A system and method for reducing modal coupling of combustion dynamics among multiple combustors are provided. Each combustor may include one or more fuel nozzles axially aligned with a combustion chamber; one or more fuel injectors downstream from the fuel nozzles; and a set of flow openings integrated with the combustor. The fuel injectors provide fluid communication through a liner that circumferentially surrounds each combustion chamber. The flow rate of compressed working fluid diverted through the fuel injectors may be different and/or variable between the combustors to produce different combustion instability frequencies.