A method and system for simulating vortex wake sea surface flow field through underwater vehicle vortex wake simulation model

Abstract

The invention discloses a vortex wake simulation model for an underwater vehicle, which belongs to the field of underwater reconnaissance and surveillance, and comprises: based on an underwater vehicle lift model, according to a calculation formula of lift and vortex strength in fluid mechanics vortex theory, and using the remote sensing data of the underwater vehicle measured at sea, the time evolution relationship of the sea surface vortex strength is calculated, and then the vortex strength attenuation coefficient is derived to obtain the vortex strength and vortex core radius of the vortex wake of the underwater vehicle; based on a Rankine vortex field model, according to the vortex strength and vortex core radius, the sea surface flow field of the vortex wake of the underwater vehicle is simulated; the invention provides a theoretical basis for remote sensing detection simulation of underwater vehicle vortex wakes, detectability analysis of vortex wakes, remote sensing load index demonstration, etc.

Description

Technical Field

[0001] The invention relates to the field of underwater reconnaissance and surveillance, and in particular to a vortex wake simulation model of an underwater vehicle. Background Art

[0002] Underwater vehicles moving underwater will cause disturbances in the surrounding ocean environment, which is called underwater vehicle wakes. Underwater vehicle wakes mainly include: wave-making wakes (or body effect internal waves), internal wave wakes (or wake collapse internal waves), turbulence wakes and vortex wakes, which can be collectively referred to as underwater vehicle internal wave wakes. The interaction between underwater vehicle wakes and sea surface waves will change the roughness of the sea surface, which can be detected by remote sensing payloads. Among them, vortex wakes are when underwater vehicles are sailing underwater. Due to the change in lift on the underwater vehicle, vortices will be generated in the water body. The vortex grows and evolves and rises to the sea surface to form a vortex wake. The vortex wake appears in a ring shape.

[0003] The underwater vehicle vortex wake model takes the underwater vehicle geometric dimensions, underwater motion parameters, seawater parameters, etc. as input conditions, and outputs a vortex wake flow field model. The model can provide basic data for remote sensing detection simulation and provide theoretical support for remote sensing load indicator demonstration and target detection processing.

[0004] At present, there is a lack of research on underwater vehicle vortex wakes, and a hydrodynamic model of underwater vehicle vortex wakes has not yet been established, which restricts the development of vortex wake detection simulation, remote sensing load index demonstration, vortex wake data processing and other technologies. Therefore, a simulation model of underwater vehicle vortex wakes is urgently needed to solve the problems existing in the existing technology. Summary of the invention

[0005] In order to make up for the deficiencies in the theory of remote sensing detection of underwater vehicle vortex wakes, the purpose of the present invention is to provide a simulation model of underwater vehicle vortex wakes. Based on many years of marine measurement data and combined with fluid mechanics theoretical analysis, a calculation model of the vortex intensity and vortex core radius of the vortex wake is established, and the Rankine vortex field model is used to simulate and calculate the sea surface flow field of the underwater vehicle vortex wake, thereby making up for the deficiencies in the remote sensing detection of underwater vehicle vortex wakes.

[0006] In order to achieve the above technical objectives, the present application provides a vortex wake simulation model for underwater vehicles.

[0007] The underwater vehicle vortex wake simulation model is used to simulate the sea surface flow field of the vortex wake of the underwater vehicle, wherein the underwater vehicle vortex wake simulation model is composed of an underwater vehicle lift model and a Rankine vortex field model;

[0008] The method for simulating by using an underwater vehicle vortex wake simulation model comprises the following steps:

[0009] Based on the underwater vehicle lift model, according to the calculation formula of lift and vortex strength in fluid mechanics vortex theory, and using the remote sensing data of underwater vehicles at sea, the time evolution relationship of sea surface vortex strength is calculated, and then the vortex strength attenuation coefficient is derived to obtain the vortex strength and vortex core radius of the vortex wake of the underwater vehicle;

[0010] Based on the Rankine eddy field model, the sea surface flow field of the vortex wake of the underwater vehicle is simulated according to the vortex intensity and vortex core radius.

[0011] Preferably, in the process of obtaining the vortex strength, the underwater vehicle lift model is used to obtain the lift experienced by the underwater vehicle based on the geometric parameters, speed, elevator rudder angle, and hull pitch angle of the underwater vehicle.

