RU2563317C1 - Method of acoustic monitoring of offshore parameters variability - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: method is proposed for acoustic monitoring of offshore parameters variability, consisting in formation of an acoustic route of sound propagation in sea medium and processing of an acoustic signal received by a receiving element of the route, which includes measurement of sound propagation speed, temperature and pressure in the reference zone of the water body at fixed horizons, free of pollution of anthropogenic nature, at the same time produced values of measured speed of sound propagation are reference values for this water body and are entered into the memory of the computing device in the acoustic monitoring facility, during formation of the acoustic sound propagation route in the sea environment and processing of the acoustic signal received by the receiving element of the route, measurement of sound propagation speed is carried out at temperature and pressure, which correspond to temperature and pressure of the received reference values of sound propagation speed at fixed horizons of the area of water of the investigated water body.

EFFECT: increased reliability of the method of acoustic monitoring of variability of parameters of offshores, expansion of functional capabilities.

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Description

The invention relates to the field of hydroacoustics and can be used to create local regional and global acoustic systems for long-term monitoring along sound propagation paths of such parameters of the marine environment as the average water temperature and its variability, projection onto the flow velocity path, the presence of hydrophysical inhomogeneities, ice on the path, movements of fish aggregations, passage of vessels, etc.

Known methods for acoustic monitoring the variability of parameters of marine areas, systematized in the journal J. Acoust. Joe Amer., 1994, 86, N 4 [1] and the article Problems of metrology and hydroacoustic measurements, Mendeleevo, VNIIFTRI, 1992, p. 96-101 [2], which can be shined to two main groups:

- monochromatic, in which a tone-pulse signal is emitted and received at a preselected frequency and the propagation time of this signal along the path is measured either along the pulse front or on the carrier phase;

- broadband, for example, when a linearly frequency-modulated signal [2] is emitted and received for spectroscopy of time delays or a pseudo-random signal in the form of a phase-shift M-sequence with determination of the propagation time by the correlation function between the received and emitted signals.

Common features of the known methods of acoustic monitoring [1, 2] are the formation in the marine environment of an acoustic receiving-emitting route circuit and processing of the acoustic signal received by the receiving element of the route circuit of the acoustic signal that has passed the sound propagation path.

Also known is the acoustic monitoring method described in W.I. Munk, R.C. Spindel, A. Baggeroel, T.C. "Birdsall The heard island feasibility test" // J. Acoust. Joe Amer., 1994, 96, N 4, pp. 2330-2342 [3] from the journal [1], has common features of known methods [1, 2].

The disadvantages of the known methods of acoustic monitoring are the need for radiation of large acoustic powers for their implementation to obtain the required measurement accuracy [2].

There is also known a method of acoustic monitoring of variability of parameters of sea water areas, the technical result obtained from the introduction of which is a significant reduction in the required radiation power for implementing the method, simplifying the scheme for implementing the method and improving the accuracy of measurements with shorter time signal processing due to self-adaptation of the oscillator to the conditions of sound propagation on the highway (patent RU No. 2134432 C1, 08/10/1999 [4]).

This technical result is achieved due to the fact that in the known method of acoustic monitoring of the variability of parameters of marine areas, which consists in the formation in the marine environment of an acoustic receiving-emitting path circuit and processing of the acoustic signal received by the receiving element of the path circuit, passing the sound path of the circuit, adopted by the receiving element of the route circuit, the signal is fed to the radiating side of the route and amplified nonlinearly until the auto-generation mode appears in the route circuit on one one of the frequencies determined by hydrophysical conditions on the sound propagation path, then the self-generation frequency is measured in the path pattern, by the value of which they are judged on changes in the parameters of the marine environment [4].

In a particular case, the formation of the auto-generation mode of the route scheme through the marine environment is carried out in two directions: direct and reverse.

At the same time, the desired group of rays (modes) can be selected in the sound propagation path, and the selected beam (mode) can be excited by using the auto-generation mode of the route circuit, while a vertically oriented sonar antenna is used as a receiving element.

When processing the acoustic signal received by the receiving element of the route circuit, the variability spectra of the autogeneration frequency are analyzed, which are used to judge the nature of the variability of the hydrophysical parameters of the marine environment.

The known method of acoustic monitoring of variability of parameters of marine waters [4] along with its advantages has a significant drawback.

