{"id":43142,"date":"2020-11-12T16:07:06","date_gmt":"2020-11-12T14:07:06","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=43142"},"modified":"2021-01-22T13:48:42","modified_gmt":"2021-01-22T11:48:42","slug":"these-de-pierre-guiraud-analyse-theorique-et-experimentale-de-lefficacite-de-mousse-de-carbone-pour-generation-acoustique-dans-des-milieux-visqueux","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/actualites\/these-de-pierre-guiraud-analyse-theorique-et-experimentale-de-lefficacite-de-mousse-de-carbone-pour-generation-acoustique-dans-des-milieux-visqueux.html","title":{"rendered":"Th\u00e8se de Pierre Guiraud \u2013 Analyse th\u00e9orique et exp\u00e9rimentale de l\u2019efficacit\u00e9 de mousse de carbone pour g\u00e9n\u00e9ration acoustique dans des milieux visqueux"},"content":{"rendered":"<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-sj83ae-cba828394457a7e5bb594166900cedfc\">\n.flex_column.av-sj83ae-cba828394457a7e5bb594166900cedfc{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-sj83ae-cba828394457a7e5bb594166900cedfc av_one_full  avia-builder-el-0  avia-builder-el-no-sibling  first flex_column_div av-zero-column-padding'     ><section  class='av_textblock_section av-kheyvp92-697f19fb02b9733cc96687cf2e361130'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h4 style=\"text-align: center;\">Soutenance de th\u00e8se de Pierre Guiraud<\/h4>\n<h5 style=\"text-align: center;\">Analyse Th\u00e9orique et Exp\u00e9rimentale de l\u2019Efficacit\u00e9 de Mousse de Carbone<br \/>\npour G\u00e9n\u00e9ration Acoustique dans des Milieux Visqueux<\/h5>\n<blockquote>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-sxxhxi-e2ffb49c40ee5137b5ef946fbbfb7943\">\n.av_font_icon.av-sxxhxi-e2ffb49c40ee5137b5ef946fbbfb7943 .av-icon-char{\nfont-size:40px;\nline-height:40px;\n}\n<\/style>\n<span  class='av_font_icon av-sxxhxi-e2ffb49c40ee5137b5ef946fbbfb7943 avia_animate_when_visible av-icon-style- avia-icon-pos-left av-no-color avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue8c9' data-av_iconfont='entypo-fontello' ><\/span><\/span>\n<p>Vendredi 20 novembre 2020 \u00e0 10h \u2013 Amphith\u00e9\u00e2tre Eug\u00e8ne Constant<br \/>\nLaboratoire central \u2013 Avenue Henri Poincar\u00e9 59652 Villeneuve d\u2019Ascq<\/p>\n<\/blockquote>\n<h5>Jury :<\/h5>\n<p>Mme Diana Baltean, Universit\u00e9 Pierre et Marie Curie, LIMSI, Rapporteure<br \/>\nM. Pierrick Lotton, LAUM, Rapporteur<br \/>\nMme Juliette Pierre, MPIA, Examinatrice<br \/>\nM. Franck Levassort, GREMAN, Examinateur, Pr\u00e9sident<br \/>\nM. Stefano Giordano, IEMN, Co-directeur de th\u00e8se<br \/>\nM. Olivier Bou-Matar, Centrale Lille, IEMN, Co-directeur de th\u00e8se<br \/>\nM. Philippe Pernod, Centrale Lille, IEMN, Co-encadrant<br \/>\nM. Raphael Lardat, Thales Underwater System, Co-encadrant<br \/>\nM. Philippe Coquet, Universit\u00e9 de Lille Invit\u00e9, Co-encadrant<br \/>\nM. Philippe Pouliguen, Responsable Acoustique, Ondes Radio-\u00c9lectrique, DGA, Invit\u00e9<\/p>\n<h5>Summary:<\/h5>\n<p>Les transducteurs \u00e9lectroacoustiques ainsi que les dispositifs pi\u00e9zo\u00e9lectriques font partie des principales m\u00e9thodes de g\u00e9n\u00e9ration acoustique dans un gaz ou un liquide. Un mouvement m\u00e9canique d\u2019une membrane cr\u00e9e une vibration de l\u2019air g\u00e9n\u00e9rant une onde acoustique. La thermoacoustique en revanche utilise des variations rapides de temp\u00e9rature d\u2019un mat\u00e9riel pour exciter l\u2019air. Ces changements thermiques rapides cr\u00e9ent une compression\/dilatation de l\u2019air qui va g\u00e9n\u00e9rer une onde acoustique. De tels mat\u00e9riaux sont appel\u00e9s thermophones. Ces derniers ont \u00e9t\u00e9 d\u00e9couvert \u00e0 la m\u00eame p\u00e9riode que les\u00a0 transducteurs \u00e9lectroacoustiques mais leur faible efficacit\u00e9 ainsi que les limitations scientifiques de l\u2019\u00e9poque ont emp\u00each\u00e9 le domaine de se d\u00e9velopper.