{"id":53009,"date":"2020-03-02T12:31:39","date_gmt":"2020-03-02T11:31:39","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/quest-ce-que-le-modele-de-flux-flux-biphase-definition\/"},"modified":"2020-03-02T12:34:38","modified_gmt":"2020-03-02T11:34:38","slug":"quest-ce-que-le-modele-de-flux-flux-biphase-definition","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-le-modele-de-flux-flux-biphase-definition\/","title":{"rendered":"Qu&#8217;est-ce que le mod\u00e8le de flux &#8211; Flux biphas\u00e9 &#8211; D\u00e9finition"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">Les structures d&#8217;\u00e9coulement observ\u00e9es sont d\u00e9finies en tant que mod\u00e8les d&#8217;\u00e9coulement \u00e0 deux phases et pr\u00e9sentent des caract\u00e9ristiques d&#8217;identification particuli\u00e8res.\u00a0Mod\u00e8les de flux &#8211; Flux biphas\u00e9<\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2>Mod\u00e8les de flux &#8211; Flux biphas\u00e9<\/h2>\n<p>L&#8217;un des aspects les plus difficiles de la gestion d&#8217;un\u00a0<strong><a title=\"D\u00e9bit de fluide \u00e0 deux phases\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-ecoulement-de-fluide-a-deux-phases-definition\/\">\u00e9coulement diphasique<\/a>\u00a0ou multiphas\u00e9<\/strong>\u00a0est le fait qu&#8217;il peut prendre de\u00a0<strong>nombreuses formes diff\u00e9rentes<\/strong>\u00a0.\u00a0<strong>Les distributions spatiales et les vitesses<\/strong>\u00a0des\u00a0<strong>phases liquide et vapeur<\/strong>\u00a0dans le canal d&#8217;\u00e9coulement sont des aspects tr\u00e8s importants dans de nombreuses branches techniques.\u00a0<strong>Les pertes de charge,<\/strong>\u00a0ainsi que\u00a0<strong>les coefficients de transfert de chaleur,<\/strong>\u00a0d\u00e9pendent fortement de la\u00a0<strong>structure de l&#8217;\u00e9coulement local<\/strong>\u00a0et jouent donc un r\u00f4le important dans l&#8217;ing\u00e9nierie des\u00a0<a title=\"R\u00e9acteur nucl\u00e9aire\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/\"><strong>r\u00e9acteurs nucl\u00e9aires<\/strong><\/a>\u00a0.\u00a0Les structures d&#8217;\u00e9coulement observ\u00e9es sont d\u00e9finies en tant que\u00a0<strong>mod\u00e8les d&#8217;\u00e9coulement \u00e0 deux phases<\/strong>et ceux-ci ont des caract\u00e9ristiques d&#8217;identification particuli\u00e8res.\u00a0Ces diff\u00e9rents mod\u00e8les d&#8217;\u00e9coulement ont \u00e9t\u00e9\u00a0<strong>class\u00e9s en<\/strong>\u00a0fonction de la\u00a0<strong>direction de l&#8217;\u00e9coulement par<\/strong>\u00a0rapport \u00e0 l&#8217;acc\u00e9l\u00e9ration gravitationnelle.<\/p>\n<ul>\n<li><strong>Profils d&#8217;\u00e9coulement dans les tubes verticaux<\/strong><\/li>\n<li><strong>Profils d&#8217;\u00e9coulement dans les tubes horizontaux<\/strong><\/li>\n<\/ul>\n<figure id=\"attachment_14848\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-14848\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-table.png\"><img loading=\"lazy\" class=\"size-medium wp-image-14848 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-table-300x198.png\" alt=\"mod\u00e8les d'\u00e9coulement\" width=\"300\" height=\"198\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-table-300x198.png\" \/><\/a><figcaption id=\"caption-attachment-14848\" class=\"wp-caption-text\">Tableau des mod\u00e8les d&#8217;\u00e9coulement de base dans les tubes verticaux.<\/figcaption><\/figure>\n<p>Les principaux r\u00e9gimes d&#8217;\u00e9coulement\u00a0<strong>dans les tubes verticaux<\/strong>\u00a0sont indiqu\u00e9s dans le tableau.\u00a0Il faut noter que les valeurs de\u00a0<a title=\"Qualit\u00e9 statique - Qualit\u00e9 du d\u00e9bit\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/two-phase-fluid-flow\/static-quality-flow-quality\/\"><strong>qualit\u00e9<\/strong><\/a>et de\u00a0<strong>d\u00e9bit<\/strong>\u00a0d\u00e9pendent du fluide et de la pression.