A sensing device and monitoring method for underwater flow field monitoring

Abstract

The application discloses a sensing device and a monitoring method for underwater flow field monitoring, and belongs to the technical field of hydrodynamic testing. The sensing device comprises a carrier with a regular tetrahedron structure, flexible pressure sensors are arranged on the four outer surfaces of the carrier, a signal acquisition module is arranged in the carrier, the flexible pressure sensors are electrically connected with the signal acquisition module, and a flexible waterproof packaging layer is covered outside the flexible pressure sensors. The sensing device adopts a carrier with a regular tetrahedron three-dimensional structure, four flexible pressure sensors are integrated on the four outer surfaces of the carrier, the combination of the dynamic pressure measurement and the static pressure reference of the back flow can be automatically formed in any flow direction, the dynamic and static water pressures are decoupled in real time, and the reliability of the flow velocity / undulation estimation is improved; the sensing device can also utilize the pressure response differences of the four surfaces to realize the rapid discrimination of the water flow undulation direction and the three-dimensional flow trend estimation.

Description

Technical Field

[0001] This invention relates to the field of hydrodynamic testing technology, specifically to a sensing device and monitoring method for underwater flow field monitoring. Background Technology

[0002] Dynamic and static water pressures in underwater flow fields are crucial physical quantities describing the motion of water bodies. Therefore, their measurement is widely used in scenarios such as hydrodynamic testing of underwater vehicles, monitoring current loads on marine engineering structures, identifying hydrodynamic characteristics of underwater targets, and environmental compensation for underwater communication and acoustic equipment. Current underwater dynamic and static pressure measurements often employ rigid pressure sensors or a combination of pressure taps and pressure gauges, using multiple sensors placed at different locations to obtain local pressure distributions. However, existing measurement methods generally suffer from the following problems: 1. The structure is large in size and complex to install, and it is easy to disturb the local flow field, which leads to increased measurement error; 2. Dynamic and static water pressure usually require different pressure tapping structures (such as Pitot tubes and static pressure holes) or different installation positions, resulting in poor spatial correspondence, limited measurement accuracy, and difficulty in achieving paired comparison and real-time decoupling of dynamic and static pressure in the same location. 3. Limited sensitivity to the direction of incoming flow, making it difficult to achieve three-dimensional direction discrimination and rapid response to water flow fluctuations in a single compact structure; 4. It is difficult to apply on curved surfaces, confined spaces, or equipment surfaces with limited shapes. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a sensing device and monitoring method for underwater flow field monitoring. This invention can simultaneously measure upstream and downstream static pressure at the same location and can determine the direction of water flow fluctuations.

[0004] The technical solution adopted in this invention is: A sensing device for underwater flow field monitoring includes a carrier with a tetrahedral structure, and flexible pressure sensors are respectively disposed on the four outer surfaces of the carrier. A signal acquisition module is installed inside the carrier, and a flexible pressure sensor is electrically connected to the signal acquisition module. A flexible waterproof encapsulation layer is applied to the outside of the flexible pressure sensor.

[0005] The present invention also provides an underwater flow field monitoring method, which employs the sensing device for underwater flow field monitoring as described above, and includes the following steps: a. Deploy sensing devices in the underwater flow field monitoring area, with one sampling window. Inside, the pressure values ​​P1, P2, P3, and P4 on all four sides of the sensing device are collected simultaneously, and the average value and fluctuation of the sampling window are calculated. The formula for calculating the mean of the sampling window is as follows: ; , respectively representing different outer surfaces of the sensing device; The formula for calculating the sampling window fluctuation is as follows: RMS stands for root mean square. b. Sort the average values ​​of the sampling windows on all four sides of the sensing device by pressure, and let... The sorting results of the average pressure on the four sides are used to number the four outer surfaces of the sensing device as 1, 2, 3, and 4. c. Determine the underwater flow field conditions; c1, when hour, To set a threshold, the underwater flow field is determined to be in a static state. At this point, the hydrostatic pressure is calculated using the following formula: ; Dynamic water pressure: .

