US3520480A - Fuel spray nozzle - Google Patents

Description

July 14, 1970 R. M. HALVORSEN 3,520,480

FUEL SPRAY NOZZLE Filed April 24, 1968 2 Sheets-Sheet l INVENTOR.

A TTORNEV July 14, 1970 R. M. HALVORSEN FUEL SPRAY NOZZLE 2 Sheets-Sheet 2 Filed April 24, 1968 INVENTOR.

foil 7 A1. HA1 VOKJZHV A 7' TORNE Y United States Patent 3,520,480 FUEL SPRAY NOZZLE Robert M. Halvorsen, Allen Park, Mich., assignor to Ex-Cell-O Corporation, Detroit, Mich. Filed Apr. 24, 1968, Ser. No. 725,265 Int. Cl. B051) 7/12 US. Cl. 239-404 10 Claims ABSTRACT OF THE DISCLOSURE A fuel spray nozzle of the type used in gas turbine engines, and more particularly fuel spray nozzles of the type having an integral pressure-responsive flow metering valve and plural separate spray systems, to provide a wide flow range with good spray atomization.

BACKGROUND OF THE INVENTION A typical fuel spray nozzle of the type presently available is supplied with fuel under pressure through a single inlet, and is utilized to spray atomized fuel into the combustion chamber of a gas turbine engine. In order to provide good atomization of the fuel at high and low flow rates, such nozzles are provided with separate low and high capacity spray systems, which discharge through concentric orifices at the spray tip of the nozzle. The high capacity spray system incorporates a spring-biased, pressure-responsive, flow-metering valve, located upstream of the high capacity spray tip. This valve remains closed, to prevent flow, when the nozzle is operating in the low flow range, and opens to meter flow when the nozzle is flowing in the high flow range. The movement, and resulting flow metering of this valve, is conventionally responsive to a pressure differential created by having the upstream end of the valve pressurized by fuel at nozzle inlet pressure, and the downstream end referenced to fuel at a back pressure created by flow through the high capacity spray tip.

With nozzles of the type described, the low capacity spray system, hereafter called primary nozzle, is independently pressurized with fuel at nozzle inlet pressure throughout the entire nozzle flow range. This results, with proper design, in obtaining the desirable maximum possible degree of spray atomization from the primary nozzle throughout the entire nozzle flow range. The high capacity spray system, hereafter called secondary nozzle, along with its spring-biased, pressure-responsive, flow-metering valve, hereafter called secondary nozzle flow-metering valve, is also pressurized with fuel at nozzle inlet pressure. The presence of the secondary nozzle flow-metering valve in the secondary nozzle system, however, requires that the nozzle fuel inlet pressure be divided up between the secondary nozzle and the secondary nozzle flow-metering valve, in order to provide the necessary pressure differential to sustain the movement and resulting flow metering action of the secondary nozzle flow-metering valve. This division of nozzle fuel inlet pressure, in which the larger amount of the fuel inlet pressure is proportioned to the secondary nozzle flow-metering valve to sustain the valve movement and resulting flow metering, does not permit providing the secondary nozzle with enough pressure to obtain the desired maximum degree of spray atomization from the secondary nozzle. This division of nozzle fuel inlet pressure, secondly, does not permit any flexibility in the use of nozzle fuel inlet pressure to obtain the optimum pressure differential across the secondary nozzle flow-metering valve for obtaining a desirable high valve loading.

It is an object of the invention to provide an improved fuel spray nozzle of the general type as described, having 3,520,480 Patented July 14, 1970 a secondary nozzle system with an integral pressure-responsive secondary nozzle flow-metering valve, which due to its design, does not require the conventional division of nozzle fuel inlet pressure to sustain valve movement and resulting flow metering, and thereby enables providing a secondary nozzle system with a separate selective means of valve loading, and a superior degree of spray atomization than that which is obtainable from similar types of nozzles that are presently available for accomplishing substantially the same function.

