Three-dimensional pipeline train shock wave suppression method based on tunnel wall biomimetic microstructure

Abstract

The embodiment of the application provides a three-dimensional tunnel train shock wave suppression method based on a tunnel wall surface biomimetic microstructure. A three-dimensional tunnel-train coupling model is constructed; based on the model, an intersection area of a recompression wave at the rear of a train and a tunnel inner wall is determined, the intersection area is located in a starting position of a streamline section at the rear of the train to a preset axial range behind the train tail; a biomimetic microstructure array distributed along the axial direction and the circumferential direction is arranged on the tunnel inner wall in the intersection area, the biomimetic microstructure array is a multi-row array composed of multiple biomimetic microstructures, the biomimetic microstructure has a blunt windward end and a downstream sharp tail end, and the downstream sharp tail end is arranged along the tunnel axial direction. The embodiment of the application can disperse, deflect and weaken the incident compression wave and the reflected wave without changing the train main body shape and without increasing the on-board active control device, simultaneously improves the near-wall flow and the pressure recovery process at the rear of the train, thereby suppressing the cross-shaped shock wave, reducing the local pressure peak value and the aerodynamic resistance.

Description

Technical Field

[0001] This invention relates to the field of train shock wave suppression technology, and in particular to a three-dimensional pipeline train shock wave suppression method based on biomimetic microstructures of tunnel walls. Background Technology

[0002] As speeds increase, high-speed ground transportation experiences a rapid increase in aerodynamic drag, aerodynamic noise, and pressure fluctuations. Low-vacuum tube maglev transportation, by reducing the gas density within the tube and employing non-contact levitation, can reduce friction and air resistance in conventional open-track operation, representing an important technological direction for speed classes of 600–1000 km / h. However, when the train operates within a closed or semi-closed tube, the train's cross-section occupies the effective flow area of ​​the tube, creating a narrow annular flow channel between the train and the tube wall, preventing air from freely diffusing to the surroundings as in open-track operation.

[0003] After passing through the streamlined contraction section, the airflow at the tail of the pipeline train first expands, forming a low-pressure, high-speed zone. Subsequently, it undergoes recompression due to the confinement of the pipeline and the replenishment of surrounding fluids. The compression wave steepens during propagation and interacts with reflected waves from the tunnel wall, wake vortices, and boundary layers, easily forming oblique shock waves, cross-wave systems, or shock trains. Relying solely on reducing the pressure inside the pipe or increasing the pipe diameter can reduce air density or blockage ratio, but it increases the costs of the vacuum system, civil engineering, and structure. Extending only the streamlined sections at the front and rear of the train sacrifices effective vehicle space and cannot directly control the reflected waves already occurring at the tunnel wall.

[0004] Therefore, how to disperse, deflect, and weaken incident compression waves and reflected waves without changing the main shape of the train or adding onboard active control devices, while improving the near-wall flow and pressure recovery process at the rear of the train, in order to suppress cross-shaped shock waves, reduce local pressure peaks, and reduce aerodynamic drag, has become an urgent technical problem to be solved. Summary of the Invention

[0005] This invention provides a three-dimensional pipeline train shock wave suppression method based on the biomimetic microstructure of the tunnel wall. It can disperse, deflect and weaken the incident compression wave and the reflected wave without changing the shape of the train body or adding on-board active control devices. At the same time, it improves the near-wall flow and pressure recovery process at the rear of the train, thereby suppressing cross-shaped shock waves, reducing local pressure peaks and aerodynamic drag.

[0006] In a first aspect, embodiments of the present invention provide a three-dimensional pipeline train shock wave suppression method based on biomimetic microstructures of tunnel walls, comprising: A three-dimensional tunnel-train coupling model is constructed to simulate the operation of a high-speed train in a tunnel under a low vacuum environment. Based on the three-dimensional tunnel-train coupling model, the intersection area between the recompression wave at the rear of the train and the inner wall of the tunnel is determined. The intersection area is located within a preset axial range from the starting position of the streamlined section at the rear of the train to the rear of the train. A biomimetic microstructure array is arranged along the axial and circumferential directions on the inner wall of the tunnel in the intersection area. The biomimetic microstructure array is a multi-row array composed of multiple biomimetic microstructures. The biomimetic microstructure has a windward rounded blunt end and a downstream pointed tail end, and the downstream pointed tail end is arranged along the tunnel axial direction.

