Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
On the synthesis of the transfer matrix of thermoacoustic cores from arbitrary engine performance
Submission Author:
Denis Gomes , SP
Co-Authors:
Denis Gomes, Flávio Bannwart
Presenter: Denis Gomes
doi://10.26678/ABCM.ENCIT2018.CIT18-0656
Abstract
Thermoacoustic engines convert thermal into mechanical energy by means of spontaneous acoustic oscillations in a working gas confined within a tubular network, whose configuration may lead to either standing or traveling waves. Its main segment is the thermoacoustic core (TAC), defined as the waveguide interval where the temperature gradient is inhomogeneous and, if sufficiently high, generates the acoustic field. The thermoacoustic phenomenon occurs within the open pores of its main component: stack or regenerator. From the transfer matrix of the TAC filled with a specific porous material, different engines can be designed by varying the lengths of the other waveguide segments, and their energetic performances estimated. Therefore, an optimization can be carried out by pursuing the best waveguide configuration for each TAC. However, such procedures may be time-demanding as they follow a forward problem for each sample of porous material under investigation, and the chances of achieving a good TAC design may not be favored in this trial and error process. As an attempt to improve the criteria for porous material selection, we explore in this work an inverse problem: the synthesis of the TAC transfer matrix from an arbitrary engine performance. Previous experimental data from TACs of two different porous materials are analyzed for a standing wave engine configuration. Each transfer coefficient is disturbed in both amplitude and phase in simulations so that to evaluate the effects on the thermoacoustic gain. The resulting artificial matrices lead to better energetic performances and rise discussions toward the feasibility of the corresponding porous materials.
Keywords
thermoacoustics, transfer matrix, thermoacoustic core, Inverse problem, thermoacoustic engine
