CN114454905B - Train and train drag reduction method for controlling tail vortex drag reduction by utilizing blowing - Google Patents

Train and train drag reduction method for controlling tail vortex drag reduction by utilizing blowing Download PDF

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CN114454905B
CN114454905B CN202111591987.5A CN202111591987A CN114454905B CN 114454905 B CN114454905 B CN 114454905B CN 202111591987 A CN202111591987 A CN 202111591987A CN 114454905 B CN114454905 B CN 114454905B
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train
drag
air
reduced
tail
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CN114454905A (en
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周忠宝
杨清源
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61D—BODY DETAILS OR KINDS OF RAILWAY VEHICLES
    • B61D17/00—Construction details of vehicle bodies
    • B61D17/02—Construction details of vehicle bodies reducing air resistance by modifying contour ; Constructional features for fast vehicles sustaining sudden variations of atmospheric pressure, e.g. when crossing in tunnels
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/15—Vehicle, aircraft or watercraft design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/10—Numerical modelling
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T30/00—Transportation of goods or passengers via railways, e.g. energy recovery or reducing air resistance

Abstract

The invention discloses a train and a train drag reduction method for controlling tail vortex drag reduction by utilizing blowing, wherein a blowing port is arranged between an air separation line and an air reattachment line at the tail of the train, the blowing port is respectively connected with an air outlet of a waste exhaust fan of each train section of the train, waste gas of each train section of the train to be drag-reduced is collected, and the waste gas of each train section of the train is concentrated and blown out through the blowing port, so that the waste gas of the train can be fully utilized, and the resistance born by the train in the running process can be effectively reduced.