\u00a0<strong>Dans les tubes horizontaux<\/strong>\u00a0, il peut \u00e9galement y avoir un\u00a0<strong>\u00e9coulement stratifi\u00e9<\/strong>\u00a0(en particulier \u00e0 faible d\u00e9bit), auquel les deux phases se\u00a0<strong>s\u00e9parent<\/strong>\u00a0sous l&#8217;effet de la gravit\u00e9.<\/p>\n<p>Pour un d\u00e9bit de liquide constant, la phase vapeur \/ gaz a tendance \u00e0 \u00eatre distribu\u00e9e sous forme de\u00a0<strong>petites bulles<\/strong>\u00a0\u00e0 de faibles d\u00e9bits de vapeur.\u00a0<strong>L&#8217;augmentation de la fraction de vide<\/strong>\u00a0provoque l&#8217;\u00a0<strong>agglom\u00e9ration<\/strong>\u00a0de bulles en\u00a0<strong>bouchons et en limaces plus gros<\/strong>\u00a0.\u00a0Une agglom\u00e9ration plus pouss\u00e9e des bouchons, causant une\u00a0<strong>augmentation<\/strong>\u00a0suppl\u00e9mentaire de\u00a0<strong>la fraction de vide,<\/strong>\u00a0provoque la s\u00e9paration des phases en\u00a0<strong>motifs annulaires<\/strong>\u00a0dans lesquels le liquide se concentre au niveau de la paroi du canal et la\u00a0<strong>vapeur s&#8217;\u00e9coule dans le noyau central<\/strong>\u00a0du canal vertical.<\/p>\n<p><strong>Pour le canal horizontal<\/strong>\u00a0, la force de gravit\u00e9 tend \u00e0 drainer l&#8217;anneau liquide vers le bas du canal, ce qui entra\u00eene un\u00a0<strong>\u00e9coulement stratifi\u00e9<\/strong>\u00a0.\u00a0La force gravitationnelle agissant sur la phase liquide peut \u00eatre surmont\u00e9e par des forces cin\u00e9tiques \u00e0 des d\u00e9bits \u00e9lev\u00e9s, entra\u00eenant le retour des flux stratifi\u00e9s en flux annulaires.\u00a0<strong>\u00c0 des d\u00e9bits tr\u00e8s \u00e9lev\u00e9s<\/strong>\u00a0, le film annulaire est aminci par le cisaillement du noyau de vapeur et tout le liquide est entra\u00een\u00e9 sous forme de gouttelettes en phase vapeur.\u00a0Ce r\u00e9gime de flux est g\u00e9n\u00e9ralement appel\u00e9\u00a0<strong>flux de brouillard<\/strong>\u00a0.<\/p>\n<p>Voir \u00e9galement:\u00a0\u00a0<strong>Recueil de donn\u00e9es techniques III, Thome, JR, Wolverine Tube Inc, 2004.<\/strong><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-50 lgc-tablet-grid-50 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Mod\u00e8les d&#8217;\u00e9coulement &#8211; Tubes verticaux<\/span><\/h2>\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<ul>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span>Flux p\u00e9tillant<\/span><\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">D\u00e9bit de limace<\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">Flux de d\u00e9sabonnement<\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">\u00c9coulement annulaire<\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">Flux de brume<\/li>\n<\/ul>\n<\/div>\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-content su-clearfix\"><\/div>\n<\/div>\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-content su-clearfix\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-50 lgc-tablet-grid-50 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_14791\" class=\"wp-caption alignleft\" aria-describedby=\"caption-attachment-14791\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Bubbly-Slug-Churn-Annular-Mist-Flow.png\"><img loading=\"lazy\" class=\"wp-image-14791 size-medium lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Bubbly-Slug-Churn-Annular-Mist-Flow-300x191.png\" alt=\"Bubbly - Slug - Churn - Annular - Mist - Flow\" width=\"300\" height=\"191\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Bubbly-Slug-Churn-Annular-Mist-Flow-300x191.png\" \/><\/a><figcaption id=\"caption-attachment-14791\" class=\"wp-caption-text\"><span>Esquisses de r\u00e9gimes d&#8217;\u00e9coulement pour un \u00e9coulement diphasique dans une conduite verticale.