SUMMARY OF THE INVENTION The invention provides a fuel spray nozzle with a secondary nozzle system having a spring-biased, pressureresponsive, secondary nozzle flow-metering valve, located upstream from the secondary nozzle, whose loading and movement is the function of a pressure differential created by having the upstream end of the valve pressurized with fuel at nozzle inlet pressure, and the downstream end referenced, by means of a communicating passage, to some specific fuel pressure existing within the primary nozzle swirl chamber. This reference pressure obtained from within the primary nozzle swirl chamber may be high or low, and is selected by varying the diametral size and/or location of the communicating passage to the primary nozzle swirl chamber, thus providing a flexible means of obtaining an optimum pressure differential to provide the desired flow-metering valve loading.

This invention further provides a fuel spray nozzle with a secondary nozzle system having a spring-biased, pressure-responsive secondary nozzle flow-metering valve whose flow metering is a function of a completely separate pressure differential than that required for loading and sustaining flow-metering valve movement. This pressure differential for metering is created by having the upstream side of the flow-metering port pressurized with fuel at nozzle inlet pressure and the downstream side pressurized with fuel at a back pressure created by flow through the orifice of the secondary nozzle. Since the flow-metering valve loading and travel pressure differential is independent of the flow metering pressure differential, the flow metering pressure differential may be reduced to a very minimum amount, or even zero when the engine flow requirements permit, thus allowing the secondary nozzle to be pressurized with fuel at a maximum pressure and thereby providing the desired maximum degree of atomization from the secondary nozzle without affecting the ability of providing the desired valve loading, and the sustaining of flow-metering valve movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a complete view of the fuel nozzle and sup port assembly.

FIG. 2 is an enlarged cross-sectional view of the fuel nozzle assembly.

FIG. 3 is a partial enlarged cross-sectional view of a modified nozzle arrangement.

FIG. 4 is a patial enlarged cross-sectional view of another modified nozzle arrangement.

FIG. 5 is a partial enlarged cross-section view of another modified nozzle arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT The complete fuel nozzle and support assembly generally indicated as 10 in FIG. 1 comprises a support housing 11 and an inlet fitting 9 and the fuel nozzle and valve assembly 12. FIG. 2 shows an enlarged cross-sectional view of the fuel nozzle and valve assembly 12. The fuel is adapted to enter through the inlet fitting 9 and flow through the passage 14 in the support housing 11. The

fuel is adapted to enter passage and filter through the fuel filter 16'to passage 17 on the inner side of the fuel filter. The fuel is adapted to flow through primary flow passages 18 and 19, the passage 19 being the primary nozzle passage in the secondary nozzle insert 20. The secondary nozzle insert 20, seated along the concentric or coaxial axis of the nozzle body 13, has a protruding element 23 incorporating a primary nozzle discharge orifice 21 which protrudes partially through the secondary discharge orifice 22 of the nozzle body 13. The primary nozzle insert 24, seated along the concentric or coaxial axis of the secondary nozzle insert 20, has an opening 28 along the central or longitudinal axis of the nozzle 12 adjacent the primary nozzle swirl chamber 25, for purposes to be hereinafter set forth.

Fuel is adapted to enter the passages 19 of the secondary nozzle insert 20, and flow through the primary nozzle insert 24 by means of passages 26 and tangential slots 27 into the primary nozzle swirl chamber 25, and exits throughthe primary nozzle orifice 21. This comprises the primary or low capacity nozzle discharge system.

