ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3pEA3. A novel active control approach for aircraft interior noise.

Brian H. Houston

Martin H. Marcus

Naval Res. Lab., Washington, DC 20375-5350

The results of numerical experiments carried out to study the broadband structural acoustics of an aircraft-like shell under point excitation have been previously reported. The dominant mechanisms that lead to the enhancement of interior acoustic levels are resonances in the structure (both in the endcap and cylinder wall) forcing high interior acoustic levels as well as structural-borne energy coupling into ``rigid wall'' cavity resonances. Wave-number domain analysis reveals the evidence of free waves on the cylinder modified by finite length effects, flexural Bloch waves, and coupling to the cavity resonances. In this paper, results are presented of active control simulations that employ novel control approaches that are wave-number-domain based. These results also show that global access to low-order interior modes is obtained through simple actuation schemes and that minimization of some of the more dominant interior modes is achieved by the application of simple constraints to the structure.