Disclosure of Invention
In view of the above, there is a need for an eddy current detection system and method for detecting and analyzing eddy currents to detect and detect the trace of an underwater vehicle.
To achieve the above object, the present invention provides an eddy current probe system and method, the system comprising:
the sound wave generating end is used for transmitting an initial sound wave signal to the area to be detected;
the sound wave receiving end is used for receiving a plurality of measurement sound pressure signals generated after the initial sound wave signals pass through the area to be measured;
and the control device is coupled with the sound wave receiving end and used for judging whether eddy current exists in the area to be detected or not according to the phase difference of the multiple measured sound pressure signals and the preset sound pressure signal phase difference.
In order to solve the above problem, the present invention further provides an eddy current detection method based on the eddy current detection system described above, including:
the sound wave generating end transmits an initial sound wave signal to the area to be detected;
the sound wave receiving end receives a plurality of measurement sound pressure signals generated after the initial sound wave signals pass through the area to be measured;
and the control device judges whether the eddy current exists in the area to be measured according to the phase difference of the plurality of measured sound pressure signals and the preset sound pressure signal phase difference.
Preferably, the sound wave generating end comprises a generating end signal generator, a power amplifier and an underwater sound transducer; the sound wave generating end transmits an initial sound wave signal to a region to be measured, and the method comprises the following steps:
the generator end signal generator generates an electric signal;
the power amplifier amplifies the power of the electric signal to obtain an amplified electric signal;
and the underwater acoustic transducer converts the amplified electric signal into an initial sound wave signal and transmits the initial sound wave signal to the area to be measured.
Preferably, the sound wave receiving end comprises a data acquisition instrument and a plurality of receiving end hydrophones distributed in an array; the sound wave receiving terminal receives a plurality of measurement sound pressure signals generated after the initial sound wave signal passes through the region to be measured, and the method comprises the following steps:
a plurality of receiving end hydrophones distributed in an array successively receive a plurality of measurement sound pressure signals generated after initial sound wave signals pass through a region to be measured;
the data acquisition instrument acquires a plurality of measurement sound pressure signals and transmits the signals to the control device.
Preferably, the control means comprises a coherence analyser; the control device judges whether eddy current exists in the region to be measured according to the phase difference of the plurality of measured sound pressure signals and the preset sound pressure signal phase difference, and the method comprises the following steps:
the coherent analyzer determines a plurality of phase differences of the plurality of measured sound pressure signals according to the plurality of measured sound pressure signals;
and comparing the phase differences with preset sound pressure signal phase differences to judge whether eddy current exists in the area to be detected.
Preferably, the coherent analyzer determines a plurality of phase differences of the plurality of measured acoustic pressure signals from the plurality of measured acoustic pressure signals, including:
the coherent analyzer obtains a plurality of time delays corresponding to the plurality of measured sound pressure signals according to the plurality of measured sound pressure signals;
and determining a plurality of phase differences according to the plurality of time delays by utilizing the relationship among the time delays, the phase differences and the underwater sound velocity.
Preferably, determining the preset sound pressure signal phase difference comprises:
the sound wave generating end respectively transmits preset sound wave signals to the eddy current field without the eddy current and the eddy current field with the eddy current;
the sound wave receiving end respectively receives two groups of measurement sound pressure signals generated after a preset sound wave signal passes through a non-eddy current field and an eddy current field;
and the control device determines a preset sound pressure signal phase difference according to the two groups of measured sound pressure signals.
Preferably, determining a preset sound pressure signal phase difference from the two sets of measured sound pressure signals comprises:
according to the two groups of measured sound pressure signals, obtaining the peak value of each group of measured sound pressure signals and the corresponding time point;
obtaining two groups of time delays by correspondingly making differences according to each group of time points;
and determining the phase difference of the preset sound pressure signals according to the two groups of time delays.
Preferably, the sound wave generating end further comprises a plurality of generating end hydrophones distributed in an array, and the sound wave receiving end further comprises a plurality of receiving end sound wave generators distributed in an array; the eddy current detection method further includes:
a plurality of receiving end sound wave generators distributed in an array emit test sound wave signals to an area to be tested;
a plurality of generating end hydrophones distributed in an array receive a plurality of detection sound pressure signals generated after detection sound wave signals pass through a region to be detected;
and the control device judges whether the eddy current exists in the area to be detected according to the phase difference of the plurality of test sound pressure signals and the preset sound pressure signal phase difference.