[0007] In some embodiments, the method for constructing the three-dimensional tunnel-train coupling model includes: The total length of the tunnel along the axial direction is set at 600m, and the total length of the train is 80m; The axial distance from the tip of the train's head to the tunnel entrance is set at 150m, and the axial distance from the tail of the train to the tunnel exit is set at 370m. A front-end densification zone is set up in front of the train head to capture stagnant high voltage and compression wave steepening; A rear-end encryption zone is set up at the rear of the train and its downstream side to capture expansion waves, backflow, and shock wave trains. The front and rear encrypted zones are divided into independent grids, and the grid density is higher than that of the rest of the tunnel.

[0008] In some embodiments, the shape of the biomimetic microstructure is one or more combinations of teardrop, semicircular, elliptical, fish-scale, and cone-teardrop composite.

[0009] In some embodiments, the biomimetic microstructure is a teardrop-shaped protrusion, the leading edge of which is a rounded curved surface, and the trailing edge of which gradually tapers to form a pointed tail.

[0010] In some embodiments, the geometric parameters of the teardrop-shaped protrusion satisfy: The structural height h ranges from 0.05m to 0.50m; The axial center distance s satisfies the relationship s=(1.5 4)h; The ratio of axial length l to structural height h is 2 to 6.

[0011] In some embodiments, the arrangement strategy of the biomimetic microstructure array is as follows: The biomimetic microstructure array is arranged within the axial range from the starting position of the streamlined section at the rear of the train to 10m behind the rear of the train. In the tunnel cross-section, the biomimetic microstructure array covers the effective flow area at the top, side walls and near the bottom of the tunnel; Multiple rows of microstructures are set along the circumference of the tunnel, and adjacent rows of microstructures are arranged in an axially staggered manner.

[0012] In some embodiments, it also includes: The tunnel inner wall and the biomimetic microstructure surface are treated with sliding wall boundary conditions, causing the tunnel inner wall and the biomimetic microstructure to move in the same direction as the axial flow velocity relative to the stationary train. The method for setting the sliding wall boundary conditions includes: The tunnel inner wall and the biomimetic microstructure surface are defined as moving walls. The magnitude of the moving speed is equal to the axial inflow velocity, and the moving direction is parallel to the train axis and points towards the rear of the train. The train surface is defined as a stationary, non-slip, thermally insulating wall surface. The fluid medium adopts the ideal gas law, the energy equation is enabled, and the turbulence model uses shear stress transport (SSTk). ω model.

[0013] In some embodiments, it also includes: Using a smooth tunnel with uniform cross-section as the benchmark model, the benchmark index I0 is calculated and obtained. The benchmark index includes the pressure ratio before and after the shock wave, the root mean square value of the pressure on the pipe wall, or the aerodynamic drag coefficient of the entire train. Under the same boundary conditions, calculate the comparison index I1 after loading the biomimetic microstructure array; The inhibition effect is calculated using the inhibition rate formula η=(I0-I1) / I0×100%.

[0014] In some embodiments, the method is applied to a shock wave suppression tunnel, the shock wave suppression tunnel comprising: Tunnel segments, which enclose a cavity for train passage; A biomimetic microstructure array is fixed to the inner wall of the chamber; The biomimetic microstructure array is distributed in a preset shock wave action area, which corresponds to the intersection area of ​​the tail recompression wave and the inner wall of the cavity when the train is running at transonic speed. Each biomimetic microstructure in the array of biomimetic microstructures has a windward rounded end and a downstream pointed end, and the downstream pointed end is arranged along the tunnel axis. The biomimetic microstructure array covers the top, side walls, and effective flow area near the bottom of the chamber.

[0015] In some embodiments, the biomimetic microstructure array is pre-formed on an independent arc-shaped inner lining plate to form a standardized functional module; the standardized functional module is fixed to the inner wall of the precast tunnel segment by bolt connection, slot fitting, bonding or embedded installation; or, the biomimetic microstructure array is directly cast integrally in the production mold of the tunnel precast segment.

