Splicing simulation method for high-speed train flow field in long pipeline

Abstract

The invention provides a splicing simulation method for a high-speed train flow field in a long pipeline, and the method comprises the steps: splitting a high-speed train whole flow field into a one-dimensional pipeline far field and a three-dimensional train near field based on the dimension characteristics of the flow field; performing quasi-one-dimensional numerical simulation on the whole flow field of the high-speed train to obtain one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the whole line in real time in a pipeline; obtaining a time-varying pressure inlet condition and a time-varying pressure outlet condition; three-dimensional unsteady numerical simulation is carried out, and three-dimensional flow field pressure distribution and three-dimensional flow field temperature distribution of the three-dimensional train near-field area along the way in real time are obtained; splicing simulation is carried out, and flow field pressure distribution and flow field temperature distribution of the high-speed train after whole-line splicing in the pipeline are obtained. The technical problems that in the prior art, a quasi-one-dimensional numerical simulation method and a three-dimensional numerical simulation method cannot be subjected to advantage complementation, and the fineness and the integrity of flow field description are difficult to complete can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of large-scale pipe / tunnel flow numerical simulation, and in particular to a splicing simulation method for a high-speed train flow field in a long pipe. Background Art

[0002] Low-vacuum tube trains are one of the important development directions of future ground high-speed transportation. It uses a low-vacuum tube to cover the maglev train to significantly reduce aerodynamic drag, making high subsonic and even supersonic ground transportation possible. Unlike open-line operation, long-distance operation of high-speed trains is confined to extremely narrow and long tube spaces, which usually induces transonic flow dominated by airflow congestion in the tube. The continuous propagation of disturbances such as motion shock waves and rarefaction waves will greatly extend the spatial and temporal scales of the flow. The flow can be carried out on a large scale with the high-speed train as the center in a pipeline of thousands of kilometers within a span of several hours. This poses a significant challenge to the relevant numerical simulation methods of the flow field, and it will be very important to explore new ways to prescribe the right remedy.

[0003] In view of the characteristics of the flow field of high-speed trains in the long pipes mentioned above, existing studies have mainly adopted two simplified simulation strategies. On the one hand, if based on the full-field perspective, this type of pipe flow problem fits well with the quasi-one-dimensional assumption in most areas in the axial direction, that is, ignoring the radial gradient of the flow and assuming that the flow on the same section of the pipe is uniform. The quasi-one-dimensional numerical simulation method is economical and fast to analyze the large aspect ratio flow problem, but it cannot accurately describe the complex geometric areas of the train neighborhood. On the other hand, if based on the near-field perspective of the train with obvious three-dimensional characteristics, the analysis of the flow requires large-scale three-dimensional numerical simulation. Since these methods require a lot of resources, it is difficult to achieve full-scale simulation over long distances and for a long time. They are only suitable for selecting a train neighborhood that is several times the length of the train to reproduce the three-dimensional flow phenomenon. However, the inherent problem is that the long-range propagation and attenuation of disturbances before and after the train should not be affected by the numerical boundary at a finite distance. The short-distance and short-time simulation lacks completeness in describing the flow and is insufficient to reflect the essence of long-range and long-time flows. It can be seen that the quasi-one-dimensional method is an important means to simulate the full-field characteristics, while the three-dimensional numerical simulation method is irreplaceable for the analysis of the near field of the train. The precision and completeness of the flow field characterization are difficult to achieve in a single numerical simulation method.

[0004] Although the quasi-one-dimensional numerical simulation method is economical and fast, it cannot accurately depict the complex geometric areas in the vicinity of the train, that is, it lacks the precision of flow field reproduction. The three-dimensional numerical simulation method requires a lot of resources and is difficult to achieve full-scale simulation over long distances and for a long time. It is only suitable for selecting a very limited train neighborhood, that is, it lacks the completeness of flow field reproduction. It is difficult to achieve both the precision and completeness of flow field characterization in a single numerical simulation method, and it will be very important to explore new ways to prescribe the right remedy. Summary of the invention

[0005] The present invention provides a splicing simulation method for the flow field of a high-speed train in a long pipeline, which can solve the technical problems in the prior art that the quasi-one-dimensional numerical simulation method and the three-dimensional numerical simulation method cannot complement each other's advantages and it is difficult to achieve both the precision and completeness of the flow field characterization.