Preferably, the test acoustic signal has the same parameters as the initial acoustic signal.
The beneficial effect of adopting above-mentioned technical scheme is: the present invention provides an eddy current detection system and method, the system comprising: a sound wave generating end; a sound wave receiving end; and the control device is coupled with the sound wave receiving end. The invention transmits an initial sound wave signal to the area to be measured through the sound wave generating end, the sound wave receiving end receives a plurality of measured sound pressure signals generated after the initial sound wave signal passes through the area to be measured, and the control device judges whether eddy current exists in the area to be measured according to the phase difference of the plurality of measured sound pressure signals and the preset sound pressure signal phase difference. The vortex can be generated inevitably during navigation of the underwater vehicle, and the vortex can exist for a long time, so that the detection analysis of the vortex is carried out by the technical scheme, the detection mode of the underwater vehicle is innovated, the dependence on a sonar system is reduced, the detection stability is improved due to the high stability of the vortex, and the accuracy of the detection result of the trace of the underwater vehicle is high.
Detailed Description
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.
At present, the trace detection of an underwater vehicle mainly depends on a sonar system, however, aiming at the characteristics of sonar, the underwater vehicle lays a sound absorption and sound insulation acoustic covering layer on the surface, and low-noise equipment and high-performance vibration isolation components are selected in the underwater vehicle, so that the noise level of the underwater vehicle is lower and lower, and the sonar detection is continuously limited.
In order to detect the track of the underwater vehicle, the technical scheme detects and analyzes the eddy current which is inevitably generated in the advancing process of the underwater vehicle, so that the track of the underwater vehicle is detected. When the detected sound wave passes through the vortex with the characteristic size far larger than the wavelength, the sound scattering phenomenon of the vortex field can be generated, the wave front distortion of the reached sound wave, namely the coherent phenomenon, is caused, wherein the phase information contained in the coherent wave is closely related to the characteristics of the vortex, and after the characteristics of the sound scattering field are obtained and analyzed, the vortex structure and the dynamic characteristics, including the radius, the distribution, the characteristic scale, the vortex amount and the like, of the vortex in the wake can be determined, so that the purpose of detection and identification can be achieved according to the characteristic values. The present invention provides an eddy current probing system and method, each of which is described in detail below.
As shown in fig. 1, fig. 1 is a schematic structural diagram of an embodiment of an eddy current detection system provided in the present invention, and the eddy current detection system 100 includes:
the acoustic wave generating end 101 is used for transmitting an initial acoustic wave signal to a region to be detected;
the sound wave receiving end 102 is used for receiving a plurality of measurement sound pressure signals generated after the initial sound wave signals pass through the area to be measured;
and the control device 103 is coupled to the sound wave receiving end 102, and configured to determine whether an eddy current exists in the region to be measured according to the phase difference between the multiple measured sound pressure signals and a preset sound pressure signal phase difference.
According to the invention, the sound wave generating end 101 transmits an initial sound wave signal to the area to be detected, the sound wave receiving end 102 receives a plurality of measured sound pressure signals generated after the initial sound wave signal passes through the area to be detected, and the control device 103 judges whether eddy current exists in the area to be detected according to the phase difference of the plurality of measured sound pressure signals and the preset sound pressure signal phase difference. The underwater vehicle inevitably generates vortex during navigation, and the vortex can exist for a long time, so that after a plurality of measured sound pressure signals are obtained through the technical scheme, vortex information is obtained through inversion, detection and analysis are carried out on the vortex, and the track detection of the underwater vehicle is realized.
In order to solve the above problem, the present invention further provides an eddy current detection method based on the above eddy current detection system, as shown in fig. 2, fig. 2 is a schematic flow chart of an embodiment of the eddy current detection method provided by the present invention, including:
step S11: the sound wave generating end transmits an initial sound wave signal to the area to be measured.
Step S12: the sound wave receiving end receives a plurality of measurement sound pressure signals generated after the initial sound wave signals pass through the area to be measured.
Step S13: and the control device judges whether the eddy current exists in the area to be detected or not according to the phase difference of the plurality of measured sound pressure signals and the preset sound pressure signal phase difference.
