01054198

Component

This paper describes how transitioning statistical energy analysis (SEA) based design and analysis tools from research to production support are a confidence building process. Confidence building is based on a model, test and check process using commercial SEA codes and in-house test facilities. Commercial SEA codes are few and relatively new when compared to the finite element codes on the market. However, SEA methods are being more widely applied and SEA results are gaining acceptance for noise control system design in the automobile, ship, rail, space and, of course, airplane transportation vehicle industries. The goal for SEA modeling is to estimate the cabin noise levels in flight in the mid to high frequencies. For double aisle airplanes the frequency range where SEA modeling is easily justified in the 500 to 20,000 Hz range. Due to lack of a practical alternative, SEA calculations for airplane cabin models are run down to 100 Hz with the understanding the variation about the mean-value estimates will increase at the lower frequencies. SEA is based on the assumption of energy transfer between resonant modes so the frequency limitations are best viewed as a requirement for the subsystems to have many modes. In other words, the dimensions of the system understudy should be large relative to the characteristic wavelength in that system. This paper uses a four window/frame bay model length with an approximate length of 2.5 meters, which is long relative to the acoustic wavelength at 1000Hz but short relative to an acoustic wavelength at 50 Hz. Uncertainty in the predictions can be viewed as three separate problems with different approaches to reducing the uncertainty. There is an uncertainty in the input power, which is a major concern for the in-flight noise predictions, there is an uncertainty in the transfer functions, which can be refined using laboratory tests, and there is an uncertainty in the definition of the SEA model and its subsystems.

01054353

English

pp 367-379

2004

Noise-Con 04. The 2004 National Conference on Noise Control Engineering

CD-ROM

Appendices (1) ; Figures; Photos

Air transportation; Aircraft; Aircraft cabins; Civil aircraft; Energy; Energy absorption; Noise control; Noise sources; Sound transmission; Statistical analysis

Aviation; Data and Information Technology; Energy; Environment; Vehicles and Equipment

TRIS, TRB

Jul 16 2007 6:10PM