Torch igniter cooling system

A torch igniter for a combustor of a gas turbine engine, the torch igniter comprising:

• a combustion chamber oriented about an axis, the combustion chamber having an axially upstream end and an axially downstream end together defining a flow direction through the combustion chamber, along the axis;
• a cap defining the axially upstream end of the combustion chamber and situated on the axis, wherein the cap is configured to receive a fuel injector and a glow plug;
• a tip defining the axially downstream end of the combustion chamber;
• an igniter wall extending from the cap to the tip and defining a radial extent of the combustion chamber;
• a structural wall coaxial with and surrounding the igniter wall;
• an outlet passage defined by the igniter wall within the tip, wherein the outlet passage fluidly connects the combustion chamber to the combustor of the gas turbine engine;
• a cooling system comprising:
• an air inlet formed within the structural wall and configured to intake a flow of air from a compressed air source;
• a first flow path disposed between the structural wall and the igniter wall and extending from the air inlet to the cap, wherein the first flow path is configured to receive a first portion of the air taken in by the air inlet;
• an aperture extending transverse to the flow direction through the igniter wall, wherein the aperture directly fluidly connects the first flow path to the combustion chamber;
• and
• a quench hole disposed at a downstream location within the combustion chamber;
• wherein:
• the quench hole directly fluidly connects the first flow path to a quenching zone;
• the quenching zone is co-spatial with the outlet passage;
• an annular divider centered on the axis and disposed at the axially downstream end of the combustion chamber at a position upstream of the quench hole, wherein the annular divider is configured to define an upstream end of the quenching zone;
• and
• a mixing nozzle attached to and extending away from a downstream face of the annular divider,
• wherein the mixing nozzle is configured to mix combustion gases formed in the combustion chamber with the air from the quench hole;
• wherein a downstream end of the mixing nozzle comprises:
• a plurality of protrusions distributed symmetrically about the axis;
• and
• a plurality of indentations distributed symmetrically about the axis;
• and
• wherein a first diameter between diametrically-opposed protrusions is greater than a second diameter between diametrically opposed indentations.