CN115508579A

CN115508579A - Seawater profile flow velocity and flow direction observation method

Info

Publication number: CN115508579A
Application number: CN202211111246.7A
Authority: CN
Inventors: 刘世萱; 陈世哲; 吴玉尚; 万晓正; 徐宇柘; 闫星魁; 张继明; 宋苗苗; 张曙伟; 付晓; 杨祥龙; 郑珊珊; 苗斌
Original assignee: Institute of Oceanographic Instrumentation Shandong Academy of Sciences
Current assignee: Institute of Oceanographic Instrumentation Shandong Academy of Sciences
Priority date: 2022-09-13
Filing date: 2022-09-13
Publication date: 2022-12-23

Abstract

The invention discloses a method for observing the flow velocity and the flow direction of a seawater profile, which comprises the following steps: an ADCP and an azimuth sensor are arranged on the buoy body; adjusting the Y-axis direction of the ADCP self coordinate system to be consistent with the north direction of the azimuth sensor; while controlling the ADCP to emit sound waves, collecting the azimuth data detected by the azimuth sensor, receiving the flow speed data collected and output by the ADCP, and calculating the north component of the flow speed in the earth coordinate system

And an east component

(ii) a Continuous collection of multiple streamsSpeed data and azimuth data, and calculating average value of north direction component

And average value of east component

(ii) a By using

And

and calculating the flow speed and the flow direction of the seawater profile. The invention adopts an external azimuth sensor to replace an internal magnetic compass of a current meter to detect the azimuth of the buoy body, and accurate azimuth data detected by the azimuth sensor and flow speed data detected by the ADCP are subjected to vector synthesis, so that accurate ocean current observation data under a terrestrial coordinate system can be obtained.

Description

Seawater profile flow velocity and flow direction observation method

Technical Field

The invention belongs to the technical field of marine environment observation, and particularly relates to an observation method for detecting the flow velocity and the flow direction of a seawater profile.

Background

In marine investigation, ocean current observation is an important factor in marine hydrological observation, which not only can provide important basic parameters for marine scientific research, but also can provide important marine hydrological data required by fields such as marine engineering construction, marine oil development, marine aquaculture, marine safety defense and the like. Therefore, how to improve the reliability of ocean current observation data is an important issue to be paid attention to by many oceanologists and engineering technicians.

An acoustic doppler profile current meter (ADCP) is a current commonly used observation instrument for sea current profile, which can observe the flow velocity and direction of sea water profile based on the doppler shift principle. The ocean current profile observation method based on the buoy and the ADCP ocean current meter is a technical scheme of ocean current fixed-point, long-term, continuous, on-site and real-time observation commonly used at present, and can provide all-weather perennial real-time observation data relative to shipborne survey; compared with satellite remote sensing observation, the accuracy of observation data is higher; compared with the submerged buoy and seabed-based observation, the electricity required by the buoy can be supplied by natural energy such as solar energy in real time, and the offshore on-site observation time is long. Therefore, the ocean current profile observation method based on the buoy and the ADCP ocean current meter has unique advantages.

In the ocean current profile observation technology based on the buoy and the ADCP ocean current meter, the flow velocity and the flow direction of the ocean current profile are usually measured directly by the ADCP ocean current meter. However, the current ADCP current meter uses a built-in magnetic compass to detect the azimuth of the current meter, and corrects the current observation data according to the azimuth of the current meter. And current buoy body is mostly steel structure or adopts the steel skeleton, and these steel materials can produce magnetic interference to the built-in magnetic compass of current meter, lead to current meter azimuth to detect inaccurately, and then influence the degree of accuracy of current observation result.

