Active control method for inhibiting unsteady flow excitation of underwater vehicle

Abstract

The invention discloses an active control method for inhibiting unsteady flow excitation of an underwater vehicle, and relates to the technical field of turbulent flow control, and the method comprises the steps: determining the position of an initial separation point of a horseshoe vortex at the front edge of a combination part of a surrounding shell and a main hull; an arrow-shaped hole is formed in the position of the initial separation point, and suction flow control is applied through the arrow-shaped hole; and comparing the flow characteristics of the joint part of the enclosure and the main boat body under different arrow-shaped hole sizes and flow suction speeds, selecting the arrow-shaped hole sizes and flow suction speeds with the optimal control effect, and carrying out active flow suction control at the initial separation point position so as to inhibit the unsteady flow excitation of the underwater vehicle. According to the method, the vortex structure and pulsating pressure of the underwater navigation body can be greatly inhibited, the external streaming of the joint part of the main body and the auxiliary body is improved and optimized, and the purpose of reducing flow-induced noise is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of turbulent flow control, in particular to an active control method for suppressing unsteady flow excitation of an underwater navigation body. Background Art

[0002] The command tower of an underwater vehicle is a streamlined fairing, a streamlined structure protruding from the hull of an underwater vehicle, which protects combat systems that need to frequently contact the water surface. These combat systems enclosed by the tower include: periscopes, communication antennas, snorkel equipment, sonar arrays, bridge access hatches, navigation equipment and other devices. Since the 1940s, the underwater vehicle tower has been designed as a wing-shaped tower, and its shape and size have been basically fixed. It was first used on American underwater vehicles and has been followed by other countries to this day.

[0003] During the cruising process of the underwater vehicle, the turbulent boundary layer of the incoming flow along the hull cannot overcome the pressure rise at the leading edge of the hull, resulting in flow separation and forming the so-called "horseshoe vortex". The "horseshoe vortex" generated by the hull significantly strengthens the turbulent pulsation pressure on the hull surface locally, and correspondingly enhances the flow excitation in the area where the hull and the hull are connected, causing a large vibration response and flow-induced noise. At the same time, the horseshoe vortex interacts with the hull boundary layer, the hull wake and the propeller, generating strong flow field disturbances, making the flow situation at the tail of the underwater vehicle very complicated, becoming a typical three-dimensional unsteady vortex flow field. After the vortex intensity in the wake increases, the pulsation of the sound source increases, which will inevitably increase the radiation noise and self-noise of the hull, reducing the stealth of the underwater vehicle. In addition, in actual engineering applications, the complex flow at the junction of the hull and the hull will also bring a series of practical problems such as deformation, fracture, and base damage at the junction.

[0004] In actual engineering applications, active control is often applied to suppress the unsteady flow excitation of underwater vehicles in order to reduce vibration response and flow-induced noise. However, the flow mechanisms corresponding to different geometric forms are inconsistent, and the active control methods are also different. There are mainly two geometric forms on underwater vehicles: one is the concave cavity, such as the water hole, which produces unsteady flow excitation mainly in the form of discrete vortices; the other is the convex hull, which produces unsteady flow excitation mainly in the form of horseshoe vortices at the junction of the hull and the hull. There have been a lot of studies on the control of cavity discrete vortices, mainly through blowing and other methods to discretize the main vortex structure to reduce the vortex strength and pressure pulsation; while there are few studies on the control of the horseshoe vortex at the root of the hull. Suppressing unsteady flow excitation by weakening the horseshoe vortex at the leading edge of the hull has very important engineering practical significance for the stealth of underwater vehicles. Summary of the invention

[0005] In view of the above problems and technical requirements, the inventors have proposed an active control method for suppressing the unsteady flow excitation of underwater vehicles. This method starts from the flow source and suppresses the generation of horseshoe vortices by applying suction control, providing a new vortex control and noise reduction idea. The technical solution of the present invention is as follows:

[0006] An active control method for suppressing unsteady flow excitation of an underwater vehicle comprises the following steps:

[0007] Determine the starting separation point of the horseshoe vortex at the leading edge of the junction between the hull and the main hull;

[0008] An arrow-shaped hole is opened at the position of the initial separation point, and suction flow control is applied through the arrow-shaped hole;

[0009] The flow characteristics at the junction of the hull and the main hull under different arrow-shaped hole sizes and suction speeds are compared, and the arrow-shaped hole size and suction speed with the optimal control effect are selected. Active suction control is carried out at the initial separation point to suppress the unsteady flow excitation of the underwater vehicle.