[0006] Furthermore, this underwater flow field monitoring method also includes the following steps: c2, when At that time, with This serves as the initial static pressure baseline. , will satisfy The surface is classified into the set of frontal surfaces. The remaining surfaces are classified into the set of non-upward-facing surfaces. ; To set a threshold; Collection on non-frontal surface Selected from The smallest surface is considered the back surface; if it is not the set of front surfaces... There exists one aspect that satisfies And the fluctuation value of this surface If the fluctuation value is greater than that of the backflow surface, then the surface is determined to be the diversion surface; Dynamic water pressure The dynamic water pressure reflects the kinetic energy pressure component caused by the flow velocity, and is calculated using the following formula: ; in, This is the equivalent total pressure at the frontal surface; when there is only one frontal surface... Average pressure at the frontal surface When there are multiple frontal surfaces, This is the average of the average pressure values ​​across all incoming surfaces. At this time, the hydrostatic pressure The static pressure is determined as follows: when a diversion surface exists, the static pressure is the weighted average of the average pressure on the back flow surface and the average pressure on the diversion surface; otherwise, the static pressure is the average of the average pressures on all non-upflow surfaces.

[0007] The beneficial technical effects of the present invention are as follows: (1) The sensing device of the present invention adopts a carrier with a three-dimensional tetrahedral structure and integrates four flexible pressure sensors on the four outer surfaces of the carrier. It can form a combination of forward flow pressure measurement and back flow static pressure reference under any incoming flow direction, realize real-time decoupling of dynamic and static water pressure, and improve the reliability of flow velocity estimation and flow field pressure fluctuation monitoring.

[0008] (2) The sensing device of the present invention utilizes the pressure response difference on four sides to realize the rapid identification of the direction of water flow fluctuation and the estimation of three-dimensional incoming flow trend, reducing the need for external mechanical turntables or complex multi-point layout.

[0009] (3) The present invention constructs a multi-condition segmented mapping model by pre-calibrating the mapping relationship between dynamic water pressure and flow velocity under different oncoming surface conditions through a water tank / water tunnel. This method effectively eliminates the measurement error caused by the flow around the tetrahedral blunt body and the separation of the wake. Even under a large deflection angle with an unknown incoming flow direction, it can achieve high-precision underwater instantaneous flow velocity measurement.

[0010] (4) The present invention has a compact structure and minimal disturbance to the flow field, making it easy to deploy in confined spaces or environments with limited form. The present invention uses a flexible pressure sensor and a flexible encapsulation layer, which can better fit the carrier surface, simplify the encapsulation, and provide good long-term underwater stability. By adjusting the size of the tetrahedron, the thickness of the encapsulation layer, the sensor range, and the sampling strategy, the present invention can flexibly adapt to the monitoring needs of water flow fluctuations at different depths, flow velocities, and frequency bands. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the sensing device for underwater flow field monitoring according to the present invention; wherein, (a) is a schematic diagram of the structure of the carrier in the sensing device from a first perspective, (b) is a schematic diagram of the structure of the carrier in the sensing device from a second perspective, (c) is a schematic diagram of the structure of the sensing device from a first perspective, and (d) is a schematic diagram of the structure of the sensing device from a second perspective. Figure 2 This is a schematic diagram of the sensing device of the present invention determining the upstream and downstream surfaces under the action of water flow; wherein, (a) is a schematic diagram of the determination under the first type of working condition, (b) is a schematic diagram of the determination under the second type of working condition, (c) is a schematic diagram of the determination under the third type of working condition, and (d) is a schematic diagram of the determination under the fourth type of working condition. Figure 3 This is a schematic flowchart of the underwater flow field monitoring method of the present invention.

[0012] In the diagram: 1-carrier, 2-flexible pressure sensor, 3-mounting hole. Detailed Implementation

[0013] This invention proposes a sensing device and monitoring method for underwater flow field monitoring. The sensing device utilizes flexible pressure sensors arranged on the four faces of a regular tetrahedron, automatically forming a "front-flowing face - back-flowing face" measurement pair under any incoming flow direction by leveraging the three-dimensional geometric symmetry of the tetrahedron. The flexible pressure sensor on the front-flowing face primarily senses the total pressure rise and fluctuation caused by dynamic water pressure, while the flexible pressure sensor on the back-flowing face, located in a relatively shielded area, mainly reflects the hydrostatic pressure baseline. This achieves real-time decoupling of dynamic and hydrostatic pressures and allows for further inference of the main direction of flow fluctuations. Simultaneously, based on the mapping relationship between pressure characteristics obtained from calibration in a flume or tunnel and flow velocity, instantaneous flow velocity estimation is achieved.

