Transfer function of small convergent-divergent (C-D) nozzles and opposite (D-C) devices filled with thermo-viscous fluid at rest

摘要

An analytical representation, which involves single integrals, is established for describing the shape of small acoustic elements (slits or tubes) more or less tapered (the shape being governed by only one parameter). This representation includes the ability to create a zero slope (horizontal) at one end and an infinite one (vertical) at the other end, the limiting shapes being small cylindrical tubes or cavities. Then, the results obtained from the analytic procedure presented in a previous paper (Honzik et al., 2013), whereby one expresses the transfer function of such elements filled with a thermo-viscous fluid and, beyond, the transfer function of components obtained when connecting them continuously, are presented and compared to numerical and experimental results. Two prototype components gradually narrowing and widening, and conversely, are considered, namely a convergent-divergent nozzle which makes a symmetric hourglass-shape and the opposite divergent-convergent device, with different loads that end the device. The results show the potentialities of such small components when used in acoustic devices. (C) 2015 Elsevier Ltd.. All rights reserved.