A splicing simulation method for flow field of high-speed train in long pipeline

Abstract

The application provides a splicing simulation method for a high-speed train flow field in a long pipeline, and the method comprises the following steps: based on the dimension characteristics of the flow field, the whole flow field of the high-speed train is divided into a one-dimensional pipeline far field and a three-dimensional train near field; the whole flow field of the high-speed train is subjected to quasi-one-dimensional numerical simulation to obtain one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the whole line in the pipeline in real time; time-varying pressure inlet conditions and time-varying pressure outlet conditions are obtained; three-dimensional unsteady numerical simulation is performed to obtain three-dimensional flow field pressure distribution and three-dimensional flow field temperature distribution along the whole line in the three-dimensional train near field in real time; and splicing simulation is performed to obtain flow field pressure distribution and flow field temperature distribution of the high-speed train after splicing along the whole line in the pipeline. The application can solve the technical problem that the quasi-one-dimensional numerical simulation method and the three-dimensional numerical simulation method in the prior art cannot complement each other, and the precision and completeness of flow field description are difficult to be both good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of numerical simulation of large-scale pipe / tunnel flow, and particularly relates to a splicing simulation method for a high-speed train flow field in a long pipe. BACKGROUND

[0002] Low-vacuum tube train is one of the important development directions of future ground high-speed transportation. It adopts the means of low-vacuum tube covering the maglev train to greatly reduce the aerodynamic resistance, so that high subsonic speed and even supersonic ground transportation becomes possible. Unlike open line operation, long-distance operation of high-speed trains is limited in a very narrow pipe space, which usually induces transonic flow dominated by pipe flow congestion. The continuous propagation of disturbances such as motion shock wave and rarefaction wave will greatly extend the spatial and temporal scales of the flow. The flow can be large-scale in the pipe with a length of thousands of kilometers and centered on the high-speed train within a time span of several hours. This poses a significant challenge to the numerical simulation method of the flow field, and it is very important to explore new ways to suit the disease.

[0003] For the above characteristics of high-speed train flow field in long pipe, existing research mainly adopts two simplified simulation strategies. On the one hand, if based on the full field perspective, such pipe flow problems are well fitted to the quasi-one-dimensional assumption in most of the axial region, that is, ignoring the radial gradient of the flow and assuming that the flow in the same cross section of the pipe is uniform. Quasi-one-dimensional numerical simulation method is economical and fast for analyzing large-length-diameter ratio flow problems, but it cannot finely depict the complex geometric region near the train. On the other hand, if based on the train near field perspective with obvious three-dimensional characteristics, the flow analysis needs large-scale three-dimensional numerical simulation. Since these methods require a large amount of resources, it is difficult to realize full-scale simulation in a long distance and a long time, and they are only suitable for depicting three-dimensional flow phenomena in a very limited train neighborhood. However, the inherent problem is that the long-range propagation and attenuation process of the train front and rear disturbance should not be affected by the numerical boundary of limited distance, and the short-distance and short-time simulation lacks the completeness of the flow description, which is not enough to reflect the essence of long-range and long-time flow. It can be seen that the quasi-one-dimensional method is an important means for simulating the full field characteristics, while the three-dimensional numerical simulation method is irreplaceable for analyzing the train near field. The fineness and completeness of the flow field description 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 finely depict the complex geometric region near the train, that is, it lacks the fineness of flow field reproduction. The three-dimensional numerical simulation method requires a large amount of resources, and it is difficult to realize full-scale simulation in a long distance and a long time, and it is only suitable for depicting a very limited train neighborhood, that is, it lacks the completeness of flow field reproduction. The fineness and completeness of the flow field description are difficult to achieve in a single numerical simulation method, and it is very important to explore new ways to suit the disease. SUMMARY

[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 existing technology 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 pipe is provided, the method comprising:

[0007] Based on the dimensional characteristics of the flow field, the full flow field of the high-speed train is divided into two regions: a one-dimensional pipe far field and a three-dimensional train near field. The three-dimensional train near field is the area radiating several times the train length forward and backward from the midpoint of the train's front and rear ends, while the one-dimensional pipe far field is the area outside the three-dimensional train near field.

[0008] A quasi-one-dimensional numerical simulation of the entire flow field of a high-speed train is performed to obtain the real-time one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the entire pipeline, and to extract the real-time one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the far-field area of ​​the one-dimensional pipeline;

[0009] The one-dimensional flow field pressure distribution and 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 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 and outlet conditions, a three-dimensional unsteady numerical simulation of the three-dimensional train near-field area is performed 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 position of the train’s midpoint radiating backwards is n1 times the train length, x front The value range of n1 is 1 to 10, and the value range of n2 is 1 to 10.

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

[0014] According to still another aspect of the present application, there is provided a computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing any of the above methods when executing the computer program.