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0015] like Figure 1 As shown, a sensing device for underwater flow field monitoring includes a carrier 1 with a tetrahedral structure. The four outer surfaces of the carrier 1 are all equilateral triangles. The carrier 1 can be a hollow shell structure or a solid structure. Flexible pressure sensors 2 are respectively disposed on the four outer surfaces of the carrier 1. A signal acquisition module is disposed inside the carrier 1, and the flexible pressure sensors are electrically connected to the signal acquisition module. A flexible waterproof encapsulation layer covers the outside of the flexible pressure sensors 2.

[0016] The aforementioned flexible pressure sensor is a flexible piezoresistive, flexible capacitive, or flexible piezoelectric pressure sensor. Mounting holes 3 are provided on all four outer surfaces of the carrier, and the flexible pressure sensor 2 is embedded in the mounting holes 3. One flexible pressure sensor 2 is provided on each outer surface of the carrier 1. Alternatively, mounting holes may not be provided on the surface of the carrier, and the flexible pressure sensor can be directly fixed to the outer surface of the carrier 1 by waterproof adhesive or heat-press bonding. That is, the flexible pressure sensor 2 is fixed to each surface of the carrier 1 by waterproof adhesive, heat-press bonding, or an embedded structure, and connected to the signal acquisition module inside the carrier.

[0017] The carrier 1 can be made of polymer, metal, or composite materials. A sealing structure is provided at the edges of the carrier; for example, a sealing strip can be further installed at the junction of the two outer surfaces of the carrier to meet the waterproof requirements for long-term underwater operation. The flexible waterproof encapsulation layer uses a polyurethane film, silicone rubber coating, or Parylene coating. The flexible waterproof encapsulation layer allows external water pressure to be effectively transmitted to the sensor's sensitive layer while simultaneously isolating the electrodes and wires from water corrosion.

[0018] To adapt to different incoming flow attitudes and fluctuation states in underwater flow fields, this invention proposes a hydrostatic and hydrodynamic pressure measurement method based on "four-sided synchronous pressure - window statistics - operating condition discrimination - differential decoupling". This method does not rely on an external turntable or mechanical orientation structure, and can adaptively select the static pressure reference surface and the dynamic pressure sensitive surface under any incoming flow direction, providing the hydrostatic pressure. With dynamic water pressure .

[0019] Specifically, such as Figure 2 , Figure 3 As shown, the present invention provides an underwater flow field monitoring method, which employs the sensing device for underwater flow field monitoring as described above, and includes the following steps: a. Deploy sensing devices in the underwater flow field monitoring area, with one sampling window. Within a specified timeframe (selectable from 10ms to 200ms), the pressure signals P1, P2, P3, and P4 from all four sides of the sensing device are simultaneously acquired, and the average value and fluctuation of the sampling window are calculated. The formula for calculating the average value of the sampling window is as follows: ; , representing different outer surfaces of the sensing device. The window mean is the integral within the window divided by the window length.

[0020] The formula for calculating the sampling window fluctuation is as follows: RMS stands for root mean square.

[0021] b. Sort the average pressure values ​​on all four sides of the sensing device, and let... The average pressure values ​​on all four sides are sorted, and the four outer surfaces of the sensing device are numbered 1, 2, 3, and 4 according to the sorting results.

[0022] c. Determine the underwater flow field conditions to identify the upstream, downstream, and downstream surfaces of the sensor. The upstream surface refers to the pressure surface with a significantly higher average pressure value than other surfaces (more pronounced total pressure increase); the downstream surface refers to the pressure surface with a lower average pressure value and smaller fluctuations (located in a relatively shielded / wake region); the downstream surface refers to the pressure surface where the incoming flow direction is approximately orthogonal to its surface normal, and where tangential flow is dominant. Its average pressure is usually close to static pressure, but the fluctuations may be higher than those on the downstream surface.

[0023] hydrostatic pressure A baseline used to characterize the static pressure near the same location at the same time. Depending on the flow field state, hydrostatic pressure... It can be determined according to the following principles: Still or near-still water: The difference in the mean pressure across the four sides is very small, and the hydrostatic pressure is low. Take the average or median of the four mean values. When there is an incoming flow: the back flow surface is preferred as the static pressure reference; when there is a clear drainage surface, the back flow surface and the drainage surface can be weighted and averaged to reduce the negative pressure deviation of the wake.

