US1998008A - Locomotive draft appliance - Google Patents

Description

April 16, 1935.

A. GlEsL-GIESLINGEN LOCOMOTIVE DRAFT APPLIANCE Filedma'rch 1, 1934 2 sheets-sheet 1 April 16, 1935. A. GIESL-GIESUNGEN 3,998,008 l LOCOMOTIVE DRAFT PPLINCE Filed March l, 1934 2 Sheets-Sheet 2 mwN-ma,

M www Patented Apr. 16, 1935' UNITED STATES PATENT 4OFFICE LOCOMOTIVE DRAFT APPLIANCE Adolf Giesl-Gieslingen, New York, N. Application March 1, 1934, Serial No. 713,552. 19 claims. (01.20-96) My present invention relates to steam locomotives wherein the draft required for the fire is created by suction obtained from an exhaust steam jet acting in the so-called draft appliance.

In my co-pending application Serial No. 592,710, I have shown how draft appliances of maximum over-all efliciency may be constructed,-

It is a primary object of my invention to simultaneously obtain greatest efficiency and simplicity of such draft appliances. Another important object is to throw the products of combustion as forcibly as possible upward while they are ejected from the smokestack. Further objects are minimum wear of the device and minimum frictional and dynamic resistance in the exhaust nozzle, as well as the creation of an exhaust nozzle which will eject a compact steam jet of, within reasonable limits, any desired divergence. Other objects will appear in the course of the following description.

In the drawings, Fig. 1 is a longitudinal vertical control section through a locomotive smokebox showing a preferred embodiment of my improved draft appliance. Fig. 2 is a plan view of the exhaust nozzle in Fig. l.

Fig. 3 is a diagrammatical sketch of my improved draft appliance, for the purpose of explaining its various features and preferred proportions.

Fig. 4 is a plan view of a modified exhaust nozzle, otherwise similar to Fig. 2.

Figures 5 to 7 are diagrammatical sketches of a draft appliance of oblong area, Fig. 5 being a vertical central section, Fig. 6 a vertical longitudinal central section at a right angle to Fig. 5, and Fig. 7 a horizontal section along the line 'l-l in Fig. 6. Fig.8 is a vertical cross section through an exhaust nozzle having diverging,

slot-like openings which I sometimes prefer to use in combination with a draft appliance ac cordingto Figures 5 to 7.

Figures 9 to l1 are diagrammatical sketches of a draft appliance wherein my'improved exhaust nozzle is combined with an intermediate nozzle of the kind claimed in my co-pending application Serial No. 592,710, Fig. 9 being a vertical central section through the draft appliance and Figures 10 and 11 showing, respectively, the outlet configurations of the intermediate nozzle and the exhaust nozzle.

In spite of the great and continued attentionl that the locomotive draft appliance is receiving since about a century ago, no reliable rules' have been established for the factors promoting efficient draft production, nor has the action of the steam jet been adequately explained. Two major principles are being advocated in the design of draft appliances: -the first and less frequently mentioned may be called the Venturitube principle of which U. S. patent to Bruce, No. 1,853,893 is a recent example. The underlying idea is that better entrainment is obtained if the steam jet acts upon a concentrated body of gas, that is within a considerably restricted cross-sectional area of the smokestack, and therefore the latter is of double conoidal form with a narrow throat above the nozzle opening. A compact steam jet is employed, flowing from a plain, undivided nozzle opening. l

The second, an entirely different lprinciple according to which draft appliances are designed, is that of providing a large contact surface between the steam jet and the gases with a View to increasing entrainment by what is commonly called frictional action. A recent example may be found in U. S. patent to Kiesel, No. 1,749,487, where an exhaust nozzle having a star-shaped outlet opening is used, whereby the nozzle diameter is large relative to its area. The large circumferencel of the steam jet makes the use of a relatively wide stack necessary, and the result is a low speed of the mixture of gas and steam escaping from the stack outlet, and consequently a tendency of the smoke to trail down to the locomotive cab.

More moderate use of the above-mentioned second principle of providing a large contact surface is made in the more generally applied draft appliances, wherein either relatively short smokestacks are provided in order to freely expose to the gases a large portion of the steam jet, or the steam is split by bridges and the like, combined with longer smokestacks contain ing no or moderate restrictions compared with their outlet area. The practices are very varied and confused, without much apparent advantage of one over the other and with much left to be desired in efficiency of draft production.

It appears that those who were concerned about providing a steam jet with a large Contact surface forgot about or felt forced to disregard the contradicting Venturi principle, while those, if any, who advocated the Venturi principle and consequently sought to employ a compact steam jet, found it impossible to employ a smokestack of adequate dimensions, because a compact steam jet would, in the relatively restricted space on a large locomotive, fill only a relatively extremely narrow stack, and would not follow an outlet taper of more than about 1 in 7, resulting in such excessive speed of the gases escaping from the stack with the accompanying energy loss that no benefit whatever would result. In fact, the Venturi principle has not found practical application in modern locomotives.