\u00a0Source: Weisman, J. Mod\u00e8les d&#8217;\u00e9coulement diphasique.\u00a0Chapitre 15 du Handbook of Fluids in Motion, Cheremisinoff NP, Gupta R. 1983, Ann Arbor Science Publishers.<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<figure id=\"attachment_14788\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-14788\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-vertical-flow-Hewitt.png\"><img loading=\"lazy\" class=\"wp-image-14788 size-full lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-vertical-flow-Hewitt.png\" alt=\"sch\u00e9mas d'\u00e9coulement - \u00e9coulement vertical - Hewitt\" width=\"428\" height=\"397\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-vertical-flow-Hewitt.png\" \/><\/a><figcaption id=\"caption-attachment-14788\" class=\"wp-caption-text\"><span>La carte du r\u00e9gime d&#8217;\u00e9coulement vertical de Hewitt et Roberts (1969) pour l&#8217;\u00e9coulement dans un tube de 3,2 cm de diam\u00e8tre, valid\u00e9e pour l&#8217;\u00e9coulement air \/ eau \u00e0 pression atmosph\u00e9rique et l&#8217;\u00e9coulement vapeur \/ eau \u00e0 haute pression.\u00a0Source: Brennen, CE, Fundamentals of Multiphase Flows, Cambridge University Press, 2005, ISBN 0521 848040<\/span><\/figcaption><\/figure>\n<div class=\"su-spacer\"><\/div>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-50 lgc-tablet-grid-50 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Mod\u00e8les d&#8217;\u00e9coulement &#8211; Tubes horizontaux<\/span><\/h2>\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<ul>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span>Flux p\u00e9tillant<\/span><\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">\u00c9coulement stratifi\u00e9<\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">D\u00e9bit en prise et d\u00e9bit en boucle<\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">\u00c9coulement annulaire<\/li>\n<li class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">Flux de brume<\/li>\n<\/ul>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-50 lgc-tablet-grid-50 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_14790\" class=\"wp-caption alignleft\" aria-describedby=\"caption-attachment-14790\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Bubbly-Slug-Plug-Annular-Stratified-Mist-Wavy.png\"><img loading=\"lazy\" class=\"wp-image-14790 size-medium lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Bubbly-Slug-Plug-Annular-Stratified-Mist-Wavy-300x252.png\" alt=\"bulle, bouchon, limace, annulaire, brouillard, flux stratifi\u00e9 ou ondul\u00e9\" width=\"300\" height=\"252\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Bubbly-Slug-Plug-Annular-Stratified-Mist-Wavy-300x252.png\" \/><\/a><figcaption id=\"caption-attachment-14790\" class=\"wp-caption-text\"><span>Esquisses de r\u00e9gimes d&#8217;\u00e9coulement pour un \u00e9coulement diphasique dans une conduite horizontale.\u00a0Source: Weisman, J. Mod\u00e8les d&#8217;\u00e9coulement diphasique.\u00a0Chapitre 15 du Handbook of Fluids in Motion, Cheremisinoff NP, Gupta R. 1983, Ann Arbor Science Publishers.<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_14789\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-14789\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-horizontal-flow.png\"><img loading=\"lazy\" class=\"wp-image-14789 size-full lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-horizontal-flow.png\" alt=\"sch\u00e9mas d'\u00e9coulement - \u00e9coulement horizontal\" width=\"436\" height=\"416\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/flow-patterns-horizontal-flow.png\" \/><\/a><figcaption id=\"caption-attachment-14789\" class=\"wp-caption-text\"><span>Une carte de r\u00e9gime d&#8217;\u00e9coulement pour l&#8217;\u00e9coulement d&#8217;un m\u00e9lange air \/ eau dans un tuyau horizontal de 2,5 cm de diam\u00e8tre \u00e0 25 \u00b0 C et 1 bar.