US3453826A - Method and apparatus for mounting a burner nozzle - Google Patents

Description

July 8, 1969 I H. HERING 7 3,453,826

METHOD AND APPARATUS FOR MOUNTING A BURNER N OZZLE Filed Nov. 25,1965 Sheet 1 of 2 July 8, 1969 H. HERING 3,453,826

METHOD AND APPARATUS FOR MOUNTING A BURNER NOZZLE Filed Nov. 23. 1966 Sheet 2 of 2 INVEN'IOR HANS HERING United States Patent 3,453,826 METHOD AND APPARATUS FOR MOUNTING A BURNER NOZZLE Hans Hering, Stuttgart-Bad Cannstatt, Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany Filed Nov. 23, 1966, Ser. No. 596,681 Claims priority, applicatign germany, Nov. 23, 1965, 8

US. Cl. 60-39.74 10 Claims ABSTRACT OF THE DISCLOSURE A nozzle for delivering the fuel to the combustion chamber of gas turbines, particularly for flight propulsion units, is circumferentially surrounded at its exit end with a removable sleeve that is accurately machined for mounting in the combustion chamber at the proper angle. The sleeve tightly engages and supports the nozzle against radial vibrations, shocks or movement. Passages are provided between the sleeve and nozzle for axially conducting air across the nozzle to cool it and into the combustion chamber adjacent to the exit opening of the nozzle for preventing carbon formation. These passages may be axial, spirals or crossed spirals throughout a portion of their extent to provide good heat transfer.

BACKGROUND OF THE INVENTION The present invention relates, in part, to nozzle supports for combustion chambers.

In prior art burners for combustion chambers, particularly gas turbines, the burner is usually provided with a plurality of fuel nozzles peripherally arranged around the burner at a specific angle relative to the axis of the burner. To assure the most advantageous combustion, the nozzles must be arranged at a specific angle relative to the longitudinal axis of the turbine combustion chamber. Sleeves have been attached to the burner at the proper angle and the nozzles have been mounted only at their rear end to extend within and through the sleeves with an annular space between the nozzles and sleeves. The positioning and support of the nozzles is accomplished at the rear end of the nozzles and propulsion unit. A portion of the air supplied by the compressor of the gas turbine passes through the annular space between the nozzle and sleeve for cooling the nozzle head and contributing to the combustion of the fuel emitted from the nozzle exit while preventing carbon formation at the nozzle exit. Another portion of the compressed air is supplied to the combustion chamber through slots and recesses in the propulsion unit spaced from the nozzles.

The above mentioned air guidance and angular mounting of the nozzles attains an optimum combustion with the best possible combustion space efficiency; also, minimum thermal loading of the propulsion unit elements or components is attained. Combustion of the fuel should be stoichiometric and in the immediate vicinity of the burner, that is, no flames of high temperature should leave the combustion chamber. The high temperatures of about 2000" C., produced-during combustion, should not be reduced by the surrounding relatively cool air that is not used for combustion; however, the combustion gasses and additional cool air not used for combustion must be mixed after combustion for flowing into the turbine so that the mixture has a temperature of only about 900 C., which is suitable for conversion into power by the turbine blade elements. These requirements have not been fully met by the above-described prior art device, because the above paragraph, particularly the first sentence 3,453,826 Patented July 8, 1969 relates to theory, which is not attained in actual operation.