[0006] According to one aspect of the present invention, a method for simulating the flow field of a high-speed train in a long pipeline is provided, the method comprising:

[0007] Based on the dimensional characteristics of the flow field, the entire flow field of the high-speed train is divided into two regions: the one-dimensional pipeline far field and the three-dimensional train near field. The three-dimensional train near field is the area radiating several times the length of the train forward and backward with the midpoint of the front and rear of the train as the center, and the one-dimensional pipeline far field is the area except the three-dimensional train near field.

[0008] The quasi-one-dimensional numerical simulation of the entire flow field of the high-speed train is carried out to obtain the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the entire line in the pipeline in real time, and the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the far field area of ​​the one-dimensional pipeline in real time are extracted;

[0009] The one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution at the starting position of the three-dimensional train near-field region obtained by the quasi-one-dimensional numerical simulation are used as the time-varying pressure inlet conditions of the three-dimensional numerical simulation of the three-dimensional train near-field region, and the one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution at the ending position of the three-dimensional train near-field region obtained by the quasi-one-dimensional numerical simulation are used as the time-varying pressure outlet conditions of the three-dimensional numerical simulation of the three-dimensional train near-field region;

[0010] Based on the time-varying pressure inlet conditions and the time-varying pressure outlet conditions, a three-dimensional unsteady numerical simulation is performed on the three-dimensional train near-field area to obtain the three-dimensional flow field pressure distribution and three-dimensional flow field temperature distribution along the three-dimensional train near-field area in real time;

[0011] The one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the far-field area of ​​the one-dimensional pipeline in real time and the three-dimensional flow field pressure distribution and three-dimensional flow field temperature distribution along the near-field area of ​​the three-dimensional train in real time are spliced ​​and simulated to obtain the flow field pressure distribution and flow field temperature distribution of the high-speed train after splicing the entire line in the pipeline.

[0012] Preferably, the range of the three-dimensional train near field area is [x back , x front ], where x back The n is the radius from the midpoint of the train to the rear. 1 times the vehicle length, x front The midpoint of the train head and tail radiates forward n 2 times the vehicle length, n 1 The value range of n is 1 to 10. 2 The value range is 1 to 10.

[0013] Preferably, the range of the one-dimensional pipeline far field region is (x front , L tube ) and (0, x back ), where L tube is the pipe length.

[0014] According to another aspect of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements any of the above methods when executing the computer program.

[0015] By applying the technical solution of the present invention, the far-field flow area with good quasi-one-dimensional characteristics is regressed to the quasi-one-dimensional numerical simulation, and the near-field flow area of ​​the train with obvious three-dimensional characteristics is subjected to three-dimensional numerical simulation, and the flow areas are spliced ​​and sutured. This method breaks through the bottleneck of existing numerical simulation methods, and can combine the advantages of quasi-one-dimensional numerical simulation, which is economical and fast, and three-dimensional numerical simulation, which is precise and accurate, taking into account the completeness and precision of flow field characterization, saving computing resources, and greatly improving computing efficiency. The present invention is suitable for the numerical simulation of the long-distance and long-term flow characteristics of the full-line operation of high-speed trains in long pipelines.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The flow field splicing simulation method is more precise and accurate than the simple quasi-one-dimensional numerical simulation, and can well reproduce the flow, wave system and aerodynamic / thermal phenomena in the train neighborhood;

[0018] 2. The flow field splicing simulation method can be used to cleverly realize the full-scale simulation of long-distance and long-term operation of the entire line using the limited train near-field calculation domain;