Description

Train and train drag reduction method for controlling tail vortex drag reduction by utilizing blowing
Technical Field
The invention relates to the technical field of train drag reduction, in particular to a train and a train drag reduction method for controlling tail vortex drag reduction by utilizing blowing.
Background
How to ensure that the aerodynamic resistance of the train is reduced as much as possible on the premise of high-speed running, and has important basic research value and engineering application significance for saving running energy and reducing the later running cost of the high-speed train. At present, in order to improve space utilization rate, short streamline length is used for subway trains and inter-city motor train units with large passenger capacity requirements in China, which means that large aerodynamic resistance is faced in the running process of the trains. In general, through regulating and controlling flow phenomena such as transition, separation, vortex and the like of a flow field around a train, local flow can be changed, so that the aim of drag reduction is fulfilled. In the existing train drag reduction method, an eddy current controller is generally arranged at the tail part to change tail eddy current for drag reduction, however, the eddy current controller has the defects of complex manufacture, high cost, high installation requirement, large influence on the appearance of the train and the like.
Usually, the train has higher fresh air inflow and exhaust emission for guaranteeing the comfort of passengers. At present, two main emission modes of waste gas of a train exist: one is discharged from the bottom of the vehicle to the outside through a special exhaust fan; another way is for a train with poor partial tightness to leak its exhaust gas directly through the body joints, car joints, etc. Neither approach uses such exhaust gases and even requires special power to the exhaust system to keep it operating stably, which adds significantly to the running cost of the train.
Therefore, how to effectively utilize the exhaust gas and solve the problem of high cost of the existing train drag reduction method has become a technical problem to be solved by those skilled in the art.
Disclosure of Invention
The invention provides a train and a train drag reduction method for controlling tail vortex drag reduction by utilizing blowing, which are used for solving the technical problems of low utilization rate of existing waste gas and high cost of the existing train drag reduction method.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a train for controlling tail vortex drag reduction by utilizing blowing is characterized in that a blowing port is arranged between an air separation line and an air reattachment line at the tail of the train, and the blowing port is respectively connected with an air outlet of a waste exhaust fan of each section of vehicle of the train and is used for collecting waste gas of each section of carriage and discharging the waste gas outwards from the tail.
Preferably, the air blowing openings are arranged at the transition part of the constant-section vehicle body and the streamline tail part of the train to be drag-reduced and are annularly arranged.
Preferably, the air blowing openings blow out at a uniform rate.
A train drag reduction method for controlling tail vortex by blowing comprises the following steps:
when a train to be drag-reduced runs, an air separation line and an air reattachment line at the tail part of the train to be drag-reduced are obtained;
an air blowing port is arranged between an air separation line and an air reattachment line at the tail part of the train to be drag-reduced;
and collecting the exhaust gas of each section of vehicle of the train to be drag-reduced, and intensively blowing out the exhaust gas of each section of vehicle through the air blowing port.
Preferably, the air blowing openings are arranged at the transition part of the constant-section vehicle body and the streamline tail part of the train to be drag-reduced and are annularly arranged.
Preferably, the air blowing openings blow out at a uniform rate.
Preferably, an air separation line and an air reattachment line at the tail part of the train to be drag-reduced are obtained when the train to be drag-reduced runs; the method comprises the following steps:
constructing a geometric model of a train to be drag-reduced and a calculation domain of aerodynamic characteristic numerical simulation, and performing grid dispersion on the geometric model and the calculation domain;
constructing a pneumatic characteristic numerical model of the train during the running of the geometric model based on the train geometric model after grid discretization and a calculation domain;
setting boundary conditions of a calculation domain, and simulating separation flow of air at the tail of a train to be subjected to drag reduction when the train to be subjected to drag reduction runs by using a pneumatic characteristic numerical model;
and determining an air separation line and an air reattachment line at the tail part of the train to be drag-reduced according to the simulation result of the aerodynamic characteristic numerical model.
Preferably, the area of the complex geometric shape of the calculation domain is scattered by adopting an unstructured tetrahedral grid, and other areas in the calculation domain are scattered by adopting a structured hexahedral grid.
Preferably, the aerodynamic property numerical model simulates turbulent flow at the tail of the train by adopting a DDES method based on a k-epsilon turbulent flow model.
The invention has the following beneficial effects:
1. according to the train and the train drag reduction method for controlling tail vortex drag reduction by utilizing blowing, the air blowing ports are arranged between the air separation line and the air reattachment line at the tail part of the train, the air blowing ports are respectively connected with the air outlets of the exhaust fans of all the vehicles of the train, the exhaust gas of all the vehicles of the train to be drag-reduced is collected, and the exhaust gas of all the vehicles is concentrated and blown out through the air blowing ports, so that the exhaust gas of the train can be fully utilized, and the resistance born by the train in the running process can be effectively reduced.
In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. The invention will be described in further detail with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a prior art train surface flow diagram;
FIG. 2 is a schematic illustration of the position of a train gas outlet in a preferred embodiment of the invention;
FIG. 3 is a side view and an elevation view of a prior art train, wherein (a) is a side view; (b) is a front view;
FIG. 4 is a graph of the aerodynamic drag reduction rate of a train after use of the train drag reduction method utilizing blow-out to control tail vortex in a preferred embodiment of the present invention;
FIG. 5 is a graph comparing the pressure distribution of the flow field of the present invention with that of the original working condition, wherein (a) is the original flow field pressure cloud; (b) is a flow field pressure cloud image after using the blowing method;
FIG. 6 is a graph comparing the velocity profile of the flow field of the present invention with that of the original operating mode, wherein (a) is the original flow field velocity cloud; (b) is a flow field velocity cloud after using the blowing method.
Detailed Description
Embodiments of the invention are described in detail below with reference to the attached drawings, but the invention can be implemented in a number of different ways, which are defined and covered by the claims.
Embodiment one:
the train comprises a train tail air separation line, an air reattachment line, a train tail air separation line, a train tail air reattachment line, a train tail vortex drag reduction control device, a train tail air separation line, a train tail air reattachment line, a train tail air separation line, a train tail vortex drag reduction control device and a train tail air reattachment line.
In addition, in the embodiment, a train drag reduction method for controlling tail vortex by blowing is also disclosed, which comprises the following steps:
when a train to be drag-reduced runs, an air separation line and an air reattachment line at the tail part of the train to be drag-reduced are obtained;
an air blowing port is arranged between an air separation line and an air reattachment line at the tail part of the train to be drag-reduced;
and collecting the exhaust gas of each section of vehicle of the train to be drag-reduced, and intensively blowing out the exhaust gas of each section of vehicle through the air blowing port.
According to the train and the train drag reduction method for controlling tail vortex drag reduction by utilizing blowing, the air blowing ports are arranged between the air separation line and the air reattachment line at the tail part of the train, the air blowing ports are respectively connected with the air outlets of the exhaust fans of all the vehicles of the train, the exhaust gas of all the vehicles of the train to be drag-reduced is collected, and the exhaust gas of all the vehicles is concentrated and blown out through the air blowing ports, so that the exhaust gas of the train can be fully utilized, and the resistance born by the train in the running process can be effectively reduced.
Embodiment two:
embodiment two is a preferred embodiment of embodiment one, which differs from embodiment one in that the specific steps of the train drag reduction method using blowing to control tail vortex are described, and specifically includes the following steps:
at present, for improving space utilization rate, short streamline length is used for meeting the requirement of high passenger capacity of subway trains and inter-city motor train units, so that large aerodynamic resistance is faced in the running process of the trains. Meanwhile, the train has higher fresh air inflow and exhaust emission for ensuring the comfort of passengers. The waste disposal system on the train is not well utilized at present, and even special energy supply for the waste disposal system is needed to keep the waste disposal system stably working.
The invention aims to provide a train drag reduction method for controlling tail vortex by utilizing blowing, which is characterized in that waste gas provided by a waste exhaust fan is collected and concentrated to tail discharge of a train, and by combining a local flow control technology, boundary layer separation at the tail of the train is controlled by a blowing mode, turbulent vortex is weakened, and the thickness of an attached surface layer is reduced, so that the drag reduction purpose is achieved. The drag reduction method for the train comprises the following specific steps:
1) Constructing a calculation model and setting calculation conditions
And selecting a blunt-end-shaped subway train as a calculation model, and calculating the train resistance by using a blowing method. The setting of the calculation domain is consistent with the calculation setting of a conventional wind blowing method, the space dispersion method adopts a mixed grid for dispersion, and the areas except for complex geometric shapes such as a bogie, a pantograph and the like in space adopt structural grid dispersion so as to obtain better calculation precision of complex near-wall surface flow, thereby obtaining a more accurate resistance simulation value.
2) Blow position determination
As shown in fig. 1, when flowing to the train equal section car body and streamline tail transition part according to the result of simulation of train open line operation of original train (without train surface blowing), the air flow accelerates, the pressure decreases, the boundary layer breaks suddenly, a larger speed gradient is formed, a larger flow separation is generated, and the resistance of the train increases. Therefore, the air blowing control is arranged between the tail part of the train, the air flow separation line and the reattachment line, and the strength of flow separation is reduced by changing the surface pressure distribution of the tail car and the thickness change of the attachment layer, so that the aim of pneumatic drag reduction is fulfilled. The final position of the blow used in the present invention is shown in figures 2 and 3.
3) Air blowing quantity and air speed estimation and setting
The air quantity of the blowing is estimated according to the waste exhaust quantity of the train. For the three-car marshalling calculation example adopted by the invention, the waste air exhaust quantity of each car is Q respectively 1 、Q 2 、Q 3 The total air volume of the blown air is set to q=q 1 +Q 2 +Q 3 . Then, according to the area S of the air blowing port set in the invention, the air blowing port wind speed v=q/S can be calculated.
4) Simulation and train resistance calculation
The invention relates to a case, wherein an ANSYS Fluent pressure base solver is used for carrying out steady state solving, a k-epsilon turbulence model is adopted as a turbulence model, a DDES method is adopted as a turbulence simulation method, and the delta t=0.001 s is calculated as a time step. Each residual error of each iteration equation is lower than 10 -3 . The measured value of the resistance is obtained through the surface integration of all the train surface discrete grids, and the average value of the final 3000 time steps is taken to obtain the calculated result of the resistance.
Through the steps and the method, the data after the original scheme and the optimized scheme can be obtained. For the original scheme, when the train runs at 140km/h, the resistance coefficients of the head, middle and tail vehicles are respectively 0.400/0.249/0.486, and the total resistance coefficient of the whole train is 1.135. After optimization by using the blowing scheme, the drag coefficients of the head, middle and tail vehicles respectively drop to 0.406/0.235/0.366, and the total drag coefficient of the whole vehicle is 1.006. The drag reduction effect of the whole vehicle can reach 11.4 percent, as shown in figure 4.
In the technical effect of the invention, the exhaust outlet on the existing vehicle is moved from the bottom of the vehicle to the transition part of the vehicle body with the same section and the streamline tail part of the train, and the region is in a negative pressure state in the running process of the train, so that the exhaust outlet is facilitated, and meanwhile, the remarkable drag reduction effect is brought, and the drag reduction rate of the whole vehicle can reach 11.4% (the drag reduction optimizing effect is shown in figure 3). Fig. 5 and 6 compare in more detail the flow field variation after use of the present invention by flow field cloud: the pressure negative pressure intensity at the rear of the train in the figure 5 is reduced, so that the pressure difference resistance applied during the running process of the train is reduced; in fig. 6, there are fewer high-speed airflows moving along with the train behind the tail, these high-speed airflows are generated by friction between the air and the surface of the train, and the lower high-speed airflows mean lower friction resistance.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (3)