[0015] By applying the technical solution of the present application, the far-field flow region with good quasi-one-dimensional characteristics is returned to quasi-one-dimensional numerical simulation, the near-field flow region of the train with obvious three-dimensional characteristics is subjected to three-dimensional numerical simulation, and the flow regions are spliced and sutured. This method breaks through the bottleneck of the existing numerical simulation method, can combine the advantages of quasi-one-dimensional numerical simulation in economy and speed and three-dimensional numerical simulation in accuracy, and can take into account the completeness and fineness of the flow field description, save computing resources, and greatly improve the computing efficiency. The present application is suitable for numerical simulation of the long-range and long-time flow characteristics of the train running in a long pipeline.

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

[0017] 1. The flow field splicing simulation method is more accurate than the quasi-one-dimensional numerical simulation alone, and can well reproduce the train neighborhood flow, wave system and aerodynamic force / heat phenomenon;

[0018] 2. The flow field splicing simulation method can use the limited train near-field calculation domain to achieve full-scale simulation of long-range and long-time running on the whole line;

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

[0020] The accompanying drawings included to provide a further understanding of the embodiments of the present application and constitute a part of the specification, illustrate embodiments of the present application and together with the text description serve to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

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

[0022] Figure 2a A full flow field pressure distribution contour plot obtained from quasi-one-dimensional numerical simulation provided according to an embodiment of the present application is shown;

[0023] Figure 2b A full flow field temperature distribution contour plot obtained from quasi-one-dimensional numerical simulation provided according to an embodiment of the present application is shown;

[0024] Figure 3a A full flow field pressure distribution contour plot obtained from quasi-one-dimensional numerical simulation provided according to an embodiment of the present application is shown; Figure 2a A pressure evolution curve plot at a position 60 m in front of the train and a position 160 m behind the train;

[0025] Figure 3b A temperature evolution curve plot at a position 60 m in front of the train and a position 160 m behind the train; Figure 2b A temperature evolution curve plot at a position 60 m in front of the train and a position 160 m behind the train;

[0026] Figure 4 A train near field pressure distribution contour plot at a typical time t = 600 s obtained from a stitching numerical simulation method provided according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The description of the at least one exemplary embodiment is actually only illustrative, but not intended to limit the present application and its application or use in any way. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0028] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of a feature, step, operation, device, component and / or combinations thereof.

[0029] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples herein are not limitations on the scope of the application unless otherwise specified. It should also be understood that the size of the various parts shown in the drawings is not to scale for ease of illustration. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail but should be considered as part of the description of the application. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Thus, other examples of the exemplary embodiments can have different values. It should be noted that like numbers and letters refer to like elements throughout the several views of the drawings and that one or more specific embodiments can be substituted for others in the following discussion without departing from the scope of the application.

[0030] As shown in Figure 1 The present application provides a splicing simulation method for flow field of high-speed train in long pipeline, the method comprises:

[0031] Step one, based on the dimension characteristics of flow field, the full flow field of high-speed train is divided into one-dimensional pipeline far field and three-dimensional train near field two regions, wherein the three-dimensional train near field region is the region radiating several times the length of the train forward and backward respectively with the midpoint position of the train head and tail as the center, and the one-dimensional pipeline far field region is the region except the three-dimensional train near field;

[0032] Step two, quasi-one-dimensional numerical simulation is performed on the full flow field of high-speed train to obtain one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the pipeline in real time, and one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the pipeline in real time in the one-dimensional pipeline far field region are extracted;

[0033] Step three, the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution at the starting position of the three-dimensional train near field region obtained by quasi-one-dimensional numerical simulation are taken as the time-varying pressure import condition of three-dimensional numerical simulation of the three-dimensional train near field region, and the one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution at the terminal position of the three-dimensional train near field region obtained by quasi-one-dimensional numerical simulation are taken as the time-varying pressure export condition of three-dimensional numerical simulation of the three-dimensional train near field region;

[0034] Step four, based on the time-varying pressure import condition and the time-varying pressure export condition, three-dimensional unsteady numerical simulation is performed on the three-dimensional train near field region to obtain three-dimensional flow field pressure distribution and three-dimensional flow field temperature distribution along the pipeline in real time in the three-dimensional train near field region;

[0035] Step five, the one-dimensional flow field pressure distribution and the one-dimensional flow field temperature distribution of the one-dimensional pipe far-field region are spliced and simulated with the three-dimensional flow field pressure distribution and the three-dimensional flow field temperature distribution of the three-dimensional train near-field region, so that the flow field pressure distribution and the flow field temperature distribution of the high-speed train after the whole line splicing in the pipe are obtained.

[0036] The present application returns the far-field flow region with good quasi-one-dimensional characteristics to quasi-one-dimensional numerical simulation, resorts to three-dimensional numerical simulation for the train near-field flow region with obvious three-dimensional characteristics, and splices and stitches the flow regions. The method breaks through the bottleneck of the existing numerical simulation method, can combine the advantages of quasi-one-dimensional numerical simulation in economy and speed and three-dimensional numerical simulation in accuracy, takes into account the completeness and accuracy of flow field description, saves computing resources, and greatly improves the computing efficiency. The present application is suitable for numerical simulation of long-range and long-time flow characteristics of high-speed trains running in long pipes.

