A method for arranging staggered tandem cavities with superior hydrodynamic characteristics

Abstract

This invention discloses a method for arranging a staggered tandem cavity group with superior hydrodynamic characteristics, relating to the field of underwater vehicle structure design technology. The key technical points are: it includes multiple cavities arranged in at least two columns, with the at least two columns of cavities staggered along the direction of travel of the underwater vehicle, forming a staggered tandem layout. Furthermore, the ratio of the distance I between two adjacent cavities in the same column to the cavity length L is I / L ≥ 2. This invention, through the staggered tandem cavity layout, reduces the total drag of the cavity group by 70.6%, effectively suppressing the downstream cavity drag multiplication and flow interference. Simultaneously, this cavity layout balances the flow field structure, significantly reduces the Reynolds stress peak, fundamentally improves acoustic stealth performance, avoids noise frequency down-frequencyization and energy amplification, and while maintaining the total number and function of cavities, it still meets the requirements of high performance and high concealment.

Description

Technical Field

[0001] This invention relates to the field of underwater vehicle structure design technology, and more specifically, to a method for arranging a group of interleaved cavities with superior hydrodynamic characteristics. Background Technology

[0002] Underwater vehicles, such as submarines and unmanned underwater vehicles, often require a series of cavity structures on their surfaces to perform critical functions such as heat dissipation, water intake, water drainage, tow cable deployment and retrieval, and sensor deployment. The hydrodynamic and acoustic properties of these cavity groups directly affect the vehicle's drag, maneuverability, and acoustic stealth capabilities. Under the influence of incoming flow, these cavities induce complex flow separation, shear layer oscillations, and intracavity backflow, generating periodic pressure pulsations, i.e., self-sustaining oscillations. These are significant sources of flow noise for underwater vehicles. Optimizing the layout of these cavity groups to suppress adverse flow interference and reduce drag and noise is of crucial engineering significance for improving the overall performance of underwater vehicles.

[0003] Currently, the cavity groups on the surface of underwater vehicles generally adopt a continuous series layout, that is, all cavities are arranged closely in sequence along the direction of navigation. This layout is simple in structure, easy to design and manufacture, and is the most common traditional solution in engineering.

[0004] However, numerous experimental and numerical studies have shown that this traditional continuous tandem layout has inherent and insurmountable technical defects. When the flow passes through the tandem cavities, the complex wake generated by the upstream cavity (including large-scale vortex structures and high-turbulence flow fields) directly impacts the downstream cavity, producing significant flow interference effects, specifically manifested as follows:

[0005] (1) Deterioration of drag characteristics: The average drag coefficient of the downstream cavity is significantly larger than that of the upstream cavity. Studies have shown that under small spacing conditions, the drag of the downstream cavity can increase by more than 80%, or even several times, resulting in a significant increase in the overall drag of the vehicle.

[0006] (2) Deterioration of flow field structure: The peak value of the flow direction Reynolds stress inside the downstream cavity increases sharply, the turbulence pulsation is intense, the flow field quality is severely deteriorated, and the energy dissipation increases;

[0007] (3) Poor acoustic performance: This flow interference will cause the self-sustaining oscillation frequency of the downstream cavity to shift to the low frequency direction. At the same time, the energy amplitude of the oscillation is greatly amplified. Since low frequency sound waves attenuate slowly and travel a long distance in water, they are easily detected by sonar systems at long distances, which seriously damages the acoustic stealth performance of underwater vehicles.

[0008] Although simply increasing the spacing between consecutive cavities can mitigate the aforementioned interference to some extent, this leads to a sharp increase in the total span of the cavity layout, which is often limited by the size of the aircraft body and cannot be achieved, or the number of cavities must be reduced to meet size constraints, thus sacrificing its intended functionality (such as heat emission efficiency).