The high capacity or secondary nozzle discharge system is described in the following terms. The fuel that enters through the passage 14 and flow through the fuel filter 16 into passages 17, to be discharged through the primary nozzle discharge orifice 21, also enters the passages 30 and 31. However, the fuel does not enter passage 32 until the metering valve seat 34 is unseated at the secondary nozzle metering valve inlet 35. As the pressure of the fuel is increased above a predetermined level, the metering valve 33 is adapted to be moved axially within valve liner 42, overcoming the bias of the metering valve spring 37, allowing the fuel to flow through the secondary nozzle metering valve inlet 35, and enter passage 32. As the metering valve 33 is adapted tomove further within the valve liner 42, the metering edge 39 of the metering valve 33 begins to uncover the secondary nozzle fuel metering ports 40 in the valve liner 42. Depending on the value of the fuel inlet pressure the metering valve 33 will be positioned accordingly, such that, the fuel flows through the valve inlet 35 and secondary nozzle fuel metering ports 40 and into secondary flow passage 43, swirl holes 44 of secondary nozzle insert 20, and secondary nozzle swirl chamber 46, and exits through the secondary discharge orifice 22. Valve liner manifold 41 separates primary flow passage 18 from secondary flow passage 43. In summary, there exists a separate primary nozzle and flow system providing the maximum degree of spray atomization for low capacity operation, and a separate secondary nozzle and flow system, which when combined with the primary fiow system results in providing a combined flow system with the maximum degree of spray atomization for high capacity operation.

Air inlet 50 allows air to enter the air passages 52 and 54 located between nozzle body 13 and air shroud 53 to help prevent formation of carbon on the discharge orifices at 21 and 22.

In operation, the fuel spray nozzle has a secondary nozzle system with a spring-biased, pressure-responsive, secondary nozzle flow-metering valve 33, whose movement and loading is a function of the pressure differential created by having the upstream or inlet end of the valve pressurized with fuel at nozzle inlet pressure, and the downstream or exit end referenced to the fuel pressure in chamber 48. The fuel pressure in chamber 48 is referenced by means of a communicating passage 28 in the primary nozzle insert 24 to a specific fuel pressure it?- ing within the primary nozzle swirl chamber 25. The valve spring 37 is seated in a spring retainer 45 having a central opening 47 which connects with the central opening 28 of the primary nozzle insert 24. However, it is to be recognized that the spring retainer 45 is not necessary to hold spring 37, since the spring can be abutting the primary nozzle insert as well. This provides a flexible means of obtaining an optimum pressure differential to permit the desired flow-metering valve loading.

This further provides a fuel spray nozzle and valve 12 with a secondary nozzle system having a spring-biased, pressure-responsive secondary nozzle flow-metering valve 33 whose fiow metering is a function of a completely separate pressure differential than that required for loading and sustaining flow metering valve movement. This pressure differential is created by having the upstream side of the fiow metering ports 40 pressurized with fuel at nozzle inlet pressure and the downstream side pressurized with fuel at a back-pressure created by the secondary nozzle flow system 44, 46 and 22. Since the fiow metering valve loading and travel pressure differential is independent of the flow metering pressure differential, the fiow metering pressure differential may be reduced to a very minimum amount, or even zero when the engine flow requirements permit, thus allowing the secondary nozzle flow system 44, 46 and 22 to be pressurized with fuel at a maximum pressure and thereby providing the desired maximum degree of spray atomization from the secondary nozzle without affecting the ability of providing the desired valve loading, and the sustaining of flow metering valve movement.

While the preferred embodiment of the invention is here described, a modified embodiment is shown in FIG. 3 wherein the primary nozzle insert 24 has a protruding element 55 which extends into the swirl chamber 25 and includes a reference pressure hole 28 having a diameter equal to or smaller than the discharge orifice 21. This protruding element 55 into the swirl chamber 25 of the primary nozzle system allows the selection of a back pressure to give a pressure differential to provide the desired flow metering valve loading as required by the design.

The embodiment as shown in FIG. 4 shows essentially the same features as in FIG. 3 except without any protruding element. However, the diameter of hole 28" is equal to or smaller than the orifice 21.

The embodiment shown in FIG. 5 is essentially the same configuration as in FIG. 4, except that the reference hole 28" is off-center or non-concentric. The location of this reference hole 28" is closer to the side walls of the primary swirl chamber 25, and as such allows a different pressure differential to provide the desired flow metering valve loading.

