{"id":52213,"date":"2020-02-17T10:34:10","date_gmt":"2020-02-17T09:34:10","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/quelle-est-la-resistance-resistance-a-lair-et-aux-fluides-definition\/"},"modified":"2020-02-17T10:34:10","modified_gmt":"2020-02-17T09:34:10","slug":"quelle-est-la-resistance-resistance-a-lair-et-aux-fluides-definition","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-resistance-resistance-a-lair-et-aux-fluides-definition\/","title":{"rendered":"Quelle est la r\u00e9sistance &#8211; R\u00e9sistance \u00e0 l&#8217;air et aux fluides &#8211; D\u00e9finition"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\"><span>Qu&#8217;est-ce que la r\u00e9sistance \u00e0 l&#8217;air et aux fluides?\u00a0En dynamique des fluides et en a\u00e9rodynamique, la tra\u00een\u00e9e est une force agissant \u00e0 l&#8217;oppos\u00e9 du mouvement relatif de tout objet en mouvement.\u00a0G\u00e9nie thermique<\/span><\/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><span>Qu&#8217;est-ce que la tra\u00een\u00e9e en physique &#8211; R\u00e9sistance \u00e0 l&#8217;air et aux fluides<\/span><\/h2>\n<p><span>En\u00a0<\/span><a title=\"Dynamique des fluides\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/\"><span>dynamique des fluides<\/span><\/a><span>\u00a0, la\u00a0<\/span><strong><span>tra\u00een\u00e9e<\/span><\/strong><span>\u00a0est une force agissant \u00e0 l&#8217;oppos\u00e9 du mouvement relatif de tout objet en mouvement.\u00a0La force qu&#8217;un fluide en \u00e9coulement exerce sur un corps dans le sens de l&#8217;\u00e9coulement.\u00a0Contrairement \u00e0 d&#8217;autres forces r\u00e9sistives, telles que le frottement \u00e0 sec, qui sont presque ind\u00e9pendantes de la vitesse,\u00a0<\/span><strong><span>les forces de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0d\u00e9pendent de la vitesse.\u00a0<\/span><strong><span>La force de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0est proportionnelle \u00e0 la vitesse pour un \u00e9coulement laminaire et \u00e0 la vitesse au carr\u00e9 pour un \u00e9coulement turbulent.\u00a0<\/span><strong><span>La tra\u00een\u00e9e<\/span><\/strong><span>\u00a0est g\u00e9n\u00e9ralement caus\u00e9e par deux ph\u00e9nom\u00e8nes:<\/span><\/p>\n<ul>\n<li>\n<figure id=\"attachment_20487\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-20487\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Drag-skin-friction-and-form-drag.png\"><img loading=\"lazy\" class=\"size-full wp-image-20487 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Drag-skin-friction-and-form-drag.png\" alt=\"Drag - friction de la peau et tra\u00een\u00e9e de forme\" width=\"228\" height=\"343\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Drag-skin-friction-and-form-drag.png\" \/><\/a><figcaption id=\"caption-attachment-20487\" class=\"wp-caption-text\"><span>Source: wikipedia.org Licence: CC BY-SA 3.0<\/span><\/figcaption><\/figure>\n<p><strong><span>Frottement de la peau<\/span><\/strong><span>\u00a0.\u00a0En g\u00e9n\u00e9ral, quand un flux de\u00a0fluide sur une\u00a0<\/span><strong><span>surface fixe<\/span><\/strong><span>\u00a0, par exemple la plaque plane, le lit d&#8217;une rivi\u00e8re, ou la paroi d&#8217;un tube, le fait de\u00a0toucher la surface du\u00a0fluide est amen\u00e9\u00a0<\/span><strong><span>au repos<\/span><\/strong><span>\u00a0par la\u00a0<\/span><strong><span>contrainte de\u00a0cisaillement<\/span><\/strong><span>\u00a0au niveau de\u00a0la paroi.