Combustor igniter assembly

1. A gas turbine engine comprising: a combustor having a combustor liner assembly defining a combustion chamber along a chamber axis in a plenum of the gas turbine engine, a plurality of fuel nozzles communicating through a dome of the combustor, and an igniter opening defined in the combustor liner assembly downstream from the fuel nozzles relative to a direction of air flow through the combustion chamber; a combustor ignitor assembly including: a mounting bracket provided on the combustor liner assembly and including an annular lip at least partially aligned with the igniter opening such as to define a cavity receiving an igniter therein; a floating collar slidingly received on the mounting bracket for relative sliding movement in a plane normal to an axis of the igniter opening, the floating collar including an annular surface defining a collar opening; the igniter having an igniter axis extending longitudinally thereof concentric with an axis of the collar opening and sealingly engaging the annular surface; and a plurality of purge openings defined in at least one of the igniter and the floating collar, the purge openings forming cooling airflow passages communicating from the plenum to the cavity, wherein the floating collar and the mounting bracket comprise planar surfaces, normal to the axis of the igniter, which provide relative displacement therebetween such that the floating collar slides at an interface with the mounting bracket, a bisecting plane extending along the igniter and at an angle to the chamber axis such that the igniter axis lies in the bisecting plane, the purge openings confined within an arc disposed upstream of the bisecting plane relative to the direction of air flow within the combustion chamber, the igniter assembly being free from the purge openings downstream of the bisecting plane relative to the direction of air flow within the combustion chamber.

2. The combustor igniter assembly as defined in claim 1 , wherein the purge openings comprise slots coaxial with the axis of the collar opening for providing the flow of purge air.

3. The combustor igniter assembly as defined in claim 1 , wherein the purge openings are within the floating collar and comprise purge bores extending through the floating collar for feeding the flow of purge air from the plenum to the cavity.

4. The combustor igniter assembly as defined in claim 1 , wherein the arc spans less than 120°.

5. The combustor igniter assembly as defined in claim 4 , wherein the arc is at least 90°.

6. The combustor igniter assembly as defined in claim 3 , wherein the purge bores extend through the floating collar at angle to the igniter axis of the igniter in a range between 0° and 55° , wherein 0° is parallel to the axis of the collar opening.

7. The combustor igniter assembly as defined in claim 2 , wherein the slots are tangential to the periphery of the cavity.

8. The combustor as defined in claim 7 , wherein the purge openings are within the floating collar and the slots are formed in the planar surface of the floating collar.

9. The combustor as defined in claim 7 , wherein the slots are formed in the planar surface of the mounting bracket.

10. The combustor as defined in claim 1 , wherein the purge openings comprise purge bores extending radially through the mounting bracket from the plenum to the cavity.

11. The combustor igniter assembly as defined in claim 10 , wherein the purge openings are tangential to the periphery of the cavity.

12. The combustor igniter assembly as defined in claim 1 , wherein the purge openings comprise slots defined at the interface which are directed to the cavity.