I have discovered that, if the Venturi principle is correct, and if 'its advantages outweigh those of a large contact surface of the steam jet, then a sharply tapering, double conoidal stack which will permit the desired outlet area to be reached within the restricted height available on the locomotive must be advantageous if a compact steam jet can be produced with a taper corresponding to that of the stack in order to ll the same in the desired manner, andI succeeded in devising such arrangements of greater efficiency' than any known simple draft appliances, as will now be described:

yFigures 1 and 2 show a preferred embodiment of my invention. The boiler barrel I, closed by the tube sheet 2 in which the fiues 3 terminate, is attached to the smokebox 4. The draft appliance consists of the smokestack 5, the stack extension 6, the basket I and the exhaust nozzle 8, all preferably secured together to form a self-contained unit and suspended from the saddle 9 in the manner described and claimed in my co-pending application Serial No. 655,161. The exhaust standpipe I is held in fixed relation to the smokebox and reaches into the annular space formed between the downward extension II of the exhaust nozzle 8 and the lower ring I2 ofthe basket 1. Thus the exhaust steam is discharged into the nozzle 8. The circumferential walls of the nozzle 8 are preferably diverging toward its outlet as illustrated, terminating in theoutlet plane I3-I3. Radial, wedge-shaped partitions I4 define preferably four steam passages I5 the center lines I6 of which diverge with respect to the central axis I'I of the exhaust nozzle and smokestack in such a way that four steam jets with the contours I8, I9 are formed, each substantially a quarter circle in cross section, and so directed that they form a compact jet as soon as possible as they expandwhile on their way upward, preferably filling the throat 2l) of the stack as indicated, and continuing to fill the stackup to itsY outlet 2I.

Referring to the diagrammatical sketch Fig. 3, the various preferred proportions of my invention will be further discussed with a view to serving as a guide for practical design. Like numerals are used for corresponding parts. 'I'he outlet diameter A vof the stack should be chosen with a view to obtaining suicient lifting power of -the exhaust to prevent trailing Whenever practicable. The nozzle diameter C follows from the expected nozzle outlet area, to which the required area of the partitions must be added. The latter depends upon the necessary spreading effect and, therefore, upon the divergence of the hypothetical cone 22 connecting the circumference of the exhaust nozzle with the top of the stack, and the proper relation is to be found from experience. A satisfactorily compact steam iet will not be Obtained if the aggregate cross-sectional area of the spaces between the individual jets is greater than the aggregate outlet area of the nozzle, and for best results said relation should be nearer forty to sixty per cent which is suicient in practice to obtain properly sized stacks. For greater spreading the number of the radial partitions may be l increased to about 6, for smaller spreading it may be reduced to v3 but not less. The partitions I4 may of course also end flush with the outer wall of the exhaust nozzle, without extending beyond plane I3-I3. The choke diameter B of the stack should be such as to give a minimum cross sectional area of between forty and fifty-five per cent of the stack outlet area -at 2l, preferably nearer the average of these figures and not much less than 4 or 5 times the outlet area of the exhaust nozzle. The stack extension 6 may be of various aring shapes without much effect upon the efficiency of the draft appliance, provided that a proper inlet area be offered to the gases between the exhaust nozzle and the stack inlet. 'Ihe latter factor is of decisive importance as the Venturi shape of the stack would become ineffective if the inlet were so placed as to permit a large, slow-moving body of gas to come in contact with the steam jet. For the purpose of definition, I place into the stack inlet and tangentially touching the same, the hypothetical cone 23 having its apex in the central axis II of the draft appliance, and opening at an angle of 60 degrees, and I define as inlet area the conoidal surface F formed between the said cone 23 and the circumference of the exhaust nozzle in the manner indicated in Fig. 3. Said inlet area should be about half-way between twenty per cent and fifty per cent of the free gas passage within the boiler fiues, and for the above explained reason, should always be smaller than said gas passage. For similar reasons, the total length E of the stack should be great, and more than seventy or better more than eighty per cent of the distance D between the outlet of the exhaust nozzle and the top of the stack. The afore-mentioned recommendations will enable those skilled in the art to put my invention into practice.

While I prefer to shape the partitions in my exhaust nozzle as shown at I4 in Figures 1 to 3, the modification illustrated in Fig. 4 may also be used without departing from the spirit of my invention. In said modification, the radial ribs 24 do not merge in the center but end at a short distance therefrom, defining the principal passages I5 having diverging center lines, and communicating with the central passage 25. HoweverI do not recommend this form for obvious reasons.