[0016] The three-dimensional pipeline train shock wave suppression method based on biomimetic microstructures of tunnel walls provided by the present invention constructs a three-dimensional tunnel-train coupling model to simulate high-speed train operation in a tunnel under low vacuum conditions. Based on the three-dimensional tunnel-train coupling model, the intersection region of the recompression wave at the train's tail and the tunnel wall is determined. The intersection region is located within a predetermined axial range from the starting position of the streamlined section at the train's tail to the rear of the train. A biomimetic microstructure array distributed axially and circumferentially is arranged on the tunnel wall in the intersection region. The biomimetic microstructure array is a multi-row array composed of multiple biomimetic microstructures, each with a blunt, windward end and a pointed, downstream end, with the downstream pointed end pointing along the tunnel axial direction. Based on this, the present invention can disperse, deflect, and weaken incident compression waves and reflected waves without changing the train's main shape or adding onboard active control devices, while simultaneously improving the near-wall flow and pressure recovery process at the train's tail, thereby suppressing cross-shaped shock waves, reducing local pressure peaks, and aerodynamic drag. Attached Figure Description

[0017] Figure 1 This is a flowchart of a three-dimensional pipeline train shock wave suppression method based on a biomimetic microstructure of tunnel wall provided by an embodiment of the present invention; Figure 2 This is a diagram showing the relationship between a 600m tunnel, the initial position of the train, and the positions of the front and rear of the train, provided in one embodiment of the present invention. Figure 3 This is a geometric model diagram of a three-dimensional tunnel-train and wall structure provided in one embodiment of the present invention; Figure 4 This is a three-dimensional arrangement diagram of a teardrop-shaped biomimetic microstructure provided in one embodiment of the present invention; Figure 5 This is a diagram of equivalent wind-blowing boundary conditions and mesh densification strategies for different regions provided in one embodiment of the present invention; Figure 6 This is a locally refined grid diagram of the flow field at the front and rear of a train and its surroundings, provided in one embodiment of the present invention; Figure 7 This is a flowchart of the numerical implementation of shock wave suppression of a three-dimensional biomimetic microstructure provided in one embodiment of the present invention; Figure 8 This is a diagram of the static pressure wave system inside the tunnel obtained by three-dimensional equivalent wind blowing calculation according to an embodiment of the present invention; Figure 9 This is an embodiment of the present invention that provides the mechanism for regulating shock wave reflection, recompression, and near-wall vortices using a teardrop-shaped biomimetic microstructure. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the following drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0020] In this embodiment of the invention, the terms "furthermore," "exemplarily," or "optionally" are used as examples, illustrations, or descriptions and should not be construed as being more preferred or advantageous than other embodiments or designs. The use of the terms "furthermore," "exemplarily," or "optionally" is intended to present the relevant concepts in a specific manner.

[0021] To facilitate a more convenient description of the working principle of the embodiments of the present invention, the following introduction of relevant technical scenarios is given first.

[0022] As speeds increase, high-speed ground transportation experiences a rapid increase in aerodynamic drag, aerodynamic noise, and pressure fluctuations. Low-vacuum tube maglev transportation, by reducing the gas density within the tube and employing non-contact levitation, can reduce friction and air resistance in conventional open-track operation, representing an important technological direction for speed classes of 600–1000 km / h. However, when the train operates within a closed or semi-closed tube, the train's cross-section occupies the effective flow area of ​​the tube, creating a narrow annular flow channel between the train and the tube wall, preventing air from freely diffusing to the surroundings as in open-track operation.

[0023] After passing through the streamlined contraction section, the airflow at the tail of the pipeline train first expands, forming a low-pressure, high-speed zone. Subsequently, it undergoes recompression due to the confinement of the pipeline and the replenishment of surrounding fluids. The compression wave steepens during propagation and interacts with reflected waves from the tunnel wall, wake vortices, and boundary layers, easily forming oblique shock waves, cross-wave systems, or shock trains. Relying solely on reducing the pressure inside the pipe or increasing the pipe diameter can reduce air density or blockage ratio, but it increases the costs of the vacuum system, civil engineering, and structure. Extending only the streamlined sections at the front and rear of the train sacrifices effective vehicle space and cannot directly control the reflected waves already occurring at the tunnel wall.