[0010] A further technical solution is to determine the starting separation point of the horseshoe vortex at the leading edge of the junction between the hull and the main hull, including:

[0011] The large eddy simulation equation considering the inverse scattering model is used to solve the vortex flow structure around the fully attached underwater vehicle.

[0012] Obtain the local flow topology on the front wall and symmetry surface of the front edge of the junction between the hull and the main appendage of the hull;

[0013] The Q-vortex criterion is used to capture the vortex structure on the symmetry plane. The center of the vortex structure is the starting separation point of the horseshoe vortex at the leading edge of the junction between the hull and the main hull.

[0014] The further technical solution is to compare the flow characteristics of the junction between the hull and the main hull under different arrow-shaped hole sizes and suction velocities, including:

[0015] Design working conditions with different arrow-shaped hole sizes and suction flow velocities;

[0016] The large eddy simulation equation considering the inverse scattering model is used to solve the vortex flow structure at the junction of the hull and the main body under different working conditions, and the vortex flow structure is displayed by the Q-vortex criterion to check the suppression effect of the horseshoe vortex at the leading edge of the junction under different working conditions.

[0017] The Q-vortex criterion is used to capture the evolution trajectory of the main vortex of the horseshoe vortex at the junction of the hull and the main body;

[0018] Several monitoring points are set on the evolution trajectory of the main vortex of the horseshoe vortex, and the pulsating pressure solution results under different working conditions are monitored.

[0019] A further technical solution is to consider the large eddy simulation equation of the inverse scattering model:

[0020] The inverse scattering term of the sub-grid vortex model in the NS equations is expressed by a completely nonlinear term in the form of decomposed vorticity.

[0021] A further technical solution is to characterize the fully nonlinear term using the scattering form of a second-order tensor:

[0022]

[0023] in, represents the unfiltered fluid velocity, the superscript L represents the solvable scale in the large eddy simulation, and the superscript S represents the unsolvable scale in the large eddy simulation; x represents the spatial position of the grid at the junction of the hull and the main hull; the subscripts i and j are 1, 2, and 3, representing the three components of the spatial coordinate system.

[0024] A further technical solution is that the Q vortex criterion is expressed as:

[0025]

[0026] Among them, S is the strain rate tensor and Ω is the vortex tensor, which are calculated by solving the three-dimensional velocity field in the vortex flow structure.

[0027] A further technical solution is that the pulsating pressure at each monitoring point is expressed as a sound pressure level SPL spectrum:

[0028]

[0029] Among them, p(f) is the pulsating pressure time domain signal p(t) in the vortex flow structure obtained by solving, the sound pressure of different frequency components is obtained by Fourier transform, and p0 is the reference sound pressure.

[0030] Its further technical solution is that the arrow-shaped hole size and suction flow speed with the best control effect are:

[0031] The opening shape adopts an arrow-shaped hole in the form of a swept wing, with a sweep angle of 37 degrees, and the arrow is facing the front of the main hull;

[0032] The optimum suction flow speed is between 1 and 2 times the navigation speed of the underwater vehicle, and the suction flow direction is perpendicular to the opening surface.

[0033] The beneficial technical effects of the present invention are:

[0034] (1) The present invention discloses a specific implementation method for suppressing the active control of unsteady flow excitation of an underwater vehicle. The method can formulate an adaptive optimal arrow-shaped hole opening suction active control strategy for different hull shapes, different hull and main hull joint structures, and different underwater vehicle navigation conditions, effectively suppressing the vortex structure and pulsating pressure of the underwater vehicle, with good use effect and wide application range.

[0035] (2) The present invention adopts the large eddy simulation equation considering the inverse scattering model to solve the position of the starting separation point of the leading edge boundary layer at the junction of the hull and the main body and the main vortex trajectory, which can better characterize the inverse scattering process of energy transfer from the sub-grid scale to the solvable scale when the horseshoe vortex at the root of the hull evolves, thereby more accurately determining the opening position of the arrow-shaped hole and improving the active control effect.