At present, one of the methods for solving the above problems is to make the ADCP current meter as far away from the buoy body as possible, so as to reduce the influence of the ferromagnetism of the buoy body on the magnetic compass inside the current meter as much as possible. Earlier researches show that the ferromagnetic influence can be basically ignored when the distance between the buoy body and the buoy body is more than one meter. Thus, in many current buoys, a nonmagnetic bracket 2 is mounted to the bottom of a steel instrument well 4 in the buoy body 1, as shown in fig. 2. The non-magnetic support 2 is located outside the instrument well 4 and extends vertically downwards. Install current meter 3 in the bottom of no magnetism support 2, apart from instrument well more than 4 meters, alright effectively reduce the interference influence that the ferromagnetism of the buoy body 1 caused the magnetic compass in current meter 3 like this. However, in the course of the operation on the sea of the buoy body 1 having such a structure, the current meter 3 is easily entangled with and damaged by foreign objects such as fishing nets and flow ropes. In addition, the magnetic compass in the current meter 3 still has a phenomenon of being magnetized by the float body 1 after being used for a long time, and therefore, there still remains a problem of affecting the quality of current observation data.

Another approach is to periodically calibrate the magnetic compass in the current meter, for example, periodically transferring the magnetic compass to a non-magnetic environment for a homodyne calibration. However, this approach is clearly difficult to implement for long term unattended buoy installations.

Disclosure of Invention

The invention provides an observation method for measuring the flow velocity and the flow direction of a sea water section by combining an external azimuth sensor and an ADCP current meter, aiming at the problem that the azimuth detection is inaccurate because a magnetic compass in the ADCP current meter is easily influenced by the magnetization of a steel material on a buoy body, so that the accuracy of sea current observation data is improved.

In order to solve the technical problems, the invention adopts the following technical scheme to realize:

a method for observing the flow velocity and the flow direction of a seawater profile comprises the following steps:

an ADCP current meter and an independent azimuth sensor are arranged on the buoy body;

adjusting the Y-axis direction of the ADCP current meter self coordinate system to be consistent with the north direction of the azimuth sensor;

while controlling the ADCP current meter to emit sound waves, collecting azimuth data theta detected by an azimuth sensor, andreceiving flow velocity data V acquired and output by ADCP current meter _x 、V _y (ii) a Indicating the north deflection angle of the Y axis of the coordinate system of the ADCP current meter relative to the earth coordinate system by utilizing theta; v _x 、V _y Respectively representing an X-axis component and a Y-axis component of flow speed data acquired by the ADCP current meter under a self coordinate system;

calculating the north component V of the flow velocity in the earth coordinate system _N And an east component V _E ：

Continuously acquiring multiple flow rate data and orientation data by using the ADCP current meter and the orientation sensor, and calculating the north component V of the flow rate under multiple groups of earth coordinate systems _N And an east component V _E Thereafter, the average of the northbound components of the flow velocity is calculated

And average value of east component

Calculating the flow velocity of the seawater profile:

calculating the flow direction of the seawater section:

in some embodiments of the present application, in order to further improve the accuracy of the ocean current observation data, after continuously collecting the flow velocity data and the azimuth data for multiple times, first screening and removing the doubt data collected during the process of drastic change of the attitude or the azimuth of the buoy body, and then calculating the north component V under the earth coordinate system _N And an east component V _E So as to avoid the influence of abnormal data on the calculation result.

In some embodiments of the present application, an ADCP current meter may be installed on the sea-entering side of the instrument well of the buoy body to ensure that the ADCP current meter can be in sufficient contact with the seawater; when installing the position sensor, can erect nonmagnetic upper platform on the deck of the buoy body, will position sensor installs on the upper platform to make position sensor break away from the produced magnetic influence of steel structure in the buoy body completely, can accurately detect out the direction of ADCP current meter with guaranteeing position sensor.

In some embodiments of the present application, in order to make the Y-axis direction of the ADCP current meter's own coordinate system coincide with the north direction of the azimuth sensor, the following positioning method may be adopted:

forming an azimuth mark on the upper platform, and adjusting the north direction of the azimuth sensor to be in the same direction as the azimuth mark when the azimuth sensor is installed on the upper platform;

forming a equidirectional azimuth mark on a deck of the buoy body by adopting a projection method according to the azimuth mark formed on the upper platform, and pointing to the instrument well;

installing an instrument well flange plate on the deck, respectively arranging a positioning pin on two opposite sides of the instrument well flange plate, wherein the connecting line of the two positioning pins is in the same direction as the azimuth mark, respectively arranging a mounting hole on the other two opposite sides of the instrument well flange plate, and the connecting line of the two mounting holes is vertical to the connecting line of the two positioning pins;