[0024] Therefore, how to disperse, deflect, and weaken incident compression waves and reflected waves without changing the main shape of the train or adding onboard active control devices, while improving the near-wall flow and pressure recovery process at the rear of the train, in order to suppress cross-shaped shock waves, reduce local pressure peaks, and reduce aerodynamic drag, has become an urgent technical problem to be solved.

[0025] Based on this, the present invention provides a three-dimensional pipeline train shock wave suppression method based on biomimetic microstructures of tunnel walls. A three-dimensional tunnel-train coupling model is constructed to simulate high-speed train operation in a tunnel under low vacuum conditions. Based on the three-dimensional tunnel-train coupling model, the intersection region between the train's rear recompression wave and the tunnel wall is determined. The intersection region is located within a predetermined axial range from the starting position of the streamlined section at the train's rear to the rear of the train. An array of biomimetic microstructures distributed axially and circumferentially is arranged on the tunnel wall in the intersection region. The array consists of multiple rows of biomimetic microstructures, each with a blunt, windward end and a pointed, downstream end, with the downstream pointed end pointing along the tunnel axial direction. Based on this, the embodiments of the present invention can disperse, deflect, and weaken incident compression waves and reflected waves without changing the train's main shape or adding onboard active control devices, while simultaneously improving the near-wall flow and pressure recovery process at the train's rear, thereby suppressing cross-shaped shock waves, reducing local pressure peaks, and aerodynamic drag.

[0026] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0027] like Figure 1 As shown, Figure 1 This is a flowchart of a three-dimensional pipeline train shock wave suppression method based on a tunnel wall biomimetic microstructure provided by an embodiment of the present invention. The three-dimensional pipeline train shock wave suppression method based on a tunnel wall biomimetic microstructure may include, but is not limited to, steps S101 to S103.

[0028] Step S101: Construct a three-dimensional tunnel-train coupling model. The three-dimensional tunnel-train coupling model is used to simulate the operation of a high-speed train in a tunnel under low vacuum conditions. Step S102: Based on the three-dimensional tunnel-train coupling model, determine the intersection area of ​​the recompression wave at the rear of the train and the inner wall of the tunnel. The intersection area is located within a preset axial range from the starting position of the streamlined section at the rear of the train to the rear of the train. Step S103: A biomimetic microstructure array distributed along the axial and circumferential directions is set on the inner wall of the tunnel in the intersection area. The biomimetic microstructure array is a multi-row array composed of multiple biomimetic microstructures. The biomimetic microstructures have a windward rounded blunt end and a downstream pointed tail end, and the downstream pointed tail end is arranged along the tunnel axial direction.

[0029] It is understood that the purpose of this invention is to provide a three-dimensional tunnel wall shock wave suppression method that does not alter the shape of the train body, does not require through-hole pressure relief, and does not require continuous active power supply. This method disperses, deflects, and weakens incident compression waves and reflected waves by arranging a teardrop-shaped biomimetic microstructure array in specific axial sections and circumferential regions, while simultaneously improving near-wall flow and pressure recovery processes at the train's rear, thereby suppressing cross-shaped shock waves, reducing local pressure peaks, and aerodynamic drag.

[0030] It is understood that this invention employs a three-dimensional tunnel-train coupled model. The total axial length of the tunnel is set to 600m, and the train adopts a simplified model consisting of a streamlined front, a uniform cross-section middle section, and a streamlined rear, with a preferred total train length of approximately 80m. The train is fixed in the computational domain, with the tip of the train head 150m from the tunnel entrance, allowing sufficient development distance for the incoming flow before reaching the train head, while retaining approximately 370m of wave propagation and attenuation space between the train tail and the exit. In actual modeling, the train length, the length of the streamlines at the front and rear, the suspension gap, and the blockage ratio can be changed according to the shape of the engineering vehicle, but the tunnel length and initial position relationship must remain sufficient to fully accommodate the compression wave at the train head, the recompression wave at the train tail, and their wall reflection processes.

