US20060201377A1

US20060201377A1 - Methods for improving the aerodynamic characteristics of railroad cars and railroad cars embodying the same

Info

Publication number: US20060201377A1
Application number: US11/078,885
Authority: US
Inventors: Robert Gielow
Original assignee: Airflow Sciences Corp
Current assignee: BNSF Railway Co; Airflow Sciences Corp
Priority date: 2005-03-11
Filing date: 2005-03-11
Publication date: 2006-09-14
Also published as: WO2006098949A2; WO2006098949A3

Abstract

A railroad car adapted for open-top transport of materials including a receptacle for receiving a selected material. The receptacle is defined vertically by a floor, defined laterally by first and second sidewalls having a height and extending at an angle from the floor and defined longitudinally by first and second end-walls having a height and extending at an angle from the floor. A lateral baffle disposed within the receptacle between the first and second sidewalls laterally partitions the receptacle into a plurality of cavities for reducing aerodynamic drag during open-top motion of the railroad car.

Description

FIELD OF INVENTION

The present invention relates in general to the design and construction of railroad cars, and in particular, to methods for improving the aerodynamic characteristics of railroad cars and railroad cars embodying the same.

BACKGROUND OF INVENTION

The railroad system is one the most efficient means for transporting bulk materials, such as coal, iron ore, coke, rock, cement, and the like. One particular railway-based transportation technique which has evolved for efficiently transporting such bulk materials utilizes open-top gondola railroad cars and rotary car dumpers. In this system, the material being transported is simply directly dumped or poured into the open-top of the required number of gondola cars at the departure point, such as a coal mine, transfer dock, or shipping terminal. The filled gondola cars, which remain open-topped, are then coupled into trains and the material transported via the railway system in a conventional fashion. At the destination, for example a power utility generation plant or steel mill, the gondola cars are individually clamped to the rail by specialized heavy equipment and both the gondola car and the track rolled-over to dump out the material within the gondola car.
Utilizing open-top gondola cars has several significant disadvantages. Among other things, current gondola cars, as well as other open-topped railway cars, are aerodynamically inefficient. The result is the creation of significant aerodynamic drag during movement, particularly when the cars are empty, and therefore an increased burden on the train engines. This increased burden directly translates to increased fuel consumption and increased costs.
To increase the aerodynamic efficiency, normally open-topped gondola cars could be covered; however, covering increases the size and weight of each car. Moreover, the addition of covers makes the process of loading and unloading each car more expensive and time consuming, and potentially more hazardous, if additional human interaction is involved.
While the aerodynamic characteristics of gondola cars are important, at the same time, the problem of structural strength of the car must also be carefully considered. Typically, vertical reinforcement ribs are provided along the exterior surfaces of the gondola sidewalls, primarily for wall support during material during transport, such that the internal surfaces of the sidewalls are free of obstructions which would otherwise impede the dumping of the material. These external ribs only further increase the problem of achieving aerodynamic efficiency by increasing aerodynamic drag during both loaded and empty operations of the railroad car.
It should be noted that the problems of aerodynamic drag and structural strength discussed above are not limited to open-top gondola cars. For example, similar problems are encountered in the design and construction of bottom-dump and hopper railroad cars, which are operated in an open-top configuration.
In sum, a new railway car design, particularly suitable for open-top transport of bulk materials is desirable. Such a design should be aerodynamically efficient, but still allow for the construction of a structurally strong railway car, which can withstand the stresses applied during dumping.

SUMMARY OF INVENTION

The principles of the present invention reduce aerodynamic drag of a gondola or similar railroad car moving with an open-top configuration. In one particular representative embodiment of these principles, a railroad car is disclosed which is adapted for open-top transport of bulk materials, such as coal. The railroad car includes a receptacle for receiving a selected material, the receptacle defined vertically by a floor, defined laterally by first and second sidewalls having a height and extending at an angle from the floor and defined longitudinally by first and second end-walls having a height and extending at an angle from the floor. At least one lateral baffle, disposed within the receptacle between the first and second sidewalls, laterally partitions the receptacle into a plurality of cavities for reducing aerodynamic drag during open-top motion of the railroad car.
Embodiments of the present principles advantageously provide for the design and construction of aerodynamic railroad cars, such as gondola cars, without resort to a cover. The resulting decrease in aerodynamic drag translates into decreased loading on the associated train engines and hence a corresponding decrease in fuel consumption. Moreover, the use of baffles not only reduces aerodynamic drag, but can also provide sufficient structural strength to the car that external drag generating appendages, such as vertical ribs, can be eliminated or modified to achieve further drag reductions.