installing a flange on the upper part of a derrick of an instrument well, wherein two positioning pin holes and two assembling holes are formed in the flange, the two positioning pin holes correspond to and are assembled with two positioning pins on a flange plate of the instrument well in position, and the two assembling holes correspond to and are assembled with two installing holes on the flange plate of the instrument well in position;

installing a current meter installation plate on the derrick, and enabling the installation plate to be perpendicular to a connecting line of the two positioning pin holes;

set up locating pin and current meter installation checkpost on the mounting panel, will ADCP current meter installs on current meter installation checkpost to in inserting the locating hole of ADCP current meter perpendicularly on the mounting panel, alright make the Y axle direction of ADCP current meter self coordinate system unanimous with the orientation sign direction on the deck like this, and then realize orientation sensor's northward and the Y axle direction syntropy of ADCP current meter self coordinate system.

In some embodiments of the present application, it is preferable to install the ADCP current meter inside the instrument well, and only expose the acoustic probe of the current meter out of the well head, so that the ADCP current meter can be prevented from being wound and damaged by foreign objects such as fishing nets, flow ropes and the like in the sea water, and the ADCP current meter can be protected.

Compared with the prior art, the invention has the advantages and positive effects that: the invention aims at the problem that an ADCP (acoustic Doppler current profiler) arranged on a buoy body is easily influenced by the magnetism of the buoy body, an external azimuth sensor is adopted to replace an internal magnetic compass of the ADCP, so as to detect the azimuth of the buoy body, accurate azimuth data detected by the azimuth sensor and flow speed data detected by the ADCP are subjected to vector synthesis, so that ocean current observation data under a terrestrial coordinate system can be obtained, the measurement of seawater section flow speed data and flow direction data is realized, and the problem of inaccurate azimuth detection caused by the fact that the internal magnetic compass of the ADCP is easily influenced by the buoy body is solved.

Other features and advantages of the present invention will become more apparent from the detailed description of the embodiments of the present invention when taken in conjunction with the accompanying drawings.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly described below, it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of an external structure of one embodiment of a buoy body;

FIG. 2 is a schematic diagram of the prior art ADCP current meter mounted on a buoy body;

FIG. 3 is a schematic diagram of an embodiment of an ADCP current meter built into an instrument well;

FIG. 4 is a schematic diagram of the installation position of an external azimuth sensor on a buoy body;

FIG. 5 is an enlarged view of a portion of FIG. 4;

FIG. 6 is a diagram showing the relationship between the flange of the instrument well and the orientation mark;

FIG. 7 is a diagram showing the corresponding position relationship between the flanges at the upper part of the derrick and the orientation mark;

FIG. 8 is a schematic view of an assembled structure of one embodiment of a derrick and current meter mounting plate;

FIG. 9 is a schematic diagram of an embodiment assembly between a derrick, current meter mounting plate and ADCP current meter;

FIG. 10 is a cross-sectional view of the mounting structure of the ADCP current meter on the current meter mounting plate;

FIG. 11 is a diagram of a coordinate system used in vector synthesis of extrinsic azimuth data and flow rate data;

FIG. 12 is a waveform diagram of the seawater profile flow rate data collected and output by an ADCP flowmeter installed in a conventional manner;

FIG. 13 is a waveform diagram of the seawater profile flow rate data collected and outputted by the external sensor and the ADCP flow meter;

FIG. 14 is a waveform diagram of the seawater cross-sectional flow data collected and output by an ADCP flow meter installed in a conventional manner;

fig. 15 is a waveform diagram of seawater cross-sectional flow direction data collected and output by an external sensor and an ADCP flowmeter.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

It should be noted that in the description of the present invention, the terms "upper", "lower", "inner", "outer", "top", "bottom", and the like, which indicate directions or positional relationships, are based on the directions or positional relationships shown in the drawings, which are only for convenience of description, and do not indicate or imply that the devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, it should be noted that in the description of the present invention, the terms "mounted," "connected," and "connected" are to be construed broadly unless otherwise explicitly specified or limited. For example, it may be a fixed connection, a detachable connection or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The embodiment adopts the mode that external azimuth sensor and ADCP current meter combined together to observe the velocity of flow and the flow direction of sea water section, and its technical problem that needs to solve mainly has:

(1) Spatial alignment problems. The ADCP current meter and the built-in magnetic compass are integrally installed, so that the north direction of the built-in magnetic compass can be easily aligned with the self direction of the current meter; and when adopting external position sensor mode, because buoy space dimension is bigger, height and diameter are generally about 10 meters, so, need to solve the direction of ADCP current meter's self direction and the direction of external position sensor aim at the problem in space.