[0031] like Figure 2 As shown, with the tunnel entrance as the origin of the axial coordinate system, the tip of the train's head is located at x=150 m. A front-end reinforcement zone is set in front of the train head to capture stagnant high voltage, compression wave steepening, and front-end shock waves; a rear-end reinforcement zone is set at the rear of the train and downstream to capture expansion waves, backflow, recompression, and shock wave trains. The reinforcement zone can be a cuboid, a cylinder, or a volume control zone enveloped by the shape of the train body.

[0032] Understandably, the geometric model can first be parametrically modeled in SolidWorks for the train, tunnel, and suppression structure, and then imported into ANSYS SpaceClaim for geometric repair, surface merging, fluid domain extraction, and Boolean operations. In SpaceClaim, independent dense bodies are arranged around the train's head, tail, and suppression structure to allow for different mesh sizes to be applied to different regions in FluentMeshing. The mesh uses a 3D tetrahedral mesh generated by FluentMeshing and can be converted to a polyhedral mesh before solving; prism boundary layers are applied to the train surface, microstructures, or stepped surfaces. The initial 3D model has approximately 22 million meshes and a minimum orthogonal mass of approximately 0.50, capable of resolving the high-pressure zone at the train's head, the low-pressure recirculation zone at the tail, the oblique shock wave front, and wall reflections under conditions of acceptable computational resources.

[0033] like Figure 3As shown, the train is located inside an arched or circular tunnel, with the bottom retaining the maglev levitation gap and track space. Independent naming options are established for the tunnel, train, and biomimetic microstructures to facilitate the subsequent assignment of moving walls, non-slip walls, and local mesh sizes. An airflow domain is obtained by subtracting the train entity from the tunnel entity, and then the encrypted volume and flow domain are used to share topology or volume influence settings.

[0034] It is understandable that, such as Figure 4 As shown, the biomimetic microstructure preferably features teardrop-shaped protrusions with a blunt, rounded leading edge and a gradually tapering trailing edge forming a pointed tail. The tips of the teardrops are arranged along the main flow direction. Individual microstructures are continuously connected to the tunnel wall to avoid forming sharp, reverse steps. The microstructures can be arranged in staggered rows along the tunnel's axial, circumferential, or axial-circumferential directions. Preferably, they are arranged within a range of approximately 10m from the beginning of the streamlined rear section to the rear of the vehicle, forming multiple rows in the effective flow area at the tunnel top, sidewalls, and near the bottom. The parameters of the teardrop-shaped biomimetic microstructure are shown in the table below.

[0035]

[0036] It should be noted that the teardrop-shaped structure can be replaced by a semi-circular, elliptical, fish-scale, conical-teardrop composite or a combination of structures of different scales; their common feature is that they have a windward rounded end and a downstream contraction end, and are arranged in an array in the main shock wave formation, reflection or convergence area.

[0037] It is understandable that, such as Figure 5 As shown, the present invention employs the equivalent blowing method for calculation: the train remains stationary, and an axial flow corresponding to the target train speed is applied at the inlet; the tunnel inner wall and its associated suppression structure are treated as sliding / moving walls moving at the same speed along the axial direction, the train surface is treated as a stationary, non-slip, adiabatic wall, and the outlet is a pressure outlet or a pressure far-field boundary. The fluid medium is set as air and an ideal gas law is used, the energy equation is enabled, and the preferred turbulence model is the shear stress transport SST k-ω model. The solver can use a density-based implicit scheme or a pressure-based coupled scheme; the spatial discretization uses a second-order upwind scheme, and convergence is determined by continuity, momentum, energy, turbulent kinetic energy, specific dissipation rate residuals, as well as the stability of train resistance and pressure at key measuring points. Target operating conditions may include Ma=0.8, 1.0, and 1.2, with Ma=1.0 being the preferred comparative operating condition.

[0038] Within the train's frame of reference, the incoming flow, tunnel walls, and microstructures move along the same axis, while the train remains stationary. This configuration prevents the formation of a thick boundary layer on the fixed tunnel walls in long computational domains that is inconsistent with the actual relative motion. If the computational focus is on shock wave propagation rather than near-wall shear, the portion of the tunnel furthest from the microstructure can be designated as an ideal slip wall, while the microstructure and its adjacent walls can be designated as moving, non-slip walls.

