Abstract:
A concentric tube resonator was investigated to determine the accuracy of the numerical method used for sound-pressure simulations. The interaction between the tube and the cavity was through a perforated surface, of which the acoustical properties were experimentally determined [J. W. Sullivan, J. Acoust. Soc. Am. 76, 479--484 (1984)]. These properties were imposed as boundary conditions to the finite-element analysis (FEA) code. Predicted and measured transmission losses were compared under no mean flow conditions. The work was then extended to include the effects of mean flow. Empirical equations given in literature were used to modify the acoustical properties of the perforated surface to incorporate the effects of flow [Garrison et al., Pratt and Whitney Aircraft Rep. (1969)]. The mean flow terms in the scalar Helmholtz equation were treated explicitly in order to avoid the additional storage requirements for the FEA code. Special attention had been paid to the design of the FEA code, such that information can be seamlessly exchanged with a computational fluid dynamics (CFD) simulation, for possible future research.