Instrumentation for In-Flight Acoustic Measurements in an Engine Inlet Duct of a Fokker 100 Aircraft

摘要

Acoustic measurement were carried out in the engine intake duct of the Fokker 100 test aircraft during flight. One of the engines was provided with an instrumented intake to determine the circumferential modes of the sound field. To collect the required data, a fully digital data acquisition system had to be developed. The paper deals with the technical requirements for the acoustic instrumentation, the selection of the transducers and a description of the new data acquisition system. The existing instrumentation of the Fokker 100 test aircraft is mentioned wherever relevant. Extensive system checks, including environmental and calibration tests, were carried out before installing the system in the aircraft. Some results of these tests are presented. In addition, the flight test program and the data processing will be described briefly.