1. A train drag reduction method for controlling tail vortex by blowing is characterized by comprising the following steps:
when a train to be drag-reduced runs, an air separation line and an air reattachment line at the tail part of the train to be drag-reduced are obtained;
an air blowing port is arranged between an air separation line and an air reattachment line at the tail part of the train to be drag-reduced;
collecting waste gas of each section of vehicles of the train to be drag-reduced, and intensively blowing out the waste gas of each section of vehicles through a blowing port;
the air blowing openings are arranged at the transition part of the constant-section vehicle body and the streamline tail part of the train to be drag-reduced and are annularly arranged;
the air blowing openings blow outwards at a uniform rate;
when a train to be drag-reduced runs, an air separation line and an air reattachment line at the tail part of the train to be drag-reduced are obtained; the method comprises the following steps:
constructing a geometric model of a train to be drag-reduced and a calculation domain of aerodynamic characteristic numerical simulation, and performing grid dispersion on the geometric model and the calculation domain;
constructing a pneumatic characteristic numerical model of the train during the running of the geometric model based on the train geometric model after grid discretization and a calculation domain;
setting boundary conditions of a calculation domain, and simulating separation flow of air at the tail of a train to be subjected to drag reduction when the train to be subjected to drag reduction runs by using a pneumatic characteristic numerical model;
and determining an air separation line and an air reattachment line at the tail part of the train to be drag-reduced according to the simulation result of the aerodynamic characteristic numerical model.
2. The drag reduction method for trains using blowing to control tail vortex according to claim 1, wherein the areas of complex geometric shapes of the computational domain are discretized by unstructured tetrahedral meshes, and other areas in the computational domain are discretized by structured hexahedral meshes.
3. The method of drag reduction in a train using blowing to control tail vortex according to claim 2, wherein the aerodynamic numerical model simulates turbulent flow at the tail of the train using a DDES method based on a k-epsilon turbulence model.
CN202111591987.5A 2021-12-23 2021-12-23 Train and train drag reduction method for controlling tail vortex drag reduction by utilizing blowing Active CN114454905B (en)