[0012] Preferably, in the process of obtaining the vortex strength, the initial vortex strength is obtained according to a calculation formula, and the vortex strength is obtained according to the vortex strength attenuation coefficient, wherein the initial vortex strength is expressed as:

[0013]

[0014] Among them, Γ o represents the initial vortex strength, F represents the lift, ρ represents the water density, and u represents the speed of the underwater vehicle.

[0015] Preferably, in the process of deriving the vortex intensity attenuation coefficient, the vortex intensity attenuation coefficient is expressed as:

[0016]

[0017] Where c is the vortex intensity attenuation coefficient, t is time, T 0 is the floating frequency period, a and b are empirical coefficients.

[0018] Preferably, in the process of obtaining the vortex strength, based on the vortex strength attenuation coefficient, by obtaining the time for the center of the vortex wake to rise to the sea surface, the attenuation coefficient of the center of the vortex wake to rise to the sea surface is obtained, and the vortex strength is obtained according to the initial vortex strength.

[0019] Preferably, in the process of obtaining the attenuation coefficient of the vortex wake center rising to the sea surface, the attenuation coefficient of the vortex wake center rising to the sea surface is expressed as:

[0020]

[0021] Where, d is the navigation depth, v is t is the vertical velocity of the vortex;

[0022] The vortex strength is expressed as:

[0023] Preferably, in the process of obtaining the vortex core radius, the vortex core radius is estimated based on the remote sensing data measured at sea, and according to the estimation result, the relationship between the vortex core radius and the hull size and motion parameters of the underwater vehicle is obtained, and a vortex core radius calculation model of the vortex wake is constructed, and the model coefficients are regressed to obtain the vortex core radius through the geometric parameters, speed and depth of the underwater vehicle.

[0024] Preferably, in the process of estimating the vortex core radius, the vortex center and the position of the vortex core radius of the vortex wake image are obtained based on the remote sensing data measured at sea, and the vortex core radius is estimated using the spatial resolution of the remote sensing image.

[0025] Preferably, in the process of simulating the sea surface flow field, the sea surface flow field is expressed as:

[0026]

[0027] Where r represents the distance to the origin, and Vθ represents the tangential velocity.

[0028] Preferably, a simulation system for implementing a simulation method of an underwater vehicle vortex wake simulation model comprises:

[0029] The data acquisition module is used to collect the measured remote sensing data, geometric parameters, speed, elevator rudder angle, hull trim angle, and navigation depth of the underwater vehicle at sea;

[0030] The data processing module is used to calculate the time evolution relationship of the vortex strength of the sea surface based on the data collected by the data acquisition module, based on the underwater vehicle lift model, according to the calculation formula of lift and vortex strength in the fluid mechanics vortex theory, and using the remote sensing data measured at sea, and then derive the vortex strength attenuation coefficient to obtain the vortex strength and vortex core radius of the vortex wake of the underwater vehicle;

[0031] The simulation module is used to simulate the sea surface flow field of the vortex wake of the underwater vehicle based on the Rankine vortex field model according to the vortex intensity and vortex core radius.

[0032] The present invention discloses the following technical effects:

[0033] The present invention uses measured data and combines fluid mechanics theory to cheaply obtain the sea surface flow field of underwater vehicle vortex wake under different underwater vehicle geometric parameters and navigation state parameters (speed, navigation depth, etc.), avoiding the complex derivation of pure fluid theory and the heavy calculation of fluid mechanics simulation. The present invention provides a theoretical basis for underwater vehicle vortex wake remote sensing detection simulation, vortex wake detectability analysis, remote sensing load index demonstration, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 This is a flow chart of an underwater vehicle vortex wake model integrating marine measured remote sensing data according to an embodiment of the present invention;

[0036] Figure 2 The seawater density profile simulation input conditions of an embodiment of the present invention;

[0037] Figure 3 This is a distribution diagram of absolute value of flow velocity in the sea surface flow field of the vortex wake of an underwater vehicle according to an embodiment of the present invention;

[0038] Figure 4 This is a flow velocity direction distribution diagram of the sea surface flow field of the vortex wake of an underwater vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0040] like Figure 1-4 As shown in the figure, when an underwater vehicle is sailing underwater, the change in lift on the underwater vehicle will generate vortices in the water body, and the vortices will grow and evolve and rise to the sea surface to form vortex wakes. The interaction between the vortex wake flow field on the sea surface and the sea surface waves will change the change in sea surface roughness, so it can be detected by remote sensing payloads.