BRIEF DESCRIPTION OF DRAWINGS

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
FIG. 1A is a drawing showing a side elevational-view of a representative aerodynamic railroad car embodying the principles of the present invention;
FIG. 1B is a drawing showing an end elevational-view of the railroad car of FIG. 1A;
FIG. 1C is a drawing showing a top plan view of the railroad car shown in FIG. 1A;
FIG. 1D is a drawing of a perspective view of the railroad car of FIG. 1A;
FIG. 2 is a drawing showing a side elevational-view of a representative alternate aerodynamic railroad car embodying the principles of the present invention; and
FIG. 3 is a drawing showing a side elevational-view of another representative alternate aerodynamic railroad car embodying the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The principles of the present invention and their advantages are best understood by referring to the illustrated embodiment depicted in FIGS. 1-3 of the drawings, in which like numbers designate like parts.
FIGS. 1A and 1B are respectively side and end elevational views of a gondola railroad car 100 embodying the principles of the present invention. While a gondola car is shown in FIGS. 1A and 1B, these principles are equally applicable to other types of railroad cars which are operated in an open-top fashion, particularly when empty.
Gondola car 100 includes an elongated receptacle 101 supported on a pair of conventional railroad car trucks 102 a and 102 b. Receptacle 101, which is adapted to receive bulk materials, for example coal, includes a pair of elongated sidewalls 103 a and 103 b, and a pair of end- walls 104 a and 104 b. An internal floor 105, a portion of which is shown in broken lines, defines the bottom of receptacle 101. In the illustrated embodiment, floor 105 is “bathtub” floor, which slopes downward from end- walls 104 a and 104 b to the dumper 110 (which may be sealed), although gondola car 100 may have a flat-bottomed configuration in alternate embodiments. External vertical reinforcing ribs 106 provide structural strength to sidewalls 103 a and 103 b during dumping of materials within receptacle 101, as well as during transport of materials within receptacle 101.
In a conventional moving gondola car, particularly one that is empty, high velocity airflow continuously enters the receptacle. Some of this high velocity air flow strikes inner surface of the receptacle rear wall of the moving car creating substantial air pressure rise in the region surrounding the rear wall. The result is significant “parachute drag.” For purposes of the present discussion, parachute drag is defined as the difference between the overall drag of the car operating empty and open-topped and the overall drag when equipped with a flat cover. Since the parachute drag accumulates with each additional gondola car added to the train, the increase drag directly translates into a higher loading on the train engine and consequently an increase in fuel consumption.
FIGS. 1C and 1D are respectively top plan and perspective views of gondola car 100. As shown in FIGS. 1C and 1D, receptacle 101 is partitioned into a plurality of cavities 107 by a plurality of lateral baffles 108 and a longitudinal baffle 109. In the illustrated embodiment, receptacle 101 is partitioned into sixteen (16) cavities 107 by seven (7) lateral baffles 108 and a single longitudinal baffle 109. As discussed further below, the number of lateral baffles 108 and longitudinal baffles 109, and consequently the number of cavities 107, may vary in alternate embodiments.
According to the principles of the present invention, partitioning the receptacle 101 of gondola car 100 into a plurality of cavities 107 significantly decreases the parachute drag generated when gondola car 100 is in motion. As those skilled in the art will readily appreciate, when an open gondola car is traveling at high speeds, significant drag is created by the pressures acting on the rear wall of the car. This drag results from the tendency of the flow to enter the interior volume of the car. In the present invention, a considerable reduction in the amount of flow entering the interior volume—and thus a reduction in the drag created—is achieved through the inclusion of lateral baffles 108, within gondola car 100. These baffles 108 essentially divide the volume of the receptacle 101 into a number of smaller cavities 107. The longitudinal spacing of the plurality of baffles 108 is sufficiently small such that the amount of airflow that circulates into the cavities 107 is far less than the airflow that circulates into the receptacle of a traditional gondola car to produce the high parachute drag associated with the traditional car. In this manner, the majority of the high velocity air flows above receptacle 101, rather than strike the major surfaces of lateral baffles 108. Although a small amount of the airflow does strike along the upper edges of lateral baffles 108, the total resulting drag is much smaller than the parachute drag generated when high velocity air flow strikes the rear wall of a conventional gondola car.