<br \/>\nEn 1999, un nouveau thermophone avec des capacit\u00e9s acoustiques bien sup\u00e9rieures \u00e0 ses pr\u00e9d\u00e9cesseurs a \u00e9t\u00e9 pr\u00e9sent\u00e9. La publication de cet article associ\u00e9e \u00e0 une plus grande facilit\u00e9 d\u2019acc\u00e8s \u00e0 des machines permettant la fabrication de mat\u00e9riaux nanostructur\u00e9s a permis un nouvel engouement pour la thermoacoustique audio.<br \/>\nDans cette th\u00e8se, une vaste revue de litt\u00e9rature est pr\u00e9sent\u00e9e et un mod\u00e8le innovant multicouche de g\u00e9n\u00e9ration thermoacoustique en est d\u00e9duit. Ce mod\u00e8le est r\u00e9solu pour la g\u00e9n\u00e9ration d\u2019ondes planes, cylindriques et sph\u00e9riques. Un second mod\u00e8le bas\u00e9 sur une hypoth\u00e8se dite de deux temp\u00e9ratures est aussi cr\u00e9\u00e9 pour repr\u00e9senter de fa\u00e7on plus fid\u00e8le la g\u00e9n\u00e9ration thermoacoustique dans un milieu poreux \u00e9pais. Une analyse \u00e9tendue des r\u00e9sultats d\u00e9coulant de ces mod\u00e8les est ensuite faite permettant la compr\u00e9hension des forces, faiblesses et particularit\u00e9s des thermophones par rapport aux m\u00e9thodes\u00a0 traditionnelles. Enfin, une analyse exp\u00e9rimentale de mousses carbon\u00e9es en partenariat avec CINTRA Singapour est pr\u00e9sent\u00e9e. Cela permet la validation des mod\u00e8les th\u00e9oriques et procure une compr\u00e9hension exp\u00e9rimentale sur la manipulation de ce type de mat\u00e9riaux flexibles et l\u00e9gers mais fragiles, ainsi que leurs potentielles applications scientifiques et commerciales.<\/p>\n<h5>Abstract:<\/h5>\n<p>Electroacoustic transducers along with piezoelectric devices are the most widely used method for acoustic sound generation in gas and in liquids. A mechanical movement of a membrane induces air vibration thus creating an acoustic wave. The thermoacoustic process on the other hand uses fast paces temperature variations in a sample to excite the air. The rapidly changing temperature generate a compression\/expansion of the air and thus creates an acoustical wave. Such materials are called thermophones. They were discovered in the same time period as traditional electroacoustic transducer but their limited efficiency coupled with the technological limits of fabrication prevented scientific craze at the time. In 1999 a new thermophone was presented with a significant improvement compared to the samples used a century prior. This article coupled with the newly found ease of access to complex fabrication process of nanomaterials rekindle the interest in thermoacoustic for audio purposes. In this thesis a thorough literature review is presented and a novel multilayer model for thermoacoustic sound generation is derived. This model was solved for plane wave, cylindrical wave and spherical wave generation. Another model based on a two temperatures hypotheses for plane wave generation is also solved to represent more accurately the generation of thick porous thermophones.<br \/>\nAn extensive analysis of those model allowed for a detailed understanding of the thermoacoustic<br \/>\nsound generation: its strengths, weaknesses and differences with traditional speakers. Lastly, experimental<br \/>\ninvestigations of porous carbon foam in partnership with CINTRA Singapore are presented. Validation of the<br \/>\nmodels and insights about the handling of such flexible and lightweighted but fragile samples are presented<br \/>\nas well at their potential applications for scientific or commercial purposes.<\/p>\n<\/div><\/section><\/div>","protected":false},"excerpt":{"rendered":"","protected":false},"author":2,"featured_media":43146,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,40],"tags":[],"class_list":["post-43142","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-actualites","category-articles-temporaires-anglais"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/43142","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=43142"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/43142\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/43146"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=43142"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=43142"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=43142"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}