[0039] It is understandable that, such as Figure 6 As shown, for mesh generation, Fluent Meshing uses a relatively coarse base size for the entire domain, and progressively reduces the element size for the train head, train tail, microstructure surface, and upstream and downstream regions of the microstructure. Prismatic layers are set on the train surface and microstructure surface to resolve the boundary layer velocity gradient; a volume refinement zone is set near the central longitudinal section through which the shock wave may pass, ensuring that the oblique shock wave front spans at least several mesh elements. All comparative cases use the same global size, growth rate, and boundary layer settings, changing only the microstructure geometry to ensure comparability of results.

[0040] It is understandable that, such as Figure 7 As shown, for the numerical implementation process of shock wave suppression using a three-dimensional biomimetic microstructure, a reference model of a smooth tunnel with a uniform cross-section is established. Mesh independence checks are performed, and the reference static pressure field, Mach number field, and drag are calculated. A teardrop-shaped microstructure is added under the same train position and boundary conditions, and the local mesh is regenerated while maintaining the global mesh strategy. Static pressure, Mach number, density gradient, and vorticity distribution are extracted from the longitudinal sections at the center of the train's front and rear, the circumferential cross-section of the tunnel, and the train surface. The pressure ratio before and after the shock wave, the maximum pressure gradient, the train drag, the root mean square value of the surface pressure, and the location of the shock wave intersection are used as evaluation indicators. The suppression rate η = (I0 - I1) / I0 × 100% is used to evaluate the structural effect, where I0 is the smooth tunnel index and I1 is the microstructure tunnel index.

[0041] It is understandable that, such as Figure 8 As shown, the preliminary three-dimensional solution results reveal multiple oblique pressure abrupt change zones around and downstream of the train. Pressure waves, after reflection from the tunnel walls, form continuous rhomboid or "X"-shaped wave systems, indicating that the approximately 22 million element three-dimensional model can capture the chain propagation and reflection convergence characteristics of shock waves within a confined flow channel. Figure 9 As shown, the teardrop-shaped microstructure is arranged in the key area where the wave system interacts with the wall. By changing the local wall curvature and near-wall velocity distribution, the originally concentrated reflected wave is dispersed into multiple weaker wave systems, and the pressure recovery downstream of the low-pressure area at the tail is made more gradual.

[0042] In the two-dimensional pilot study, the teardrop-shaped structure showed the best overall effect compared to the smooth tunnel, reducing train resistance by up to 5% and shrinking the flow separation zone. The three-dimensional scheme further utilizes a circumferential array to control the non-uniform wave system at the top, sidewalls, and bottom, thus extending the suppression effect beyond a single two-dimensional cross-section.

[0043] It is understood that the three-dimensional pipeline train shock wave suppression method based on biomimetic microstructures of tunnel walls of the present invention can be applied to shock wave suppression tunnels. Shock wave suppression tunnels include: tunnel segments enclosing a chamber for train passage; a biomimetic microstructure array fixed to the inner wall of the chamber; the biomimetic microstructure array is distributed in a pre-defined shock wave action zone, corresponding to the intersection area of ​​the tail recompression wave of the train running at transonic speeds and the inner wall of the chamber; each biomimetic microstructure in the array has a windward blunt end and a downstream pointed end, with the downstream pointed end pointing along the tunnel axis; the biomimetic microstructure array covers the top, side walls, and effective flow area near the bottom of the chamber. For the specific wave system of pipeline train tail expansion-recompression-wall reflection, a teardrop-shaped three-dimensional microstructure with low additional separation risk is adopted, and a spatial array design is performed in conjunction with the train bottom suspension gap, circumferential wave system differences, and wake vortex distribution.

[0044] It should be noted that the teardrop-shaped protrusions of this invention can be configured as a grooved teardrop structure, a detachable inner lining module, a continuous corrugated strip, or a composite array of different scales; they can be arranged only on the top and side walls, or arranged along the entire circumference. Numerical verification can be replaced by scaled-down wind tunnel, shock tube, or low-vacuum dynamic model tests, with high-frequency pressure sensors arranged on the tunnel wall and train surface, and the shock wave position and intensity measured in conjunction with a schlieren or background schlieren system. The equivalent blowing method can also be replaced by a sliding mesh, overlapping mesh, or moving mesh to simulate the actual movement of the train.

