Pantograph guide resistance reduction structure and high-speed train

Abstract

The application provides a sunken pantograph pan structure and a high-speed train, and relates to the field of rail vehicles, which comprises: a pan formed by a downward recess of a train roof; at least one drag reduction unit, the drag reduction unit comprising a flow passage inlet and a flow passage outlet, the flow passage inlet being arranged on the rear wall of the pan, the flow passage outlet being arranged on the train roof downstream of the pan, a drag reduction flow passage being in communication between the flow passage inlet and the flow passage outlet, the top wall and the bottom wall of the drag reduction flow passage being respectively fitted by double Boltzmann functions, the application can relieve the problem of increased resistance of the pan itself caused by high-speed airflow impact, the drag reduction unit can greatly reduce the resistance of the pantograph system and the whole train without changing the overall layout of the pantograph system and the smooth characteristics of the train body, and is helpful to improve the drag reduction and noise reduction level of the high-speed train.

Description

Technical Field

[0001] This invention relates to the field of rail vehicles, and in particular to a sunken pantograph basin current guiding and drag reduction structure and a high-speed train. Background Technology

[0002] The ever-increasing speeds of high-speed trains have brought about increasingly significant aerodynamic problems. Studies have shown that aerodynamic drag is proportional to the square of the speed, while aerodynamic noise is proportional to the sixth power of the speed. When the speed of a high-speed train exceeds the critical speed (generally 300 km / h), aerodynamic noise becomes the dominant component of train noise. When the speed of a high-speed train increases from 350 km / h to 400 km / h, the total drag increases by 28.8%, with aerodynamic drag accounting for a significant increase to 92%. The sharply rising aerodynamic drag has become one of the main factors restricting further increases in train speed and hindering energy conservation. Further reducing operational aerodynamic drag is a key issue facing even higher-speed trains. Research has found that in a high-speed train consisting of 8 CRH3 cars operating at 350 km / h without crosswinds, the aerodynamic drag of the pantograph system accounts for 12% of the total aerodynamic drag, making it one of the main sources of aerodynamic drag in high-speed trains.

[0003] The recessed pantograph (A) is an important method for optimizing pantograph systems, offering good drag reduction and noise reduction effects, but it also has shortcomings. To better reduce the aerodynamic effects of the pantograph, a deeper pantograph (A) design is often adopted. However, this leads to significant pressure drag and internal pressure oscillations within the pantograph (A), limiting the improvement of drag reduction and noise reduction performance. Especially under higher speed operating conditions, the aerodynamic drag and noise degradation effects of this recessed pantograph (A) become increasingly significant due to the strong impact of high-speed airflow on the rear wall of the pantograph (A). Considering the widespread use of the recessed pantograph (A) design in existing high-speed trains, it is necessary to explore new drag reduction mechanisms and optimization methods for this type of pantograph (A), providing important references for drag reduction in pantograph systems of high-speed and higher-speed trains. Summary of the Invention

[0004] This invention provides a recessed pantograph basin current guiding and drag reduction structure and a high-speed train, the purpose of which is to solve the problem that the aerodynamic drag and noise deterioration of the recessed pantograph basin are more serious when the train is running at high speed.

[0005] To achieve the above objectives, embodiments of the present invention provide a recessed pantograph basin current-guiding and drag-reducing structure, comprising:

[0006] The bow basin is formed by a downward indentation in the top wall of the train.

[0007] At least one drag reduction unit, the drag reduction unit comprising a flow channel inlet and a flow channel outlet, the flow channel inlet being arranged on the rear sidewall of the pantograph, the flow channel outlet being arranged on the roof of the train downstream of the pantograph, a drag reduction flow channel being communicated between the flow channel inlet and the flow channel outlet, the top wall and the bottom wall of the drag reduction flow channel being respectively fitted by double Boltzmann functions.

[0008] Preferably, the cross sections of the flow channel inlet and the flow channel outlet are rectangular.

[0009] Preferably, the flow channel inlet is formed by extending upward along the rear sidewall of the pantograph from the bottom wall of the pantograph, and the flow channel outlet is tangent to the roof of the train downstream of the pantograph.

[0010] Preferably, a plurality of the drag reduction units are arranged, and the plurality of flow channel inlets are arranged in the spanwise direction of the train.

[0011] Preferably, the opening area proportions of the flow channel inlets at the two ends of the spanwise direction to the middle of the plurality of drag reduction units are increasing.