[0019] 3. Compared with simple three-dimensional numerical simulation, it is more economical and faster. Taking a high-speed train running at a speed of 1000km / h in a 200km long pipeline as an example, the number of computational grids of the flow field splicing simulation method is only 1 / 100 of the full-domain three-dimensional numerical simulation, and the calculation time is only about 1 / 200. The calculation cost is small and the calculation efficiency is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1A flow chart of a method for simulating the splicing of a high-speed train flow field in a long pipeline provided according to an embodiment of the present invention is shown;

[0022] Figure 2a A full flow field pressure distribution cloud diagram obtained by quasi-one-dimensional numerical simulation according to an embodiment of the present invention is shown;

[0023] Figure 2b A cloud diagram of temperature distribution of the entire flow field obtained by quasi-one-dimensional numerical simulation according to an embodiment of the present invention is shown;

[0024] Figure 3a Shows Figure 2a The pressure evolution curves over time at the position 60m in front of the train and 160m behind the train;

[0025] Figure 3b Shows Figure 2b The temperature evolution curves over time at the position 60m in front of the train and 160m behind the train;

[0026] Figure 4 A train near-field pressure distribution cloud diagram at a typical time t=600s obtained by using a splicing numerical simulation method provided in accordance with an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0030] like Figure 1 As shown, the present invention provides a method for simulating the splicing of a high-speed train flow field in a long pipeline, the method comprising:

[0031] Step 1: Based on the dimensional characteristics of the flow field, the entire flow field of the high-speed train is divided into two regions: a one-dimensional pipeline far field and a three-dimensional train near field. The three-dimensional train near field region is an area radiating several times the length of the train forward and backward with the midpoint of the front and rear of the train as the center, and the one-dimensional pipeline far field region is the area other than the three-dimensional train near field.

[0032] Step 2: Perform quasi-one-dimensional numerical simulation on the entire flow field of the high-speed train to obtain the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the entire line in the pipeline in real time, and extract the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the far field area of ​​the one-dimensional pipeline in real time;

[0033] Step 3: Using the one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution at the starting position of the three-dimensional train near-field region obtained by the quasi-one-dimensional numerical simulation as the time-varying pressure inlet conditions of the three-dimensional numerical simulation of the three-dimensional train near-field region, and using the one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution at the ending position of the three-dimensional train near-field region obtained by the quasi-one-dimensional numerical simulation as the time-varying pressure outlet conditions of the three-dimensional numerical simulation of the three-dimensional train near-field region;

[0034] Step 4: Perform a three-dimensional unsteady numerical simulation on the three-dimensional train near-field area based on the time-varying pressure inlet condition and the time-varying pressure outlet condition to obtain the three-dimensional flow field pressure distribution and the three-dimensional flow field temperature distribution along the three-dimensional train near-field area in real time;

[0035] Step 5. The one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution in the far field area of ​​the one-dimensional pipeline in real time and the three-dimensional flow field pressure distribution and the three-dimensional flow field temperature distribution in the near field area of ​​the three-dimensional train in real time are spliced ​​and simulated to obtain the flow field pressure distribution and flow field temperature distribution after the high-speed train is spliced ​​throughout the pipeline.

[0036] The present invention regresses the far-field flow area with good quasi-one-dimensional characteristics to the quasi-one-dimensional numerical simulation, and resorts to three-dimensional numerical simulation for the near-field flow area of ​​the train with obvious three-dimensional characteristics, and performs flow splicing and suture between the flow areas. This method breaks through the bottleneck of existing numerical simulation methods, and can combine the advantages of quasi-one-dimensional numerical simulation, which is economical and fast, and three-dimensional numerical simulation, which is precise and accurate, taking into account the completeness and precision of flow field characterization, saving computing resources, and greatly improving computing efficiency. The present invention is suitable for the numerical simulation of the long-distance and long-term flow characteristics of high-speed trains running along the entire line in long pipelines.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The flow field splicing simulation method is more precise and accurate than the simple quasi-one-dimensional numerical simulation, and can well reproduce the flow, wave system and aerodynamic / thermal phenomena in the train neighborhood;