However, it is to be recognized that the diameter and/ or location of the holes 28, 28', 28" or 28" in the swirl chamber of the primary nozzle system can be varied to allow selection of a back pressure to give a pressure differential in order to provide the desired flow-metering valve loading as required by the design.

While the embodiments of the present invention have been considered in detail, it will be understood that other embodiments and modifications thereof are contemplated. It is the intent to include all embodiments and modifications as are defined by the appended claims within the scope of the invention.

What I claim as my invention is:

1. In a liquid fuel spray nozzle of the type having a single inlet, and separate high and low capacity swirl chambers and separate spray outlets, supplied by separate high and low capacity flow passages, of which the low capacity flow passage provides a constant communication between the inlet and the low capacity swirl chamber and spray outlet; a spring-biased valve located upstream from the high capacity swirl chamber and spray outlet, in the high capacity flow passage, for controlling flow through the high capacity swirl chamber and spray outlet, the upstream end of the valve being exposed to nozzle inlet pressure, and the downstream end of the valve being exposed to a specific pressure from within the low capacity swirl chamber by means of a communicating passage, the flow-metering side of the valve being exposed to a back pressure from the high capacity swirl chamber and spray outlet, and a spring biasing the valve in a direction to reduce flow through high capacity swirl chamber and spray outlet.

2. A liquid fuel spray nozzle of the type having a spring-biased valve for controlling flow through the high capacity swirl chamber and spray outlet as defined in claim 1, comprising: a means for adjusting the pressure to which the downstream end of the valve is exposed by changing the size and/ or location of the pressure pickup point of the communicating passage to the low capacity swirl chamber.

3. In a fuel spray nozzle, comprising:

(a) a single inlet means;

(b) a separate primary nozzle flow means, said separate primary nozzle flow means having a primary nozzle swirl chamber and a primary nozzle discharge orifice;

(c) a separate secondary nozzle flow means, said secondary nozzle flow means having a separate secondary nozzle swirl chamber and a secondary nozzle discharge orifice, said secondary nozzle flow means including:

(1) a metering valve; and

(2) a reference means; whereby said metering valve is referenced to specific fuel pressure within said separate primary nozzle swirl chamber.

4. A fuel spray nozzle, as defined in claim 3, wherein said reference means includes a communicating means comprising a reference pressure hole between said primary nozzle swirl chamber and the downstream end of said metering valve.

5. A fuel spray nozzle, as defined in claim 3, wherein said separate secondary nozzle flow means includes a metering valve port means having the upstream side pressurized with fuel at nozzle inlet pressure and the downstream side of the said port means pressurized with fuel at a back-pressure created by the secondary nozzle flow.

6. A fuel spray nozzle, as defined in claim 4, wherein said reference pressure hole includes a diameter that is concentric to and smaller than the diameter of said primary nozzle discharge orifice.

7. A fuel spray nozzle, as defined in claim 4, wherein said reference pressure hole includes a diameter that is concentric to and larger than the diameter of said primary nozzle discharge orifice.

8. A fuel spray nozzle, as defined in claim 4, wherein said reference pressure hole includes a diameter that is concentric to and equal to the diameter of said primary nozzle discharge orifice.

9. A fuel spray nozzle, as defined in claim 4, wherein said reference pressure hole is off-center with respect to the longitudinal axis of said primary nozzle discharge orifice.

10. A fuel spray nozzle, as defined in claim 4, wherein said reference pressure hole in a part of a protruding element extending substantially into said primary nozzle swirl chamber.

References Cited UNITED STATES PATENTS 2,786,719 3/1957 Kingsley 239464 2,921,747 1/1960 Burman 239464 2,954,172 9/1960 Grundman 239443 3,032,279 5/ 1962 Czarnecki 239464 3,081,952 3/1963 Woodward et al. 239404 X 3,443,760 5/1969 Simmons 239-403 X M. HENSON WOOD, JR., Primary Examiner .T. I. LOVE, Assistant Examiner US. Cl. X.R.

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