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JPH05262226A (en) * 1992-03-17 1993-10-12 Yasuaki Kohama Stabilizing device for travel of track travel high speed vehicle such as train
FR2695097A1 (en) * 1992-08-31 1994-03-04 Bonnotte Michel Vehicle having arrangement for reduction of ambient frictional resistance to forward movement - arrangement includes reducing compression of ambient fluid such as air or water by moving belts or ducts modifying speed relative to surroundings
US20050139726A1 (en) * 2003-12-25 2005-06-30 Yoshioki Tomoyasu Head wind against the transports converting into lift & air driven down force to save fuels & ecology
US7784409B2 (en) * 2008-05-09 2010-08-31 Union Pacific Railroad Company Drag reducing devices for stacked intermodal rail cars
CN104317994A (en) * 2014-10-16 2015-01-28 湖南大学 Vehicle body pneumatic drag reduction method combining non-smooth surface and jet flow
EP3075622B1 (en) * 2015-04-01 2020-09-30 Bombardier Transportation GmbH Vehicle comprising an air duct that discharges at the surface of the vehicle
CN110386156B (en) * 2018-04-18 2024-04-23 宁波大艾激光科技有限公司 Air film drag reduction system, method and high-speed train
CN110356424B (en) * 2019-06-26 2020-06-16 同济大学 System for reducing air friction resistance on surface of train by disturbing air flow in blowing mode
CN110481578B (en) * 2019-08-23 2020-07-21 西南交通大学 Control method of drag reduction system of high-speed train
CN211308562U (en) * 2019-12-05 2020-08-21 中南大学 High-speed train damping device based on low-density gas injection
CN112395694B (en) * 2020-12-03 2023-05-02 中国人民解放军国防科技大学 Drag reduction control method for ultra-high-speed turbulence boundary layer
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