(2) The problem of time synchronization. The ADCP current meter is based on the doppler shift principle, and when measuring the current, the ADCP current meter needs to synchronize the time of transmitting sound waves with the azimuth sampling time. When the built-in magnetic compass of ADCP current meter is utilized to measure the azimuth, the emission time of sound wave and the azimuth sampling time of magnetic compass can be processed by ADCP current meter in a unified way, so that the method is easy to realize. When the external direction sensor mode is adopted, the direction sampling value of the external direction sensor at the moment corresponding to the sound wave transmitted and measured by the ADCP current meter needs to be obtained in real time, and calculation is carried out, so that the problem of time synchronization needs to be solved.

(3) And (4) solving the problem of data fusion. In order to obtain accurate ocean current observation data, vector synthesis needs to be performed on accurate direction data output by an external azimuth sensor and flow speed data output by an ADCP current meter in a self coordinate system so as to obtain flow speed data and flow direction data of a sea water profile in a real space coordinate system, and therefore a vector synthesis algorithm needs to be designed.

The present embodiment proposes the following solution to the problem of spatial alignment of an external azimuth sensor with an ADCP current meter.

As shown in fig. 1, an upper deck 20 is erected on the deck 10 of the buoy body for mounting the azimuth sensor. The upper deck 20 should be made of non-magnetic material, and the height of the top surface from the buoy body deck 10 should be ensured: when the orientation sensor is mounted on the top surface of the upper stage 20, the orientation sensor can be completely free from the ferromagnetic influence of the steel structure in the buoy body. In this embodiment, the height of the upper platform 20 may be designed to be about 10 meters or more than 10 meters, so that the azimuth sensor can be far away from the deck 10 of the buoy body, thereby ensuring that the direction data detected by the azimuth sensor is accurate.

As shown in fig. 4 and 5, an orientation indicator 21 is disposed on the upper stage 20, for example, an arrow is drawn on the top surface of the upper stage 20 to indicate the north direction of the orientation sensor 22. When the position sensor 22 is mounted on the upper stage 20, the north direction of the position sensor 22 is made to coincide with or be the same as the arrow direction of the position indicator 21, thereby completing the positioning of the position sensor 22 on the upper stage 20.

The orientation marks 11 are formed in the same direction on the deck 10 of the buoy body by a projection method based on the orientation marks 21 formed on the upper deck 20. The specific method comprises the following steps: a straight rod is placed on the upper-layer platform 20, and the straight rod is collinear with the azimuth mark 21; hanging heavy hammers at two ends of the straight rod respectively and falling towards the direction of the deck 10; the two heavy hammers form two projection points on the deck 10 and connect the two projection points to form a straight line; an orientation mark 11 is formed on the deck 10, which coincides with the straight line, for example, an arrow is drawn, and the direction of the arrow is the same as the direction of the arrow of the orientation mark 21 on the upper platform 20, so that it is ensured that the orientation mark 21 on the upper platform 20 is in the same direction as the orientation mark 11 on the deck 10.

In order to facilitate accurate positioning of the installation direction of the ADCP current meter based on the azimuth mark 11 on the deck 10, it is preferable that the azimuth mark 11 is pointed to the position of the instrument well 12 when the azimuth marks 11, 21 are formed on the deck 10 and the upper stage 20, respectively, as shown in fig. 4.

The instrumentation well 12 is an instrumentation mounting well for mounting an environmental factor sensor and other sensors on the buoy, is provided on the buoy body 1, vertically penetrates the buoy body 1, and is shown in fig. 3. In the instrument well 12 is mounted a derrick 14, on which derrick 14 the ADCP current meter can be mounted.