[0036] (3) The present invention applies arrow-shaped hole suction flow control at the horseshoe vortex head at the leading edge of the hull in the downstream direction, which can suppress or weaken the growth of the horseshoe vortex head at the root of the hull from the source, effectively suppress the vortex flow and pulsating pressure at the junction of the hull and the main hull, improve and optimize the flow field around the junction of the main appendage and the flow structure in the boundary layer, so as to achieve the purpose of improving and optimizing the external flow at the junction of the main appendage, reducing the pulsating pressure caused by the vortex, and further reducing the flow-induced noise.

[0037] (4) By adopting the active control method proposed in the present invention, the horseshoe vortex at the leading edge of the enclosure is effectively suppressed, and the pulsating pressure in the area where the horseshoe vortex passes is reduced, with a reduction of more than 2dB to 10dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of the active control method for suppressing unsteady flow excitation of an underwater vehicle provided in the present application.

[0039] Figure 2 It is a schematic diagram of the structure of the underwater vehicle provided in this application.

[0040] Figure 3 It is a schematic diagram of the flow topology structure on the front wall and symmetry surface of the leading edge of the junction between the hull and the main appendage of the hull provided by the present application.

[0041] Figure 4 This is a schematic diagram of the evolution of the horseshoe vortex at the junction of the hull and the main appendage provided by this application.

[0042] Figure 5 It is a schematic diagram of the arrow-shaped hole opening form provided in this application.

[0043] Figure 6 It is a schematic diagram comparing the vortex flow structure at the junction of the hull and the main hull under non-suction flow control and suction flow control provided in the present application.

[0044] Figure 7 This is a schematic diagram of the location distribution of pulsating pressure monitoring points provided in this application.

[0045] Figure 8 It is a schematic diagram of the solution results of the pulsating pressure at the monitoring point under different suction flow speeds provided in this application.

[0046] Among them: 1-underwater vehicle body; 2-command room enclosure; 3-arrow-shaped hole; 4-starting separation point; 5-horseshoe vortex trajectory. DETAILED DESCRIPTION

[0047] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0048] Please refer to Figure 1 As shown, an embodiment of the present application provides an active control method for suppressing unsteady flow excitation of an underwater vehicle, which specifically includes the following steps:

[0049] Step 1: Determine the starting separation point of the horseshoe vortex at the leading edge of the junction between the hull and the main hull. As the vortex legs of the horseshoe vortex gradually move away from the hull as they evolve along the flow direction, they continuously dissipate and merge into the wake of the hull, destroying the uniformity of the tail flow field. However, the excitation effect of the wake on the hull structure decays quickly. Therefore, the influence of the horseshoe vortex on the hull is mainly limited to the root area where the hull 2 ​​is connected to the main hull 1, such as Figure 2 In this application, the large eddy simulation equation considering the inverse scattering model is used to solve the vortex flow structure around the fully attached underwater vehicle 1. The large eddy simulation control equation, that is, the continuity equation (1) and the NS equation (2) after grid filtering can be expressed as:

[0050]

[0051] Where ρ is the fluid density; represents the fluid velocity after filtering; x represents the spatial position of the grid at the junction of the hull and the main hull; the subscripts i, j and l in the following text are 1, 2, and 3, representing the three components of the spatial coordinate system; represents the fluid pressure after filtering; σ ij is the stress tensor caused by molecular viscosity; τ ij It is sub-grid stress and needs to be simulated using a sub-grid vortex model.

[0052]

[0053] Where, μ is the dynamic viscosity coefficient, δ ij Represents the Kronecker symbol.

[0054] If you represents small-scale motion, then τ ij This breaks down into:

[0055]

[0056] Among them, the first term is called the outward scattering term, which represents the interaction between two large eddies to produce small-scale turbulence; the second term is called the cross term, which represents the interaction between large and small eddies; the third term is called the backscattering term, which represents the interaction between small eddies to produce large eddies and bring about the transfer of energy from small eddies to large eddies. This interaction is also called the backscattering effect.

