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  
       [0001]     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  
       [0002]     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.  
         [0003]     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.  
         [0004]     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.  
         [0005]     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.  
         [0006]     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.  
         [0007]     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  
       [0008]     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.  
         [0009]     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  
       [0010]     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:  
         [0011]      FIG. 1A  is a drawing showing a side elevational-view of a representative aerodynamic railroad car embodying the principles of the present invention;  
         [0012]      FIG. 1B  is a drawing showing an end elevational-view of the railroad car of  FIG. 1A ;  
         [0013]      FIG. 1C  is a drawing showing a top plan view of the railroad car shown in  FIG. 1A ;  
         [0014]      FIG. 1D  is a drawing of a perspective view of the railroad car of  FIG. 1A ;  
         [0015]      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  
         [0016]      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  
       [0017]     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.  
         [0018]      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.  
         [0019]     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 .  
         [0020]     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.  
         [0021]      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.  
         [0022]     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.  
         [0023]     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.  
         [0024]     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 .  
         [0025]     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 .  
         [0026]     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 .  
         [0027]     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.  
         [0028]     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.  
         [0029]     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.  
         [0030]     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.  
         [0031]     It is therefore contemplated that the claims will cover any such modifications or embodiments that fall within the true scope of the invention.