In order to enable the Y-axis direction of the ADCP current meter's own coordinate system to be in the same direction as the azimuth mark 11 on the deck 10 when the ADCP current meter is installed in the instrument well 12, the following positioning method is designed in this embodiment:

on one hand, as shown in fig. 6, the instrument well flange 13 is installed at the position where the instrument well 12 is disposed on the deck 10, and two positioning

pins

131 and 132 are respectively installed at two opposite sides of the instrument well flange 13, and a connection line of the two

positioning pins

131 and 132 should be collinear or in the same direction as the orientation mark 11 formed on the deck 10. The other two opposite sides of the instrumentation well flange 13 are respectively provided with a mounting

hole

133, 134, and the connecting line of the two mounting

holes

133, 134 is perpendicular to the connecting line of the two

positioning pins

131, 132. The instrument well flange 13 is fixed in the welding direction on the deck 10, so that the installation direction of the derrick 14 installed in the instrument well 12 can be fixed.

On the other hand, as shown in fig. 7, a flange 15 is mounted on the upper portion of the derrick 14, positioning pin holes 151 and 152 are respectively formed on opposite sides of the flange 15, and mounting

holes

153 and 154 are respectively formed on the other opposite sides of the flange 15. When the flange 15 is mounted on the instrument well flange 13, the two positioning pin holes 151 and 152 on the flange 15 and the two

positioning pins

131 and 132 on the instrument well flange 13 are positioned and assembled with each other, so that the connection line of the two positioning pin holes 151 and 152 on the flange 15 can be ensured to be in the same direction as the orientation mark 11 formed on the deck 10. Meanwhile, the two

assembly holes

153 and 154 on the flange 15 and the two mounting

holes

133 and 134 on the instrument well flange 13 correspond to each other in position and can be assembled and fixed by using screws and nuts, so that the connection line of the two

assembly holes

153 and 154 on the flange 15 can be ensured to be perpendicular to the azimuth mark 11 formed on the deck 10.

In three aspects, a current meter mounting plate 16 is mounted on the derrick 14, and the mounting surface of the current meter mounting plate 16 is perpendicular to the line connecting the two positioning pin holes 151 and 152 on the flange 15. In some embodiments, the derrick 14 may be designed as a triangular prism frame, as shown in fig. 7, and when the flange 15 is mounted on top of the derrick 14, one of the prism faces 141 of the triangular prism frame is perpendicular to the line connecting the two

dowel holes

151, 152 on the flange 15. Thus, when current meter mounting plate 16 is mounted on prism surface 141, it is ensured that the mounting surface of current meter mounting plate 16 is perpendicular to the line connecting two positioning pin holes 151 and 152 on flange 15.

Since the current meter is required to be in contact with the sea water when in use, it is preferable to mount the current meter at the bottom of the instrument well. For such installation location requirement of current meter, the present embodiment preferably installs current meter mounting plate 16 at the bottom position of derrick 14, as shown in fig. 9, so that when ADCP current meter 17 is installed on current meter mounting plate 16, ADCP current meter 17 can be brought into sufficient contact with the sea water, and then the current observing requirement is satisfied.

In the fourth aspect, as shown in fig. 8, positioning pins 161 perpendicular to the mounting surface are mounted on the current meter mounting plate 16, and mounting holes 162 are opened. The mounting holes 162 may be formed in two pairs in the upper portion of the current meter mounting plate 16 and in one pair in the lower portion of the current meter mounting plate 16, so as to be used for assembling the current meter mounting clip 163, as shown in fig. 9 and 10.

Two pairs of mounting holes 162 are provided in the upper portion of the current meter mounting plate 16 to accommodate current meters of different lengths. A pair of mounting holes 162 selected according to the actual length of ADCP current meter 17 are fitted with a current meter mounting clip 163 at the upper portion of current meter mounting plate 16, and a current meter mounting clip 164 is fitted at mounting holes 162 at the lower portion of current meter mounting plate 16. The upper end and the lower end of the ADCP current meter 17 are respectively clamped on the current

meter mounting clamps

163 and 164, the angle of the ADCP current meter 17 is adjusted, and the positioning hole of the ADCP current meter 17 is aligned and inserted with the positioning pin 161 on the mounting plate, so that the Y-axis direction of the self coordinate system of the ADCP current meter 17 is perpendicular to the mounting surface of the current meter mounting plate 16. Because the mounting surface of the current meter mounting plate 16 is perpendicular to the connecting line of the two positioning pin holes 151 and 152 on the flange 15, and the connecting line of the two positioning pin holes 151 and 152 on the flange 15 is in the same direction as the azimuth mark 11 formed on the deck 10, the Y-axis direction of the coordinate system of the ADCP current meter 17 can be ensured to be consistent with the direction of the azimuth mark 11 formed on the deck 10 as long as the ADCP current meter 17 is assembled in place on the mounting plate 16.

