22-10-2012, 05:23 PM
Effect of Blowing on Boundary Layer of Scarf Inlet
ABSTRACT
When aircraft operate in stationary or low speed conditions, airflow into the engine accelerates around the inlet lip and
pockets of turbulence that cause noise and vibration can be ingested. This problem has been encountered with engines
equipped with the scarf inlet, both in full scale and in model tests, where the noise produced during the static test makes it
difficult to assess the noise reduction performance of the scarf inlet. NASA Langley researchers have implemented boundary
layer control in an attempt to reduce the influence of the flow nonuniformity in a 12-in. diameter model of a high bypass fan
engine mounted in an anechoic chamber. Static pressures and boundary layer profiles were measured in the inlet and far field
acoustic measurements were made to assess the effectiveness of the blowing treatment. The blowing system was found to lack
the authority to overcome the inlet distortions. Methods to improve the implementation of boundary layer control to reduce
inlet distortion are discussed