SECONDARY AIR SUPPLY SYSTEM WITH FEED PIPES HAVING SONIC ORIFICES

A secondary air system (SAS) (30) of an aircraft engine that produces secondary airflow (34) from a source of secondary air (32) includes a hollow strut (28) and one or more SAS feed pipes upstream thereof. The hollow strut (28) extends radially through the main gas path (13) of the engine and defines therein a strut conduit extending between a strut inlet and a strut outlet at opposite ends of the hollow strut (28). The strut outlet is in fluid flow communication with a buffer cavity for feeding the secondary airflow (34) to the engine core (15). The SAS feed pipe includes an inlet receiving the secondary airflow (34) from the source of secondary air (32), and an outlet in fluid flow communication with the strut inlet to feed the secondary airflow (34) into the strut conduit. The SAS feed pipe has a sonic orifice therein, between the inlet and the outlet thereof.