Target Setting and Prediction for Cabin Noise and Vibration in Aircraft Development

A methodology to secure cabin noise and vibration targets is presented. Early in the design process, typically in the Joint Definition Phase, Targets are cascaded from system to component level to comply with the overall cabin noise target in various load cases. During the Detailed Design Phase, 3D simulation models are build up to further secure and refine the vibro-acoustic performance of the cabin noise related subsystems. Noise sources are estimated for the target setting based on layer analytical and empirical expressions from literature. This includes various types of engine noise - fan, jet, and propeller noise - as well as turbulent boundary layer noise. For other noise sources, ECS and various auxiliaries, targets are set such as to ensure the overall cabin noise level. To synthesize the cabin noise, these noise sources are combined with estimates of the noise transfer through panels and the cavity effect of the cabin. This part is again based on analytical and empirical formulations. Targets for interior components such as panels and blankets can be derived here, early in the development process, and comprehensive parameter studies can be easily carried out. The whole process is validated against in flight measurement data. Later in the design process, detailed simulation takes place to confirm the cabin noise design. Noise sources such as turbulent boundary layer, propeller, ECS, and engine fan can be simulated with good accuracy. A vibroacoustic model including fuselage structure, blankets, interior panels, floor and other relevant components is used for low and mid frequency cabin noise prediction, to secure and refine the noise targets.