[0041] Based on the above analysis, if Figure 1 As shown, the present invention provides a method for simulating an underwater vehicle vortex wake by using an underwater vehicle vortex wake simulation model, comprising the following steps:

[0042] S1. Based on the underwater vehicle lift model, fluid mechanics vortex theory and offshore remote sensing data, a calculation model for the vortex wake vortex strength of the underwater vehicle is established; specifically:

[0043] S11. Using the underwater vehicle lift model, the lift force on the underwater vehicle is calculated with the underwater vehicle geometric parameters (length L, diameter D), speed u, elevator rudder angle, and hull trim angle as input. During the design and test phases, an underwater vehicle lift model will be constructed for each boat type.

[0044] S12. Using the calculation formula of lift and vortex strength in fluid mechanics vortex theory, the calculation formula of initial vortex strength is derived as follows:

[0045]

[0046] Among them, Γ o is the initial vortex strength; F is the lift; ρ is the water density; u is the speed of the underwater vehicle.

[0047] S13. Calculate the time evolution relationship of the sea surface vortex strength using the measured data, and derive the empirical formula for calculating the vortex strength attenuation coefficient; use the initial strength and attenuation coefficient formula to establish a calculation model for the vortex wake vortex strength of an underwater vehicle. The formula for calculating the time evolution relationship of the sea surface vortex strength using the measured data is:

[0048]

[0049] Where c is the vortex intensity attenuation coefficient, t is time, T 0 is the floating frequency period, a and b are empirical coefficients, a=0.71, b=-0.21. The time for the center of the vortex wake to rise to the sea surface is:

[0050]

[0051] Where, d is the navigation depth, v is t is the vertical velocity of the vortex. Therefore, the attenuation coefficient of the vortex wake center rising to the sea surface can be expressed as:

[0052]

[0053] v t The calculation formula for the vertical velocity of the vortex is as follows:

[0054]

[0055] Where D is the diameter of the underwater vehicle.

[0056] Therefore, the calculation formula for the vortex wake strength of the sea surface vortex is as follows:

[0057]

[0058] S2, using the above underwater vehicle vortex wake eddy strength calculation model, with underwater vehicle geometric parameters (length, diameter), speed, navigation depth, elevator rudder angle, hull trim angle, ocean water density profile conditions as input, into the formula in the implementation process of S1, calculate the vortex wake eddy strength Γ s .

[0059] S3. Based on the measured remote sensing data at sea, a calculation model for the vortex core radius R of the underwater vehicle vortex wake is established; specifically:

[0060] S31, performing image processing on the measured remote sensing data at sea to obtain the vortex core radius. The image processing method is: firstly, the vortex wake image after detection is obtained by vortex detection technology, then the vortex center and the vortex core radius position (i.e., the streamline is more dense) are found in the image, and then the vortex core radius size is estimated by using the spatial resolution of the remote sensing image.

[0061] S32. Statistical analysis of vortex core radius is performed using remote sensing data measured at sea.

[0062] S33. By analyzing the relationship between the vortex core radius and the hull size and motion parameters, a calculation model for the vortex core radius of the underwater vehicle vortex wake is established, and the model coefficients are regressively calculated.

[0063] S4. Based on the above vortex core radius calculation model, the underwater vehicle geometric parameters (length, diameter), speed, and depth are used as inputs and substituted into the formula in the implementation process of S3 to calculate the vortex core radius R of the vortex wake.

[0064] S5. Using the Rankine eddy flow model, the eddy strength Γ is introduced s and the vortex core radius R, calculate the sea surface flow field of the underwater vehicle vortex wake. The calculation formula of the sea surface flow field of the Rankine vortex field model is as follows:

[0065]

[0066] In the formula, r represents the distance to the origin, V θ Expressed as tangential velocity; the above is a technical process of underwater vehicle vortex wake model integrating offshore measured remote sensing data.

[0067] Example 1

[0068] The present invention is further illustrated below by simulating the sea surface flow field of the vortex wake of an underwater vehicle using a model under typical conditions.

[0069] Simulation input condition settings:

[0070] (1) Seawater density profile: Take the historical average field of a certain location in the South China Sea in summer. The density profile and buoyancy profile are as follows: Figure 2 shown.