[0009] Therefore, the present invention aims to provide a method for arranging staggered cascade cavity groups with better hydrodynamic characteristics, so as to fundamentally suppress flow interference between cavities without reducing the total number of cavities or significantly increasing the total span of the layout, thereby simultaneously achieving the dual goals of reducing drag and improving acoustic stealth performance. Summary of the Invention

[0010] The purpose of this invention is to provide a method for arranging staggered cascade cavity groups with superior hydrodynamic characteristics. This invention reduces the total resistance of the cavity group by 70.6% through the staggered cascade cavity layout, effectively suppressing the multiplication of downstream cavity resistance and flow interference. At the same time, this cavity layout balances the flow field structure, significantly reduces the peak Reynolds stress, fundamentally improves acoustic stealth performance, avoids the low-frequency reduction of noise (maximum reduction of 55.1%) and energy amplification (maximum amplification of 25 times), and still meets the requirements of high performance and high concealment while maintaining the total number and function of cavities.

[0011] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an interlaced tandem cavity group arrangement structure with better hydrodynamic characteristics, comprising multiple cavities, the multiple cavities being arranged in at least two columns, the at least two columns of cavities being staggered in the direction of travel of the underwater vehicle to form an interlaced tandem layout, and the ratio of the distance I between two adjacent cavities in the same column to the cavity length L is I / L≥2.

[0012] The present invention is further configured such that the cavity is a rectangular cavity, a trapezoidal cavity, or an arc-shaped cavity.

[0013] The present invention is further configured such that the cavity is preferably a rectangular cavity.

[0014] The present invention is further configured such that the length L of the rectangular cavity is 0.6 m, the depth D is 0.3 m, and the width B is 0.3 m.

[0015] The present invention is further configured such that the distance I between two adjacent cavities in the same column is 1.704 m.

[0016] The present invention also provides a method for arranging staggered tandem cavities with better hydrodynamic characteristics, comprising the following steps:

[0017] S1. Determine the total number N of cavities required on the surface of the underwater vehicle, the length L, depth D, and width B of each cavity;

[0018] S2. Divide the total number of cavities N into at least two columns;

[0019] S3. Arrange the cavities, which are divided into at least two columns, in an alternating pattern along the direction of travel of the underwater vehicle to form an alternating array layout, while ensuring that the distance between two adjacent cavities in the same column is I≥2L;

[0020] S4. The hydrodynamic performance of the layout scheme is verified and optimized through computational fluid dynamics numerical simulation. The optimization objectives include reducing the total drag coefficient, balancing the Reynolds stress in each cavity, and avoiding the shift of the self-sustaining oscillation frequency to a lower frequency.

[0021] The present invention is further configured such that the total length of the staggered array layout in step S3 is equal to the total length of the continuous array layout, so as to keep the total number of cavities N unchanged.

[0022] The present invention is further configured such that: when the total number of cavities N are arranged in an interleaved series layout, the overall drag coefficient of the cavity group is reduced by more than 70% compared with the continuous series layout.

[0023] The present invention also provides an underwater vehicle, the surface of which is provided with an interlaced cascade cavity group arrangement structure with better hydrodynamic characteristics.

[0024] The present invention is further configured such that the cavity on the underwater vehicle is used to realize the functions of heat discharge, water intake or drainage.

[0025] In summary, the present invention has the following beneficial effects:

[0026] 1. This invention significantly improves the hydrodynamic performance of underwater vehicles, greatly reduces flow resistance, and solves the problem that in traditional continuous tandem layouts, the downstream cavity is severely interfered with by the wake of the upstream cavity, leading to a sharp increase in its drag coefficient (experimental calculations show that the drag of the downstream cavity can increase by up to 365% compared to the upstream cavity). This invention, through a staggered tandem layout, greatly reduces the unfavorable flow coupling effect between cavities, making the drag coefficient of the downstream cavity basically consistent with that of the upstream cavity. The total drag of the entire cavity group is reduced by 70.6% compared to the traditional continuous tandem layout, thereby significantly reducing the navigation resistance of underwater vehicles and improving their maneuverability and economy.