[0024] That is, when a diversion surface exists, the hydrostatic pressure is the weighted average of the average pressure on the back flow surface and the average pressure on the diversion surface; otherwise, the hydrostatic pressure is the average of the average pressures on all non-upflow surfaces.

[0025] Dynamic water pressure With total pressure The principle for obtaining it: Dynamic water pressure The pressure component reflecting the kinetic energy caused by the flow velocity is usually .in The equivalent total pressure at the frontal surface is used. To accommodate different numbers of frontal surfaces, this invention uses a ensemble averaging method to determine the total pressure. .

[0026] When it is a single frontal surface, the total pressure Average pressure at the frontal surface When there are multiple frontal surfaces, the total pressure is... This is the average of the average pressure values ​​across all the incoming surfaces.

[0027] Specifically, the identification and calculation of typical operating conditions includes the following steps: c1, when hour, To set a threshold, the underwater flow field is determined to be in a static state. (Setting the threshold) Used to determine if the means are approximately equal (can be determined by static water calibration noise and drift, typically 3 times the noise standard deviation).

[0028] At this point, the formula for calculating hydrostatic pressure is as follows: ; At this time, the dynamic water pressure is: .

[0029] This operating condition indicates that the sensing device is completely still underwater, meaning that there is equal pressure on all four sides.

[0030] c2, when At that time, with This serves as the initial static pressure baseline. , will satisfy The surface is classified into the set of frontal surfaces. The remaining surfaces are classified into the set of non-upward-facing surfaces. ; To set a threshold. This threshold setting... Used to determine "significant uplift against the flow" (which can be determined by calibration or experience).

[0031] Collection on non-frontal surface Selecting volatility The smallest surface is taken as the back surface (static pressure reference preferred surface); if it is not the front surface... There exists one aspect that satisfies And the fluctuation value of this surface If the fluctuation value is greater than that of the backflow surface, then the surface is determined to be the diversion surface.

[0032] Based on the measurement results of the pressure values ​​on the four sides of the sensing device, the four sides of the sensing device are divided into the front side, the back side, and the guide side, and the static water pressure and dynamic water pressure are calculated.

[0033] c31. When there is one frontal surface and three non-frontal surfaces; Frontal surface collection ,in, Maximum; the other three sides are non-frontal surfaces. The pressure is close to static pressure or low pressure in the backflow.

[0034] Hydrostatic pressure: Take the average value of the three non-flow-facing surfaces. .

[0035] Total pressure: ; Dynamic water pressure: .

[0036] At this point, it can be determined that the direction of the incoming flow is approximately facing a certain surface, or in other words, perpendicular to the incoming surface.

[0037] c32. When there is one guiding surface, two upstream surfaces, and one downstream surface; When the direction of the incoming flow is approximately orthogonal to the normal of a certain surface, that surface is the guiding surface; the other two surfaces have positive normal components and form the incoming surface; the remaining surface is located on the back side and is the back surface.

[0038] at this time Includes two outer surfaces ;exist There exists a surface that satisfies and Relatively large (drainage surface), and one surface Minimum and Lower (backward flow side) .

[0039] Hydrostatic pressure: Take the weighted average of two non-current-facing surfaces. ,in .

[0040] Total pressure: .

[0041] Dynamic water pressure: .

[0042] At this point, it can be determined that the incoming flow direction is parallel to the guiding surface. If there is a significant pressure difference between the two incoming surfaces, the flow direction is closer to the normal direction of the incoming surface with greater pressure, which can be used for a rough estimation of the main incoming direction.

[0043] c33. When there are two frontal surfaces and two backal surfaces; When the direction of the incoming flow is close to the direction of a certain edge of a regular tetrahedron, the two faces adjacent to that edge form the frontal face; the two faces opposite to it are the backal face.

[0044] At this time, the frontal surface converges. Contains two faces Furthermore, the other two surfaces exhibit low mean / low fluctuations (no obvious flow-inducing surface), and are non-flow-facing surface aggregates. Includes two backflow surfaces .

[0045] Hydrostatic pressure: To suppress the potential negative pressure deviation of the wake on a single backflow surface, the average value of the two backflow surfaces is taken. .

[0046] Total pressure: .

[0047] Dynamic water pressure: .

[0048] At this point, it can be determined that the direction of the incoming flow is perpendicular to the edge between the two opposing surfaces. Or, roughly speaking, the incoming flow is approximately pointing towards a certain edge.