In the priorart, it has been impossible or at least very difiicult to support the nozzles at a relatively large distance from the nozzle exit at the nozzle rearward end and simultaneously attain an accurate positioning of the nozzles at their forward exit end where they are unsupported. The accurate positioning of the forward exit end is the important consideration for combustion efficiency. Moreover, such a cantilever supporting of the nozzle would contribute to undesirable substantial radial shaking and vibrations of the nozzle forward exit end during operation of the propulsion unit. This would produce an' unsatisfactory combustion process and long flames that would cause local thermal overloading of the materials. Such undesirable results would require the reduction of the propulsion unit output after a very short time or the rapid deterioration of the thermally overloaded propulsion unit components.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nozzle mounting in a combustion chamber, particularly a gas turbine flight propulsion chamber, that will satisfy the above-mentioned requirements and avoid the abovementioned disadvantages of the prior art. A nozzle for delivering the fuel to the combustion chamber of gas turbines, particularly for flight units, is circumferentially surrounded at its exit end with a removable sleeve that is accurately machined for mounting in. the combustion chamber at the proper angle. The sleeve tightly engages and supports the nozzle against radial vibrations, shocks or movement. Passages are provided between the sleeve and nozzle for axially conducting air across the nozzle to cool it and into the combustion chamber adjacent to the exit opening of the nozzle for preventing carbon formation. These passages may be axial, spirals or crossed spirals throughout a portion of their extent to provide good heat transfer. At its downstream exit end, the nozzle may be constructed with a separate removable nozzle head that is provided with splines or other tool engaging deformations on its outer surface for engagement by a tool to remove the nozzle head from the nozzle body after the nozzle assembly has been removed from the propulsion unit, for example.

With the above-mentioned inventive construction, an accurate and quick alignment of the nozzle downstream exit end is assured; this alignment will not change during operation of the propulsion unit. On the other hand, the advantage of good ventilation to produce a cooling of the nozzle is retained when compared with the abovementioned prior art devices; in fact, the cooling effect is improved because very accurate concentricity between the nozzle head or downstream end and the sleeve provides for uniform air passages around the nozzle head to assure uniform cooling of the nozzle head.

The actual internal construction of the nozzle may be conventional, but weight consideration should be considered in a flight propulsion unit. If the nozzle is constructed with a removable head at its downstream end that has the above-mentioned tool engaging splines or other deformations on its outer downstream surface and a smooth rearward surface that is still a part of the downstream end of the entire nozzle unit, the present invention proposes the advantages support of the nozzle head in the sleeve by engagement of the sleeve with the smooth surface throughout their circumference to prevent any relative vibrations or shocks in the radial directions. It is contemplated that the nozzle head may be supported at other portions of its outer peripheral surface. However, the above specifically mentioned support position involves surfaces that have good machinability and large dimen- 3 sions of the contact surfaces to produce an exceptionally accurate and durable support.

It is contemplated that the sleeve may be attached to the burner wall by any suitable conventional method, such as welding. Advantageously, the present invention contemplates the support of a sleeve throughout its outer surface and downstream axially facing surface by a surrounding holder sleeve that is rigidly secured to the burner. The advantage of the sleeve mounting resides in that the holder sleeve may be fastened to the burner by welding, for example, and the sleeve accurately bored afterwards.

, Therefore, the alignment of the holder sleeve bore is not affected by its attachment to the burner because the accurate boring is accomplished after the attachment. The sleeve surrounding the nozzle may advantageously be accurately machined as a separate item and subsequently inserted into the accurately aligned and bored holder sleeve bore.

The nozzle sleeve may be provided with a relatively large inner diameter downstream surface and a relatively small off set rear surface. Between the nozzle outer surface and the adjacent sleeve relatively large diameter inner front surface there is formed an annular space. The outer surface of the nozzle forming this annular space may be the above-mentioned splined surface of the removable nozzle head. The cooling and combustion air is directed into this annular space so that it advantageously flows around the entire circumference of the nozzle head splined portion for efficiently cooling the nozzle head. The splines on the nozzle head contribute to the cooling effect by increasing the outer surface area of the nozzle head in a manner similar to heat exchanger fins. The guidance of the air to this annular space may be accomplished by many means and is not essential to the broader aspects of the present invention. However, an advantageous feature of the present invention utilizes the relatively small inner diameter surface portion of the nozzle sleeve for engaging and supporting the correspondingly shaped smooth outer surface of the nozzle head immediately upstream of the outer splined nozzle head surface, which also centers and aligns the nozzle; passages may be provided between these two surfaces for axially conducting the cooling air to the annular space with the web portions between the passages accomplishing the nozzle support function. The air moving through these passages will contribute to the cooling of the nozzle head, because this air will be in direct contact with the smooth portion of the nozzle head. With increased oassage cross section, increased cooling effects and air fiow may be obtained. A further feature of the present invention proposes that these air conducting passages be constructed with a clove tailed shape enlarging in cross section radially outwardly so a relatively large passage way is obtained simultaneously with relatively large support web surfaces between the passages. However, these passage ways may have any shape according to the broader aspects of the present invention, for example straight line. Straight line passage ways would be relatively simple to machine, for example by slotting. However, the machining should not present any problems because of the removable sleeve and the relatively large number of pieces involved. Removability of the nozzle supporting sleeve greatly facilitates the machining, for example broaching. Therefore, a more specific aspect to the present invention involves the use of straight air passage ways in the nozzle sleeve.

