Methods of Controlling Distortion of Inlet Airflow During Static Acoustical Tests of Turbofan Engines and Fan Rigs AIR1935

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.