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

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

[0039] 2. The flow field splicing simulation method can realize full-scale simulation of long-range and long-time running of the whole line by using limited train near-field calculation domain;

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

[0041] According to an embodiment of the present application, in step one, the range of the three-dimensional train near-field region is [x back , x front ], wherein x back is the position of the midpoint of the train head and tail radiating n1 times the length of the train to the rear, x front is the position of the midpoint of the train head and tail radiating n2 times the length of the train to the front, n1 is in the range of 1-10, and n2 is in the range of 1-10. The range of the one-dimensional pipe far-field region is (x front , L tube ) and (0, x back ), wherein L tube is the length of the pipe.

[0042] For example, assuming that the length of the train is L train , and the real-time movement position of the train center is x train(t), n1 is 5.5, and n2 is 1.5, the region from the front of the train to 1.5 times the length of the train to the rear of the train 5.5 times the length of the train is (x train (t)-5.5L train ≤x≤x train (t)+1.5L train ); the far field region of the pipe has two parts: the front region of the train x train (t)+1.5L train <x<L tube and the rear region of the train 0<x<x train (t)-5.5L train .

[0043] In this embodiment, the near field region of the train is the vicinity of the train, and the far field region of the pipe is the region far from the train.

[0044] In order to have a further understanding of the present application, the following Figure 1 and Figure 4 The method for splicing simulation of the flow field of a high-speed train in a long pipe is described in detail.

[0045] In this embodiment, the flow field of a high-speed train running in a 200000m long closed pipe is investigated. The high-speed train runs in a concave groove of a sleeper track and is covered by a circular pipe, and the equivalent cross section of the pipe is 23.8m 2 , and the pipe is in a low vacuum environment of 12kPa; the high-speed train is a single 34m long bullet-shaped train, and the maximum cross section of the middle part of the train is 8.2m 2 ; the initial position is 200m away from the end of the pipe, and the running mode of the train is "uniform acceleration→uniform speed→uniform deceleration"; the acceleration during the acceleration and deceleration processes is ±1m / s 2 , and the speed during the uniform speed cruising stage is 1000km / h. Thus, the running time of the train for a single trip is nearly 1000s.

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

[0047] For step two, the full flow field of the train running process is simulated quasi-one-dimensionally, and the x-t distribution cloud map of the full flow field pressure and temperature obtained by quasi-one-dimensional calculation is shown in FIG. 2.

[0048] For step three, according to the pipe far-field region and the train near-field region divided in step one, the flow field pressure and temperature distribution at the pipe far-field boundary are cut from the flow field in figure 2 and obtained as the boundary condition of the next step train near-field simulation. Referring to figure 3, the pressure and temperature evolution curves at the position 60m in front of the train and the position 160m behind the train in figure 2 are shown.

[0049] For step four, the pressure and temperature at the position 60m in front of the train obtained by the quasi-one-dimensional numerical simulation in step two are taken as the time-varying pressure inlet condition of the train near-field three-dimensional numerical simulation, and the pressure and temperature at the position 160m behind the train are taken as the time-varying pressure outlet condition of the train near-field three-dimensional numerical simulation, so that the train near-field three-dimensional unsteady numerical simulation is carried out to obtain the real-time flow field parameter distribution in the train near-field. Figure 4 For the train near-field pressure cloud distribution at a typical time t=600s obtained by using the splicing numerical simulation method, under high-speed running, the flow is in congestion, and the train wake flow area is the most complex flow area, and phenomena such as shock wave string, flow separation, shock wave-boundary layer interference and the like are generated.

[0050] The application further provides a computer device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor realizes the method described above when executing the computer program.

[0051] In summary, the application provides a splicing simulation method for the flow field of a high-speed train in a long pipe, and compared with the prior art, the application has the following beneficial effects:

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

[0053] 2. The flow field splicing simulation method can realize full-scale simulation of long-time running on a full line by using a limited train near-field calculation domain.

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

[0055] The part not described in detail in the application is the technology known to those skilled in the art.

[0056] In the description of the application, it should be understood that the orientation words such as "front, back, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the scope of protection of the application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0057] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0058] In addition, it should be noted that the use of "first", "second" and the like to define parts only facilitates the differentiation of corresponding parts, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as a limitation on the scope of protection of the application.

[0059] The above only describes the preferred embodiments of the application and is not intended to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the scope of protection of the application.

Claims

1. Based on the dimensional characteristics of the flow field, the high-speed train flow field is divided into two regions: the one-dimensional pipeline far field and the three-dimensional train near field. The three-dimensional train near-field area is the area radiating several times the train length forward and backward from the midpoint of the train's front and rear ends. The one-dimensional pipeline far-field area is the area outside the three-dimensional train near-field area. A quasi-one-dimensional numerical simulation of the entire flow field of a high-speed train is performed to obtain the real-time one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the entire pipeline, and to extract the real-time one-dimensional flow field pressure distribution and one-dimensional flow field temperature distribution along the far-field area of ​​the one-dimensional pipeline; The one-dimensional flow field pressure distribution and 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 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 and outlet conditions, a three-dimensional unsteady numerical simulation of the three-dimensional train near-field area is performed 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 of the train’s midpoint radiating backwards is n1 times the train length, 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 1~10, and the value range of n2 is 1~10.

3. The method according to claim 1 or 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, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 3 is implemented.

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