\u00a0Les lignes et les points pleins sont des observations exp\u00e9rimentales des conditions de transition tandis que les zones hachur\u00e9es repr\u00e9sentent des pr\u00e9dictions th\u00e9oriques.\u00a0Source: Mandhane, JM, Gregory, GA et Aziz, KA (1974).\u00a0Une carte de configuration d&#8217;\u00e9coulement pour l&#8217;\u00e9coulement gaz-liquide dans des tuyaux horizontaux.\u00a0Int.\u00a0\u00c9coulement multiphasique<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Mod\u00e8les d&#8217;\u00e9coulement pendant l&#8217;\u00e9vaporation<\/span><\/h2>\n<p><span>La section pr\u00e9c\u00e9dente d\u00e9crit divers\u00a0<\/span><strong><span>mod\u00e8les de flux<\/span><\/strong><span>\u00a0et d\u00e9crit bri\u00e8vement leur comportement.\u00a0Ces sch\u00e9mas d&#8217;\u00e9coulement \u00e9taient consid\u00e9r\u00e9s comme\u00a0<\/span><strong><span>\u00e0 fraction de vide constante<\/span><\/strong><span>\u00a0et\u00a0<\/span><strong><span>\u00e0 vitesses superficielles constantes<\/span><\/strong><span>\u00a0.\u00a0Mais il existe de nombreuses applications industrielles qui doivent prendre en compte une\u00a0<\/span><strong><span>fraction de vide<\/span><\/strong><span>\u00a0variable et des vitesses superficielles variables.\u00a0Dans l&#8217;industrie nucl\u00e9aire, nous devons g\u00e9rer les sch\u00e9mas d&#8217;\u00e9coulement lors de l&#8217;\u00a0<\/span><strong><span>\u00e9vaporation<\/span><\/strong><span>\u00a0(c&#8217;est-\u00e0-dire lors des changements dans la\u00a0<\/span><a title=\"Fraction nulle - \u00e9coulement diphasique\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/two-phase-fluid-flow\/void-fraction-two-phase-flow\/\"><span>fraction de vide<\/span><\/a><span>\u00a0).<\/span><\/p>\n<p><span>Une connaissance d\u00e9taill\u00e9e des\u00a0<\/span><strong><span>changements<\/span><\/strong><span>\u00a0de\u00a0<strong>phase<\/strong>\u00a0et du comportement de l&#8217;\u00e9coulement pendant le changement de phase est l&#8217;une des consid\u00e9rations les plus importantes dans la conception d&#8217;un\u00a0<\/span><a title=\"R\u00e9acteur nucl\u00e9aire\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/\"><strong><span>r\u00e9acteur nucl\u00e9aire<\/span><\/strong><\/a><span>\u00a0, en particulier dans les applications suivantes:<\/span><\/p>\n<ul>\n<li><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/convective-evaporation-vertical-channel-fig.png\"><img loading=\"lazy\" class=\"alignright size-full wp-image-14854 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/convective-evaporation-vertical-channel-fig.png\" alt=\"\u00e9vaporation convective - canal vertical\" width=\"262\" height=\"633\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/convective-evaporation-vertical-channel-fig.png\" \/><\/a><a title=\"BWR - R\u00e9acteur \u00e0 eau bouillante\" href=\"https:\/\/www.nuclear-power.com\/bwr-boiling-water-reactor\/\"><span>BWR &#8211; R\u00e9acteurs \u00e0 eau bouillante<\/span><\/a>\n<ul>\n<li><span>Un\u00a0<\/span><strong><span>r\u00e9acteur \u00e0 eau bouillante<\/span><\/strong><span>\u00a0est refroidi et\u00a0<\/span><a title=\"Mod\u00e9rateur de neutrons\" href=\"https:\/\/www.nuclear-power.com\/neutron-moderator\/\"><span>mod\u00e9r\u00e9<\/span><\/a><span>\u00a0par de l&#8217;eau comme un PWR, mais \u00e0 une\u00a0<\/span><strong><span>pression inf\u00e9rieure<\/span><\/strong><span>\u00a0(7 MPa), ce qui permet \u00e0 l&#8217;eau de\u00a0<\/span><strong><span>bouillir \u00e0 l&#8217;int\u00e9rieur de l&#8217;<\/span><\/strong><span>\u00a0enceinte\u00a0<strong>sous pression<\/strong>\u00a0produisant la vapeur qui fait fonctionner les turbines.