FLIGHT TEST WEEK 'OPEN CONFERENCE' - hosted by Society of Flight Test Engineers (SFTE)

Running in Auditorium 3 on the Exhibits floor) on 18, 19, 20 Nov 2008


Reconstruction of in-flight interior vibro-acoustic response
Tuesday 18th November 2008
14.00 - 14.30
Auditorium 3

Vibro-acoustic responses inside the fuselage of an in-flight business jet are reconstructed. Two microphone arrays were built to take acoustic pressure measurements inside the fuselage. One circular array was mounted on a track so that it could be moved in the longitudinal direction to measure the acoustic pressures along the circumference of the fuselage. Another planar array was used to measure the acoustic pressures on the closing surface of the fuselage in the bulkhead and cockpit positions, respectively. Over four thousand measurements of acoustic pressure were taken while the jet was flying at constant speed and altitude of 30,000 ft in the air. These measured acoustic pressures were taken as input to the Helmholtz Equation Least Squares (HELS) method to reconstruct the interior acoustic field, including the fuselage surface. The reconstructed normal surface velocities were checked with respect to the benchmark velocity spectra measured by the accelerometers mounted on the interior surface of the fuselage. This experiment demonstrates that HELS can be used to acquire a good understanding of vibro-acoustic responses inside an arbitrary interior region.