Whether the dividing members in the exhaust nozzle are .of the forms 24 or I4, an essential feature is that they extend far enough axially to give practically every particle of the escaping steam the desired diverging direction; and to this end I give `said dividing members a smallest axial dimension preferably double or at least equal to the maximum diametrical dimension of the passages defined between said dividing members; that is, I make the dimension H in Fig. 3 greater than K in Fig. 2. In order that the steam may properly touch the confining Walls, I give each one of the Vpassagesa. substantially constant area throughout its length. I do not desire to contract the steam while owing through the passages because this would be contrary to the object of obtaining a. greatly diverging jet, nor do I favor a' I the steam would then not fully touch the vconfining walls and would not be properly guided.

Smokestacks having an oblong cross-sectional area, with correspondingly slot-like exhaust nozzle openings have heretofore been proposed with the primary purpose of obtaining a steam jet with maximum entraining surface, yet they have not been regarded as successful. I have discovered that highly eilicient draft appliances malr be created if such oblong smokestacks are designed according to Venturi principles, as illustrated in Figures to 7. In my copending application Serial No. 592,710, I have explained that one may regard an oblong draft appliance as being composed of a number of circular draft appliances corresponding to Fig. 5, all arranged in line and with their adjacent walls removed;

vthus the principles explained in connection with Fig. 3 may be applied here without requiring further discussion, and corresponding parts are indicated by like reference numbers. However, since the width A and the length L of such oblong draft appliances may be chosen at will for any desired outlet area, artificial spreading of the steam in the exhaust nozzle isusually not necessary, and the exhaust nozzle 26 may be formed with a plain, slot-like opening as shown. If a relatively short length L and a consequently greater Width A is required, I employ an exhaust nozzle 21, Fig. 8, having a longitudinal partition 28 and circum"A ferential walls of such shape that two passages 29 are formed with their longitudinal central planes diverging in the direction of the flow as shownv in the cross-section.

Due to the peculiarities of oblong draft appliances, I preferito give them aslightly wider throat and a relatively longer stack than recommended for circular devices, both increases being in the order of five per cent.

My improved exhaust nozzle may also be used with advantage in connection with a split intermediate nozzle of the general form claimed in my co-pending application Serial No. 592,710. A preferred combination is shown in Figures 9 to 11, wherein the intermediate nozzle-3| is interposed between the exhaust nozzle 30 and the stack 32.

The partitions 33 -in the exhaust nozzle are situated in line with those 34 in the intermediate nozzle whereby the exhaust channels 35 eject steam jets 36 corresponding to the channels 3'! in the intermediate nozzle; This arrangement enables a very gentle spreading to be used, whereby, in connection with a more correct fiow through the intermediate nozzle, energy losses are minimized; to this end I also prefer to give a lesser angular divergence to the partitions 33 which are exposed to the higher jet speed, and I give a greater angular divergence to the partition 34 in the intermediate nozzle.

Having described my invention to enable those skilled in the art to `make and reproduce the same, I claim:

1. In a locomotive, a smokestack and an exhaust nozzle, and partitions at the outlet of the said exhaust nozzle defining at least three steam passages, the geometric center lines of said steam passages diverging with respect to the central axis of the nozzle in the direction of the steam flow, said smokestack diverging toward its outlet and having a minimum cross-sectional area of more'than forty per cent but not more than fifty-five per cent of its outlet area and having a length of at least eighty per cent of the distance from the outlet of the exhaust nozzle to the outlet of the stack.

2. The combination claimed in claim 1, characterized thereby that the partitions defining the said diverging steam passages of the said exhaust nozzle have a minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage.

3. The combination claimed in claim 1, characterized thereby that the partitions deiining the said diverging steam passages of the said exhaust nozzle have a minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at la right angle to the center line of the steam passage, and further characterized thereby that the aggregate cross-sectional area of the spaces formed between the said steam passages is smaller than the agg'regate outlet area of the said steam passages; whereby a relatively compact steam jet of unlform divergence is obtained.

4. Ina locomotive, a smokestack and an ex-` haust nozzle, and partitions at the outlet of the f said exhaust nozzle defining at least three steam passages, the geometric center lines of said steam passages diverging With respect to the central axis of the nozzle in the direction of the steam ow, said smokestack diverging toward its outlet and having a minimum cross-sectional area of more than forty per cent but not more than fifty-five per cent of its outlet area and having a. length of at least eighty per cent of the distance from the outlet-of the exhaust nozzle to the outlet of the stack, and an inlet area for the combustion gases defined between the circumference of the exhaust nozzle and the inlet of the stack of at last two-tenths, but not more than one-half of the total gas passage within the boiler iiues.

5. The combination claimed in claim 4, characterized thereby that the partitions defining the said diverging steam passages of the said exhaust nozzle have a minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage.