\u00a0La r\u00e9gion dans laquelle l&#8217;\u00e9coulement s&#8217;ajuste de la vitesse nulle \u00e0 la paroi \u00e0 un maximum dans le courant principal de l&#8217;\u00e9coulement est appel\u00e9e la\u00a0<\/span><a title=\"Couche limite\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-couche-limite-definition\/\"><strong><span>couche limite<\/span><\/strong><\/a><span>\u00a0.\u00a0Par cons\u00e9quent, un fluide en mouvement exerce des forces de cisaillement tangentielles sur la surface en raison de l&#8217;\u00a0<\/span><strong><span>\u00e9tat antid\u00e9rapant<\/span><\/strong><span>\u00a0provoqu\u00e9 par des effets visqueux.\u00a0Ce type de\u00a0<\/span><strong><span>force<\/span><\/strong><span>\u00a0de\u00a0<strong>tra\u00een\u00e9e<\/strong>\u00a0, d\u00e9pend notamment de la g\u00e9om\u00e9trie, de la rugosit\u00e9 de la surface solide et du type d&#8217;\u00e9coulement de fluide.<\/span><\/li>\n<li><strong><span>Faire glisser le formulaire<\/span><\/strong><span>\u00a0.\u00a0<\/span><strong><span>La tra\u00een\u00e9e de forme,<\/span><\/strong><span>\u00a0\u00e9galement appel\u00e9e\u00a0<strong>tra\u00een\u00e9e<\/strong>\u00a0de\u00a0<\/span><strong><span>pression,<\/span><\/strong><span>\u00a0r\u00e9sulte de la forme et de la taille de l&#8217;objet.\u00a0Ce type de force de tra\u00een\u00e9e est une cons\u00e9quence int\u00e9ressante de l&#8217;\u00a0<\/span><strong><a title=\"Th\u00e9or\u00e8me de Bernoulli\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/bernoullis-theorem\/\"><span>effet de Bernoulli<\/span><\/a><span>\u00a0.\u00a0<\/span><\/strong><span>Selon le principe de Bernoulli, l&#8217;air en mouvement plus rapide exerce moins de pression.\u00a0Cela provoque, qu&#8217;il peut y avoir une diff\u00e9rence de pression entre les surfaces de l&#8217;objet.\u00a0La taille g\u00e9n\u00e9rale et la forme du corps sont les facteurs les plus importants de la\u00a0<\/span><strong><span>tra\u00een\u00e9e de forme<\/span><\/strong><span>\u00a0.\u00a0En g\u00e9n\u00e9ral, les corps ayant une section g\u00e9om\u00e9trique pr\u00e9sent\u00e9e plus grande auront une tra\u00een\u00e9e plus \u00e9lev\u00e9e que les corps plus minces.<\/span><\/li>\n<\/ul>\n<p><span>Ces deux forces, en g\u00e9n\u00e9ral, ont des composants dans la direction de l&#8217;\u00e9coulement, et donc la\u00a0<\/span><strong><span>force de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0r\u00e9sultante\u00a0est due aux effets combin\u00e9s de la\u00a0<\/span><strong><span>pression<\/span><\/strong><span>\u00a0et\u00a0<\/span><strong><span>des<\/span><\/strong><span>\u00a0forces de\u00a0<strong>frottement cutan\u00e9<\/strong>\u00a0dans la direction de l&#8217;\u00e9coulement.<\/span><\/p>\n<p><span>Lorsque les coefficients de frottement et de tra\u00een\u00e9e de pression sont disponibles, le coefficient de tra\u00een\u00e9e total est d\u00e9termin\u00e9 en les ajoutant simplement:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20488 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\" alt=\"friction de la peau - tra\u00een\u00e9e de forme - coefficients\" width=\"308\" height=\"54\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\" \/><\/a><\/p>\n<p><span>Aux\u00a0<\/span><strong><span>faibles\u00a0<\/span><a title=\"Le num\u00e9ro de Reynold\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\"><span>nombres de Reynolds<\/span><\/a><\/strong><span>\u00a0, la tra\u00een\u00e9e est principalement due \u00e0\u00a0<\/span><strong><span>la tra\u00een\u00e9e de friction<\/span><\/strong><span>\u00a0.\u00a0C&#8217;est particuli\u00e8rement le cas pour les corps tr\u00e8s a\u00e9rodynamiques tels que les profils a\u00e9rodynamiques.