[0027] 2. This invention effectively balances the flow field structure of the cavity group, suppresses the intensity of turbulent pulsation, and avoids the order-of-magnitude increase (up to 428%) in the flow direction Reynolds stress peak inside the downstream cavity in the traditional continuous tandem layout, which indicates that the flow field turbulent pulsation is severe, energy dissipation is serious, and the flow field quality is deteriorated. However, through the staggered tandem layout provided by this invention, the flow field structure inside each cavity tends to be consistent, the Reynolds stress peak is significantly reduced and evenly distributed, indicating that the flow of the cavity group is more stable and orderly, and effectively improves the flow environment on the surface of the underwater vehicle.

[0028] 3. This invention fundamentally improves the acoustic stealth performance of the cavity group, avoids the generation and amplification of low-frequency noise, and solves the problem that the self-sustaining oscillation frequency (sound source frequency) of the downstream cavity will shift drastically to the low-frequency direction (with a maximum reduction of 55.1%) due to the traditional continuous series layout, while the energy amplitude of the oscillation will be amplified sharply (with a maximum increase of 25 times). Low-frequency noise has a long propagation distance in water and is not easy to attenuate, making it very easy to detect and seriously damaging stealth. However, this invention, through the staggered series layout, ensures that the self-sustaining oscillation frequency of all cavities is kept in a stable high-frequency range, and the energy amplitude is significantly reduced. High-frequency noise attenuates faster in water and has a shorter propagation distance, thereby greatly improving the acoustic stealth of the underwater vehicle.

[0029] 4. This invention achieves performance optimization without compromising the total number of cavities and total functionality. The staggered tandem layout in this invention does not require reducing the number of cavities (such as increasing the spacing between consecutive layouts would reduce the total number of cavities), perfectly balancing the functional requirements of underwater vehicles such as heat emission and water intake and drainage with the design requirements of high performance and high stealth, and solving the problem that functionality and performance cannot be achieved simultaneously in traditional consecutive tandem layouts.

[0030] 5. The layout design of this invention is flexible, has strong engineering applicability, and is easy to promote and apply. The staggered serial layout method in this invention can be applied to cavities with different geometric configurations (such as rectangles, trapezoids, etc.) and can be adaptively adjusted according to different underwater vehicle platforms and space constraints. It has broad engineering application prospects and provides a brand-new technical path and strong technical support for the research and development of new underwater vehicles in my country. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the layout of continuous series cavity groups and staggered series cavity groups in embodiments of the present invention;

[0032] Figure 2 This is a schematic diagram of the mid-longitudinal cross-sectional grid of the continuous series cavity group and the staggered series cavity group in the embodiments of the present invention;

[0033] Figure 3These are line graphs showing the dimensionless drag coefficient characteristics under two cavity group arrangement forms in the embodiments of the present invention.

[0034] Figure 4 This is a schematic diagram of the flow direction time-averaged velocity characteristics of continuous series cavity groups and staggered series cavity groups at different stations in an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram of the dimensionless flow-direction stress characteristics of a group of cascaded cavities at different stations in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the dimensionless flow stress characteristics of the interleaved cavities at different stations in an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of the single-cavity flow spectrum monitoring point arrangement when L / D=2 in an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram of the vertical pulsation velocity spectrum characteristics at different monitoring points under continuous serial deployment in an embodiment of the present invention;

[0039] Figure 9 This is a schematic diagram of the vertical pulsation velocity spectrum characteristics at different monitoring points under an interleaved array configuration in an embodiment of the present invention. Detailed Implementation

[0040] The following is in conjunction with the appendix Figures 1-9 The present invention will be described in further detail below.