[0057] At present, there are more than ten kinds of sub-grid vortex models commonly used in large eddy simulation. Not only are they not universal, but most of them do not consider the backscattering effect. Therefore, the existing sub-grid vortex models are not very successful in dealing with the backscattering process of energy transfer from the sub-grid scale to the solvable scale. The reason is that these models do not consider this phenomenon and do not deal with its influence. In the previous research, the applicant found that because the hull of the underwater vehicle is a protrusion with longitudinal curvature, the local pressure change is obvious, and the backscattering effect has a particularly obvious influence on the evolution of the surrounding flow field, especially the horseshoe vortex. Therefore, in the existing large eddy simulation equation, the applicant expresses the backscattering term of the sub-grid vortex model in the NS equation (that is, the third term of equation (5)) with a completely nonlinear term in the form of decomposed vorticity, and then performs subsequent large eddy simulation method calculations. The nonlinear term is expressed as follows:

[0058]

[0059] in, is the complete velocity field and vorticity field. The superscript L represents the large scale after filtering, that is, the solvable scale in the large eddy simulation, and the superscript S represents the small scale after filtering, that is, the unsolvable scale in the large eddy simulation.

[0060] For the sake of clarity, a wavy line is added to the top of the original unfiltered variable. Then formula (6) can be written as:

[0061]

[0062] Formulas (6) and (7) give the vector product of the solvable scale velocity and the unsolvable scale vorticity, and after filtering, return to the solvable scale. In order to model this expression in large eddy simulation, the solvable scale of formula (7) is decomposed into two scales through filtering operation again. Let this filtering operation be represented by the superscript "". The model is:

[0063]

[0064] The second-order tensor scattering form can be used to express equation (8) as follows:

[0065]

[0066] The final formula (9) is the inverse scattering model term added in the large eddy simulation process. The large eddy simulation equation with the added formula (9) is used to solve the vortex flow structure around the submarine model, and the local flow topology structure on the front wall and symmetry surface of the front edge of the junction between the hull and the main appendage is further extracted, as shown in Figure 3 shown. Figure 3 According to the direction indicated by the arrows, the red circle in the first figure shows the overall flow topology on the front wall and symmetry plane (longitudinal section in the enclosure, equivalent to the xoz plane) of the main appendage joint. The second figure is an enlarged display of the flow structure at the red circle in the first figure. The third figure shows the local flow topology characteristics on the symmetry plane of the leading edge, and the fourth figure is an enlarged processing of the flow at the red circle in the third figure, showing the starting position of the horseshoe vortex at the main appendage joint. The two-dimensional coordinate system shown in the third and fourth figures is located on the symmetry plane, the origin is the intersection position just in front of the junction of the enclosure and the main hull, the horizontal axis represents the longitudinal direction of the hull, and the direction from the bow to the stern is positive. The vertical axis represents the vertical direction of the hull, and the vertical direction is positive. The line is the local streamline topology on the symmetry plane in front of the enclosure.

[0067] The Q-vortex criterion is used to capture the vortex structure on the symmetry plane. The center 4 of the vortex structure is the starting separation point of the horseshoe vortex at the leading edge of the junction between the hull and the main hull. This position is used to determine the opening position of the arrow-shaped hole. The Q-vortex criterion is expressed as:

[0068]

[0069] Among them, S is the strain rate tensor and Ω is the vortex tensor, which are calculated by solving the three-dimensional velocity field in the vortex flow structure.

[0070] At the same time, the Q-vortex criterion is also used to display the evolution trajectory of the horseshoe vortex main vortex at the junction of the hull and the main appendage of the hull5, which is used to provide the reference position of the monitoring point to evaluate the control effect, such as Figure 4 As shown in the figure, from the perspective of the flow mechanism at the root of the hull of the underwater vehicle, the front incoming flow is subjected to the adverse pressure gradient at the leading edge of the hull to produce flow separation, and the vortex head of the horseshoe vortex is generated at the initial separation point, followed by a vortex neck, and gradually evolves into a vortex leg to form a complete horseshoe vortex structure. The horseshoe vortex is a "U"-shaped horseshoe leg structure in the top view.