\u00a0En revanche, \u00e0\u00a0<\/span><strong><span>un nombre de Reynolds \u00e9lev\u00e9<\/span><\/strong><span>\u00a0, la\u00a0<\/span><a title=\"Perte de t\u00eate - Perte de pression\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/head-loss\/\"><span>chute de pression<\/span><\/a><span>\u00a0est importante, ce qui augmente la tra\u00een\u00e9e de forme.<\/span><\/p>\n<p><span>Les composantes des forces de pression et de frottement cutan\u00e9 dans la\u00a0<\/span><strong><span>direction normale<\/span><\/strong><span>\u00a0de l&#8217;\u00e9coulement ont tendance \u00e0 d\u00e9placer le corps dans cette direction, et leur somme est appel\u00e9e\u00a0<\/span><strong><a title=\"Force de levage\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/lift-force\/\"><span>portance<\/span><\/a><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>En a\u00e9ronautique,\u00a0<\/span><strong><span>la portance<\/span><\/strong><span>\u00a0est une force \u00e0 action ascendante sur une aile ou une aile d&#8217;\u00a0<\/span><strong><span>avion.\u00a0Le principe de Bernoulli<\/span><\/strong><span>\u00a0exige que le profil a\u00e9rodynamique soit de\u00a0<\/span><strong><span>forme asym\u00e9trique<\/span><\/strong><span>\u00a0.<\/span><\/p>\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\"><\/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<h2><span>Friction de la peau &#8211; Friction Drag<\/span><\/h2>\n<p><span>Comme on l&#8217;\u00a0a \u00e9crit, quand un flux de\u00a0fluide sur une\u00a0<\/span><strong><span>surface fixe<\/span><\/strong><span>\u00a0, par exemple la plaque plane, le lit d&#8217;une rivi\u00e8re, ou la paroi d&#8217;un tube, le fait de\u00a0toucher la surface du\u00a0fluide est amen\u00e9\u00a0<\/span><strong><span>au repos<\/span><\/strong><span>\u00a0par la\u00a0<\/span><strong><span>contrainte de\u00a0cisaillement<\/span><\/strong><span>\u00a0au niveau de\u00a0la paroi.\u00a0La r\u00e9gion dans laquelle l&#8217;\u00e9coulement s&#8217;ajuste de la vitesse nulle \u00e0 la paroi \u00e0 un maximum dans le courant principal de l&#8217;\u00e9coulement est appel\u00e9e la\u00a0<\/span><a title=\"Couche limite\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-couche-limite-definition\/\"><strong><span>couche limite<\/span><\/strong><\/a><span>\u00a0.\u00a0Par cons\u00e9quent, un fluide en mouvement exerce des forces de cisaillement tangentielles sur la surface en raison de l&#8217;\u00a0<\/span><strong><span>\u00e9tat antid\u00e9rapant<\/span><\/strong><span>\u00a0provoqu\u00e9 par des effets visqueux.\u00a0Ce type d&#8217;\u00a0<\/span><strong><span>effort<\/span><\/strong><span>\u00a0de\u00a0<strong>tra\u00een\u00e9e<\/strong>\u00a0, d\u00e9pend notamment de la g\u00e9om\u00e9trie, de la rugosit\u00e9 de la surface solide (uniquement en\u00a0<\/span><a title=\"\u00c9coulement turbulent\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-ecoulement-turbulent-definition\/\"><span>\u00e9coulement turbulent<\/span><\/a><span>\u00a0) et du\u00a0<\/span><a title=\"R\u00e9gime de flux\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/flow-regime\/\"><span>type d&#8217;\u00e9coulement du fluide<\/span><\/a><span>\u00a0.\u00a0le<\/span><strong><span>la tra\u00een\u00e9e de friction<\/span><\/strong><span>\u00a0est proportionnelle \u00e0 la surface.\u00a0Par cons\u00e9quent, les corps ayant une surface plus grande subiront une tra\u00een\u00e9e de friction plus importante.\u00a0C&#8217;est pourquoi les avions commerciaux r\u00e9duisent leur surface totale pour \u00e9conomiser du carburant.