[0041] Example: Research and Analysis of an Interleaved Tandem Cavity Group Arrangement with Superior Hydrodynamic Characteristics

[0042] This embodiment proposes an interleaved array of cavity group layout scheme, which reduces mutual interference between cavities by increasing the spacing between them while keeping the total number of cavities constant; for example... Figure 1 Two layout configurations of a cavity group consisting of nine cavities are shown. Figure 1 (Above) is a traditional continuous series arrangement, with cavity length L=0.6 m, depth D=0.3 m, width B=0.3 m, and spacing between adjacent cavities I1=0.12 m; Figure 1 (Below) is a novel cavity group layout scheme proposed in this embodiment, referred to as the staggered series method. To ensure consistency with the total span of the continuous series cavity group, the spacing between two adjacent cavities in the same column is set to I² = 1.704m. In this staggered series cavity group layout scheme, the spacing between two adjacent cavities satisfies I² > 2L. For ease of description, the cavity groups under the two layout schemes are respectively numbered, as follows: Figure 1 As shown.

[0043] In this embodiment, for the two cavity group layouts described above, the length of the inlet section at the leading edge of cavity A1 / B1 is set to 10 D, and the length of the outlet section at the trailing edge of cavity A9 / B8 / B9 is set to 4 D; the spanwise widths are set to 6 D and 10 D respectively. Based on these dimensions, corresponding mesh generation is performed, resulting in a total mesh size of 2.63 × 10⁻⁶ for the entire computational domain under both layout configurations. 7 and 4.45×10 7 ,like Figure 2 This is a schematic diagram of the local meshing of the longitudinal section of the computational domain under two different layout configurations.

[0044] By comparing and analyzing the calculation results of the dimensionless drag coefficient characteristics under two cavity arrangement forms, namely continuous series and staggered series, as follows: Figure 3 As shown in the figure, the results indicate that for a continuously arranged group of cavities, the drag coefficients of each cavity exhibit significant differences, as detailed below: the dimensionless drag coefficient value of the first cavity A1... (=0.0033) is basically the same as the case of a rectangular single cavity, as shown in Table 1:

[0045] Table 1. Calculation results of time-averaged drag coefficients for three types of cavities.

[0046]

[0047] The drag coefficients of cavities A2-A4 show a step-like increasing trend, with the drag coefficient of cavity A4 reaching a peak of 0.0146, an increase of 342% compared to the drag coefficient of the first cavity; the drag coefficients of the middle and rear cavities A5-A9 remain in the range of 0.0135-0.0154, with an average of 0.0143, an increase of 333% compared to the drag coefficient of the first cavity.

[0048] However, the staggered arrangement of cavities exhibits superior drag characteristics, as follows: the drag coefficient of the first cavities B1-B3 remains stable at 0.0033, consistent with the case of a rectangular single cavity, as shown in Table 1 above; the drag coefficient of the second cavities B4-B9 only slightly increases to the range of 0.0041-0.0044, with an average of 0.0042, which is less than 27% of the increase in drag coefficient compared to the first cavities. Comparing the two cavity arrangement schemes, the staggered arrangement scheme optimizes the spacing between cavities by changing the cavity layout, thereby effectively reducing the flow interference between cavities and reducing the overall drag coefficient of the cavity group by approximately 70.6%.

[0049] This embodiment further analyzes the first-order and second-order statistical characteristics at different locations within each cavity under two cavity group layout configurations, such as... Figure 4The figure shows the calculated dimensionsless flow-direction time-averaged velocity characteristics of the cavity group at three different stations under two cavity group layouts. The stations inside each cavity are located at distances of 0.25, 0.50, and 0.75 from its leading edge, and are named stations S1, S2, and S3, respectively. As can be seen from the figure, the dimensionsless flow-direction time-averaged velocity characteristics of each cavity at different stations are basically the same under the two layout methods. That is, although the two layouts have a certain impact on the flow-direction time-averaged velocity characteristics, the difference between the two is not significant.