[0071] Step 2: If Figure 2As shown, an arrow-shaped hole 3 is opened at the starting separation point, and suction control is applied through the arrow-shaped hole. In previous studies on blowing flow control for square cavities, rectangular plane elongated holes were used, and this hole type is more suitable for square cavities. However, both the main body 1 and the hull 2 ​​of the underwater vehicle have obvious curvatures, so the above-mentioned rectangular plane elongated holes are no longer applicable. In order to follow the principle of flow control from the "source", it has been found through research that the control of horseshoe vortex is mainly the suppression of vortex head. Only by using flow control means to suppress or weaken the growth of vortex head can the effective control of flow excitation around the hull be achieved. Under the guidance of this basic idea, the applicant has found through a large number of calculations and studies that a relatively ideal control effect can be achieved by opening a hole with an arrow-shaped hole in the form of "^" at the vortex head of the horseshoe vortex at the leading edge of the hull to absorb flow along the flow direction. The principle is that the vortex legs of the "U"-shaped horseshoe vortex are cut off, and the local geometry of its head is similar to the form of an arrow-shaped hole.

[0072] The opening shape of the embodiment of the present application adopts an arrow-shaped hole 3 in the form of a swept wing, with a sweep angle of 37 degrees, an initial tentative arrow-shaped hole extension of 8.1 mm (hypotenuse length 5 mm), a chord length of 2.5 mm, and the opening position is taken at the starting separation position of the junction between the hull and the main hull, such as Figure 5 As shown. The effect of this opening form and opening size on resistance can be ignored. The arrow-shaped hole is used to apply suction control from the inside of the hull, and the suction direction is perpendicular to the opening surface, effectively ensuring the suction effect.

[0073] Step 3: Compare the flow characteristics at the junction of the hull and the main hull under different arrow-shaped hole sizes and suction speeds, select the arrow-shaped hole size and suction speed with the optimal control effect, and carry out active suction control at the initial separation point to suppress the unsteady flow excitation of the underwater vehicle.

[0074] First, different suction flow speeds are designed under the opening size in step 2, and the flow characteristics such as vortex flow and pulsating pressure at the junction of the hull and the main hull are solved. In the embodiment of the present application, the suction flow speed is selected in the range of 1 to 3 times the navigation speed of the underwater vehicle, and the large eddy simulation equation considering the inverse scattering model is used to solve the vortex flow structure at the junction of the hull and the main hull under different suction flow speeds, and the vortex flow structure is displayed by the Q vortex criterion, such as Figure 6 As shown in the figure, it is convenient to check the suppression effect of the horseshoe vortex at the leading edge of the joint under different suction flow speeds. It can be seen from the comparison figure that when the suction flow control of 10m / s is applied through the arrow-shaped hole, the "U" shape of the horseshoe vortex at the leading edge of the joint is destroyed, indicating that this control method effectively suppresses the formation of the horseshoe vortex.

[0075] Indicative, such as Figure 7 As shown in Figure 1, three monitoring points P1, P2, and P3 are selected on the evolution trajectory of the main vortex of the horseshoe vortex at the junction of the hull and the main body, and the pulsating pressure solution results under different suction flow speeds are monitored, as shown in Figure 1. Figure 8As shown in the figure, it can be seen that the flow noise corresponding to the suction flow control of 10m / s is the smallest after 100Hz. The pulsating pressure size of each monitoring point is expressed in the sound pressure level (SPL) spectrum as follows:

[0076]

[0077] Among them, p(f) is the pulsating pressure time domain signal p(t) in the vortex flow structure obtained by solving, the sound pressure of different frequency components is obtained by Fourier transform, and p0 is the reference sound pressure.

[0078] Then, the vortex flow at the junction of the hull and the main hull and the pulsating pressure at each monitoring point under different suction flow speeds are compared and analyzed to determine the suction flow speed with the optimal control effect under the opening size in step 2. At the suction flow speed with the optimal control effect, the arrow-shaped hole extension and chord length are changed, and steps 2 to 3 are repeated to determine the arrow-shaped hole size with the optimal control effect. The optimal active control method for suppressing the vortex structure and pulsating pressure of the underwater vehicle is iteratively formed and applied to the actual flow control of the underwater vehicle. The criteria for the optimal control effect are: 1) There is an inhibitory effect on the horseshoe vortex at the leading edge of the hull; 2) The pulsating pressure at different frequency bands at each monitoring point on the horseshoe vortex evolution trajectory, the smaller the control effect, the better.

[0079] In this embodiment, the arrow-shaped hole size and suction flow speed with the best control effect are: the opening shape adopts an arrow-shaped hole in the form of a swept wing, the sweep angle is 37 degrees, and the arrow is facing the front of the main hull. The best suction flow speed is between 1 and 2 times the navigation speed of the underwater vehicle. Since the opening area is very small, the suction flow pump commonly used in the industrial field can meet the above requirements on the model scale.