Since the north direction of the azimuth sensor 22 is consistent with the direction of the azimuth mark 21 on the upper platform 20, the direction of the azimuth mark 21 on the upper platform 20 is consistent with the direction of the azimuth mark 11 on the deck 10, and the Y-axis direction of the ADCP current meter 17's own coordinate system is consistent with the direction of the azimuth mark 11 on the deck 10, the Y-axis direction of the ADCP current meter 17's own coordinate system is consistent with the north direction of the azimuth sensor 22. Therefore, the external azimuth sensor 22 can be used to replace the built-in magnetic compass of the ADCP current meter 17 to detect the azimuth of the buoy body, and then the azimuth is fused with the flow speed data detected by the ADCP current meter 17 to calculate the current observation data in the terrestrial coordinate system.

In this embodiment, as shown in fig. 3 and 10, it is preferable to install the ADCP current meter 17 inside the instrument well 12, and only the acoustic probe 171 of the ADCP current meter 17 is exposed out of the well head, so that not only can the ADCP current meter 17 be ensured to normally transmit sound waves and receive reflected waves, and the measurement requirement be satisfied, but also the problem that the ADCP current meter 17 is easily damaged by winding of external objects such as fishing nets and flow ropes due to being completely exposed in seawater can be effectively solved, and the long-term, continuous and safe operation of the ADCP current meter 17 in seawater is practically ensured, and the ADCP current meter is very suitable for being applied to long-term unattended buoy equipment.

In order to solve the problem of synchronous acquisition of the flow rate data of the ADCP current meter 17 and the azimuth data of the azimuth sensor 22, in the present embodiment, a high-speed data processor with a CPU main frequency above 72MHz, such as an STM32 series single chip microcomputer, is preferably configured in the control system of the buoy, so as to realize high-speed and high-precision acquisition of the flow rate data and the azimuth data.

For the problem of vector synthesis between the flow speed data collected and output by the ADCP current meter 17 and the azimuth data detected and output by the azimuth sensor 22, the present embodiment proposes the following vector synthesis algorithm:

step 1: the control system on the buoy is utilized to control the ADCP current meter 17 to emit sound waves, simultaneously, the high-speed data processor is used for collecting the direction data theta detected by the direction sensor 22, and the flow speed data V collected and output by the ADCP current meter 17 is received _x 、V _y The shielding ADCP current meter 17 is internally provided with a magnetic compass to collect output azimuth data, thereby obtaining a set of vector data { theta, V ] with synchronous sampling time _x ，V _y }. Wherein, V _x The X-axis component of the flow velocity data acquired by the ADCP current meter 17 in the self coordinate system is represented; v _y And represents the Y-axis component of the flow velocity data acquired by the ADCP current meter 17 in its own coordinate system.

Fig. 11 shows the positional relationship between the ADCP current meter 17 itself coordinate system and the terrestrial coordinate system. Wherein YOX denotes the own coordinate system of ADCP current meter 17; NOE represents an earth coordinate system, N represents a geographical north direction, and E represents a geographical east direction; θ is a deflection angle between the buoy body and the north of the earth detected by the azimuth sensor 22. Since the Y-axis direction of the ADCP current meter 17's own coordinate system coincides with the north direction of the azimuth sensor 22, θ also represents the deflection angle between the Y-axis of the ADCP current meter 17's own coordinate system and the north direction of the earth.

Step 2: the ADCP current meter 17 is periodically controlled to emit sound waves, and step 1 is repeatedly performed at each cycle to obtain a plurality of sets of flow velocity data and azimuth data.