[0050] Furthermore, this embodiment investigates the differences in the second-order statistical characteristics of cavity groups under two different layout configurations. First, it discusses the dimensionless flow-direction stress characteristics of continuously tandem cavity groups at different locations, with results as follows: Figure 5 As shown, in order to conduct quantitative analysis, Table 2 presents the statistical results of the dimensionless flow-direction Reynolds stress peak value and its dimensionless location information for the cavity group in a continuous series arrangement:

[0051]

[0052] Table 2 Statistical results of dimensionless flow stress characteristics of different cavities in continuous series arrangement

[0053] As shown in Table 2, at station S1, the peak flow stress in the cavities from A1 to A5 along the flow direction exhibits an increasing trend, with the peak value reaching its maximum at cavity A5. Specifically, the peak flow stress in the downstream cavities (A2 to A5) increased by 134.6%, 266.3%, 275.9%, and 370.1% respectively compared to the first upstream cavity (A1). After the peak flow stress was reached at cavity A5, the subsequent cavities (A6 to A9) maintained a high level of flow stress, with the average value of their peak flow stress increasing by 331.5% compared to cavity A1. Except for cavities A7 and A8, the peak flow stress positions in the other cavities remained consistent, while the peak flow stress positions in cavities A7 and A8 shifted slightly downwards.

[0054] At station S2, the peak flow stress in the cavities from A1 to A5 along the flow direction showed a fluctuating upward trend. Specifically, the peak flow stress in the downstream cavities (A2 to A5) increased by 28.5%, 91.7%, 83.4%, and 132.7% respectively compared to cavity A1. After the flow stress reached a high level at cavity A5, the subsequent cavities (A6 to A9) maintained a high level of flow stress, with the average value of their peak flow stress increasing by 131.3% compared to cavity A1. Except for cavities A6, A7, and A9, the positions of the peak flow stress in the other cavities remained consistent, while the positions of the peak flow stress in cavities A6, A7, and A9 shifted upwards by a factor of two.

[0055] At station S3, the peak flow stress in the cavities from A1 to A7 along the flow direction also showed an oscillating increasing trend. Specifically, the peak flow stress in the downstream cavities (A2 to A7) increased by 31.1%, 70.6%, 69.3%, 137.8%, 127.8%, and 185.3% respectively compared to cavity A1. Furthermore, the peak flow stress in cavities A8 and A9 remained at a high level, increasing by 129.4% and 136.6% respectively compared to cavity A1, and no clear pattern of change was observed at the location of the peak flow stress in each cavity.

[0056] Secondly, by discussing the dimensionless flow stress characteristics of staggered cascade cavity groups at different stations, the results are as follows: Figure 6 As shown in the figure, compared with the dimensionless flow stress characteristics of continuously arranged cavities, the difference between the peak flow stress at the downstream cavities (B2 to B9) and the peak stress at the upstream cavity B1 is very small under the staggered arrangement. This means that under the staggered arrangement, the upstream cavity has little interference with the peak flow stress characteristics of the downstream cavity. Furthermore, at station S1, the peak positions of the flow stress in each cavity are consistent; at station S2, except for cavities B2 and B4, the peak positions of the flow stress in the other cavities are consistent; and at station S3, there is no clear pattern of change in the peak positions of the flow stress in each cavity.

[0057] To conduct quantitative analysis, Table 3 presents the statistical results of the dimensionless flow-direction Reynolds stress peaks and their dimensionless location information for the cavity group in an alternating series arrangement:

[0058] Table 3 Statistical results of dimensionless flow stress characteristics of different cavities under staggered series arrangement

[0059]

[0060] Finally, the differences in the self-sustaining oscillation frequency characteristics within the cavity group under the two layout configurations were investigated, with the monitoring point arrangement referencing... Figure 7 The settings in Figure 7 Six monitoring points were set up near the cavity opening to monitor the velocity fluctuation characteristics near the cavity opening. The spectral characteristics of the fluid oscillation excitation in the cavity were obtained by Lomb-Scargle transform. The coordinate information of these six monitoring points is shown in Table 4.

[0061] Table 4. Coordinate information of single-cavity flow spectrum monitoring points when L / D=2.

