Prefilming air blast (PAB) pilot for low emissions combustors

Patent metadata

Field	Value
Publication number	US-9927126-B2
Application number	US-201514735694-A
Country	US
Kind code	B2
Filing date	Jun 10, 2015
Priority date	Jun 10, 2015
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A pilot fuel injector is provided for a fuel nozzle of a gas turbine engine. The pilot fuel injector can include an axially-elongated, inner pilot centerbody wall extending from an upstream end to a downstream end, with the axially-elongated, inner pilot centerbody wall having a diverging-converging orientation with respect to a centerline axis to define a hollow tube having an upstream diameter, a throat, and a downstream diameter such that the throat has an inner diameter that is less than both of the upstream diameter and the downstream diameter. The pilot fuel injector also includes a center air circuit positioned at the upstream end, and an annular fuel passage defining the downstream end and intersecting with the centerbody wall at a pilot fuel metering orifice. A pilot fuel film surface is downstream from the annular fuel passage.

First claim

What is claimed is:

1. A pilot fuel injector of a fuel nozzle of a gas turbine engine, comprising:
an axially-elongated, inner pilot centerbody wall extending from an upstream end to a downstream end, wherein the axially-elongated, inner pilot centerbody wall has a diverging-converging orientation with respect to a centerline axis to define a hollow tube having an upstream diameter, a throat, and a downstream diameter, wherein the throat has an inner diameter that is less than both of the upstream diameter and the downstream diameter, and wherein the inner diameter of the throat occurs at a single axial location relative to the centerline axis;
a center air circuit positioned at the upstream end of the hollow tube, wherein the center air circuit is defined by a center swirler having center swirl vanes;
an annular fuel passage defining the downstream end of the pilot fuel injector, the annular fuel passage intersecting with the axially-elongated, inner pilot centerbody wall at a pilot fuel metering orifice;
a pilot fuel film surface downstream from the annular fuel passage;
an outer pilot centerbody wall surrounding the axially-elongated, inner pilot centerbody wall;
a pilot fuel cartridge positioned between the axially-elongated, inner pilot centerbody wall and the outer pilot centerbody wall, wherein the pilot fuel cartridge is in fluid communication with the annular fuel passage so as to provide fuel therethrough and onto the pilot fuel film surface; and
an inner purge air inlet port extending from an inner purge air cavity defined between the axially-elongated, inner pilot centerbody wall and the pilot fuel cartridge,
wherein the throat is positioned between the center swirler and the pilot fuel metering orifice, and
wherein inner purge air in the inner purge air cavity is configured to flow from the inner purge air cavity into the hollow tube through the inner purge air inlet port placed in series with a controlled exit gap dimension.

2. The pilot fuel injector as in claim 1 , wherein the axially-elongated, inner pilot centerbody wall defines an average diverging angle of 3° to 7° relative to the centerline axis in the downstream portion between the throat and the pilot fuel metering orifice.

3. The pilot fuel injector as in claim 1 , wherein the axially-elongated, inner pilot centerbody wall defines an average diverging angle of 4° to 6° relative to the centerline axis in the downstream portion between the throat and the pilot fuel metering orifice.

4. The pilot fuel injector as in claim 1 , wherein the axially-elongated, inner pilot centerbody wall defines an average converging angle of 3° to 7° relative to the centerline axis in the upstream portion between the center swirler and the throat.

5. The pilot fuel injector as in claim 1 , wherein the axially-elongated, inner pilot centerbody wall defines an average converging angle of 4° to 6° relative to the centerline axis in the upstream portion between the center swirler and the throat.

6. The pilot fuel injector as in claim 1 , wherein the inner diameter of the throat is 0.75 to 1.25 times a throat-to-prefilmer distance measured along the centerline axis from the throat to a downstream end of the pilot fuel film surface.

7. The pilot fuel injector as in claim 1 , wherein the inner diameter of the throat is 0.9 to 1.1 times a throat-to-prefilmer distance measured along the centerline axis from the throat to a downstream end of the pilot fuel film surface.

8. The pilot fuel injector as in claim 1 , further comprising a length to diameter ratio of the pilot fuel film surface, wherein the length to diameter ratio of the pilot fuel film surface is 0.3 to 0.75, as measured by dividing a distance of the pilot fuel film surface from the pilot fuel metering orifice to an inner air circuit downstream of the pilot fuel film surface by a smallest diameter defined by the pilot fuel film surface.

9. The pilot fuel injector as in claim 1 , wherein the pilot fuel film surface has a constant diameter extending from the pilot fuel metering orifice to an inner air circuit downstream of the pilot fuel film surface.

10. The pilot fuel injector as in claim 9 , wherein the constant diameter of the pilot fuel film surface is greater than the downstream diameter of the axially-elongated, inner pilot centerbody wall.

11. The pilot fuel injector as in claim 1 , wherein the inner purge air cavity has an expanding region where a first distance between the axially-elongated, inner pilot centerbody wall and the pilot fuel cartridge is increasing, and a contracting region where a second distance between the axially-elongated, inner pilot centerbody wall and the pilot fuel cartridge is decreasing, wherein the inner purge air inlet port extends from the contracting region at its smallest dimension opposite from the expanding region of the inner purge air cavity.

12. The pilot fuel injector as in claim 11 , further comprising:
an outer purge air inlet port extending from an outer purge air cavity defined between the pilot fuel cartridge and the outer pilot centerbody wall, the outer purge air inlet port placed in series with a controlled exit gap dimension.

13. The pilot fuel injector as in claim 12 , wherein the outer purge air cavity has an expanding region where a first distance between the outer pilot centerbody wall and the pilot fuel cartridge is increasing, and a contracting region where a second distance between the outer pilot centerbody wall and the pilot fuel cartridge is decreasing, wherein the outer purge air inlet port extends from the contracting region at its smallest dimension opposite from the expanding region of the outer purge air cavity.

14. A fuel nozzle of a gas turbine engine, comprising:
the pilot fuel injector of claim 1 ; and
an annular splitter surrounding the pilot fuel injector, wherein the annular splitter defines a splitter throat downstream of the pilot fuel film surface, wherein the splitter throat has a diameter that is larger than a constant diameter defined by the pilot fuel film surface.

15. The fuel nozzle of claim 14 , further comprising:
an annular first housing surrounding the pilot fuel injector and the annular splitter, the annular first housing having an exit positioned axially downstream of the pilot fuel injector and the splitter.

16. The fuel nozzle of claim 15 , further comprising:
a plurality of fuel injection ports positioned in a radial array outside the annular first housing, the plurality of fuel injection ports disposed in communication with a fuel supply and positioned to discharge a second fuel stream into a third air stream at a position axially upstream of the exit of the annular first housing.

Assignees

• Gen Electric

Inventors

• Benjamin Michael Anthony
• Mancini Alfred Albert
• Chandrasekaran Rameshkumar Muthuvel

Classifications

• F23D2900/11101

  Pulverising gas flow impinging on fuel from pre-filming surface, e.g. lip atomizers · CPC title

• F23D11/14

  with a single outlet, e.g. slit · CPC title

• F23R3/14

  by using swirl vanes · CPC title

• F23D11/105

  at least one of the fluids being submitted to a swirling motion · CPC title

• F23D11/104

  intersecting at a sharp angle, e.g. Y-jet atomiser · CPC title