emission probe are positioned on the same height layer;
a current calculation cycle reference value determining unit, configured to analyze the n forward flow flight times and the n reverse flow flight times to obtain a forward flow flight time reference value and a reverse flow flight time reference value of a current calculation cycle;
a forward flow flight time correction unit, configured to correct the n forward flow flight times based on the forward flow flight time reference value, so as to obtain n corrected forward flow flight times;
the countercurrent flight time correction unit is used for correcting the n countercurrent flight times based on the countercurrent flight time reference value to obtain n corrected countercurrent flight times;
a time difference of flight calculation unit, configured to calculate n time differences of flight based on the corrected n forward flow flight times and the corrected n reverse flow flight times;
and the flow velocity calculation unit is used for calculating the flow velocity of the fluid in a first height layer according to the average value of the n flight time differences, wherein the first height layer is the height layer where the first ultrasonic transmitting probe is located.
7. The flow rate measurement device according to claim 6, wherein the current calculation cycle reference value determination unit specifically includes:
the classification unit is used for classifying the n forward flow flight times and the n reverse flow flight times according to time to obtain at least one forward flow flight time set and at least one reverse flow flight time set;
a forward flow flight time reference value determining unit, configured to determine whether a first forward flow flight time set exists, where the first forward flow flight time set is a forward flow flight time set with a forward flow flight time number greater than n/2, if the first forward flow flight time set exists, an average value of all forward flow flight times in the first forward flow flight time set is used as a forward flow flight time reference value in a current calculation period, and if the first forward flow flight time set does not exist, a forward flow flight time reference value obtained by calculating in a previous calculation period is used as a forward flow flight time reference value in the current calculation period;
and the counter-flow flight time reference value determining unit is used for judging whether a first counter-flow flight time set exists or not, the first counter-flow flight time set is a counter-flow flight time set of which the number of counter-flow flight times is greater than n/2, if so, the average value of all counter-flow flight times of the first counter-flow flight time set is used as a counter-flow flight time reference value, and if not, the counter-flow flight time reference value obtained by calculating in the previous calculation period is used as the counter-flow flight time reference value of the current calculation period.
8. The time-difference-based flow rate measurement device according to claim 6, further comprising:
and the flow rate correction unit is used for judging whether the difference value between the flow rate of the fluid in the first height layer and the flow rate of the fluid in the second height layer is larger than a preset first height layer fluid flow rate threshold value or not, if so, taking the flow rate of the fluid in the first height layer obtained by calculation in the previous calculation period as the flow rate of the fluid in the first height layer in the current calculation period, and the second height layer is a height layer which is adjacent to and lower than the first height layer.
9. A readable storage medium on which a program is stored, wherein the program, when executed by a processor, implements the steps of the time-difference-based flow rate measurement method according to any one of claims 1 to 5.
10. A time-difference-based flow velocity measurement apparatus comprising a memory for storing a program and a processor, wherein the processor is configured to execute the program to carry out the steps of the time-difference-based flow velocity measurement method according to any one of claims 1 to 5.
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