On the Coupling Between Successive Nonlinear Acoustic Resonance

S.Frikha, M.Ayadi (Laboratoire de Mecanique Physique, Saint Cyr l'Ecole , France)

e-mail: frikha@ccr.jussieu.fr

This contribution investigates the finite amplitude standing wave generated in a closed pipe by a transient source when its instantaneous frequency varies and successively meets a set of resonance frequencies. This situation is typically encountered when dealing with accelerating or a decelerating alternative machines. The piping systems to these machines at their inlet and/or outlet are commonly subjected to highly transient source whose may excite several resonance frequencies. Based on the well known nonlinear Burgers equation governing nonlinear propagation in viscous media, a new updated incident wave schema is developed and its efficiency to compute the nonlinear resonance modes of a closed tube is demonstrated. This schema is then used to investigate the coupling between successive resonance modes. The obtained results show that a part of the energy of a given eigenmodes is transferred to the previous ones and so sustains them. This gives rise to a dense high frequency contents.


Section : 1