In the embodiment of the invention, as the underwater vehicle inevitably generates vortex during navigation and the vortex can exist for a long time, the sound wave generating end transmits an initial sound wave signal to the area to be measured; the sound wave receiving end receives a plurality of measurement sound pressure signals generated after the initial sound wave signals pass through the area to be measured; the control device obtains phase differences of the plurality of measured sound pressure signals through analysis and calculation according to the plurality of measured sound pressure signals, and compares and judges whether the phase differences of the plurality of measured sound pressure signals are consistent with a preset sound pressure signal phase difference or not, so that whether eddy current exists in the area to be detected or not is judged.
As a preferred embodiment, in step S11, the sound wave generating terminal includes a generating terminal signal generator, a power amplifier and an underwater sound transducer, in order to clearly illustrate the process of the sound wave generating terminal transmitting the initial sound wave signal, as shown in fig. 3, fig. 3 is a schematic flow chart of an embodiment of the sound wave generating terminal transmitting the initial sound wave signal provided by the present invention, and the sound wave generating terminal transmitting the initial sound wave signal includes:
step S111: the generator-side signal generator generates an electrical signal.
Step S112: the power amplifier amplifies the power of the electric signal to obtain an amplified electric signal.
Step S113: and the underwater acoustic transducer converts the amplified electric signal into an initial sound wave signal and transmits the initial sound wave signal to the area to be measured.
It can be understood that after the sound wave generating end acquires the instruction for transmitting the initial sound wave signal, the signal generator at the generating end generates an electric signal for transmitting the sound wave; in order to improve the power of electric signal transmission, the power of the electric signal is amplified through a power amplifier, and the electric signal can be accurately transmitted to an underwater acoustic transducer; and the underwater acoustic transducer converts the amplified electric signal into an initial acoustic signal and transmits the initial acoustic signal to the area to be measured.
In step S112, the electrical signal generated by the generator-side signal generator is amplified by the power amplifier, so that the underwater acoustic transducer can receive an accurate electrical signal, and when the underwater acoustic transducer converts the electrical signal into an initial acoustic signal, the power of the initial acoustic signal can be ensured to meet the use requirement.
In a particular embodiment, the types of power amplifiers include, but are not limited to, Class A, Class B, Class AB, Class D, and Class T.
In step S113, the initial acoustic wave signal includes, but is not limited to, a triangle wave, a sawtooth wave, and a rectangular wave, and a waveform of a specific waveform parameter may also be set, that is, a waveform of the specific waveform parameter is obtained by designing parameters such as amplitude, leading edge and rising time, trailing edge and falling time, width, interval, period, and frequency of the initial acoustic wave signal; so as to more accurately capture, analyze and judge the underwater signals.
In step S113, the initial acoustic signal may be set to a fixed frequency mode or a frequency sweep mode, where the lower limit of the frequency is not lower than 1kHz and the upper limit is not higher than 10 kHz. When the frequency is too low, the wavelength of the sound wave is longer, and the sound wave bypasses the vortex field to generate missing judgment; the frequency is too high, so that the acoustic wave wavelength is short, and the error in phase analysis is large; the upper frequency limit is also related to the attenuation of sound waves in water, and the lower the frequency, the smaller the absorption and attenuation of the sea water to the sound waves, so the frequency of the sound wave signals is not suitable to be too high.
In step S12, the sound wave receiving end includes a data acquisition device and a plurality of receiving end hydrophones distributed in an array.
After the initial sound wave signal passes through the area to be detected, the plurality of receiving end hydrophones are distributed according to the array, so that the plurality of obtained measured sound pressure signals are distributed according to certain characteristics, and the subsequent data analysis is facilitated; the data acquisition instrument transmits a plurality of acquired measurement sound pressure signals to the control device.
Furthermore, in order to ensure certain target intensity and enough sound wave propagation distance, the distance between the signal generator at the generating end and the hydrophone at the receiving end can be adjusted, and the signal receiving time interval can be changed. That is, when the distance between the signal generator at the generating end and the hydrophone at the receiving end is reduced, the signal receiving time interval is shortened, and the time delay caused by the eddy current field occupies the characteristic of the time domain signal obviously.
In a specific embodiment, the underwater acoustic transducer and the acoustic wave receiving end both select transducers with high sensitivity, strong anti-interference and anti-signal crosstalk capabilities, and a large dynamic range of low-frequency vectors.
In one embodiment, to ensure the accuracy of the multiple measured acoustic pressure signals, the error of the synchronous sampling of the multiple receiving-end hydrophones is no greater than 100 ns.