A further advantageous inventive feature of the present invention involves the use of parallel and/or crossed spirial air passages in the nozzle sleeve. With spiral passages, the air travels a greater distance to the nozzle exit to increase the heat transfer between the nozzle head and the air than if straight lined axially extending passages were employed. Also, the spiral passage ways will impart a riffling effect, vorticity, or spiral movement to the air to favorably influence the combustion process. Advantageously, these spiral passages or grooves may be formed in the upstream larger inner diameter portion of the nozzle sleeve so that the air is discharged from the spiral grooves directly into the annular space around splines 16 to thereafter discharge into the combustion chamber to enhance the rotational discharge of the air into the combustion chamber for improving the combustion process.

The following passage way may be employed instead of the aforementioned air passages in the smaller inner diameter portion of the nozzle sleeve. For example, another inventive feature of the present invention would provide an annular groove at the transition from the larger inner diameter portion to the smaller inner diameter portion of the nozzle sleeve; the smaller inner diameter sleeve portion may be provided with axially extending channels to form air passages between the upstream end of the nozzle head and the annular groove. The abovementioned spiral air passage ways may be employed in the larger inner diameter sleeve portion between the annular groove and the forward frontal end face of the nozzle head.

-A further inventive advantageous feature of the present invention utilizes an uninterrupted smooth smaller diameter inner surface with any of the aforementioned larger inner diameter nozzle sleeve surfaces. This construction will provide complete support for the entire outer smooth surface of the nozzle head. Axially extending bores may be employed to conduct the air from the rear of the nozzle head through the sleeve to discharge the air into the space between the larger inner diameter sleeve surface and the adjacent nozzle outer surface at the transition between the smaller inner diameter surface and the larger inner diameter surface of the nozzle sleeve.

Further objects, features and advantages of the present invention will appear from the following description of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 illustrates a portion of a ring type burner viewed in the axial direction looking upstream, with the nozzles removed.

FIGURE 2 is a partial cross sectional view taken along line 2-2 of FIGURE 1 showing the nozzle assembled in the ring burner.

FIGURE 3 is a partial cross sectional view similar to FIGURE 2 but without the nozzle and showing another embodiment of the present invention.

FIGURES 4-8 each shows a partial cross sectional view taken on a plane through the longitudinal axis of a different embodiment of the nozzle sleeve; the sleeves of FIGURES 4-6 are shown in a position rotated in the plane of the drawing with respect to the views of FIGURES 2, 3, 7 and 8.

In FIGURE 1, there is shown a portion of a ring shaped burner to be used in the combustion chamber of a flight propulsion unit, for example. The propulsion unit may be the conventional aircraft gas turbine. The structure of the ring portion shown in FIGURE 1 is repeated throughout the circumferential extent of the burner ring. The frontal surface, that is the surface shown in FIGURE 1 that faces the combustion chamber (not shown) employs a plurality of holder sleeves 11 or 11a, which are spaced equal distances around the perimeter of the ring burner. The holder sleeves 11 or 11a are rigidly attached to the ring burner, for example by welding. The holder sleeves of FIGURE 1 may be either constructed as the holder sleeve 11 of FIGURE 2 or the modified holder sleeve 11a of FIGURE 3. The holder sleeves are used to mount the nozzles and the nozzle sleeves at the correct angle in the burner ring 10 (the nozzles and nozzle sleeves not being shown in FIGURE 1). On the outer and inner periphery of the burner ring 10, a plurality of air discharge conduits 12 and 13, respectively, are provided to discharge air into the combustion chamber.