[0012] When the number of the drag reduction units is even, the opening areas of the flow channel inlets at the two ends of the spanwise direction are the same or different.

[0013] When the number of the drag reduction units is odd, the opening areas of the flow channel inlets at the two ends of the spanwise direction are the same.

[0014] Preferably, the width proportions of the plurality of flow channel inlets are increasing.

[0015] Preferably, the plurality of flow channel outlets are arranged in the spanwise direction of the roof of the train in an arc shape.

[0016] Preferably, the double Boltzmann functions are as follows:

[0017]

[0018] Wherein, y0 is an offset, A represents a vertical span, x 01 is the horizontal coordinate of the first segment distribution center 1 of the upper wall or the lower wall of the drag reduction flow channel, x 02 is the horizontal coordinate of the second segment distribution center 2 of the upper wall or the lower wall of the drag reduction flow channel, k1 is a slope factor at the first segment distribution center point, k2 is a slope factor at the second segment distribution center point, and p is the proportion of the first segment distribution to the total distribution.

[0019] The application also provides a high-speed train adopting the pantograph guide flow drag reduction structure as described above.

[0020] The above scheme of the application has the following beneficial effects:

[0021] The sinking pantograph bow guide flow resistance reduction structure provided by the application can alleviate the problem of increased resistance of the pantograph bow itself caused by high-speed airflow impact, and the resistance reduction unit can greatly reduce the pantograph system and the whole vehicle resistance without changing the overall layout of the pantograph system and the smooth characteristics of the vehicle body, which helps to improve the high-speed train resistance reduction and noise reduction level.

[0022] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is an axonometric view of the bow part;

[0024] Figure 2 is a sectional view of the sinking pantograph bow guide flow resistance reduction structure;

[0025] Figure 3 is a sampling point of the resistance reduction flow channel of the present application;

[0026] Figure 4 is a fitting curve of the resistance reduction flow channel of the present application

[0027] Figure 5 is the pressure distribution of the original model and the optimized model at 30° view angle;

[0028] Figure 6 is the pressure distribution of the original model and the optimized model at the overhead view angle;

[0029] Figure 7 is the velocity distribution of the longitudinal section of the original model and the optimized model.

[0030]

BRIEF DESCRIPTION OF REFERENCE NUMERALS

[0031] 1-flow channel inlet, 2-flow channel outlet, 3-resistance reduction flow channel.

[0032] A-pantograph bow. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and advantages of the present application more clear, the following will be described in detail with reference to the drawings and specific embodiments.

[0034] Reference Figures 1-2As shown, the application provides a sinking pantograph bow basin flow guiding and drag reducing structure, which comprises a bow basin A and a drag reducing unit, wherein the bow basin A is formed by downward concave of the train roof wall, and the concave of the bow basin A forms a front side wall and a rear side wall. The aforementioned drag reducing unit comprises a flow channel inlet 1 and a flow channel outlet 2, wherein the flow channel inlet 1 is arranged in the bow basin A, specifically on the rear side wall, and the flow channel outlet 2 is arranged on the train roof, specifically downstream of the bow basin A. The drag reducing flow channel 3 connecting the flow channel inlet 1 and the flow channel outlet 2 comprises a top wall and a bottom wall, which are respectively fitted by double Boltzmann functions.

[0035] Specifically, referring to Figure 3 and Figure 4 , the double Boltzmann function is:

[0036]

[0037] The overall shape of the double Boltzmann function is approximately S-shaped two-section, comprising a first curve and a second curve, wherein y0 represents the offset, here referring to the vertical height of the two curves of the drag reducing flow channel 3 from the coordinate origin, A represents the vertical span, here referring to the vertical height of the starting point to the ending point of the upper or lower wall of the drag reducing flow channel 3, x 01 The horizontal coordinate of the distribution center 1 of the first section in the upper or lower wall of the drag reducing flow channel 3, x 02 The horizontal coordinate of the distribution center 2 of the second section, k1 is the slope factor at the distribution center point of the first section, k2 is the slope factor at the distribution center point of the second section, and p is the proportion of the first section distribution to the total distribution.

[0038] In the application, the high-pressure airflow extruded in the bow basin A is guided to the downstream of the bow basin A through the drag reducing unit, which can greatly reduce the aerodynamic drag and pressure oscillation of the bow basin A itself without affecting the overall layout of the pantograph system and the smoothness of the car body, and can also alleviate the pressure oscillation in the basin, achieving the purpose of noise reduction and drag reduction.

