US 2857204 A
Description (OCR text may contain errors)
Oct. 21, 1958 Q H GROSS FUEL INJECTOR NOZZLE Filed Sept. l, 1955 WMM Unite gua FUEL murieron NozzLE Charles Henry Gross, Cincinnati, Ollio, assigner to General Electric Company, a corporation of New York Application September 1, 1955, Serial No. 531,911
1 Claim. (Cl. 299-140) The present invention relates to fuel injection systems and more particularly to an improved system for atomizing and inducing fuel evenly throughout a combustion chamber.
The fuel injection systems presently in use frequently create difficulties in the combustion chambers due to uneven burning of the fuel causing hot spots in the liners. These hot spots result in uneven stresses in the walls of the liners which cause fatigue and buckling or cracking, thus necessitating early replacement of the liner. The most common deficiencies of injection systems which cause uneven burning are incomplete atomization and non-uniform injection of the fuel. When it is not completely atomized, quantities of the fuel fall to the bottom of the liner before burning. With non-uniform injection, unequal quantities of the fuel are supplied to different areas of the liner. In both cases localized burning occurs in Various portions of the liner thus heating the walls of the liner unevenly causing hot spots.
An object of the present invention is the provision of an injection system for completely atomizing and evenly distributing liquid fuel within a combustion chamber.
An additional object is the provision of an improved injection system which permits uniform burning throughout the combustion zone, thus increasing the average useful life of combustor liners.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawing, wherein:
Fig. l is an elevation view in longitudinal section of an injection system according to the present invention;
Fig. 2 is a fragmentary elevation view of the nozzle head of Fig. l in longitudinal section showing the patterns of spray from the various orifices;
Fig. 3 is a plan view of a modified nozzle head for use in an annular combustor;
Fig. 4 is a cross-sectional view taken on the lines 4-4 of Fig. 3; and,
Fig. 5 is a cross-sectional View taken on lines 5 5 of Fig. 3.
The present invention provides a means for obtaining complete atomization and even distribution of fuel in a a combustion chamber, thus improving combustion efficiency and obtaining improved life of structural elements of combustion chambers. The invention may be practiced by providing fuel metering means, a distribution nozzle, means for supplying heated and pressurized fluid capable of supporting combustion, and by the provision of means for injecting fuel into the combustionsupporting uid before the fluid-fuel mixture is supplied to the distribution nozzle.
Referring more particularly to Fig. l in the drawing, the improved fuel injection system of the present invention consists of a fuel atomizer 11, central conduit 12 for supplying heated combustion supporting fluid under pressure and fuel nozzle 13. The atomizer 11 includes 2,857,204 Patented Oct. 2l, 1958 a body portion which is provided with two bosses 14 and 15, each of which is connected to the central airline 12 by the passages 16 and 17. Each of the bosses 14 and 15 is provided with a longitudinal bore 18 and 19 in which is received a fuel regulator or valve 21 and 22. The coupling nuts 23 and Z4 are threadedly received in the open ends of the bores 18 and 19 and are adapted to be connected to a fuel line or lines (not shown). Each of the coupling nuts 23 and 24 is provided with an elongated cylindrical extension 25 in which is positioned an inlet screen assembly 26. A metering plate 27 bears against the end surface of the extension 25 and a cylindrical exit screen assembly 28 surrounds the extension and abuts the periphery of the plate 27. The metering plate is countersunk at the center of its front surface and is provided with a series of openings 29 which communicate between the countersunk front surface and a circular groove 31 on the rear surface of the plate. A metering disc 32 bears against the rear surface of the metering plate 27 and is provided with a hollow chamber 33 at its center which is open to the passage 17. The front surface of the metering disc 32 is provided with a plurality of small slots which communicate between the groove 31 and the chamber 33, said slots opening into the chamber 33 at a very slight angle. The metering disc is also provided with a plurality of small holes 34 which extend between the chamber and the outer edge of the disc. To complete the atomizer assembly each of the bosses 14 and 15 is provided with an excess fuel return 35 and 36 which are adapted to be connected to the fuel overow lines not shown.
The fuel nozzle 13 is attached to the discharge end of the central conduit 12 and is mounted on the upstream end of the combustor, such that the nozzle head extends into the combustor liner 37. The nozzle head of Fig. 2 is provided with a central bore 38 forming a hollow interior which is open to the conduit, and a plurality of radial orifices 39 which extend between the central bore and the outer surface of the nozzle head. As shown in Fig. 2, each orifice is hollow ground at the outer surface of the nozzle head. The orifices at and adjacent the apex of the paraboloid nozzle head are ground in a circular pattern while the orifices at the side of the nozzle head nearest the liner walls are ground in a semi-circular pattern. The intermediate orifices can be hollow ground in a circular, semi-circular or an intermediate pattern depending upon the spray pattern desired.