[0049] c34. When there are three frontal surfaces and one backal surface; When the incoming flow direction is close to a certain vertex direction, the three sides adjacent to that vertex simultaneously face the flow, while the remaining side is located on the back side.

[0050] At this time, the frontal surface converges. Contains three faces Non-upward surface collection It contains only one backflow surface Furthermore, the mean value and fluctuation of the backflow side are the lowest.

[0051] hydrostatic pressure: ; Total pressure: ; Dynamic water pressure: .

[0052] At this point, the incoming flow direction is determined to point to the vertices of the three opposing surfaces, and the direction of the incoming flow is parallel to the center line of the sensing device passing through that vertex. Or, roughly speaking, the incoming flow approximately points to a certain vertex.

[0053] Furthermore, the relative sizes of the three incoming surfaces can be used to estimate which surface the incoming flow is closer to in the normal direction, thus obtaining the three-dimensional main incoming trend. For example, the incoming flow is closer to the normal direction of the surface with the larger mean value.

[0054] The steps c31-c34 above correspond to typical operating conditions such as one side facing the flow, one side diverting the flow + two sides facing the flow, two sides facing the flow + two sides facing the flow, and three sides facing the flow + one side facing the flow.

[0055] Furthermore, the underwater flow field monitoring method of the present invention also includes a step of estimating the instantaneous velocity of the underwater flow field. Since a regular tetrahedron is a typical non-streamlined bluff body, its local pressure distribution is affected not only by ideal hydrodynamic pressure but also by the combined interference of structural flow resistance, boundary layer separation, and wake effects. Directly applying Bernoulli's equation will lead to significant errors. Therefore, the present invention uses a multi-condition piecewise mapping model based on flume / tunnel calibration for velocity estimation, with the specific steps as follows: e1. Independent mapping under multiple operating conditions: Conduct experiments in a water tank or water tunnel to calibrate the mapping relationship; During the calibration phase, measured decoupled hydrostatic pressures were obtained under various operating conditions (one side facing the flow, one side with diversion + two sides facing the flow, two sides facing the flow + two sides with back flow, and three sides facing the flow + one side with back flow). With flow rate Each working condition's corresponding mapping function is fitted and established. , where j represents the specific working condition type identified. The mapping function can be a polynomial fitting curve or a multidimensional interpolation lookup table, such as containing variables of different dimensions such as dynamic water pressure, temperature, and depth.

[0056] e2. Calculate instantaneous flow velocity: Within the actual underwater dynamic measurement window, firstly, determine the current flow field's incoming flow state to the appropriate condition category based on the multi-condition discrimination method. Then, call the mapping function corresponding to the appropriate condition category and substitute the dynamic water pressure obtained from real-time decoupling calculation. This results in the output of a high-precision instantaneous flow velocity estimate. .

[0057] The invention will be further explained below with reference to specific application examples.

[0058] (1) Array carrier preparation: a tetrahedral shell with a side length of 50 mm and a shell thickness of 4 mm is prepared by 3D printing of pressure-resistant polycarbonate (PC) or photosensitive resin; wiring grooves and circuit mounting positions are reserved on the inner side of each face; the splicing edges of the shell are sealed with epoxy potting compound to form a watertight structure.

[0059] (2) Selection and mounting of flexible pressure sensor: A flexible resistive pressure sensor is selected. The substrate is polydimethylsiloxane (PDMS), which contains two layers of microstructure. A conductive layer is formed by magnetron sputtering silver plating. The effective sensitive area is rectangular (about 10 mm long and about 6 mm wide), with a range of 0-300 kPa. One sensor is mounted on the outer side of each of the four faces of a regular tetrahedron. Two-component silicone is used as the adhesive layer, and four leads are introduced into the housing to connect with the signal conditioning circuit.

[0060] (3) Waterproof encapsulation: Cover the sensor surface with a 0.1mm thick polyurethane waterproof film and seal the sensor connection port with vulcanized glue to ensure that there is no leakage after long-term immersion in water.

[0061] (4) Acquisition and processing circuit: A four-channel signal conditioning module (including voltage divider / bridge circuit, amplification and low-pass filter) is installed inside the housing, and the pressure signals on the four sides are acquired synchronously through multiple ADCs at a sampling rate of 500Hz; the control unit performs noise reduction, zero drift compensation and temperature compensation on the signal.

