US2856170A - Fuel injection means for use in supplying liquid fuel to the combustion chamber of a turbine - Google Patents

Description

Oct. 14, 1958 M. x. M. SCIARD 2,

FUEL INJECTION MEANS FOR USE IN SUPPLYING LIQUID FUEL TO THE COMBUSTION CHAMBER OF' A TURBINE Filed Feb. 20, 1956 2 Sheets-Sheet 1 FIGB FIG.9 FIG. 10

lNvaNToR MARC XM, SCIARD M flw/fl Oct. 14, 1958 M. x. M. SCIARD 2,

FUEL INJECTION MEANS FOR USE IN SUPPLYING LIQUID FUEL TO THE COMBUSTION CHAMBER OF A TURBINE Filed Feb. 20, 1956 2 Sheets-Sheet 2 FIG.4

INVLNT R MARC X.M. SCIARD a I M54 Z L United States Patent FUEL INJECTION MEANS FOR USE IN SUPPLYING LIQUID FUEL TO THE COMBUSTION CHAMBER OF A TURBINE Marc Xavier Marie Sciard, Paris, France Application February 20, 1956, Serial No. 566,687

Claims priority, application France March 16, 1955 2 Claims. (Cl; 261-90) My invention relates to a new article of manufacture consisting of fuel injecting means employing centrifugal force and designed to be used in connection with reaction turbines.

It is well known that in conventional reaction and impulse type turbines an injector, which is ordinarily actuated by a piston-type feed pump, is used to mix the air which has been compressed in the compressor with the fuel in order to formthe mixture which will be burned in the combustion chamber before its expansion in the turbine.

The feeding of a combustible fluid in this manner involves certain diflficulties:

The fuel circuit is a high pressure circuit since it is necessary to inject and atomize the fuel in the air which has been compressed by the compressor.

This circuit must therefore be rendered air tight, which is not easy.

The feed pump comprises reciprocating elements which must operate under pressure and must also be air tight.

My invention seeks to overcome these difficulties by providing for injection by means of a centrifugal compressor supplied with fuel by means of a greatly simplified low pressure circuit comprising a pump and which does not comprise any reciprocating element. It is relatively easy to render the low pressure supply circuit air tight and the low pressure injection means feeding the centrifugal compressor may be readily controlled by regulating the speed of a low pressure volumetric pump. The turbulence and mixing of the fuel into the air are brought about through the juncture of a primary stream produced by the centrifugal compressor type injector which consists of a rich carbureted fuel mixture and a second stream produced by the axial or centrifugal compressor of the reaction or impulse type turbine which consists of compressed air.

According to my invention, centrifugal injection means mounted within a housing comprises a centrifugal compressor having a rotor or impeller provided with a plurality of vanes, the ends of which are curved in the direction of rotation of the rotor and the free edges of which are ribbed. The vanes are thickened at the bases by means of which they are fixed to the hub of the wheel and oblique grooves are provided in this zone near the base in such a manner as to direct the fuel atomized by a volumetric pump toward the outer portion of the vane.

Certain means for carrying out my invention will now be described purely by way of example without in any way limiting the scope of my invention to the particular embodiments which are described and shown on the accompanying schematic drawings in which:

Figure 1 is a transverse cross-section taken along the line I-I of Figure 2, showing injection means according to my invention;

Figure 2 is an axial cross-section taken along the line II-II of Figure 1, showing the same apparatus;

Figure 3 is a plan view on a larger scale showing a vane of the rotor of Figures 1 and 2;

Figure 4 is a section taken along the line IV-IV of Figure 3;

Figure 5 is a section taken along the line VV of Figure 3;

Figure 6 is a section taken along the line VI-VI of Figure 3;

Figure 7 is a section taken along the line VII-VII of Figure 3;

Figure 8 is a detail view showing the end of a slightly modified rotor vane on a larger scale;

Figure 9 is a section along the line IX--IX of Figure 8; and

Figure 10 is a section taken along the line X--X of Figure 8.

The injection means, according to my invention, comprises, as shown in Figures 1 and 2, a casing 1 carrying a deflector 2, a rotor or impeller 3 for the centrifugal compressor which carries vanes 4, and low pressure injection means 5 controlled by a volumetric pump (not shown).