Computer models representing gondola car 100 and wind tunnel tests of models of the structure of receptacle 101, including lateral baffles 108 and longitudinal baffle 109, have clearly demonstrated that the addition of lateral baffles 108 alone significantly reduces the drag on gondola car 100 in comparison to prior art gondola cars moving with an open-top configuration. The addition of longitudinal baffle 109 further improved the realized reduction in drag at yaw angles other than zero degrees, for example when operating in a cross-wind. In alternate embodiments, a plurality of longitudinal baffles may be provided for further reducing drag with changes in yaw angle. Moreover, while the drag savings realized by gondola car 100 are less than the drag savings achieved by operating a gondola car in a covered configuration, the savings in drag realized by gondola car 100 are substantial with respect to the open-top configuration.
The computer modeling and wind-tunnel testing revealed that most of the reduction in drag is provided by a configuration of gondola car 100 having at least four (4) cavities 107 defined by at least three (3) lateral baffles 108, along with longitudinal baffle 109, although improvement in drag over the conventional single-cavity configuration was still found with only a single lateral baffle 108 dividing receptacle 101 into two (2) large cavities. It should be noted that to optimize aerodynamic efficiency, the number of lateral baffles 108 may vary depending on the length of the railroad car; for example, longer cars may require more lateral baffles 108, while shorter cars fewer lateral baffles 10.
Additionally, the best performance is found when lateral baffles 108 and/or longitudinal baffle 109 are of full depth (i.e. extending from floor 105 of receptacle 101 to substantially the top of receptacle 101 defined by the heights of sidewalls 103 and end-walls 104. Notwithstanding, significant reductions in drag are still realized with lateral baffles 108 and longitudinal baffle 109 of ⅓ or ⅔ of the depth of receptacle 101, as measured downward from the upper edges of sidewalls 103 a and 103 b, which are positioned such that top edges of lateral baffles 108 and longitudinal baffle 109 are at substantially the same height as the top edges of sidewalls 103.
Advantageously, the principles of the present invention, as discussed above with respect to gondola car 100, provide for the design and construction of an aerodynamically efficient railroad car operating open-top, especially when empty. Additional advantages are illustrated in the embodiments shown in FIGS. 2 and 3.
In gondola car 200 shown in FIG. 2, lateral baffles 108 shown in FIGS. 1C and 1D have provided sufficient structural strength to allow external 106 of the embodiment of FIG. 1A to be eliminated. The elimination of external vertical ribs 106 realizes a further reduction in aerodynamic drag. Additionally, receptacle 101 could be widened, if sidewalls 103 a and 103 b are moved laterally outward to the extent of the former vertical ribs. Moreover, if receptacle 101 is widened, the height of sidewalls 103 a-103 b and end-walls 104 a-104 b may be reduced, further reducing aerodynamic drag.
Similarly, in gondola car 300 shown in FIG. 3, the improved structural support provided by lateral baffles 108 allow vertical ribs 106 of FIG. 1A to be replaced with longitudinal ribs 301. Longitudinal ribs 301 provide additional structural strength, while at the same time producing reduced aerodynamic drag relative to external vertical ribs.
In sum, the principles of the present invention provide for the design and construction of aerodynamic railroad cars, such as gondola cars, which can be efficiently operated open-top. The resulting decrease in aerodynamic drag translates into decreased loading on the associated train engines and hence a corresponding decrease in fuel consumption. Moreover, the use of baffles not only reduces aerodynamic drag, but can also provide sufficient structural strength to the car that external drag-generating appendages, such as vertical ribs, can be eliminated or modified to achieve further drag reductions.
Although the invention has been described with reference to specific embodiments, these descriptions are not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed might be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
It is therefore contemplated that the claims will cover any such modifications or embodiments that fall within the true scope of the invention.