\u00a0L&#8217;\u00e9vaporation se produit donc directement dans les canaux de combustible.\u00a0Par cons\u00e9quent, les REB sont le meilleur exemple pour cette zone, car l&#8217;\u00e9vaporation du liquide de refroidissement se produit en fonctionnement normal et c&#8217;est un ph\u00e9nom\u00e8ne tr\u00e8s souhait\u00e9.<\/span><\/li>\n<li><span>Dans les REB, il existe un ph\u00e9nom\u00e8ne de la\u00a0<\/span><strong><span>plus haute importance pour la s\u00fbret\u00e9 des r\u00e9acteurs<\/span><\/strong><span>\u00a0.\u00a0Ce ph\u00e9nom\u00e8ne est connu sous le nom de\u00a0<\/span><strong><span>\u00abtarissement\u00bb<\/span><\/strong><span>\u00a0et il est directement associ\u00e9 aux\u00a0<\/span><strong><span>changements dans le sch\u00e9ma d&#8217;\u00e9coulement<\/span><\/strong><span>\u00a0pendant l&#8217;\u00e9vaporation.\u00a0\u00c0 la normale, la surface du carburant est efficacement refroidie par \u00e9bullition du liquide de refroidissement.\u00a0Cependant, lorsque le flux de chaleur d\u00e9passe une\u00a0<\/span><strong><span>valeur critique<\/span><\/strong><span>\u00a0(CHF &#8211; flux de chaleur critique), le sch\u00e9ma d&#8217;\u00e9coulement peut atteindre les\u00a0<\/span><strong><span>conditions de s\u00e9chage<\/span><\/strong><span>\u00a0(une mince couche de liquide dispara\u00eet).\u00a0Le transfert de chaleur de la surface du carburant vers le liquide de refroidissement est d\u00e9t\u00e9rior\u00e9, avec pour r\u00e9sultat une\u00a0<\/span><strong><span>temp\u00e9rature de surface du carburant consid\u00e9rablement augment\u00e9e<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<\/ul>\n<\/li>\n<li><a title=\"PWR - R\u00e9acteur \u00e0 eau sous pression\" href=\"https:\/\/www.nuclear-power.com\/pwr-pressurized-water-reactor\/\"><span>PWR &#8211; R\u00e9acteurs \u00e0 eau sous pression<\/span><\/a>\n<ul>\n<li><span>Dans les\u00a0<\/span><strong><span>REP<\/span><\/strong><span>\u00a0en\u00a0<\/span><strong><span>fonctionnement normal,<\/span><\/strong><span>\u00a0le d\u00e9bit est consid\u00e9r\u00e9 comme monophas\u00e9.\u00a0Mais de nombreuses \u00e9tudes ont \u00e9t\u00e9 men\u00e9es sur la nature des\u00a0<\/span><strong><span>\u00e9coulements diphasiques<\/span><\/strong><span>\u00a0en cas de\u00a0<\/span><strong><span>transitoires et d&#8217;accidents<\/span><\/strong><span>\u00a0(tels que l&#8217;\u00a0<\/span><strong><span>accident de perte de liquide de refroidissement &#8211; LOCA ou le d\u00e9clenchement des RCP<\/span><\/strong><span>\u00a0), qui sont importants pour la s\u00fbret\u00e9 des r\u00e9acteurs et doit \u00eatre prouv\u00e9e et d\u00e9clar\u00e9e dans le\u00a0<\/span><strong><span>rapport d&#8217;analyse de<\/span><\/strong><span>\u00a0la\u00a0<strong>s\u00e9curit\u00e9<\/strong>\u00a0(SAR).\u00a0Dans le cas des REP, le ph\u00e9nom\u00e8ne probl\u00e9matique n&#8217;est pas l&#8217;ass\u00e8chement.\u00a0Dans le cas des REP, le flux critique est\u00a0<\/span><strong><span>un flux annulaire invers\u00e9<\/span><\/strong><span>\u00a0.\u00a0Cet \u00e9coulement se produit lorsqu&#8217;une surface de rev\u00eatement de barre de combustible est surchauff\u00e9e, ce qui provoque la formation d&#8217;une\u00a0<\/span><strong><span>couche de vapeur locale<\/span><\/strong><span>, entra\u00eenant une r\u00e9duction spectaculaire de la capacit\u00e9 de transfert de chaleur.\u00a0Ce ph\u00e9nom\u00e8ne est connu comme le\u00a0<\/span><strong><span>d\u00e9part de l&#8217;\u00e9bullition nucl\u00e9\u00e9e &#8211; DNB<\/span><\/strong><span>\u00a0.