And step 3: after continuously collecting the flow speed data and the azimuth data for a plurality of times, screening and removing the doubt data collected in the process of drastic change of the posture or the azimuth of the buoy body.

In this embodiment, the in-doubt data may be determined in two ways: one is to judge the adjacent data with the variation exceeding the limit as the in-doubt data and eliminate the in-doubt data, namely, the data with violent variation collected before and after is considered as the in-doubt data; and the other is to sort the collected multiple groups of azimuth data, and judge the azimuth data corresponding to the maximum value and the minimum value and the flow speed data synchronously collected with the azimuth data as the in-doubt data to be removed.

And 4, step 4: the flow velocity data V output by each acquisition of the ADCP current meter 17 _x 、V _y (flow rate data V here _x 、V _y Flow velocity data after removing the doubt data) is projected under the earth coordinate system, and the north component V of the flow velocity under the earth coordinate system is calculated _N And an east component V _E The calculation formula is as follows:

therefore, the north component V of the flow velocity under a plurality of groups of earth coordinate systems can be obtained _N And an east component V _E 。

And 5: according to the obtained north component V of the flow velocity under the multiple groups of earth coordinate systems _N And an east component V _E Respectively calculating the average value of the north components of the flow velocity

And average value of east component

Step 6: using average of the northbound component of the flow velocity

And average value of east component

Calculating the flow velocity value V of the seawater section by the following formula:

and 7: using average of the northbound component of the flow velocity

And average value of east component

Calculating the flow direction A of the seawater section, wherein the calculation formula is as follows:

wherein arccot () represents an inverse cotangent function.

The defect that this embodiment exists to present ADCP current meter mounting means, designs new current meter mounting structure, settles the current meter in the inside of buoy body steel instrument well, and only the acoustic probe of current meter exposes the well head slightly, has solved the current meter from this and has easily received the problem of external force destruction such as fishing net. Simultaneously, through shielding the built-in magnetic compass of ADCP current meter, adopt external position sensor's mode to detect the real-time position of the buoy body to through installing position sensor on keeping away from the upper platform of the internal steel material of buoy, realized the accurate detection of position data from this. In addition, accurate azimuth data acquired and output by an external azimuth sensor and flow speed data acquired and output by an ADCP current meter and relative to a self coordinate system are subjected to data fusion to obtain current data under a real space coordinate system, so that the problems that the azimuth detection is inaccurate and accurate current observation data cannot be obtained due to the fact that the ADCP current meter is easily influenced by a buoy body due to the built-in magnetic compass of the ADCP current meter are solved.

Specific examples are as follows:

an ADCP current meter is installed on the buoy in a conventional manner as in the prior art, as shown in fig. 2, and is continuously operated at sea for a period of approximately 1 year. Then, an ADCP current meter and an external azimuth sensor are arranged on the same buoy according to the improvement proposed in this embodiment.

During the same time period, the ocean current observation data output by the ADCP flowmeter installed in a conventional manner and the ocean current observation data calculated according to the observation method provided by the embodiment are respectively collected. Through 2 days of observation, the seawater profile flow velocity data and the seawater profile flow direction data obtained by the two methods are compared, and the following results can be found:

the consistency of the seawater profile flow velocity data obtained by the conventional method and the observation method provided by the embodiment is good, as shown in fig. 12 and 13. Wherein FIG. 12 shows the first five flow rates of the output collected by an ADCP flow meter installed in a conventional manner; fig. 13 shows the data of the flow velocity of the first five layers of the seawater profile obtained by the observation method proposed in this embodiment.

The sea water profile obtained by the conventional method and the observation method provided by the embodiment has the same basic trend of flow direction data, the flow direction has an obvious sinusoidal trend, and the flow diversion process is performed twice in one day, so that the characteristics of the local half-day tidal current of the sea area to be measured are met, as shown in fig. 14 and 15. Wherein figure 14 shows the first five flow directions of the acquisition output of an ADCP flow meter installed in a conventional manner; fig. 15 shows the first five-layer flow data of the seawater profile obtained by the observation method proposed in this embodiment.