\u00a0<\/span><strong><span>La tra\u00een\u00e9e de friction<\/span><\/strong><span>\u00a0est une fonction importante de la viscosit\u00e9, et un fluide \u00abid\u00e9alis\u00e9\u00bb avec une viscosit\u00e9 nulle produirait une tra\u00een\u00e9e de friction nulle puisque la contrainte de cisaillement de la paroi serait nulle.<\/span><\/p>\n<p><strong><span>Le frottement de la peau<\/span><\/strong><span>\u00a0est caus\u00e9 par une tra\u00een\u00e9e visqueuse dans la couche limite autour de l&#8217;objet.\u00a0Les caract\u00e9ristiques de base de toutes\u00a0<\/span><strong><span>les couches limites laminaires et turbulentes<\/span><\/strong><span>\u00a0sont pr\u00e9sent\u00e9es dans le flux de d\u00e9veloppement sur une plaque plate.\u00a0Les \u00e9tapes de la formation de la couche limite sont illustr\u00e9es dans la figure ci-dessous:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Boundary-layer-on-flat-plate.png\"><img loading=\"lazy\" class=\"aligncenter size-large wp-image-14390 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Boundary-layer-on-flat-plate-1024x357.png\" alt=\"Couche limite sur plaque plate\" width=\"669\" height=\"233\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Boundary-layer-on-flat-plate-1024x357.png\" \/><\/a><\/p>\n<p><strong><span>Les couches limites<\/span><\/strong><span>\u00a0peuvent \u00eatre soit\u00a0<\/span><strong><span>laminaire<\/span><\/strong><span>\u00a0ou\u00a0<\/span><strong><span>turbulent<\/span><\/strong><span>\u00a0en fonction de la valeur de\u00a0<\/span><strong><span>la\u00a0<\/span><a title=\"Le num\u00e9ro de Reynold\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\"><span>nombre de\u00a0Reynolds<\/span><\/a><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>Pour\u00a0<\/span><strong><span>les nombres de Reynolds inf\u00e9rieurs<\/span><\/strong><span>\u00a0, la couche limite est laminaire et la vitesse du flux change uniform\u00e9ment lorsque l&#8217;on s&#8217;\u00e9loigne du mur, comme indiqu\u00e9 sur le c\u00f4t\u00e9 gauche de la figure.\u00a0<\/span><strong><span>\u00c0 mesure que le nombre de Reynolds augmente<\/span><\/strong><span>\u00a0(avec x), l&#8217;\u00a0<\/span><strong><span>\u00e9coulement devient instable<\/span><\/strong><span>\u00a0et, enfin, pour les nombres de Reynolds plus \u00e9lev\u00e9s, la couche limite est turbulente et la vitesse dans le sens du flux est caract\u00e9ris\u00e9e par des flux tourbillonnants instables (changeant avec le temps) \u00e0 l&#8217;int\u00e9rieur de la couche limite.<\/span><\/p>\n<p><strong><span>La transition de la<\/span><\/strong><span>\u00a0couche limite\u00a0<strong>laminaire \u00e0 la<\/strong>\u00a0couche\u00a0<strong>turbulente<\/strong>\u00a0se produit lorsque le nombre de Reynolds \u00e0 x d\u00e9passe\u00a0<\/span><strong><span>Re\u00a0<\/span><\/strong><strong><sub><span>x<\/span><\/sub><\/strong><strong><span>\u00a0~ 500 000<\/span><\/strong><span>\u00a0.\u00a0La transition peut se produire plus t\u00f4t, mais elle d\u00e9pend surtout de la\u00a0<\/span><strong><span>rugosit\u00e9 de<\/span><\/strong><span>\u00a0la\u00a0<strong>surface<\/strong>\u00a0.\u00a0La couche limite turbulente s&#8217;\u00e9paissit plus rapidement que la couche limite laminaire en raison de l&#8217;augmentation de la contrainte de cisaillement \u00e0 la surface du corps.<\/span><\/p>\n<p><span>Il existe deux fa\u00e7ons de\u00a0<\/span><strong><span>r\u00e9duire la tra\u00een\u00e9e de friction<\/span><\/strong><span>\u00a0:<\/span><\/p>\n<ul>\n<li><span>la premi\u00e8re consiste \u00e0 fa\u00e7onner le corps mobile de mani\u00e8re \u00e0 ce que l&#8217;\u00e9coulement laminaire soit possible<\/span><\/li>\n<li><span>la deuxi\u00e8me m\u00e9thode consiste \u00e0 augmenter la longueur et \u00e0 diminuer la section transversale de l&#8217;objet en mouvement autant que possible.