[0062]

[0063] It is important to note that, Figure 7The six monitoring points numbered 1-6 actually refer to P1-P6 respectively. In this embodiment, monitoring points P1-P3 were selected to monitor the vertical velocity fluctuation characteristics at the cavity opening, and the Lomb-Scargle transform method was used to obtain the corresponding spectral characteristics. Figure 8 The self-sustaining oscillation spectrum characteristics of each cavity in a continuous series arrangement are presented. It should be noted that, for ease of interpretation, the oscillation amplitude of the upstream cavity (cavities P1-P4) has been amplified in the figure, while the oscillation amplitude of the downstream cavity (cavities P5-P8) has been reduced. Table 5 summarizes the spectral statistics of each cavity at different measurement points:

[0064] Table 5. Statistical results of the self-sustaining oscillation frequency of each cavity in a continuous series configuration.

[0065]

[0066] The first order shown in Table 5 ( ) and second order ( The self-sustaining oscillation frequency and its corresponding energy amplitude were both taken as the arithmetic mean of the results obtained from the three monitoring points P1-P3. Table 5 shows that, under continuous series arrangement, there are significant differences in the self-sustaining oscillation frequencies of each cavity. From the perspective of self-sustaining oscillation frequency values, both the first-order and second-order self-sustaining oscillation frequencies show a clear trend towards lower frequencies. Specifically, for the first-order self-sustaining oscillation frequency, the frequency values ​​at A8 and A9 decreased by 54.6% and 55.1% respectively compared to the frequency value at A1. Similarly, for the second-order self-sustaining oscillation frequency, the frequency values ​​at A8 and A9 decreased significantly by 41.3% and 41.0% respectively compared to the frequency value at A1.

[0067] Further analysis of the energy amplitude variation characteristics of each cavity frequency reveals that the energy amplitude of both the first-order and second-order self-sustaining oscillations shows an increasing trend along the flow direction. Specifically, for the first-order self-sustaining oscillation frequency, the energy amplitude at the downstream cavity A7 is significantly larger than that at the upstream cavity A1, with an increase of 25.4 times. For the second-order self-sustaining oscillation frequency, the energy amplitude reaches its maximum at cavity A9, with a significant increase of 11.1 times compared to the energy amplitude at the first cavity A1, demonstrating a clear energy accumulation effect along the flow direction.

[0068] Figure 9 The self-sustaining oscillation spectral characteristics of each cavity in the interleaved series arrangement are presented. Table 6 summarizes the spectral statistics of each cavity at different measurement points:

[0069] Table 6. Statistical results of the self-sustaining oscillation frequency of each cavity under the staggered series layout.

[0070]

[0071] As shown in Table 6, under the staggered series arrangement, there was no significant difference in the self-sustaining oscillation frequencies among the cavities. From the perspective of the self-sustaining oscillation frequency values, the first-order self-sustaining oscillation frequency values ​​of each cavity ranged from 0.694 to 0.766, with a variance of 2.4%; while the second-order self-sustaining oscillation frequency ranged from 0.991 to 1.107, with a variance of 0.0301. From the perspective of the oscillation frequency energy amplitude, the energy amplitude of the first-order self-sustaining oscillation frequency was 0.0019. The variance of the energy amplitude is between 1 and 0.00927, with a variance of 0.34%. For the second-order self-sustaining oscillation frequency, the energy amplitude is between 0.00089 and 0.00462, with a variance of 0.16%. It can be seen that under the staggered arrangement, there is no adverse phenomenon of a sharp decrease in the self-sustaining oscillation frequency and a sharp increase in the energy amplitude due to the flow interference of the upstream cavity to the downstream cavity. Therefore, it has important practical value for the stealth design of hydrodynamic noise of underwater vehicle cavities.