As you know, the speed of sound in water (s) depends on temperature, its composition (the presence of various chemical elements and impurities in it) and density. And it can be measured both directly and calculated according to empirical formulas, which are dependencies of the type (Handbook of hydroacoustics / A.P. Evtyutov, A.E. Kolesnikov, W.A. Korepin et al. - 2nd ed., Rev. and add. - L.: Shipbuilding, 1988. - 552 p.):

where c ₀ is the reference value of the speed of sound at T = 0 ° C, S = 35 ‰, P = 9.806 Pa;

ΔС _T , ΔC _S , ΔС _P , ΔС _TSP - corrections for temperature, salinity, pressure and the combined influence of temperature, salinity and pressure.

The greatest influence on the change in the speed of sound is exerted by water temperature. So when the temperature changes by 1 ° C at a water temperature of 10 ° C, the speed of sound changes by 3.6 m / s, at a temperature of 15 ° C it changes by 3.2 m / s. At the same time, a change in salinity by 1 ‰ (at S = 30 ... 35 ‰) will cause a change in the speed of sound by 1.40 ± 0.01 m / s; a change in pressure at 10 m depth causes a change in the speed of sound by 0.165 ... 0.185 m / s.

In addition, a change in the composition and density of water caused by its pollution will lead to a change in the speed of sound propagation in it.

The objective of the proposed technical solution is to increase the reliability of the method of acoustic monitoring of the variability of the parameters of marine waters, as well as expanding the functionality.

The problem is solved due to the fact that in the method of acoustic monitoring of the variability of parameters of marine areas, which consists in the formation in the marine environment of an acoustic sound propagation path and processing of the acoustic signal received by the receiving element, in which a vertically oriented hydroacoustic antenna is used as the receiving element of the route, by means of which the required group of rays is extracted in the acoustic path of sound propagation, the auto-generation mode is excited using by extracting the extracted rays by directing the signal received by the hydroacoustic antenna to the radiating side of the path and non-linear amplification until the auto-generation mode appears at one of the frequencies determined by the hydro-acoustic conditions on the path, while processing the received hydro-acoustic antenna signal, the variability spectra of the auto-generation frequency are analyzed, which are used to judge the nature variability of hydrophysical parameters of the marine environment, in contrast to the prototype method of acoustic monitoring of variability of parameters The Orsk waters additionally includes measuring the speed of sound propagation, temperature and pressure in the model zone of the reservoir at fixed horizons, free from technogenic pollution, while the obtained values of the measured velocity of sound propagation are the reference values for this reservoir and are stored in the memory of the computing device of acoustic monitoring means, during the formation in the marine environment of an acoustic sound propagation path and processing received by the receiving element race acoustic signal, measuring the sound propagation velocity is performed at a temperature and pressure corresponding to the temperature and pressure of the obtained reference values the speed of sound at fixed depths studied reservoir area.

By simultaneously measuring at the same temperature and pressure the speed of sound propagation at the studied point of the reservoir and in the sample zone using the direct method and obtaining a certain difference in readings, it is possible with a certain degree of probability to reveal the difference in the composition (mineralization) and density of the studied water samples.

To implement the method of acoustic monitoring of variability of parameters of marine waters, schemes of measuring the sound propagation velocity of the prototype [4] with the addition of temperature and hydrostatic pressure measuring channels or similar industrial underwater probes can be used.

The method is as follows.

The method of acoustic monitoring of variability of parameters of sea water areas includes measuring the speed of sound propagation, temperature and pressure in the model zone of a reservoir at several fixed horizons, free from industrial pollution, for example, using a known meter [6], additionally equipped with channels for measuring temperature and hydrostatic pressure.

The obtained values of the measured speed of sound propagation are the reference values for a given reservoir and are recorded in the memory of the computing device acoustic monitoring means.

When an acoustic sound propagation path is formed in the marine environment and the acoustic signal path received by the receiving element is processed, measurements of the sound propagation velocity are performed at a temperature and pressure corresponding to the temperature and pressure of the obtained reference values of the sound propagation velocity at several horizons of the studied water body.

A number of contact and non-contact methods have been developed and are being applied for determining the physicochemical composition of water bodies and measuring water pollution (neutron activation, X-ray spectral, atomic absorption and atomic emission analysis, spectrophotometric and fluorimetric methods, infrared spectrometry, etc. ) Given that the speed of sound propagation in water depends on its hydrophysical and hydrochemical characteristics, the proposed method for determining water pollution by measuring the speed of sound in it can be proposed as one of them.

