Fuel nozzle and swirler

A fuel nozzle assembly comprising:

• a fuel nozzle, defining a central longitudinal axis, includes a central gaseous fuel passage extending along the central longitudinal axis and terminating at a nozzle tip, with a nozzle cap located in the central gaseous fuel passage upstream of the nozzle tip and having multiple orifices through which a flow of gaseous fuel passes;
• and
• an annular swirler circumscribing the fuel nozzle, the annular swirler defining a first swirler passage and a second swirler passage, the annular swirler comprising:
• a forward wall,
• an aft wall spaced from the forward wall,
• a center wall provided between the forward wall and the aft wall and defining the first swirler passage between the center wall and the forward wall, and further defining the second swirler passage between the center wall and the aft wall, and
• a first set of vanes extending between the forward wall and the center wall,
• a second set of vanes extending between the center wall and the aft wall, and
• a splitter extending from the center wall and further defining the first swirler passage between the splitter and the forward wall and the second swirler passage between the splitter and the aft wall,
• wherein the first set of vanes are configured to impart a first tangential swirl to a first air flow passing through the first swirler passage, the first air flow having a first axial velocity with respect to the central longitudinal axis along an exterior of the fuel nozzle circumscribing the flow of gaseous fuel emitted from the nozzle tip;
• wherein the second set of vanes are configured to impart a second tangential swirl to a second air flow passing through the second swirler passage, the second air flow circumscribing the first air flow and having a second axial velocity with respect to the central longitudinal axis;
• wherein the first tangential swirl is less than the second tangential swirl such that the second axial velocity is slower than the first axial velocity;
• wherein the first tangential swirl has a first swirl number of greater than 0 and less than or equal to 0.6, while the second tangential swirl has a second swirl number of greater than 0 and less than or equal to 1.4,
• wherein the fuel nozzle is configured to receive hydrogen fuel, and
• wherein the splitter terminates at a splitter end that is spaced a length from the nozzle tip axially with respect to the center longitudinal axis, the splitter end is located a height from the aft wall radially with respect to the center longitudinal axis, and the length is greater than or equal to −10 times the height and less than or equal to 10 times the height.

A turbine engine comprising:

• a compressor section, a combustor section, and a turbine section in serial flow arrangement, wherein the combustor section including a fuel nozzle assembly comprising:
• a fuel nozzle defining a central longitudinal axis, and including a central gaseous fuel passage extending along the central longitudinal axis, the fuel nozzle terminating at a nozzle tip, with a nozzle cap located in the central gaseous fuel passage upstream of the nozzle tip and having multiple orifices through which a flow of gaseous fuel passes;
• and
• a swirler, having a first swirler passage and a second swirler passage, provided about the fuel nozzle, the swirler comprising:
• a forward wall terminating along the fuel nozzle at a location upstream of the nozzle tip,
• an aft wall spaced from the forward wall,
• a center wall provided between the forward wall and the aft wall and defining the first swirler passage between the center wall and the forward wall, and further defining the second swirler passage between the center wall and the aft wall, with a first air flow and a second air flow from the compressor section respectively supplied to the first swirler passage and the second swirler passage,
• a first set of vanes extending between the forward wall and the center wall,
• a second set of vanes extending between the center wall and the aft wall, and
• a splitter extending from the center wall and further defining the first swirler passage between the splitter and the forward wall and the second swirler passage between the splitter and the aft wall,
• wherein the first set of vanes are arranged to impart a first tangential swirl to the first air flow passing through the first swirler passage, the first air flow having a first axial velocity with respect to the central longitudinal axis along an exterior of the fuel nozzle circumscribing the flow of gaseous fuel emitted from the nozzle tip,
• wherein the second set of vanes are arranged to impart a second tangential swirl to the second air flow passing through the second swirler passage, the second air flow circumscribing the first air flow and having a second axial velocity with respect to the central longitudinal axis,
• wherein the first tangential swirl is less than the second tangential swirl such that the second axial velocity is slower than the first axial velocity,
• wherein the first tangential swirl has a first swirl number of greater than 0 and less than or equal to 0.6, while the second tangential swirl has a second swirl number of greater than 0 and less than or equal to 1.4,
• wherein the fuel nozzle is configured to receive hydrogen fuel, and
• wherein the splitter terminates at a splitter end that is spaced a length from the nozzle tip axially with respect to the center longitudinal axis, the splitter end is located a height from the aft wall radially with respect to the center longitudinal axis, and the length is greater than or equal to −10 times the height and less than or equal to 10 times the height.