As a preferred embodiment, in step S13, the control device includes a coherence analyzer, in order to clearly illustrate the process of determining whether an eddy current exists in the region to be measured according to the multiple measured sound pressure signals, as shown in fig. 4, fig. 4 is a schematic flow chart of an embodiment of the present invention for determining whether an eddy current exists in the region to be measured, where determining whether an eddy current exists in the region to be measured includes:
step S131: and the coherent analyzer obtains a plurality of time delays corresponding to the plurality of measured sound pressure signals according to the plurality of measured sound pressure signals.
Step S132: and determining a plurality of phase differences according to the plurality of time delays by utilizing the relationship among the time delays, the phase differences and the underwater sound velocity.
Step S133: and comparing the phase differences with preset sound pressure signal phase differences to judge whether eddy current exists in the area to be detected.
It can be understood that after the coherent analyzer acquires the plurality of measured sound pressure signals, because the position of each receiving end hydrophone is different, the plurality of measured sound pressure signals are compared with each other, and a plurality of time delays can be obtained; further, since the product of the time delay and the underwater sound velocity is equal to the phase difference, that is, the phase difference between the plurality of measured sound pressure signals can be determined by the plurality of acquired time delays; finally, the phase differences of the sound wave signals generated due to the influence of the eddy currents have a certain number relation, so that whether the eddy currents exist in the area to be detected can be judged by comparing the obtained phase differences with the preset phase differences of the sound pressure signals.
That is to say, in this embodiment, a plurality of time delays are obtained by comparing a plurality of measured sound pressure signals, then phase differences of the plurality of measured sound pressure signals are obtained according to the plurality of time delays, and finally, whether an eddy current exists in the region to be measured is determined by comparing the plurality of phase differences with a preset sound pressure signal phase difference.
As a preferred embodiment, in step S13, after acquiring the phase differences of the plurality of measured sound pressure signals, a preset sound pressure signal phase difference needs to be acquired to perform the determination, and in order to clearly describe the process of acquiring the preset sound pressure signal phase difference, as shown in fig. 5, fig. 5 is a schematic flow chart of an embodiment of the present invention for acquiring the preset sound pressure signal phase difference, and acquiring the preset sound pressure signal phase difference includes:
step S21: the sound wave generating end respectively transmits an initial sound wave signal to the eddy current field without the eddy current and the eddy current field with the eddy current.
Step S22: the sound wave receiving end respectively receives two groups of measurement sound pressure signals generated after the initial sound wave signals pass through the non-eddy current field and the eddy current field.
Step S23: and the control device determines a preset sound pressure signal phase difference according to the two groups of measured sound pressure signals.
It can be understood that an initial sound wave signal is transmitted to a vortex field with known vortices, a plurality of vortex measurement sound pressure signals received by a sound wave receiving end are necessarily delayed, and a plurality of vortex phase differences corresponding to the plurality of vortex measurement sound pressure signals are obtained by solving each time delay; further, in order to avoid the influence of other external factors such as the environment, in this embodiment, an initial sound wave signal is further transmitted to a known vortex field without a vortex, a sound wave receiving end receives a plurality of vortex-free measured sound pressure signals, then, whether a plurality of vortex-free measured sound pressure signals have a vortex-free time delay or not is analyzed and judged, if yes, a plurality of vortex-free phase differences are calculated, and a plurality of vortex-free phase differences are correspondingly subtracted from a plurality of values with the vortex phase differences, so that a preset sound pressure signal phase difference is determined; if not, the plurality of eddy phase differences are preset sound pressure signal phase differences.
Further, a coherent analysis system in the control device calculates the eddy current acoustic scattering based on an eddy current model, and the eddy current velocity profile is as follows:
wherein r represents the distance from a certain point in space to the center of the vortex core, a is the radius of the vortex core, Γ is 2.8 pi acMa represents the vortex ring amount, c is the sound velocity in water, the sound velocity and the sound velocity profile in water change with different underwater environments, and Ma is Mach number.
And calculating and analyzing according to an axisymmetric calculation phase algorithm, wherein a vortex eddy field exists between the sound signal transmitting end and the receiving end of the underwater acoustic transducer, and a vortex with a certain vortex ring amount and radius exists. The steady-state eddy current field can be regarded as a stable axisymmetric moving medium, and the eddy current field is divided into n radial ranges with the radius r i (i∈[1,n]) Defining a first ring r 1 Is positioned at the edge of the vortex field, because of stable vortex, the speed of the vortex field in each circular ring can be approximately considered as a constant value u i 。
A vortex-free vortex field calculation database and a vortex-containing vortex field calculation database are arranged in the coherent analysis system, and the propagation time t of the acoustic signal under the condition of vortex parameters of each parameter is stored 0 . And measuring the propagation time t of the acoustic signal under the condition that the eddy current field exists, wherein the difference value of the acoustic signals of different hydrophones in the array is time delay deltat, and the product of the time delay and the sound velocity is the phase difference.