As shown in FIGURE 2, a separate removable support means in the form of cylindrical tubular sleeve 14 is mounted in the holder sleeve 11. The holder sleeve 11 completely surrounds and engages the outer surface of the sleeve 14 and is provided with a radially inwardly extending flange that axially engages the forward axially facing frontal surface of the sleeve 14. A nozzle of suitable construction is provided at its downstream end with a nozzle head 15 that is received within and supportingly engages the support sleeve 14. On its downstream most outer surface, the nozzle head 15 is provided with a plurality of splines 16, which may be engaged by a wrench or the like during assembly or disassembly of the nozzle head 15 from the nozzle body 17, particularly when the nozzle assembly has been removed from the burner ring. The inner circumference of the downstream portions of the support ring 14 is spaced a distance S from the outermost portions of the adjacent splines 16 of the nozzle head 15; this provides an annular space between the nozzle head 15 and the inner wall of the sleeve 14. Immediately upstream of the splines 16, the nozzle head 15 is provided with an outer smooth unbroken cylindrical support surface 18, which is in supporting engagement with the adjacent inner surface of the support ring 14. This adjacent inner surface of the support ring 14 may advantageously be constructed of a smaller inner diameter than the relatively large inner diameter of the support ring 14 adjacent to the splines 16. The support, centering and alignment of the nozzle head 15 is provided by the surface 18 of the nozzle head 15 in engagement throughout substantially its entire periphery with the immediately adjacent contacting inner surface of the support sleeve 14. Cooling and combustion air enters from the rear of the burner ring and follows the arrows 21. A portion of this air moves into an air passage shown in FIGURE 2 between the top most portion of the surface 18 and the adjacent portion of the sleeve 14; this air passage may be in the form of an inwardly opening channel in the inner portion of the sleeve 14 opposite to the outer support surface 18. From this air passage, the air enters and travels through the annular space between the splines 16 and the adjacent inner portion of the support sleeve 14 to be discharged into the combustion chamber immediately adjacent to the exit forward end of the nozzle. The cylindrical nozzle, cylindrical sleeve 14, and cylindrical inner bore of the holder sleeve 11 are concentric with respect to the axis 22 of the assembly. By first welding the holder sleeve 11 to the burner ring, the bore of the holder sleeve may thereafter be accurately formed at the proper angle with respect to the axis 23 of the combustion chamber, preferably the combustion chamber of a gas turbine used in a flight propulsion unit; this angle is designated as 24 between the propulsion unit axis 23 and the nozzle assembly 22. The accuracy of this angle may be maintained by the accurately and separately formed support ring 14. The remainder of the air following the arrow 21 that does not pass between the support ring 14 and the nozzle head 15 will travel through either the air discharge conduits 12 or the air discharge conduits 13 into the combusion chamber.

As shown in FIGURE 4, the support sleeve 14 may be provided with a plurality of straight line longitudinally extending grooves 19 in its upstream portion to conduct the air, in addition to the above-mentioned annular space, between the nozzle head 15 and the sleeve 14. The radially inwardly extending webs between the grooves 19 will act as heat exchanger fins to greatly increase the surface area of the sleeve 14 that is exposed to the cooling air. According to another aspect of the present invention, it is contemplated that the grooves 19 and Webs 20 may be provided on the nozzle head 15 instead of the relatively small depth splines 16. The air that is discharged from the annular space between the nozzle head 15 and the support sleeve 14 into the combustion chamber will have the effect of preventing carbon formation at the nozzle exit. This air will enter the combustion space annularly around the nozzle to mix with the atomized fuel discharged from the nozzle to support the combustion process immediately in front of the nozzle. Further combustion air for the attainment of the stoichiometric mixture ratio is supplied to the combustion zone by means of the air discharge conduits 12 and 13. The optimum combustion process will limit the combustion zone to a relatively small space immediately adjacent to the nozzle to avoid local overheating of the individual propulsion unit components by excessively long combustion flames by correct coordination of the nozzle end air supply. It is therefore extremely important that the nozzle head 15 be located extremely accurately. This is accomplished by the sleeve 14 of the present invention which will assure the accurate positioning of the nozzle axis 22 with respect to the propulsion unit axis 23 and provide for the radially rigid support of the forward end of the nozzle immediately adjacent to the combustion chamber for avoiding any radial shaking or vibrations produced during operation, particularly during high power output of the propulsion unit.