[0072] This embodiment proposes an innovative method for staggered cascade cavity layout. Through a systematic comparison and analysis of the differences in drag coefficients, first-order and second-order statistics, and self-sustaining oscillation frequencies between continuous and staggered cavity configurations, the following conclusions are drawn:

[0073] For a continuous series of cavities, the downstream cavity flow will be significantly disturbed by the upstream cavity flow. The dimensionless drag coefficient of the downstream cavity will increase by 153%-365% compared to the upstream cavity flow, the dimensionless flow stress amplitude will increase significantly by up to 428%, and the self-sustaining oscillation frequency will show a significant shift to lower frequencies, with a maximum decrease of 55.1%. At the same time, the energy amplitude will show a significant increase, with a maximum increase of 25.4 times.

[0074] However, these anomalies did not occur with the staggered cavity group. That is, the flow interference between cavities was very small, and the differences between the drag coefficients, first-order and second-order statistics, and self-sustaining oscillation frequencies of each cavity were very small. The practical engineering significance of this discovery is that the new cavity group configuration has less impact on the hydrodynamic performance of underwater vehicles and has better cavity hydrodynamic noise stealth performance. Therefore, the new staggered tandem cavity group configuration method proposed in this embodiment is expected to provide a new idea and theoretical basis for the research and development of new surface cavity group systems for underwater vehicles in my country.

[0075] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A staggered tandem cavity group arrangement structure with superior hydrodynamic characteristics, characterized in that: It includes multiple cavities, which are arranged in at least two columns. The at least two columns of cavities are staggered in the direction of travel of the underwater vehicle to form an interleaved array layout, and the ratio of the distance I between two adjacent cavities in the same column to the cavity length L is I / L≥2.

2. The staggered tandem cavity group arrangement structure with superior hydrodynamic characteristics according to claim 1, characterized in that: The cavity is configured as a rectangular cavity, a trapezoidal cavity, or an arc-shaped cavity.

3. The staggered tandem cavity group arrangement structure with superior hydrodynamic characteristics according to claim 2, characterized in that: The cavity is rectangular.

4. The staggered tandem cavity group arrangement structure with superior hydrodynamic characteristics according to claim 3, characterized in that: The rectangular cavity has a length L of 0.6 m, a depth D of 0.3 m, and a width B of 0.3 m.

5. The staggered tandem cavity group arrangement structure with superior hydrodynamic characteristics according to claim 4, characterized in that: The spacing I between two adjacent cavities in the same column is 1.704 m.

6. A method for arranging staggered tandem cavities with superior hydrodynamic characteristics, applied to a staggered tandem cavities arrangement structure with superior hydrodynamic characteristics as described in any one of claims 1-5, characterized in that: Includes the following steps: S1. Determine the total number N of cavities required on the surface of the underwater vehicle, the length L, depth D, and width B of each cavity; S2. Divide the total number of cavities N into at least two columns; S3. Arrange the cavities, which are divided into at least two columns, in an alternating pattern along the direction of travel of the underwater vehicle to form an alternating array layout, while ensuring that the distance between two adjacent cavities in the same column is I≥2L; S4. The hydrodynamic performance of the layout scheme is verified and optimized through computational fluid dynamics numerical simulation. The optimization objectives include reducing the total drag coefficient, balancing the Reynolds stress in each cavity, and avoiding the shift of the self-sustaining oscillation frequency to a lower frequency.

7. The method for arranging staggered tandem cavities with superior hydrodynamic characteristics according to claim 6, characterized in that: In step S3, the total length of the staggered arrangement is equal to the total length of the continuous arrangement, in order to keep the total number of cavities N constant.

8. The method for arranging staggered tandem cavities with superior hydrodynamic characteristics according to claim 7, characterized in that: Compared to a continuous arrangement, a staggered arrangement of N cavities reduces the overall drag coefficient of the cavity group by more than 70%.

9. An underwater vehicle, characterized in that: The surface of the underwater vehicle is provided with an alternating cascade cavity group arrangement structure with better hydrodynamic characteristics as described in any one of claims 1-5.

10. An underwater vehicle according to claim 9, characterized in that: The cavities on the underwater vehicle are used to achieve heat discharge, water intake, or water drainage functions.

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