Generally it is desirable during static engine noise testing to simulate the noise-generating processes that occur during takeoff or landing. One factor that may have significant influence on fan noise from turbofan engines during static testing is the airflow distortion encountered by the low-pressure fan stage. This report presents technical details on devices that "condition" the airflow entering the engine to more nearly simulate flight operations without introducing a detrimental impact on sound propagating from the engine.
This Aerospace Information Report provides guidelines for hardware design. Guidelines on such items as engine types, test arrangements, and test purposes that would benefit from the use of an inflow control device during static noise testing are outside the scope of this report.
To present a summary of the guidelines and practices presently being used by the aerospace industry for the selection of coiled tubes, flexible hoses, swivel fittings, and extension fittings in aircraft fluid systems.