The modification shown in FIGURE 3 employs numerals that are identical to those used in FIGURES 2 and 4 for illustrating identical elements. In FIGURE 3, the holder sleeve 11a is modified with respect to the holder sleeve 11 of FIGURE 2. The relatively long axially extending smooth wall cylindrical bore in. the forward portion of the holder sleeve 11a forms an annular space with the downstream outer surface of the nozzle head in a manner similar to the formation of the annular space between the sleeve 14 and the splines 16 in FIGURE 2; the nozzle assembly of FIGURE 2 may be used with the construction shown in FIGURE 3. The sleeve 14a of FIGURE 3 is a modification of the sleeve 14 shown in FIGURES 2 and 4. Because the holder sleeve 11a is used to form the annular space, the support sleeve 14a may be constructed with relatively small axially dimensions. The sleeve 14 a consists of a cylindrical tubular sleeve having grooves 19 and intermediate webs 14 formed on its entire inner surface. The longitudinal grooves 19 in the sleeve 14a may be advantageously broached into the sleeve.

In the nozzle support sleeve embodiment 14b of FIG- URE 5, spiral grooves 19a are formed in the upstream internal portion of the sleeve 14b instead of the longitudinal extending grooves 19 of FIGURE 4. Also, the sleeve 14b is provided with a radially outwardly extendly flange at its forward-most end for engagement with the axially facing frontal surface of an appropriately modified holder sleeve that is provided with a straight through bore; the nozzle support sleeve 14b would be inserted from the front of the holder sleeve. In other respects, the nozzle support sleeve 14b is the same as the nozzle support sleeve 14 of FIGURES 2 and 4.

A further modification of the support sleeve is shown in FIGURE 6 as nozzle support sleeve 14c. A plurality of oppositely spiraled grooves 19b are provided in the support sleeve 14c so that they cross each other along the internal upstream portion of the support sleeve 14c.

Except for the difference between the grooves 19b of FIGURE 6 and the grooves 19 of FIGURE 4, the support sleeve 14c is identical to the support sleeve 14 of FIGURE 4 and may be used in a burner ring construction according to FIGURE 2.

In the support sleeve embodiments of FIGURES 5 and 6, a greater cooling of the nozzle head 15 is attained, because the cooling air must travel a greater distance along the spiral in contact with the nozzle head in comparison with the axial travel in a sleeve according to FIGURE 4. Additional effects may be obtained with the spiral grooving to produce, for example a right hand or a left hand riifling effect or vorticity of the air as it enters the combustion chamber.

In the embodiment according to FIGURE 7, the support sleeve 14d is provided with a plurality of longitudinal bores 25 instead of longitudinal grooves or channels as in the case of the aforementioned embodiments. In this respect, the sleeve embodiments according to FIGURES 2 and 4, FIGURE 3, FIGURE 5, and FIGURE 6 may be provided with the longitudinally extending channel as illustrated in FIGURE 2 or with bores similar to those illustrated in FIGURE 7 as axially extending bores 25. FIGURE 7, the bores 25 will supply the cooling air to the annular groove 26 from where it will enter the annular space between the downstream outer portion of the nozzle head and downstream cylindrical inside surface of the sleeve 14d in a manner similar to the previously described embodiments.

In the embodiment according to FIGURE 8, a plurality of exterior channels 27 are provided instead of the interior channel illustrated in FIGURE 2 and the bores 25 illustrated in FIGURE 7 for supplying the cooling air to the downstream annular space between the inside surface of the sleeve 14c and the nozzle head portion 15. The air will flow through the longitudinally extending outer channel 27 into the exterior annular channel 28 and then through the radially extending bores 19 into the annular space between the sleeve 14c and the nozzle head 15.

