The role of fluid-structure interaction in the prediction of cabin noise for internal weapons bays

Other conference contribution, 2025

The primary purpose of adopting an internal weapons bay (IWB) is to reduce the aircraft radar cross-section (RCS). The reduction of RCS is a strategical advantage, although it is accompanied with challenges pertaining to structural integrity. Flow passing the IWB—also known as cavity flow—generates a highly turbulent and unsteady environment. In addition to broadband noise, it also generates energetic tonal noise, known as Rossiter tones, which are commonly present in deep cavities. The turbulence and the tonal noise excite the structure, generating internal noise inside the aircraft. In this process, potential risks are high vibration levels and resonances between the Rossiter modes, structural eigenfrequencies and cabin acoustic eigenfrequencies. Vibrations may endanger the functionality or expose apparatuses to levels beyond their certified limit. Moreover, vibrations may lead to acoustic fatigue, which shortens the expected lifespan of the airframe. Hence, understanding of the multi-physics as well as performing accurate simulations for prediction are essential for the development of IWB configurations.

The results show that at specific scenarios, the coupling between the structure and external acoustics are important in the generation of structural vibrations, and internal and external noise. This effect is apparent in the tonal generation and is related to Rossiter modes and structural eigenfrequencies, as well as the cabin acoustic eigenfrequencies.