Each vane 4 has a specific shape (see Figs. 4-7):

Its end 6 is bent in the direction of rotation of rotor 3, as indicated by arrow F (Fig. 1).

Its free edge carries a flange 7.

both axially and outwardly of each vane are cut into its base.

Its substantially central portion 10 is roughened near the base 8. The roughened area 11 may be seen on Fig. 7.

The injection means operates as follows:

The liquid fuel supplied under low pressure by a volumetric pump is thrown out by the ends of the injection tubes or low pressure atomizers 5 so as to bring about a crude atomization.

The small drops of liquid are drawn into the stream of air arriving at 12 (following the arrow 7) which is drawn in by the centrifugal rotor 3. The finely divided fuel partially evaporates in the air. The remaining droplets are spread over the vanes 4 and guided by the grooves 9 to the roughened zone 10, where they are diverted from their axial direction and turned centrifugally outward following the line of the arrow f.

The flange 7 is designed to provide guide means for those droplets in zone 8 which have not entered any groove 9 and maintain a layer of liquid having a certain thickness on the rectilinear portion 13 of the vanes.

The fuel is finally ejected at high speed in the direction of the arrow f towards the ends 6 of the vanes; the curvature of the ends 6 of the vanes directs the stream of liquid fuel which travels at high speed in the direction of the arrow 1" against the stream of air moving in the direction shown by the arrow F at a substantial angle of incidence.

The fuel which comes in under low pressure from the tubes 5 which serve as low pressure atomizers is thus very finely divided.

The ejection speed of the fuel, which must theoretically equal the product of the angular speed of rotation of the compressor (expressed in radians per second) and the radius of the rotor, is in practice about half of this value. It is thus easy to obtain an ejection speed of 200 meters per second with a vaned rotor having a diameter of some 60 centimeters and a speed of 250 revolutions per second. In order to obtain as large an ejection speed as possible the portions 13 and 6 near the outer ends of the vanes should be highly polished.

Since it is necessary to provide when starting under certain circumstances an ejection of fuel at a relatively slight angle of incidence with respect to the air (a small angle between f'" and F as seen on Fig. 4) and with a. direct penetration into the secondary stream of air which Patented Oct. 14, 1958 3 follows the direction indicated by thearrow F, the ends 6 of the vanes may be modified as shown in Figures 8. 9 and 10, on which the same reference numerals have been. used as inv Figures 1- to 7.

The end 6 of each vane 4 is split along the line 14, the free part 15. of the end 6 remainingstraight insteadwof being curved, like the remainder 16 of the end 6,: in. the direction of rotation (show by the arrow F).

As a result of this arrangement, at very low speeds of rotation (enduringstarting) the thin layer of fluid is concentrated on the portion 15 of the end 6 of the vane 4 and leaves it along thelineindicated by the arrow at a negligible angle to the air stream followingv the line indicated .by thearrow F. Only a small portion of :the fuel flows over the curved part 16 of the end 6 and leaves in the direction of thearrow f' at a substantial angle to the air which flows in the direction indicated by the .arrow F.

It will, .ofcourse, begappreciated thatthespecific embodiments, herein. described may be-modified by replacing various parts by equivalent elements withoutdeparting from the spirit of. myinvention. The grooves 9, for example, may beiextendedto the ejection zone, and their extended portions may be covered: over.

I claim:

1. Fuel injection meansfor use in supplying fuel to the combustionchamber of a turbine, consisting of a centrifugal, compressor comprising ,a housing, arotor in said housing having a hub carrying a plurality of radially projecting vanes, means for l'eadinga stream of air to said vanes and means for projecting liquid fuelonto the bases of said vanes, each of said vanes being thicker near its base than near its outer end and having a portion of its surface lying intermediate its ends and just outwardly of said thickened portion roughened, each vane being provided with-.aplurality of grooves in the surface ofsaid thicker portion for receiving; said liquid References :Cited, inrthefileofithis 'patent' UNITED STATES PATENTS 1,447,916 Watkins Mar-. 6, 1923 1,510,423 Tedman Sept. 30,1924 1,649,161 Foster Nov. 15, 1927' 1,728,204 Falla Sept. 17, 1929; 1,753,936 Moore Apr. 8, 1930' 2,294,313 Mock a Aug. 25, 1942 FOREIGN PATENTS 472,987 Great Britain Oct.4, 1937

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