[0039] Further, the drag reducing flow channel 3 optimized based on the double Boltzmann function distribution can maximize the total pressure loss of the airflow, and use Bernoulli's principle to improve the passing efficiency of the airflow, having good flow control ability and pressure relief performance.

[0040] In the embodiment, the cross sections of the flow channel inlet 1 and the flow channel outlet 2 are both rectangular, the flow channel inlet 1 is formed by extending upward along the rear side wall of the bow basin A from the bottom wall of the bow basin A, and the flow channel outlet 2 is tangent to the train roof wall downstream of the bow basin A.

[0041] Under the joint action of the rectangular cross section and the extension from the bottom wall as the starting end, the high pressure in the arch A can be fully guided to the train roof wall downstream of the arch A. When there is water, snow and the like in the arch A, the water and snow can also be guided out of the arch A under the guidance of the flow channel 3.

[0042] Considering the state of bidirectional running of the train, when the train runs reversely, the flow channel outlet 2 is tangent to the train roof wall, the flow pressure difference between the train roof wall and the front side wall in the arch A is small, the train roof wall smoothness does not change, and thus the airflow entering the arch from the flow channel outlet 2 is small, which does not affect the train resistance.

[0043] In the present application, at least one resistance reduction unit is included, and a plurality of flow channel inlets 1 are uniformly arranged on the rear side wall of the arch A along the train span direction. It is emphasized that the uniform arrangement here means that the interval distances of the plurality of flow channel inlets 1 in the span direction are the same. The span direction refers to the width direction of the train, that is, the direction perpendicular to the train running direction.

[0044] Further, the opening area proportion of the flow channel inlets 1 at both ends of the span direction to the middle of the plurality of resistance reduction units increases in proportion, and the increasing proportion is determined based on the span length of the arch A and the number of resistance reduction units. When the number of resistance reduction units is even, the opening areas of the flow channel inlets 1 at both ends of the span direction can be the same or different. When the number of resistance reduction units is odd, the opening areas of the flow channel inlets 1 at both ends of the span direction are the same.

[0045] The proportional increasing mode can relieve the pressure of the rear side wall of the arch A, and the uniform relief of the pressure of the rear side wall of the arch A avoids the formation of turbulence in the arch A due to flow guiding.

[0046] In the present embodiment, the heights of the flow channel inlets 1 are the same, and the opening areas of the flow channel inlets 1 are changed by changing the span length of the flow channel inlets 1. Maintaining the same height of the flow channel inlets 1 helps to maintain the rigidity of the train roof wall and reduce the influence of the opening on the train roof wall.

[0047] Further, a plurality of flow channel outlets 2 are arranged in an arc shape along the span direction on the train roof wall. The arc-shaped arrangement of the flow channel outlets 2 can relieve the turbulence and turbulence above the train caused by the simultaneous flow guiding of the plurality of flow channel outlets 2, and avoid the generation of new running resistance of the train.

[0048] In the present embodiment, eight resistance reduction units are used to analyze the resistance suffered by a three-section train (the head car, the middle car and the tail car, and the arch is arranged at the top of the middle car).

[0049] The double Boltzmann function is based on the Boltzmann distribution accumulation, and the specific function expression is as follows:

[0050]

[0051] The initial width of the flow channel entrance 1 on both sides is 110mm, the width of the flow channel entrance 1 towards the middle is 132mm, 154mm and 176mm in turn, and the height of the flow channel entrance 1 is 176.54mm.

[0052] Based on the determination of the position and opening area of the flow channel entrance 1, the flow channel entrance 1 is opened as a starting end, the top wall and the bottom wall of the flow channel 3 are fitted by double Boltzmann functions, and the flow channel exit 2 is formed on the curved surface at the top of the train. Figure 3

[0053] The flow channel 3 fitted by the double Boltzmann functions has the characteristics of gradually narrowing downstream, and the flow entering the channel can use the flow acceleration effect brought by Bernoulli's principle to help the high-pressure gas flow in the bow basin A to be discharged more quickly and smoothly.

[0054] Table 1 is the design size parameter of the channel air inlet:

[0055]

[0056]

[0057] The above scheme is numerically simulated and calculated by fluid mechanics software STAR CCM+:

[0058] (1) Calculation grid:

[0059] The cutting body grid is used, wherein the total grid amount is 38 million, the train body adopts four-level encryption, the grid scale of the encryption area is doubled, the grid scale of the first layer of the wrapped train is 0.16m, 12 layers of boundary layers are arranged on the surface of the train, and the full y+ function transition is used.

