A gas turbine engine including a trapped vortex combustor assembly is generally provided. The combustor assembly includes an inner liner wall extended annularly around a combustor centerline, and an outer liner wall extended annularly around the combustor centerline. The inner liner wall and the outer liner wall together define an involute wall extended at least partially as a spiral curve from a circumferential reference line around the combustor centerline. The involute wall defines an involute combustion chamber. One or more of the inner liner wall and the outer liner wall each define a first dilution opening and a shaped dilution opening.