Dilution passages for combustor of a gas turbine engine

A gas turbine engine, comprising:

• a compressor section;
• a turbine section;
• and
• a combustor section, the combustor section including a wall assembly for use in a combustor of the combustor section, the wall assembly comprising:
• a support shell;
• a liner panel, the liner panel being separately secured to the support shell;
• and
• an annular grommet extending from the liner panel, the annular grommet defining a dilution passage having a dilution passage axis and the annular grommet extends through an opening in the support shell when the support shell and the liner panel are secured to each other, the annular grommet having a top portion that defines a portion of a periphery of the dilution passage;
• and
• a backstop extending from the top portion of the annular grommet, the backstop defining another portion of the periphery of the dilution passage and the backstop extending through and above the opening in the support shell when the liner panel is secured to the support shell, wherein a portion of an inner wall of the annular grommet includes a linearly converging contoured inner wall portion that extends from the top portion to a bottom portion of the annular grommet, the bottom portion being opposite the top portion and located at a hot side of the liner panel, the linearly converging contoured inner wall portion has a first inner periphery defining a portion of a first cross-sectional area of the dilution passage and a second inner periphery defining a portion of a second cross-sectional area of the dilution passage, the second inner periphery being smaller than that of the first inner periphery and the linearly converging contoured inner wall portion is only located at a leading edge portion of the dilution passage and the inner wall of the annular grommet or extending from the backstop is linear and parallel to the dilution passage axis from the backstop to the bottom portion of the annular grommet.

A method of guiding airflow into a combustor of a gas turbine engine, the method comprising:

• locating a portion of an annular grommet in an opening of a support shell of the combustor, the annular grommet extending from a liner panel secured to the support shell, the annular grommet defining a dilution passage, the liner panel being separately secured to the support shell;
• and
• directing airflow into the dilution passage via a backstop extending from a top portion of the annular grommet, the top portion defining a portion of a periphery of the dilution passage, wherein a portion of an inner wall of the annular grommet includes a linearly converging contoured inner wall portion that extends from the top portion to a bottom portion of the annular grommet, the bottom portion being opposite the top portion and located at a hot side of the liner panel, the linearly converging contoured inner wall portion has a first inner periphery defining a portion of a first cross-sectional area of the dilution passage and a second inner periphery defining a portion of a second cross-sectional area of the dilution passage, the second inner periphery being smaller than that of the first inner periphery and the linearly converging contoured inner wall portion is only located at a leading edge portion of the dilution passage and the inner wall of the annular grommet extending from the backstop is linear and parallel to the dilution passage axis from the backstop to the bottom portion of the annular grommet.