[0045] In one embodiment, a 600 m long three-dimensional arched tunnel and an approximately 80 m long streamlined train were constructed, with the train's front end 150 m from the entrance. Teardrop-shaped protrusions, with a structural height of 0.3 m and an axial center-to-center spacing of 0.6 m, were placed in a staggered arrangement along the top and side walls of the train's rear transition section, corresponding to the tunnel's inner wall. The model was built using SolidWorks, with the fluid domain and head-and-tail compacted volumes extracted in SpaceClaim, and approximately 22.12 million three-dimensional meshes generated in Fluent Meshing, with a minimum orthogonal mass of approximately 0.50. Using the equivalent blowing method, Ma=1.0, and assuming ideal air, the energy equation and the SST k-ω turbulence model were enabled to compare the smooth tunnel and the microstructured tunnel under the same conditions.

[0046] It is understood that the direct applications of this invention are shock wave suppression tunnel linings, prefabricated pipe segments, and detachable pneumatic rectification modules for the retrofitting of existing pipes in low-vacuum pipeline maglev transportation systems. The products can be directly molded into teardrop-shaped, elliptical teardrop-shaped, or composite teardrop-shaped microstructures on the inner walls of prefabricated circular, arched, or rectangular pipes in the factory. Alternatively, the microstructures can be machined onto arc-shaped inner lining plates and then fixed to the inner wall of the tunnel using bolts, slots, adhesives, or embedding methods.

[0047] This product is primarily deployed in sections at the train's tail where the expansion flow, recompression wave, and shock wave reflection interact strongly with the tunnel walls. It is used in low-vacuum pipeline maglev trains traveling at speeds of 600 km / h and above, ultra-high-speed pipeline logistics transport devices, low-pressure pipeline aircraft test lines, and other confined space transonic transport systems. Its function is to alter the near-wall velocity distribution, boundary layer momentum transport, and shock wave reflection path, thereby reducing local pressure gradients, tail wave superposition, and train aerodynamic drag, without the need for through-wall pressure relief holes, additional onboard active equipment, or continuous energy input.

[0048] In addition to physical products, this invention can also form a three-dimensional aerodynamic optimization method and digital design software module for pipeline design: first, the intersection position of strong shock wave and wall is determined by constant cross-section tunnel benchmark calculation; then, the microstructure action area, structural height, axial spacing, circumferential spacing and arrangement direction are determined according to train speed, blockage ratio, pipe pressure and suspension gap; finally, structural parameters suitable for segment manufacturing or existing tunnel renovation are output.

[0049] Understandably, this invention starts from the tunnel boundary rather than the train itself, eliminating the need for additional onboard active control devices or pressure relief channels penetrating the pipe wall, thus maintaining the airtightness of the low-vacuum pipeline. The teardrop-shaped structure, with its rounded front end and tapered rear end, alters the shock wave reflection path and reduces additional separation and drag caused by abrupt protrusions.

[0050] It is understandable that the present invention uses a complete three-dimensional model, which can take into account the suspension gap, track space, circumferential flow area difference and three-dimensional wake vortex, and is closer to the actual engineering situation than the two-dimensional scheme; at the same time, through parametric modeling and partitioned mesh strategy, the structure can be quickly optimized for different speeds, blockage ratios and vacuum levels.

[0051] The above provides a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present invention.

Claims

1. A three-dimensional pipeline train shock wave suppression method based on biomimetic microstructures of tunnel walls, comprising: A three-dimensional tunnel-train coupling model is constructed to simulate the operation of a high-speed train in a tunnel under a low vacuum environment. Based on the three-dimensional tunnel-train coupling model, the intersection area between the recompression wave at the rear of the train and the inner wall of the tunnel is determined. The intersection area is located within a preset axial range from the starting position of the streamlined section at the rear of the train to the rear of the train. A biomimetic microstructure array is arranged along the axial and circumferential directions on the inner wall of the tunnel in the intersection area. The biomimetic microstructure array is a multi-row array composed of multiple biomimetic microstructures. The biomimetic microstructure has a windward rounded blunt end and a downstream pointed tail end, and the downstream pointed tail end is arranged along the tunnel axial direction.