[0039] 2. The flow field splicing simulation method can be used to cleverly realize the full-scale simulation of long-distance and long-term operation of the entire line using the limited train near-field calculation domain;

[0040] 3. Compared with simple three-dimensional numerical simulation, it is more economical and faster. Taking a high-speed train running at a speed of 1000km / h in a 200km long pipeline as an example, the number of computational grids of the flow field splicing simulation method is only 1 / 100 of the full-domain three-dimensional numerical simulation, and the calculation time is only about 1 / 200. The calculation cost is small and the calculation efficiency is greatly improved.

[0041] According to an embodiment of the present invention, in step 1, the range of the three-dimensional train near field area is [x back , x front ], where x back The n is the radius from the midpoint of the train to the rear. 1 times the vehicle length, x front The midpoint of the train head and tail radiates forward n 2 times the vehicle length, n 1 The value range of n is 1 to 10. 2 The value range of is 1 to 10. The range of the one-dimensional pipeline far field is (x front , L tube ) and (0, x back ), where L tube is the pipe length.

[0042] For example, assume the length of the train is L train , and the real-time moving position of the train center is x train (t), n 1 Take 5.5, n 2 Take 1.5, then the area from 1.5 times the train length in front of the train to 5.5 times the train length behind the train is (x train (t) - 5.5L train ≤x≤x train (t) + 1.5L train ); The far-field area of the pipeline has two parts: the area in front of the train x train (t) + 1.5L train <x<L tube and the area behind the train 0<x<x train (t) - 5.5L train .

[0043] In this embodiment, the near-field area of the train is also the train neighborhood, and the far-field area of the pipeline is also the area far from the train.

[0044] To further understand the present invention, the following combines Figure 1 and Figure 4 to describe in detail the splicing simulation method of the flow field of a high-speed train in a long pipeline of the present invention.

[0045] In this embodiment, the flow field of a high-speed train running the whole line in a 200,000 m long closed pipeline is investigated. Among them, the high-speed train runs in a lying-rail type groove and is covered with a circular pipeline. The equivalent cross-section of the pipeline is 23.8 m 2 , and the inside of the pipeline is a low-vacuum environment of 12 kPa; the high-speed train is a single-section 34 m long bullet-shaped head, and the maximum cross-section in the middle of the train is 8.2 m 2 , the initial position is 200 m away from the end of the pipeline, the train operation mode is "uniform acceleration → uniform speed → uniform deceleration", and the acceleration during the acceleration and deceleration process is ±1 m / s 2 , and the speed during the uniform cruising stage is 1000 km / h. It is calculated from this that the one-way running time of the train is nearly 1000 s.

[0046] For step one, the real-time moving position of the train center is x train (t), and the area from 60 m in front of the train to 160 m behind the train (x train (t) - 160 ≤ x ≤ x train (t) + 60) is delimited as the near-field area of the train, then the far-field area of the pipeline is: the area in front of the train x train (t) + 60 < x < 200000 and the area behind the train 0 < x < x train (t) - 160.

[0047] For step 2, a quasi-one-dimensional numerical simulation of the entire flow field during the train operation process is carried out. See Figure 2, which is a distribution cloud diagram of the pressure and temperature xt of the entire flow field obtained by quasi-one-dimensional calculation.

[0048] For step 3, according to the far-field area of ​​the pipeline and the near-field area of ​​the train divided in step 1, the flow field pressure and temperature distribution at the far-field boundary of the pipeline is intercepted and obtained from the flow field in Figure 2 as the boundary conditions for the near-field simulation of the train in the next step. See Figure 3, which is the pressure and temperature evolution curves over time at the position 60m in front of the train and 160m behind the train in Figure 2.

