According to one aspect of the invention, a gas turbine engine includes a combustor, a fuel nozzle placed in an end of the combustor, and a passage configured to receive an air flow from a compressor discharge casing, wherein the passage directs the air flow into a chamber downstream of the nozzle, wherein a chamber pressure is lower than a compressor discharge casing pressure. The gas turbine engine also includes a flow control device configured to control the air flow from the compressor discharge casing into the passage.