The above described embodiments according to FIG- URES 7 and 8 have the advantage that the inner wall of the sleeve provides an unbroken closed flat surface that is uninterrupted by longitudinal grooves so that it will support the nozzle head surface 18 throughout its entire circumferentially extent. The sleeves according to the embodiments of FIGURES 7 and 8 may be employed in the burner ring structure and with the nozzle structure as shown in FIGURES 1 and 2 or FIGURE 3.

The above-described embodiments have been shown and described only as examples of the preferred constructions of the present invention, and additional modifications and embodiments are contemplated with the spirit and scope of the present invention as defined by the following claims.

I claim:

1. For use in a combustion chamber having a support wall: a burner nozzle having a downstream axial end, an upstream axial end, and an outer support surface adjacent said downstream end; a generally tubular support means separate from said nozzle circumferentially surrounding and radially supporting said nozzle, and preventing relative rocking movement of said nozzle at said outer support surface for solely determining the nozzle angle of axial orientation; said tubular support means having an inner support surface in engagement with said nozzle outer support surface at least at circumferentially spaced areas and axially spaced areas; said tubular support means having passage means for conducting cooling and combustion air generally axially along said nozzle; said support wall having a rigidly fixed holder means determining the angle of said support means relative to said. wall; said holder means having an accurately formed bore therein removably telescopically mounting therein said support means.

2. The device of claim 1, wherein said support means consists of an upstream portion, an intermediate portion and a downstream portion; said passage means including a plurality of bores axially extending completely through said upstream portion of said support means, an inwardly opening annular groove in said intermediate portion communicating with said bores, and a smooth cylindrical surface constituting the inside surface of said downstream portion that is radially spaced from the adjacent outer surface of said nozzle to form an annular space in communication with said annular groove.

3. The device of claim 1, wherein said support means consists of an upstream portion, an intermediate portion and a downstream portion; said passage means consists essentially of a plurality of radially outwardly opening grooves generally axially extending the entire axial length of said upstream sleeve portion, a radially outwardly opening annular groove in said intermediate portion in communication with said last mentioned grooves, a plurality of bores generally radially extending through said intermediate portion in communication with said annular groove, and a smooth cylindrical surface constituting the inner surface of said downstream portion spaced from the adjacent outer surface of said nozzle to form an annular space in communication with said radially extending bores.

4. The device of claim 1, wherein said support means consists essentially of an upstream portion, an intermediate portion and a downstream portion; said passage means including an annular groove in said intermediate portion and the inner surface of said downstream portion being spaced from the adjacent outer surface of said nozzle to constitute an annular space therebetween.

5. The device of claim 1, wherein said nozzle includes a tubular removable nut constituting the outer portion of its downstream end, and provided at the downstream end thereof with tool engaging splines at the upstream end thereof with a smooth cylindrical surface constituting said nozzle outer support surface; said support means has a relatively small inner diameter portion forming said inner support surface, and a relatively large inner diameter portion radially spaced from the adjacent outer surface of said nozzle having said splines to form an annular space.

6. The device of claim 5, wherein the relatively small inner diameter portion of said support means is provided with a plurality of radially inwardly opening generally axially extending grooves partially forming said passage means and intermediate webs in engagement with said nozzle.

7. The device of claim 6, wherein the transverse cross sectional area of said longitudinal grooves is larger than the corresponding cross sectional area of said webs.

8. The device of claim 7, wherein said longitudinal grooves are dove-tail shaped in the transverse plane and widened in the radially outward direction.

9. The device of claim 5, wherein said relatively small inner diameter portion of said support means is provided with a plurality of parallel spiral inwardly opening channels constituting in part said passage means.

10. The device of claim 5, wherein said relatively small inner diameter portion of said support means is provided with a plurality of inwardly opening alternate oppositely spiraling and crossing grooves constituting in part said passage means.

References Cited UNITED STATES PATENTS 2,701,164 2/1955 Purchas et al. 2,907,171 10/1959 Lysholm 6039.65 3,026,675 3/1962 Vesper et al. 6039.74 3,154,516 10/ 1964 Seiiferlein 60-39.75 XR JULIUS E. WEST, Primary Examiner.

US. Cl. X.R.

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