Claims

1. A railroad car adapted for open-top transport of materials comprising:

a receptacle for receiving a selected material, the receptacle defined vertically by a floor, defined laterally by first and second sidewalls having a height and extending at an angle from the floor, and defined longitudinally by first and second end-walls having a height and extending at an angle from the floor; and

a lateral baffle disposed within the receptacle between the first and second sidewalls for laterally partitioning the receptacle into a plurality of cavities for reducing aerodynamic drag during open-top motion of the railroad car.

2. The railroad car of claim 1, further comprising at least one longitudinal baffle disposed between the first and second end-walls for longitudinally partitioning the plurality of cavities into additional cavities for further reducing aerodynamic drag.

3. The railroad car of claim 1, wherein the lateral baffle has a height and extends downward from an upper edge of the receptacle defined by the first and second sidewalls.

4. The railroad car of claim 2, wherein the longitudinal baffle has a height substantially equal to a height of the lateral baffle and extends downward from an upper edge of the receptacle defined by the first and second end-walls.

5. The railroad car of claim 3, wherein the height of the lateral baffle is substantially equal to the height of the first and second sidewalls.

6. The railroad car of claim 3, wherein the height of the lateral baffle is less than a height of the first and second sidewalls.

7. The railroad car of claim 1, wherein the first and second sidewalls include inner surfaces defining the receptacle and outer surfaces, wherein a substantial length of the railroad car is substantially free of structures extending outward from the outer surfaces of the first and second sidewalls.

8. The railroad car of claim 1, wherein the first and second sidewalls include inner surfaces defining the receptacle and outer surfaces and the railroad car further comprises at least one longitudinal reinforcing rib extending along at least a portion of the outer surface of each of the sidewalls.

9. The railroad car of claim 1, wherein the lateral baffle comprises one of a plurality of at least three spaced apart lateral baffles disposed between the first and second sidewalls.

10. The railroad car of claim 1, wherein at least a portion of the lateral baffle contacts the floor of the receptacle.

11. A method of reducing the aerodynamic drag of a railroad car having a receptacle for transporting material comprising:

partitioning the receptacle into a plurality of cavities for reducing parachute drag during open-top motion of the railroad car.

12. The method of claim 11, wherein the receptacle is defined vertically by a floor, defined laterally by first and second sidewalls, and defined longitudinally by first and second end-walls, and the method comprises:

partitioning the receptacle with at least one lateral baffle extending from the first sidewall to the second sidewall.

13. The method of claim 12, further comprising partitioning the receptacle with at least one longitudinal baffle extending from the first end-wall to the second end-wall.

14. The method of claim 12, wherein the first and second sidewalls have a height relative to the floor and partitioning the receptacle comprises partitioning the receptacle with a lateral baffle having a height substantially equal to the height of the first and second sidewalls.

15. The method of claim 12, wherein the first and second sidewalls have a height relative to the floor and partitioning the receptacle comprises partitioning the receptacle with a lateral baffle having a height less than the height of the first and second sidewalls.

16. The method of claim 13, wherein the first and second end-walls have a height relative to the floor and partitioning the receptacle comprises partitioning the receptacle with a longitudinal baffle having a height substantially equal to the height of the first and second end-walls.

17. A railroad car including a receptacle for transporting materials, the receptacle including a floor, first and second sidewalls having a height and extending at an angle from the floor, and first and second end-walls having a height and extending at an angle from the floor, the railroad car comprising:

a plurality of baffles partitioning the receptacle into a plurality of cavities for reducing aerodynamic drag during open-top motion of the railroad car.

18. The railroad car of claim 17, wherein the plurality of baffles includes a plurality of lateral baffles extending between the first and second sidewalls and a longitudinal baffle extending between the first and second end-walls.

19. The railroad car of claim 17, wherein at least a portion of an external surface of the first and second sidewalls is free of external ribs.

20. The railroad car of claim 18, further comprising at least one longitudinal rib extending along a portion of an external surface of the first and second sidewalls.