[0060] (2) Boundary conditions:

[0061] The calculation of the incoming flow velocity is 111.11m / s, that is, 400km / h.

[0062] In the present application, the bow basin A with the flow resistance reduction unit is used, compared with the original working condition without the channel, the system resistance relief rate reaches 10.77%, and the maximum resistance relief rate of the single pantograph bow basin A reaches 28.84%.

[0063] Table 2 is the resistance coefficient and resistance relief rate of each part of the original bow basin and the optimized bow basin train body:

[0064]

[0065] As shown in Table 2, the basin resistance is obviously reduced after the flow resistance reduction unit is added, and the whole train resistance relief rate reaches 2.03%. Further, combined with Figure 5 ​and 6 As shown in the pressure distribution, the positive pressure distribution area of the rear edge of the arch basin A is greatly reduced, and the positive pressure amplitude is weakened. Combined with the pressure distribution of the rear edge of the arch basin A of the prior art, it can be seen that the pressure distribution of the rear edge of the arch basin A is greatly improved. Figure 7 As shown in the velocity distribution, the velocity flow field of the rear edge of the arch basin A changes, and the airflow acceleration effect in the drag reduction channel 3 is obvious, which proves that the design scheme of the drag reduction channel 3 is beneficial to drag reduction.

[0066] The application also provides a high-speed train adopting the sunken pantograph arch basin flow guide drag reduction structure. The sunken pantograph arch basin flow guide drag reduction structure is arranged at the arch basin A of the pantograph in the train set, and the sunken pantograph arch basin flow guide drag reduction structure is directionally symmetrical, so that the sunken pantograph arch basin flow guide drag reduction structure can play a role in reducing drag and noise when the high-speed train runs forward and reversely.

[0067] The above is the preferred embodiment of the application. It should be pointed out that for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be regarded as the protection scope of the application.

Claims

1. A recessed pantograph basin current-guiding and drag-reducing structure, characterized in that, The utility model relates to a kind of structures of reducing drag of sunken pantograph, including: Bow basin (A), is formed by train top wall downward concave; At least one drag reduction unit, the drag reduction unit includes flow passage entrance (1) and flow passage exit (2), the flow passage entrance (1) is arranged in the rear side wall of the bow basin (A), the flow passage exit (2) is arranged on the train top wall downstream of bow basin (A), the flow passage entrance (1) and the flow passage exit (2) are communicated with drag reduction flow channel (3), the top wall and the bottom wall of the drag reduction flow channel (3) are fitted by double Boltzmann function respectively; The flow passage entrance (1) is formed by the bottom wall of bow basin (A) as the beginning end and extends upwards along the rear side wall of bow basin (A), and the flow passage exit (2) is tangent to the train top wall downstream of bow basin (A); The drag reduction unit is provided with multiple, multiple flow passage entrances (1) are arranged uniformly along the span of train; The opening area proportion of flow passage entrance (1) at both ends of span to middle of multiple drag reduction units increases gradually; When the number of the drag reduction unit is double, the opening area of flow passage entrance (1) at both ends of span is same or different; When the number of the drag reduction unit is single, the opening area of flow passage entrance (1) at both ends of span is same. The width proportion of multiple flow passage entrances (1) increases gradually.

2. The pantograph under-buoyant pantograph fairing structure of claim 1, wherein: The cross section of the flow passage entrance (1) and flow passage exit (2) is rectangular.

3. The pantograph under-buoyant pantograph fairing structure according to claim 1 or 2, characterized in that: Multiple flow passage exits (2) are arranged in arc shape along the span on the top wall of train.

4. The pantograph under-buoyant pantograph fairing structure of claim 1, wherein: The double Boltzmann function is as follows: wherein, is an offset, denotes a vertical span, is the abscissa of the first segment distribution center 1 of the upper or lower wall of the flow channel, is the abscissa of the second segment distribution center 2 of the upper or lower wall of the flow channel, is the slope factor at the first segment distribution center point, is the slope factor at the second segment distribution center point, is the fraction of the first segment distribution of the total distribution.

5. A high-speed train, characterized in that, The sunken pantograph guide flow drag reduction structure of any one of claims 1-4 is used.

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