[0062] (5) Decoupling of dynamic and static water pressure under multiple operating conditions and determination of flow direction: Calculate the average value of the pressure on all four sides within each sampling window. With volatility Based on the aforementioned operating condition discrimination rules, the system automatically identifies the upstream / backstream / diversion surface and calculates the corresponding operating conditions. and For example, in the case where the incoming flow is approximately parallel to a certain surface (i.e., one side is the inlet flow, two sides are the outlet flow, and one side is the outlet flow), the control unit can use the surface with the smallest fluctuation and the lowest mean as the outlet flow surface, and the surface with a mean value close to the static pressure but a larger fluctuation as the inlet flow surface, and obtain the result by weighting the two. The average value of the two frontal surfaces is obtained by averaging. And thus obtain .

[0063] (6) Velocity estimation: The instantaneous velocity was solved with high accuracy using a flume / tunnel calibration mapping model. During the tunnel calibration stage, the set velocity was increased in steps from 0.1 m / s to 3 m / s. The angle of the tetrahedron facing the flow was changed by a rotating mechanism to obtain the corresponding values ​​for "one-sided facing", "two-sided facing", and "three-sided facing". The pattern is used to generate third-order polynomial velocity mapping curves specific to three states through least squares fitting. This information is then stored in the control unit register. During underwater monitoring operations, the control unit identifies the current incoming flow as being in a "one-sided oncoming flow" state through the current window, and at this time, it calls the coefficient matrix specific to the "one-sided oncoming flow" state. Substitute into decoupling to obtain dynamic water pressure This allows for the direct calculation of real-time flow velocity dimensions. Through this classification and mapping mechanism, the shape drag error caused by non-streamlined carriers can be reduced by more than 80%, significantly improving flow velocity measurement performance across all attitudes.

[0064] For any parts not mentioned above, existing technologies can be adopted or referenced.

[0065] Of course, the above description is only a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. It should be noted that any equivalent substitutions or obvious modifications made by those skilled in the art under the guidance of this specification fall within the scope of this specification and should be protected by the present invention.

Claims

1. A sensing device for underwater flow field monitoring, characterized in that: It includes a carrier with a tetrahedral structure, and flexible pressure sensors are set on the four outer surfaces of the carrier. A signal acquisition module is installed inside the carrier, and a flexible pressure sensor is electrically connected to the signal acquisition module. A flexible waterproof encapsulation layer is applied to the outside of the flexible pressure sensor.

2. The sensing device for underwater flow field monitoring according to claim 1, characterized in that: The flexible pressure sensor is fixed to the outer surface of the carrier by means of waterproof adhesive or hot pressing; or a mounting hole is provided on the outer surface of the carrier, and the flexible pressure sensor is embedded in the mounting hole; a flexible pressure sensor is provided on each outer surface of the carrier.

3. The sensing device for underwater flow field monitoring according to claim 1, characterized in that: The flexible pressure sensor is a flexible piezoresistive, flexible capacitive, or flexible piezoelectric pressure sensor; the flexible waterproof encapsulation layer is made of polyurethane film, silicone rubber coating, or Parylene coating.

4. A method for monitoring underwater flow fields, employing the sensing device for underwater flow field monitoring as described in any one of claims 1-3, characterized in that, Includes the following steps: a. Deploy sensing devices in the underwater flow field monitoring area, with one sampling window. Inside, the pressure values ​​P1, P2, P3, and P4 on all four sides of the sensing device are collected simultaneously, and the average value and fluctuation of the sampling window are calculated. The formula for calculating the mean of the sampling window is as follows: ; , respectively representing different outer surfaces of the sensing device; The formula for calculating the sampling window fluctuation is as follows: RMS stands for root mean square. b. Sort the average values ​​of the sampling windows on all four sides of the sensing device by pressure, and let... The sorting results of the average pressure on the four sides are used to number the four outer surfaces of the sensing device as 1, 2, 3, and 4. c. Determine the underwater flow field conditions; c1, when hour, To set a threshold, the underwater flow field is determined to be in a static state. At this point, the hydrostatic pressure is calculated using the following formula: ; Dynamic water pressure: .