However, the difference between the incoming flow and the outgoing flow of the semisolar tide observed by the observation method provided by the embodiment is substantially 180 °, as shown in fig. 15, which is more suitable for the local tidal current characteristics. The difference between the incoming flow and the outgoing flow of the semisolar tide observed by the conventional method is substantially 120 degrees, and as shown in fig. 14, a large observation error exists. Therefore, the effectiveness of the observation method provided by the embodiment is proved.

Of course, the above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many modifications and embellishments can be made without departing from the principle of the present invention, and these should also be regarded as the protection scope of the present invention.

Claims

1. A method for observing the flow velocity and the flow direction of a seawater section is characterized in that,

while controlling the ADCP current meter to emit sound waves, collecting azimuth data theta detected by an azimuth sensor, and receiving flow speed data V collected and output by the ADCP current meter _x 、V _y (ii) a Indicating the north deflection angle of the Y axis of the coordinate system of the ADCP current meter relative to the earth coordinate system by utilizing theta; v _x 、V _y Respectively representing an X-axis component and a Y-axis component of flow speed data acquired by the ADCP current meter under a self coordinate system;

Continuously acquiring multiple times of flow velocity data and orientation data by using the ADCP current meter and the orientation sensor, and calculating the north component V of the flow velocity under multiple groups of earth coordinate systems _N And an east component V _E Then, the average value of the north component of the flow velocity is calculated

And average value of east component

Calculating the flow velocity of the seawater profile:

calculating the flow direction of the seawater profile:

2. the method for observing flow velocity and flow direction of sea water profile according to claim 1, wherein after continuously collecting flow velocity data and orientation data for a plurality of times, firstly screening and removing suspicious data collected in the process of drastic change of the attitude or orientation of the buoy body, and then calculating the northbound component V under the plurality of groups of terrestrial coordinate systems _N And an east component V _E 。

3. The method for observing sea water profile, flow velocity and flow direction according to claim 1 or 2,

installing the ADCP current meter on the sea-entering side of the instrument well of the buoy body;

a nonmagnetic upper layer platform is erected on a deck of the buoy body, the azimuth sensor is installed on the upper layer platform, and the azimuth sensor is completely separated from magnetic influence generated by a steel structure in the buoy body.

4. The method for observing sea water profile flow velocity and flow direction according to claim 3, wherein the process of adjusting the Y-axis direction of the ADCP current meter coordinate system to be consistent with the north direction of the azimuth sensor comprises:

forming equidirectional azimuth marks on the deck and the upper-layer platform of the buoy body respectively;

installing the azimuth sensor on the upper-layer platform, and adjusting the north direction of the azimuth sensor to be in the same direction as the azimuth identifier;

installing an instrument well flange plate at the instrument well position of the deck, respectively arranging a positioning pin at two opposite sides of the instrument well flange plate, wherein the connecting line of the two positioning pins is in the same direction as the azimuth mark, respectively arranging a mounting hole at the other two opposite sides of the instrument well flange plate, and the connecting line of the two mounting holes is vertical to the connecting line of the two positioning pins;

installing a flange on the upper part of a derrick of an instrument well, wherein two positioning pin holes and two assembling holes are formed in the flange, the two positioning pin holes correspond to and are assembled with two positioning pins on a flange plate of the instrument well, and the two assembling holes correspond to and are assembled with two installing holes on the flange plate of the instrument well;

set up locating pin and current meter installation checkpost on the mounting panel, will ADCP current meter is installed on current meter installation checkpost, and the angle of adjustment ADCP current meter makes the perpendicular cartridge of locating pin on its locating hole and the mounting panel, and the Y axle direction of ADCP current meter self coordinate system is unanimous with the on-board position sign direction this moment, realizes orientation sensor's northward and the Y axle direction syntropy of ADCP current meter self coordinate system.

5. The method for observing sea water profile, flow velocity and flow direction according to claim 4, wherein the process of forming the equidirectional orientation marks on the deck and the upper platform of the buoy body respectively comprises the following steps:

forming an orientation mark on the upper platform;

and forming the equidirectional azimuth mark on the deck of the buoy body by adopting a projection method according to the azimuth mark formed on the upper platform, and pointing to the instrument well.

6. The method of observing sea water profile flow velocity flow direction according to claim 3, wherein the ADCP current meter is installed inside an instrument well, and only the acoustic probe is exposed out of a wellhead.