\u00a0La diff\u00e9rence de r\u00e9gime d&#8217;\u00e9coulement entre l&#8217;\u00e9coulement post-dess\u00e8chement et l&#8217;\u00e9coulement post-DNB est illustr\u00e9e sur la figure.<\/span><\/li>\n<li><span>Dans les REP, l&#8217;\u00e9vaporation se produit \u00e9galement dans les g\u00e9n\u00e9rateurs de vapeur.\u00a0Les g\u00e9n\u00e9rateurs de vapeur sont\u00a0<\/span><strong><span>des \u00e9changeurs de chaleur<\/span><\/strong><span>\u00a0utilis\u00e9s pour convertir l&#8217;\u00a0<\/span><strong><span>eau d&#8217;alimentation en vapeur \u00e0<\/span><\/strong><span>\u00a0partir de la chaleur produite dans un\u00a0<\/span><a href=\"https:\/\/www.reactor-physics.com\/what-is-reactor-core-definition\/\"><span>c\u0153ur de r\u00e9acteur nucl\u00e9aire<\/span><\/a><span>\u00a0.\u00a0La vapeur produite entra\u00eene la turbine.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-accordion\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-content su-clearfix\"><\/div>\n<\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/convective-evaporation-horizontal-channel-fig.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-14855 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/convective-evaporation-horizontal-channel-fig.png\" alt=\"\u00e9vaporation convective - canal horizontal\" width=\"587\" height=\"226\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/convective-evaporation-horizontal-channel-fig.png\" \/><\/a><\/p>\n<div class=\"su-spacer\"><\/div>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-accordion\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\"><\/div>\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<p>&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.<\/p>\n<p>Cet article est bas\u00e9 sur la traduction automatique de l&#8217;article original en anglais. Pour plus d&#8217;informations, voir l&#8217;article en anglais. Pouvez vous nous aider Si vous souhaitez corriger la traduction, envoyez-la \u00e0 l&#8217;adresse: translations@nuclear-power.com ou remplissez le formulaire de traduction en ligne. Nous appr\u00e9cions votre aide, nous mettrons \u00e0 jour la traduction le plus rapidement possible. Merci<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Les structures d&#8217;\u00e9coulement observ\u00e9es sont d\u00e9finies en tant que mod\u00e8les d&#8217;\u00e9coulement \u00e0 deux phases et pr\u00e9sentent des caract\u00e9ristiques d&#8217;identification particuli\u00e8res.\u00a0Mod\u00e8les de flux &#8211; Flux biphas\u00e9 Mod\u00e8les de flux &#8211; Flux biphas\u00e9 L&#8217;un des aspects les plus difficiles de la gestion d&#8217;un\u00a0\u00e9coulement diphasique\u00a0ou multiphas\u00e9\u00a0est le fait qu&#8217;il peut prendre de\u00a0nombreuses formes diff\u00e9rentes\u00a0.\u00a0Les distributions spatiales et les &#8230; <a title=\"Qu&#8217;est-ce que le mod\u00e8le de flux &#8211; Flux biphas\u00e9 &#8211; D\u00e9finition\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-le-modele-de-flux-flux-biphase-definition\/\" aria-label=\"En savoir plus sur Qu&#8217;est-ce que le mod\u00e8le de flux &#8211; Flux biphas\u00e9 &#8211; D\u00e9finition\">Lire la suite<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[8],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Qu&#039;est-ce que le mod\u00e8le de flux - Flux biphas\u00e9 - D\u00e9finition<\/title>\n<meta name=\"description\" content=\"Les structures d&#039;\u00e9coulement observ\u00e9es sont d\u00e9finies en tant que mod\u00e8les d&#039;\u00e9coulement \u00e0 deux phases et pr\u00e9sentent des caract\u00e9ristiques d&#039;identification particuli\u00e8res. 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