5. The underwater flow field monitoring method according to claim 4, characterized in that, It also includes the following steps: c2, when At that time, with This serves as the initial static pressure baseline. , will satisfy The surface is classified into the set of frontal surfaces. The remaining surfaces are classified into the set of non-upward-facing surfaces. ; To set a threshold; Collection on non-frontal surface Selected from The smallest surface is considered the back surface; if it is not the set of front surfaces... There exists one aspect that satisfies And the fluctuation value of this surface If the fluctuation value is greater than that of the backflow surface, then the surface is determined to be the diversion surface; Dynamic water pressure The dynamic water pressure reflects the kinetic energy pressure component caused by the flow velocity, and is calculated using the following formula: ； in, This is the equivalent total pressure at the frontal surface; When it is a single frontal surface Average pressure at the frontal surface When there are multiple frontal surfaces, This is the average of the average pressure values ​​across all the frontal surfaces. At this time, the hydrostatic pressure The static pressure is determined as follows: when a diversion surface exists, the static pressure is the weighted average of the average pressure on the back flow surface and the average pressure on the diversion surface; otherwise, the static pressure is the average of the average pressures on all non-upflow surfaces.

6. The underwater flow field monitoring method according to claim 5, characterized in that, It also includes the following steps: Based on the measurement results of the pressure values ​​on the four sides of the sensing device, the four sides of the sensing device are divided into the front side, the back side, and the guide side, and the static water pressure and dynamic water pressure are calculated. c31. When there is one frontal surface, the other three outer surfaces are non-frontal surfaces; Frontal surface collection ,in, Maximum; the other three sides are non-frontal surfaces. ; Hydrostatic pressure: Take the average value of the three non-flow-facing surfaces. ; Total pressure: ; Dynamic water pressure: ; c32. When there is one guiding surface, two upstream surfaces, and one downstream surface; Frontal surface collection The set of non-upstream surfaces includes one downstream surface and one downstream surface. ; Hydrostatic pressure: Take the weighted average of one diversion surface and one backflow surface. ,in ; Total pressure: ; Dynamic water pressure: ; c33. When there are two frontal surfaces and two backal surfaces; Frontal surface collection The set of non-upstream surfaces includes two downstream surfaces. ; Hydrostatic pressure: Take the average value of the two backflow surfaces. ; Total pressure: ; Dynamic water pressure: ; c34. When there are three frontal surfaces and one backal surface; Frontal surface collection The set of non-upstream surfaces includes one downstream surface. ; hydrostatic pressure: ; Total pressure: ; Dynamic water pressure: .

7. The underwater flow field monitoring method according to claim 6, characterized in that, It also includes the following steps: Based on the measurement results of the pressure values ​​on all four sides of the sensing device, the direction of the incoming flow is determined. d41. When there is one oncoming surface and three non-oncoming surfaces, the direction of the incoming flow is determined to be perpendicular to the oncoming surface. d42. When there is one diversion surface, two incoming surfaces and one back surface, the direction of the incoming flow is determined to be parallel to the diversion surface. d43. When there are two incoming flow surfaces and two outgoing flow surfaces, the direction of the incoming flow is determined to be perpendicular to the edge between the two incoming flow surfaces. d44. When there are three incoming flow surfaces and one outgoing flow surface, the direction of the incoming flow is determined to be the vertex of the three incoming flow surfaces, and the direction of the incoming flow is parallel to the center line of the sensing device passing through that vertex.

8. The underwater flow field monitoring method according to claim 7, characterized in that, It also includes the following steps: Estimating the instantaneous flow velocity of the underwater flow field; e1. Conduct experiments in a water tank or water hole to calibrate the mapping relationship; Obtain dynamic water pressure under various operating conditions With flow rate Mapping functions corresponding to various working conditions were fitted and established respectively. , where j represents the specific working condition type; e2. Calculate instantaneous flow velocity: In actual underwater dynamic measurement, first determine the current flow field state and the corresponding operating condition type. Then, use the mapping function corresponding to the operating condition type and substitute it into the dynamic water pressure obtained from real-time calculation. This outputs an estimated instantaneous flow velocity. .

9. The underwater flow field monitoring method according to claim 8, characterized in that, In step e1: the various operating conditions include the condition with one frontal surface and three non-frontal surfaces; the condition with one guide surface, two frontal surfaces and one back surface; the condition with two frontal surfaces and two back surface; and the condition with three frontal surfaces and one back surface; the mapping function is a polynomial fitting curve or a multidimensional interpolation lookup table.

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