6. The combination claimed in claim 4, characterized thereby that'the partitions defining the said diverging steam passages of the said exhaust nozzle have a minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage, and vfurther characterized thereby that the aggregate crosssectional area of the spaces formed between the said steam passages is smaller than the aggregatey outlet area of the said steam passages; whereby a relatively compact steam jet of uniform divergence is obtained.

7. In a locomotive, a smokestack and lan exhaust nozzle, and partitions at the outlet of the said exhaust nozzle defining a plurality of steam passages, the geometric center lines of said steam passages diverging with respect to the central axis of the nozzle in the direction of the steam' flow, said smokestack diverging toward its outlet and having a minimum cross-sectional area said diverging steam passages of the said exhaust nozzle have a minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage.

9. The combination claimed in claim 7, characterized thereby that the partitions defining the said diverging steam passages of the said exhaust nozzle have a. minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage, and further characterized thereby that the aggregate crosssectional area of the spaces formed between the said steam passages is smaller than the aggregate outlet area of the said steam passages; whereby a relatively compact steam jet of uniform divergence is obtained.

10. In a locomotive, a smokestack and an exhaust nozzle, and partitions at the outlet of the said exhaust nozzle defining a plurality of steam passages, the geometric center lines of said steam passages divergingwith respect to the lcentral axis of the nozzle in the direction of the steam flow, said smokestack diverging toward its outlet and having a minimum cross-sectional area of not more than sixty per cent of its outlet area and having a length of at least Iseventy per cent of the distance from the outlet of the exhaust nozzle to the outlet of the stack, and an inlet area for the combustion gases, dened between the circumference of the exhaust nozzle and the inlet of the stack, of less than the total lgas passage within the boiler fiues.

11. The combination claimed in claim 10, characterized thereby that the partitions defining the said diverging steam passages of the said exhaust nozzle have a minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage.

12. The combination claimed in claim 10, charaoterized thereby that the partitions defining the said diverging steam passages of the said exhaust nozzle have minimum axial length that is greater than the maximum diametrical dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage, and further characterized thereby that the aggregate cross-sectional area of the spaces formed between the said steam passages is smaller than the aggregate outlet area of the said steam passages; whereby a relatively compact steam jet of uniform divergenceis obtained.

13. In a locomotive, a smokestack having an oblong cross section, an exhaust nozzle offering to thesteam flow at least one elongated, slotlike outlet area, said stack diverging toward its staclz, of more than two-tenths but not more than one half of the total gas passage within the boiler flues.

14. In a locomotive, a smokestaok having an oblong cross section, said stack diverging toward its4 outlet and having a minimum cross-sectional area of not morethan sixty-five per cent of its outlet area.

15. In a locomotive, a smokestack having an oblong cross section and an exhaust nozzle oiering to the steam ow at least one outlet area, said stack having an axial length in the direction of the steam flow of at least seventy-five per` cent of the distance from the outlet of the exhaust nozzle to the outlet of the stack, and an inlet area for the combustion gases, defined between the circumference of the exhaust nozzle and the inlet of the stack, of less than the total gas passage within the boiler flues.

16. In a locomotive, an exhaust nozzle having circumferential walls divering toward its outlet, and partitions at its outlet defining a small number of steam passages, all of said passages having a substantially constant cross-sectional area throughout their axial length, the geometric center lines of said steam passages diverging with respect to the central axis of the nozzle in the direction of the steam flow, the minimum axial length of said partitions being greater than the maximum diametrioal dimension of any such steam passage defined between the respective partitions, taken at a right angle to the center line of the steam passage, and further characterized th'ereby that the aggregate cross-sectional area of the spaces formed between the said 'steam passages is smaller than the aggregate outlet area of the said steam passages.

17. In a locomotive, an exhaust nozzle having circumferential walls diverging toward its outlet, and partitions at its outlet defining a small number of steam passages, all of said steam passages having a substantially constant cross-sectional area throughout their axial length, the geometric center lines of said steam passages diverging with respect to the central axis of the nozzle in the direction of the steam fiow.

18. In a locomotive, an exhaust nozzle having an outside confining wall diverging toward the nozzle outlet and enclosing an oblong slot-like outlet area, and a longitudinally disposed wedgeshaped partition dividing said outlet area and defining outlet passages diverging from the central plane of the said partition in the direction of the steam flow.

19. In a locomotive'a smokestack, an exhaust nozzle having radially disposed partitions definling a plurality of steamv passages, said partitions forming Wedges directed against the steam flow and splitting the same; and an intermediate nozzle interposed between said exhaust nozzle and smokestack, said intermediate nozzle having similar radially disposed partitions situated in line with the said partitions in the exhaust nozzle and forming wedges having a larger apex than the corresponding wedges in the exhaust nozzle.

ADOLF GIESL-GIESLINGEN.

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