The obvious advantage of this approach is the ability to quickly determine the speed of sound in a direct way (by measuring the time span of the passage of an acoustic beam of a certain distance) in situ and thereby quickly establish the fact of contamination of this section of the reservoir. As statistical material is accumulated from these measurements, a relative method for determining pollution can be used (by measuring corrections due to the difference in the speed of sound, electrical conductivity, and water density using the corresponding empirical dependencies).

The task of eliminating the influence of temperature changes during measurements can be solved by simultaneously measuring the speed of sound propagation under the same conditions (at the same temperature and pressure) in a reference (uncontaminated) sample and in water determined for pollution at several fixed horizons.

Measurement of water temperature is necessary because its effect on the speed of sound in water at different values varies. As a rule, modern sound velocity meters are equipped with temperature sensors.

Depending on the purpose of the research, the measurement technology in this way may vary. So to examine the contamination of any part of the reservoir, it is possible to take measurements at the nodes of a uniform or uneven network of measurements located along the studied reservoir (figure).

If the location of the source of pollution is presumably or accurately known, then it is advisable to thicken the measurement network at this source, followed by rarefaction of the network as it moves away from it. To determine the degree of water pollution by any industrial or agricultural enterprise, it is possible to organize comparative control by taking measurements at the water intake and at the sewage system of this enterprise.

Considering the error value of the proposed method and assuming, in a first approximation, the measured sound velocities in the test water and the reference sample are statistically independent, it can be assumed that the mean square error (UPC) of the method will be equal to:

where m _from - UPC sound velocity meter;

UPC of modern sound velocity meters, for example Valeport Mini SVS, is not more than 0.02 m / s. That is, the SKP of the method does not exceed 0.028 m / s.

For comparison, such a change in the speed of sound at a water temperature of 15 ° C in practically fresh water (salinity 0 ÷ 1 ‰) will be determined by a change in salinity of about 0.25 ‰. (Zubov NN Oceanological tables. Hydrometeorological publication. L. 1957 - 407 p.).

The proposed method for measuring the speed of sound propagation allows with sufficient resolution and speed to establish the fact of water pollution in the reservoir and to evaluate the magnitude of this pollution, followed by analysis of the physico-chemical composition by known methods.

Information sources

1. Copyright certificate SU No. 640221 A, 12/30/1978.

2. Smirnov A.D. Pulse ultrasonic measuring equipment. - M .: Energy, 1967, p. 100.108.

3. Kolesnikov A.E. Ultrasonic measurements. - M .: Publishing house of standards, 1970, p. 55-73.

4. DE patent No. 4409999 A1, 15.15.1994.

5. DE patent No. 4315794 Al, 11.17.1994.

6. Patent RU No. 2208823 C2, 07/10/2003.

Claims (1)

The method of acoustic monitoring of variability of parameters of marine areas, which consists in forming an acoustic sound propagation path in the marine environment and processing the acoustic signal path received by the receiving element, in which a vertically oriented hydroacoustic antenna is used as the receiving element of the path, with which the desired sound path is extracted in the acoustic path a group of rays, excite the mode of auto-generation using the selected rays by the direction taken the hydroacoustic antenna signal on the radiating side of the path and non-linear amplification until the auto-generation mode appears at one of the frequencies determined by the hydroacoustic conditions on the path, while processing the received hydroacoustic antenna signal, the variability spectra of the autogeneration frequency are analyzed, which are used to judge the nature of the variability of hydrophysical parameters of the marine environment characterized in that the method of acoustic monitoring of variability of parameters of marine areas further includes measuring e the speed of sound propagation, temperature and pressure in the model zone of the reservoir at fixed horizons, free from technogenic pollution, while the obtained values of the measured velocity of sound propagation are the reference values for this reservoir and entered into the memory of the computing device acoustic monitoring, when forming in the marine the environment of the acoustic sound propagation path and processing the received acoustic signal path received by the receiving element, measuring the velocity p sound propagation is performed at a temperature and pressure corresponding to the temperature and pressure of the obtained reference values of the speed of sound propagation at fixed horizons of the water body of the studied reservoir.