Energy finite element analysis (EFEA) approach for fuselage noise prediction

This paper presents an approach used to determine the acoustic noise in a fuselage of a regional turboprop aircraft. The acoustic noise is due to diffuse field pressure (DFP) generated by turboprop engines and to the acoustic power generated by air vent of the Environmental Control Sub-System (ECS). Frequency dependency has been also taken into account. The analysis has been conducted by using new software distributed by MSC Software and developed by University of Michigan, MSC EFEA. It is based on Energy Finite Element Analysis (EFEA) that has been developed for evaluating the vibro-acoustic behavior of complex systems. A finite element approach is employed for solving the governing differential equations numerically. Joint finite element matrices are developed at all the locations where the primary variable of the EFEA formulation is discontinuous. The numerical model of the fuselage has been covered (externally and on the floor) by skins with proper structural characteristics associated with transmission loss to reproduce the real conditions. Acoustic treatments in the different part of the structure have been modeled in all their components. The acoustic effects of the seats and the passengers have been taken into account by defining the proper adsorption coefficients in the affected volumes of the cabin. DFP and ECS frequency dependency are also taken into account.