2. The method according to claim 1, characterized in that, The method for constructing the three-dimensional tunnel-train coupling model includes: The total length of the tunnel along the axial direction is set at 600m, and the total length of the train is 80m; The axial distance from the tip of the train's head to the tunnel entrance is set at 150m, and the axial distance from the tail of the train to the tunnel exit is set at 370m. A front-end densification zone is set up in front of the train head to capture stagnant high voltage and compression wave steepening; A rear-end encryption zone is set up at the rear of the train and its downstream side to capture expansion waves, backflow, and shock wave trains. The front and rear encrypted zones are divided into independent grids, and the grid density is higher than that of the rest of the tunnel.

3. The method according to claim 1, characterized in that, The shape of the biomimetic microstructure is one or more combinations of the following: teardrop, semicircle, ellipse, fish scale, and cone-teardrop composite.

4. The method according to claim 1, characterized in that, The biomimetic microstructure is a teardrop-shaped protrusion. The leading edge of the teardrop-shaped protrusion is a rounded curved surface, and the trailing edge of the teardrop-shaped protrusion gradually tapers to form a pointed tail.

5. The method according to claim 4, characterized in that, The geometric parameters of the teardrop-shaped protrusion satisfy: The structural height h ranges from 0.05m to 0.50m; The axial center distance s satisfies the relationship s=(1.5 4)h; The ratio of axial length l to structural height h is 2 to 6.

6. The method according to claim 1, characterized in that, The arrangement strategy of the biomimetic microstructure array is as follows: The biomimetic microstructure array is arranged within the axial range from the starting position of the streamlined section at the rear of the train to 10m behind the rear of the train. In the tunnel cross-section, the biomimetic microstructure array covers the effective flow area at the top, side walls and near the bottom of the tunnel; Multiple rows of microstructures are set along the circumference of the tunnel, and adjacent rows of microstructures are arranged in an axially staggered manner.

7. The method according to claim 1, characterized in that, Also includes: The tunnel inner wall and the biomimetic microstructure surface are treated with sliding wall boundary conditions, causing the tunnel inner wall and the biomimetic microstructure to move in the same direction as the axial flow velocity relative to the stationary train. The method for setting the sliding wall boundary conditions includes: The tunnel inner wall and the biomimetic microstructure surface are defined as moving walls. The moving speed is equal to the axial inflow velocity, and the moving direction is parallel to the train axis and points to the rear of the train. The train surface is defined as a stationary, non-slip, thermally insulating wall surface. The fluid medium adopts the ideal gas law, the energy equation is opened, and the turbulence model uses shear stress transport (SST k). ω model.

8. The method according to claim 1, characterized in that, Also includes: Using a smooth tunnel with uniform cross-section as the benchmark model, the benchmark index I0 is calculated and obtained. The benchmark index includes the pressure ratio before and after the shock wave, the root mean square value of the pressure on the pipe wall, or the aerodynamic drag coefficient of the entire train. Under the same boundary conditions, calculate the comparison index I1 after loading the biomimetic microstructure array; The inhibition effect is calculated using the inhibition rate formula η=(I0-I1) / I0×100%.

9. The method according to claim 1, characterized in that, The method is applied to shock wave suppression tunnels, which include: Tunnel segments, which enclose a cavity for train passage; A biomimetic microstructure array is fixed to the inner wall of the chamber; The biomimetic microstructure array is distributed in a preset shock wave action area, which corresponds to the intersection area of ​​the tail recompression wave and the inner wall of the cavity when the train is running at transonic speed. Each biomimetic microstructure in the array of biomimetic microstructures has a rounded end facing the wind and a pointed end facing the flow, and the pointed end facing the flow is arranged along the tunnel axis. The biomimetic microstructure array covers the top, side walls, and effective flow area near the bottom of the chamber.

10. The method according to claim 9, characterized in that, The biomimetic microstructure array is pre-formed on an independent arc-shaped inner lining plate to form a standardized functional module; the standardized functional module is fixed to the inner wall of the precast tunnel segment by bolt connection, slot matching, bonding or embedded installation; or, the biomimetic microstructure array is directly cast integrally in the production mold of the tunnel precast segment.

Images