[0071] (2) Underwater vehicle geometry and navigation state parameters: A certain type of underwater vehicle (length 170.7m, width 12.8m), navigation depth 70m, speed 12 knots, elevator rudder angle -6°, hull trim angle 4°.

[0072] Under the above conditions, the lift force obtained by step S11 is 1.5×10 6 N, the initial strength of the vortex wake obtained by step S12 is 300m 2 / s, the attenuation coefficient calculated by S13 is 0.71, and the resulting sea surface vortex wake intensity is 213m 2 / s; the vortex core radius obtained by step S4 is 1277 meters; the vortex wake sea surface flow field obtained by step 5 is as follows Figure 3 and Figure 4 shown.

[0073] The present invention uses measured data and combines fluid mechanics theory to cheaply obtain the sea surface flow field of underwater vehicle vortex wake under different underwater vehicle geometric parameters and navigation state parameters (speed, navigation depth, etc.), avoiding the complex derivation of pure fluid theory and the heavy calculation of fluid mechanics simulation. It can provide a theoretical basis for underwater vehicle vortex wake remote sensing detection simulation, vortex wake detectability analysis, remote sensing load index demonstration, etc.

[0074] In order to realize the above technical process, the present invention also designs a simulation system for the sea surface flow field of the vortex wake of an underwater vehicle, comprising:

[0075] The data acquisition module is used to collect the measured remote sensing data, geometric parameters, speed, elevator rudder angle, hull trim angle, and navigation depth of the underwater vehicle at sea;

[0076] The data processing module is used to calculate the time evolution relationship of the vortex strength of the sea surface based on the data collected by the data acquisition module, based on the underwater vehicle lift model, according to the calculation formula of lift and vortex strength in the fluid mechanics vortex theory, and using the remote sensing data measured at sea, and then derive the vortex strength attenuation coefficient to obtain the vortex strength and vortex core radius of the vortex wake of the underwater vehicle;

[0077] The simulation module is used to simulate the sea surface flow field of the vortex wake of the underwater vehicle based on the Rankine vortex field model according to the vortex intensity and vortex core radius.

[0078] In addition, the present invention implements the above-mentioned sea surface flow field simulation method through a computer program, and forms an executable program, which is embedded in a smart device, so that the device can have the ability to simulate the sea surface flow field.

[0079] In addition, the present invention also provides a removable storage device for the simulation system, which is used to carry the simulation system of the sea surface flow field, thereby realizing the simulation system's simulation capability of the sea surface flow field, and through data interaction with other intelligent devices, the removable storage device is used as a peripheral of the intelligent device, so that the intelligent device has the system functions of the simulation system.

[0080] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0081] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0082] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for simulating a vortex wake sea surface flow field using an underwater vehicle vortex wake simulation model, characterized in that: The underwater vehicle vortex wake simulation model is used to simulate the sea surface flow field of the vortex wake of the underwater vehicle, wherein the underwater vehicle vortex wake simulation model is composed of an underwater vehicle lift model and a Rankine vortex field model; the method for simulating by using the underwater vehicle vortex wake simulation model comprises the following steps: Based on the underwater vehicle lift model, according to the calculation formula of lift and vortex strength in fluid mechanics vortex theory, and using the remote sensing data of the underwater vehicle at sea to calculate the time evolution relationship of the sea surface vortex strength, and then derive the vortex strength attenuation coefficient, the vortex strength and vortex core radius of the vortex wake of the underwater vehicle are obtained; Based on the Rankine vortex field model, simulating the sea surface flow field of the vortex wake of the underwater vehicle according to the vortex intensity and the vortex core radius; In the process of obtaining the vortex strength, the underwater vehicle lift model is used to obtain the lift received by the underwater vehicle according to the geometric parameters, speed, elevator rudder angle, and hull pitch angle of the underwater vehicle; In the process of obtaining the vortex strength, the initial vortex strength is obtained according to the calculation formula, and the vortex strength is obtained according to the vortex strength attenuation coefficient, wherein the initial vortex strength is expressed as: Among them, Γ o represents the initial vortex strength, F represents the lift, ρ represents the water density, and u represents the speed of the underwater vehicle; In the process of deriving the vortex intensity attenuation coefficient, the vortex intensity attenuation coefficient is expressed as: Where c is the vortex intensity attenuation coefficient, t is time, T0 is the floating frequency period, and a and b are empirical coefficients; In the process of obtaining the vortex strength, based on the vortex strength attenuation coefficient, by obtaining the time for the center of the vortex wake to rise to the sea surface, obtaining the attenuation coefficient of the center of the vortex wake rising to the sea surface, and obtaining the vortex strength according to the initial vortex strength; In the process of obtaining the attenuation coefficient of the vortex wake center rising to the sea surface, the attenuation coefficient of the vortex wake center rising to the sea surface is expressed as: Where, d is the navigation depth, v is t is the vertical velocity of the vortex; The eddy strength is expressed as: In the process of obtaining the vortex core radius, the vortex core radius is estimated based on the remote sensing data measured at sea, and the relationship between the vortex core radius and the hull size and motion parameters of the underwater vehicle is obtained according to the estimation result, a vortex core radius calculation model of the vortex wake is constructed, and the model coefficients are regressed to obtain the vortex core radius through the geometric parameters, speed, and depth of the underwater vehicle; In the process of estimating the vortex core radius, based on the offshore measured remote sensing data, the vortex center and the position of the vortex core radius of the vortex wake image are obtained, and the vortex core radius is estimated using the spatial resolution of the remote sensing image; In the process of simulating the sea surface flow field, the sea surface flow field is expressed as: Where r is the distance to the origin, v θ It is expressed as the tangential velocity, and R is the vortex core radius.