[0049] For step 4, the pressure and temperature at the position 60m in front of the train obtained by the quasi-one-dimensional numerical simulation in step 2 are used as the time-varying pressure inlet conditions of the three-dimensional numerical simulation of the train near field, and the pressure and temperature at the position 160m behind the train are used as the time-varying pressure outlet conditions of the three-dimensional numerical simulation of the train near field. In this way, the three-dimensional unsteady numerical simulation of the train near field is carried out to obtain the real-time flow field parameter distribution of the train near field. See Appendix Figure 4 , is the distribution of the near-field pressure cloud map of the train at a typical time t=600s obtained by the splicing numerical simulation method. Under high-speed operation, the flow is congested, and the train wake area is the most complex flow area, resulting in shock wave trains, flow separation, shock wave-boundary layer interference and other phenomena.

[0050] The present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements any of the above methods when executing the computer program.

[0051] In summary, the present invention provides a method for simulating the splicing of a high-speed train flow field in a long pipeline. Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. The flow field splicing simulation method is more precise and accurate than the simple quasi-one-dimensional numerical simulation, and can well reproduce the flow, wave system and aerodynamic / thermal phenomena in the train neighborhood;

[0053] 2. The flow field splicing simulation method can be used to cleverly realize the full-scale simulation of long-distance and long-term operation of the entire line using the limited train near-field calculation domain;

[0054] 3. Compared with simple three-dimensional numerical simulation, it is more economical and faster. Taking a high-speed train running at a speed of 1000km / h in a 200km long pipeline as an example, the number of computational grids of the flow field splicing simulation method is only 1 / 100 of the full-domain three-dimensional numerical simulation, and the calculation time is only about 1 / 200. The calculation cost is small and the calculation efficiency is greatly improved.

[0055] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0056] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0057] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0058] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for simulating the flow field of a high-speed train in a long pipeline, characterized in that: The method comprises: Based on the dimensional characteristics of the flow field, the entire flow field of the high-speed train is divided into two regions: the one-dimensional pipeline far field and the three-dimensional train near field. The three-dimensional train near field is the area radiating several times the length of the train forward and backward with the midpoint of the front and rear of the train as the center, and the one-dimensional pipeline far field is the area except the three-dimensional train near field. The quasi-one-dimensional numerical simulation of the entire flow field of the high-speed train is carried out to obtain the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the entire line in the pipeline in real time, and the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the far field area of ​​the one-dimensional pipeline in real time are extracted; The one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution at the starting position of the three-dimensional train near-field region obtained by the quasi-one-dimensional numerical simulation are used as the time-varying pressure inlet conditions of the three-dimensional numerical simulation of the three-dimensional train near-field region, and the one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution at the ending position of the three-dimensional train near-field region obtained by the quasi-one-dimensional numerical simulation are used as the time-varying pressure outlet conditions of the three-dimensional numerical simulation of the three-dimensional train near-field region; Based on the time-varying pressure inlet conditions and the time-varying pressure outlet conditions, a three-dimensional unsteady numerical simulation is performed on the three-dimensional train near-field area to obtain the three-dimensional flow field pressure distribution and three-dimensional flow field temperature distribution along the three-dimensional train near-field area in real time; The one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the far-field area of ​​the one-dimensional pipeline in real time and the three-dimensional flow field pressure distribution and three-dimensional flow field temperature distribution along the near-field area of ​​the three-dimensional train in real time are spliced ​​and simulated to obtain the flow field pressure distribution and flow field temperature distribution of the high-speed train after splicing the entire line in the pipeline.

2. The method according to claim 1, characterized in that The range of the three-dimensional train near field area is [x back , x front ], where x back The position radiating backward from the midpoint of the train head and tail is n1 times the length of the train, x front It is the position radiating forward from the midpoint of the front and rear of the train to a distance of n2 times the train length. The value range of n1 is 1 to 10, and the value range of n2 is 1 to 10.

3. The method according to claims 1 and 2, characterized in that The range of the one-dimensional pipeline far field region is (x front , L tube ) and (0, x back ), where L tube is the pipe length.

4. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 3 is implemented.

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