The nozzle head 41 of Fig. 3 is adapted for use with an annular combustion system and is curved to correspond to the curvature of the liner. A number of rows of orifices 42 are provided in the downstream surface of the nozzle head and are hollow ground on the outer face thereof, as shown in Fig. 3. A chamber 43 is formed in the interior of the nozzle head, as shown in Figs. 4 and 5, to facilitate distribution of fuel to each orifice. The downstream surface of the nozzle head is curved, as shown in Fig. 5, to direct the fuel into the combustion zone. The orifices are positioned so that the sprays therefrom will intersect and uniformly distribute the fuel.
In the operation of the present invention, fuel lines are connected to the coupling nuts 23 and 24 and fuel is pumped into the interior of the extension 25. The fuel in the extension is then passed through the inlet screen assembly 26 to the metering plate 27. The openings 29 carry the fuel from the countersunk forward portion of the metering plate to the circular groove 31 on the rear of the plate. Slots in the forward surface of the metering disc 32 then carry the fuel to the central chamber 33 where it is discharged in a circular motion at a very high rate of speed. The fuel then drains out through the holes 34 or is discharged into the passage 17 and then into the conduit 12. Using the principle that any type of matter under pressure will exit through the line or outlet of least resistance, when the overflow line connected to the excess return is completely open the circular motion set up by the fuel under pressure in the chamber 33 in the metering disc will form a Vacuum at the opening which feeds fuel to the passage 17. This vacuum acts in the same manner as a valve, decreasing the ow of fuel to the conduit in the same ratio as the vacuum is increased. By completely opening the fuel overflow line, a high degree of vacuum is formed. This forces all the fuel to drain out through the openings 34, then through the exit screen assembly 28 and into the excess return. When the fuel overow line is closed, the vacuum is broken and the entire quantity of fuel is injected into the conduit. Therefore, by opening or closing the overow line, the vacuum in the chamber 33 is increased or decreased to allow the proper amount of fuel to be injected into the conduit. The fuel leaving the metering disc on its way to the conduit is broken up or atomized into a mist type spray. The force behind the spray plus the siphon effect of the fluid passing the passage 17 will carry the atomized fuel into the conduit. Before the fuel is passed through the valves 21 and 22 it should be preheated to at least its flash point. When the preheated fuel is injected into the conduit, the heat from the uid will completely evaporate the fuel. When the fuel is evaporated it is carried downstream in the conduit to the nozzle head where it is sprayed through the small openings or orices into the combustion chamber. The orifices are spaced to direct the fuel in all directions and each orice is hollow ground in order to spread an even pattern of fuel throughout the combustion chamber. The size of the orifices and the shape and depth to which each orifice is ground will determine the amount and pattern of the fuel as it leaves each orifice. As shown in Figs. 2 and 5 the orices are spaced so that the patterns from the dilferent rows thereof intersect each other.
As illustrated the atomizer is provided with two valves to inject fuel, one for regular use and one either for emergency or for alcohol (or alcohol and water). By the addition of alcohol (or alcohol and water) with the present invention, the extra heat provided will not result in stressing of any part of the combustion chamber with hot spots since the added temperature is spread evenly throughout the combustion liners. The fuel and alcohol (or alcohol and water) may be blended in any desirable combination since the turbulence set up by the two fuels entering the central conduit will completely mix them so that one highly combustible gas is forced down to the nozzle head.
The body of the atomizer may be made by any suitable process, such as, die casting or sand-casting or it may be prefabricated. While the bosses 14 and 15 are illustrated in Fig. l as being evenly spaced on opposite sides of the airline, such spacing is not necessary to the operation of the invention. The bosses may be staggered with one moved forward or backward, the angles may be increased up to degrees of the center line, and the bosses may lie in different planes.
While a particular embodiment of the invention has been illustrated and described, it will be obvious to those skilled in the art that various changes and modications may be made without departing from the invention and it is intended to cover in the appended claim all such changes and modifications that come within the true spirit and scope of the invention.
What is claimed is:
For use in a fuel injection system: a nozzle head, said nozzle head being paraboloidal in shape and having a centrol bore extending from its base towards its apex; and a plurality of small orifices extending from the bore through the nozzle head, said orifices being spaced apart in an even pattern from the apex towards the base, each orice being hollow ground at the outer surface of the head, the orifices adjacent the apex of the nozzle head being ground in a circular pattern and the orifices farthest removed from the apex being ground in a semi-circular pattern, whereby fuel is sprayed through the orices in an intersecting pattern and distributed uniformly within the space surrounding the nozzle head.
References Cited in the file of this patent UNITED STATES PATENTS 140,465 Burns July 1, 1873 430,549 Thompson June 17, 1890 735,287 Neuendorff Aug. 4, 1903 1,529,531 Young Mar. 10, 1925 1,546,752 Rohr July 21, 1925 2,411,181 Altorfer Nov. 19, 1946 2,508,766 Morel Mar. 23, 1950 2,524,820 Miles Q.. Oct. 10, 1950 2,593,166 Meyer Apr. 15, 1952 FOREIGN PATENTS 489,546 Canada Jan. 13, 1953 1,088,427 France Sept. 8, 1954