2. A system for simulating the sea surface flow field of a vortex wake using an underwater vehicle vortex wake simulation model, characterized in that: include: The data acquisition module is used to collect the measured remote sensing data, geometric parameters, speed, elevator rudder angle, hull trim angle, and navigation depth of the underwater vehicle at sea; A data processing module is used to calculate the time evolution relationship of the sea surface vortex intensity based on the data collected by the data collection module, based on the underwater vehicle lift model, according to the calculation formula of lift and vortex strength in fluid mechanics vortex theory, and using the offshore measured remote sensing data, and then derive the vortex intensity attenuation coefficient to obtain the vortex intensity and vortex core radius of the vortex wake of the underwater vehicle; A simulation module, for simulating the sea surface flow field of the vortex wake of the underwater vehicle based on the Rankine vortex field model according to the vortex intensity and the vortex core radius; In the process of obtaining the vortex strength, the underwater vehicle lift model is used to obtain the lift received by the underwater vehicle according to the geometric parameters, speed, elevator rudder angle, and hull trim angle of the underwater vehicle; In the process of obtaining the vortex strength, the system obtains the initial vortex strength according to the calculation formula, and obtains the vortex strength according to the vortex strength attenuation coefficient, wherein the initial vortex strength is expressed as: Among them, Γ o represents the initial vortex strength, F represents the lift, ρ represents the water density, and u represents the speed of the underwater vehicle; In the process of deriving the vortex intensity attenuation coefficient, the vortex intensity attenuation coefficient is expressed as: Where c is the vortex intensity attenuation coefficient, t is time, T0 is the floating frequency period, and a and b are empirical coefficients; In the process of obtaining the vortex strength, the system obtains the time for the center of the vortex wake to rise to the sea surface based on the vortex strength attenuation coefficient, obtains the attenuation coefficient of the center of the vortex wake rising to the sea surface, and obtains the vortex strength according to the initial vortex strength; In the process of obtaining the attenuation coefficient of the vortex wake center rising to the sea surface, the attenuation coefficient of the vortex wake center rising to the sea surface is expressed as: Where, d is the navigation depth, v is t is the vertical velocity of the vortex; The eddy strength is expressed as: In the process of obtaining the vortex core radius, the system estimates the vortex core radius based on the remote sensing data measured at sea, obtains the relationship between the vortex core radius and the hull size and motion parameters of the underwater vehicle according to the estimation result, constructs a vortex core radius calculation model of the vortex wake, and regresses the calculation model coefficients to obtain the vortex core radius through the geometric parameters, speed, and depth of the underwater vehicle; In the process of estimating the vortex core radius, based on the offshore measured remote sensing data, the vortex center and the position of the vortex core radius of the vortex wake image are obtained, and the vortex core radius is estimated using the spatial resolution of the remote sensing image; When the system simulates the sea surface flow field, the sea surface flow field is expressed as: Where r is the distance to the origin, v θ It is expressed as the tangential velocity, and R is the vortex core radius.

Images