Noise Reduction of a Rocket Payload Fairing Using Tuned Vibration Absorbers with Translational and Rotational DOFs

Numerical optimisations were conducted to reduce the noise levels inside the payload bay of a rocket by using vibration and acoustic absorbers attached to the fairing walls. The vibration absorbers act in both translational and rotational axes. The acoustic absorbers were modelled as simplified Helmholtz resonators. A Finite Element model of the vibro-acoustic system was created in ANSYS and the uncoupled structural and acoustic modal responses were calculated. The combined response of the acoustic and vibration absorbers, the acoustic cavity and structural modal responses were coupled using modal coupling theory in Matlab. The optimisation of the parameters and locations of the absorbers were conducted using a semi-synchronous parallel genetic algorithm and a large number of networked desktop computers.