Gas turbine cooling circuit including a seal for a perforated plate

A method of controlling airflow through a plate in a gas turbine, the plate including a plurality of through-holes and a plurality of tube holes formed therein, the tube holes being adapted to accommodate a plurality of mixing tubes with which the tube holes form a plurality of annulus areas between the plate and the mixing tithes, the method comprising:

• establishing an airflow adapted to pass, respectively, through the through-holes and the annulus areas to a common area immediately adjacent the plate where the airflow passing through the through-holes and the airflow passing through the annulus areas intermix;
• and
• providing a flow management device to adjust an effective size of the annulus areas, the flow management device having a first portion directly attached to the plate and a plurality of second portions extending into the annulus areas formed between the plate and the mixing tubes to control a distribution of the airflow through the through-holes and the annulus areas of the plate, wherein the plurality of second portions of the flow management device respectively engages the plurality of mixing tubes.