The phase difference of the sound wave after passing through the eddy current field can be defined as:
wherein, ω is the frequency of the rotating circle, the upper integral limit represents the transmitting end, the lower integral limit represents the receiving end, c is the sound velocity in water, u is the tangential velocity of the vortex field, and n is the number of small concentric rings.
The above formula is expanded in series, and then high-order small quantity is omitted, so that the following formula can be obtained:
in the first ring r 1 In the medium, the tangential velocity of the eddy current field is u 1 The velocity component in the y-axis being u 1 cos θ, the phase difference of the acoustic signal passing through the first ring of eddy currents is:
in the same way, the second ring r can be obtained 2 In the vortex field, the tangential velocity is u 2 The velocity component in the y-axis being u 2 cos θ, acoustic signal passing through the ring r 2 The resulting phase difference is:
here, the acoustic signal passes through r 1 ,r 2 The total phase difference of the received acoustic signals of the two circular rings is as follows:
the phase difference of the sound wave passing through each ring is independent, so the steps can be repeated until the sound signal is deduced to pass through the vortex coreCenter ring r n A general expression for the phase difference can be generalized:
Δφ i =E ij u j 。
in a specific embodiment, the data of the preset sound pressure signal phase difference is obtained based on the parameters of the propeller blade geometry, different working conditions of the propeller and the underwater environment, and in order to improve the accuracy and speed of phase difference matching, the database of the preset sound pressure signal phase difference needs to be updated periodically.
Further, in order to improve the accuracy of the eddy current detection result, the sound wave generating end further includes a plurality of generating end hydrophones distributed in an array, the sound wave receiving end further includes a plurality of receiving end sound wave generators distributed in an array, the eddy current detection method further includes a reverse detection eddy current, as shown in fig. 6, fig. 6 is a schematic flow diagram of an embodiment of the reverse detection eddy current provided by the present invention, and the reverse detection eddy current includes:
step S31: and a plurality of receiving end sound wave generators distributed in an array emit test sound wave signals to the area to be tested.
Step S32: and a plurality of generating end hydrophones distributed in an array receive a plurality of detection sound pressure signals generated after the detection sound wave signals pass through the area to be detected.
Step S33: and the control device judges whether the eddy current exists in the area to be detected according to the phase difference of the plurality of test sound pressure signals and the preset sound pressure signal phase difference.
It can be understood that, in this embodiment, based on the above-described eddy current detection method, one eddy current detection is added, the positions of the sound wave generating end and the sound wave receiving end are exchanged to obtain the phase difference of the multiple detection sound pressure signals, and then the phase difference of the multiple detection sound pressure signals is compared with the preset sound pressure signal phase difference, so that the determination method and the determination criterion are the same as those described above, and are not described herein again.
By the mode, the identification and judgment of the eddy current field are improvedThe accuracy of (2). Assuming that the probability of successful detection is P, and also because the same detection device and method are adopted, the probability of successful reverse detection is P, the probability of success after detection and direction detection conforms to a generalized addition formula, namely the probability of success after reverse detection is 2P + P 2 And because the detection success probability is always larger than 0 and smaller than 1, the reverse detection process can greatly increase the detection success probability.
Furthermore, the control device also comprises an alarm, and after the eddy current is detected, the alarm gives an alarm prompt.
By the method, after the plurality of measured sound pressure signals generated after the initial sound wave signal passes through the region to be measured are obtained, the plurality of phase differences corresponding to the plurality of measured sound pressure signals are calculated by using a coherent analysis method and are compared with the preset sound pressure signal phase difference, and whether the vortex exists is judged. Further, in order to improve the eddy current detection accuracy, a reverse detection method is also provided.
The eddy current is detected through the technical scheme provided by the application, so that whether the track of the underwater vehicle exists or not is determined. The vortex is a necessary product of the travel of the underwater vehicle and has long existence time, so that the dependence on a sonar system is reduced in the field of track detection of the underwater vehicle.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.