This paper presents a technique for determining the amount of noise reaching an aircraft's interior via a structureborne path when high levels of airborne noise are also present. The technique involves the measurement of transfer functions between vibration levels on the wing and interior noise. The magnitude of the structureborne noise transfer function is established by exciting the aircraft with an electrodynamic shaker. A second transfer function with the aircraft's engine operating. Comparison between these two transfer functions and utilization of the measured interior noise data for both shaker or aircraft engine operation provides sufficient information to determine the level of structureborne noise during engine operation. The structureborne noise during single ground operation of a twin turboprop OV-10A aircraft was measured by applying this technique. The resulting transfer function values at the discrete frequencies which correspond to the propeller blade passage frequency and its first four harmonics are tabulated and graphically illustrated. Plots of the values of the overall sound pressure level and acceleration at discrete frequencies are also included.
Structureborne noise in aircraft
Koerperschallgeraeusch in Flugzeugen
1987
5 Seiten, 7 Bilder, 8 Quellen
Aufsatz (Konferenz)
Englisch