[0080] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. An active control method for suppressing unsteady flow excitation of an underwater vehicle, characterized in that: The method comprises: Determine the starting separation point of the horseshoe vortex at the leading edge of the junction between the hull and the main hull; An arrow-shaped hole is opened at the position of the starting separation point, and suction flow control is applied through the arrow-shaped hole; The flow characteristics at the junction of the hull and the main hull are compared under different arrow-shaped hole sizes and suction speeds, and the arrow-shaped hole size and suction speed with the optimal control effect are selected. Active suction control is carried out at the starting separation point to suppress the unsteady flow excitation of the underwater vehicle.

2. The active control method for suppressing unsteady flow excitation of an underwater vehicle according to claim 1, characterized in that: Determining the starting separation point position of the horseshoe vortex at the leading edge of the junction between the hull and the main hull includes: The large eddy simulation equation considering the inverse scattering model is used to solve the vortex flow structure around the fully attached underwater vehicle. Obtain the local flow topology on the front wall and symmetry surface of the front edge of the junction between the hull and the main appendage of the hull; The Q-vortex criterion is used to capture the vortex structure on the symmetry plane. The center of the vortex structure is the starting separation point of the horseshoe vortex at the leading edge of the junction between the hull and the main hull.

3. The active control method for suppressing unsteady flow excitation of an underwater vehicle according to claim 1, characterized in that: The comparison of flow characteristics at the junction of the hull and the main hull under different arrow-shaped hole sizes and suction flow velocities includes: Design working conditions with different arrow-shaped hole sizes and suction flow velocities; The large eddy simulation equation considering the inverse scattering model is used to solve the vortex flow structure at the junction of the hull and the main body under different working conditions, and the vortex flow structure is displayed by the Q-vortex criterion to check the suppression effect of the horseshoe vortex at the leading edge of the junction under different working conditions. The Q-vortex criterion is used to capture the evolution trajectory of the main vortex of the horseshoe vortex at the junction of the hull and the main body; Several monitoring points are set on the evolution trajectory of the main vortex of the horseshoe vortex, and the pulsating pressure solution results under different working conditions are monitored.

4. The active control method for suppressing unsteady flow excitation of an underwater vehicle according to claim 2 or 3, characterized in that: In the large eddy simulation equation considering the inverse scattering model: The inverse scattering term of the sub-grid vortex model in the NS equations is expressed by a completely nonlinear term in the form of decomposed vorticity.

5. The active control method for suppressing unsteady flow excitation of an underwater vehicle according to claim 4, characterized in that: Characterize the fully nonlinear term using a scattering form of a second-order tensor: in, represents the unfiltered fluid velocity, the superscript L represents the solvable scale in the large eddy simulation, and the superscript S represents the unsolvable scale in the large eddy simulation; x represents the spatial position of the grid at the junction of the hull and the main hull; the subscripts i and j are 1, 2, and 3, representing the three components of the spatial coordinate system.

6. The active control method for suppressing unsteady flow excitation of an underwater vehicle according to claim 2 or 3, characterized in that: The Q-vortex criterion is expressed as: Among them, S is the strain rate tensor and Ω is the vortex tensor, which are calculated by solving the three-dimensional velocity field in the vortex flow structure.

7. The active control method for suppressing unsteady flow excitation of an underwater vehicle according to claim 3, characterized in that: The pulsating pressure at each monitoring point is expressed in the sound pressure level SPL spectrum as follows: Among them, p(f) is the pulsating pressure time domain signal p(t) in the vortex flow structure obtained by solving, the sound pressure of different frequency components is obtained by Fourier transform, and p0 is the reference sound pressure.

8. The active control method for suppressing unsteady flow excitation of an underwater vehicle according to claim 1, characterized in that: The arrow-shaped hole sizes and suction flow rates with the best control effect are: The opening shape adopts an arrow-shaped hole in the form of a swept wing, with a sweep angle of 37 degrees, and the arrow is facing the front of the main hull; The optimum suction flow speed is between 1 and 2 times the navigation speed of the underwater vehicle, and the suction flow direction is perpendicular to the opening surface.

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