<\/span><\/li>\n<\/ul>\n<p><span>Le\u00a0<\/span><strong><span>coefficient de frottement cutan\u00e9<\/span><\/strong><span>\u00a0,\u00a0<\/span><strong><span>C\u00a0<\/span><sub><span>D, frottement<\/span><\/sub><\/strong><span>\u00a0, est d\u00e9fini par<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-equation-drag-coefficient.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20489 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-equation-drag-coefficient.png\" alt=\"friction de la peau - \u00e9quation - coefficient de tra\u00een\u00e9e\" width=\"217\" height=\"126\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-equation-drag-coefficient.png\" \/><\/a><\/p>\n<p><span>Il faut noter que le\u00a0<\/span><strong><span>coefficient de frottement cutan\u00e9<\/span><\/strong><span>\u00a0est \u00e9gal au\u00a0<\/span><strong><a title=\"Facteur de friction de ventilation\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/fanning-friction-factor\/\"><span>facteur de frottement de Fanning<\/span><\/a><\/strong><span>\u00a0.\u00a0Le facteur de friction de Fanning, nomm\u00e9 d&#8217;apr\u00e8s John Thomas Fanning, est un nombre sans dimension, c&#8217;est-\u00e0-dire un quart du\u00a0<\/span><a title=\"Facteur de friction Darcy\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-le-facteur-de-friction-de-darcy-definition\/\"><strong><span>facteur de friction de Darcy<\/span><\/strong><\/a><span>\u00a0.\u00a0Comme on peut le voir, il existe un lien entre\u00a0<\/span><strong><span>les forces de friction cutan\u00e9e<\/span><\/strong><span>\u00a0et les\u00a0<\/span><a title=\"Perte de t\u00eate majeure - Perte par friction\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/\"><strong><span>pertes de charge par friction<\/span><\/strong><\/a><span>\u00a0.<\/span><\/p>\n<p><span>Voir aussi:\u00a0<\/span><a title=\"Facteur de friction Darcy\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-le-facteur-de-friction-de-darcy-definition\/\"><strong><span>Facteur de friction Darcy<\/span><\/strong><\/a><\/p>\n<p><span>Pour\u00a0<\/span><a title=\"\u00c9coulement laminaire - \u00c9coulement visqueux\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lecoulement-laminaire-ecoulement-visqueux-definition\/\"><span>l&#8217;\u00e9coulement laminaire<\/span><\/a><span>\u00a0dans une conduite, le\u00a0<\/span><strong><span>facteur de frottement de Fanning<\/span><\/strong><span>\u00a0(coefficient de frottement cutan\u00e9) est une cons\u00e9quence de\u00a0<\/span><strong><span>la loi<\/span><\/strong><span>\u00a0de\u00a0<strong>Poiseuille<\/strong>\u00a0et il est donn\u00e9 par les \u00e9quations suivantes:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-laminar-flow.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20490 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-laminar-flow.png\" alt=\"coefficient de tra\u00een\u00e9e - \u00e9coulement laminaire\" width=\"312\" height=\"195\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-laminar-flow.png\" \/><\/a><\/p>\n<p><span>Dans\u00a0<\/span><a title=\"\u00c9coulement turbulent\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-ecoulement-turbulent-definition\/\"><span>les \u00e9coulements turbulents<\/span><\/a><span>\u00a0, cependant, les choses sont plus difficiles, car le facteur de friction d\u00e9pend fortement de la\u00a0<\/span><a title=\"Rugosit\u00e9 relative du tuyau\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/relative-roughness-of-pipe\/\"><span>rugosit\u00e9<\/span><\/a><span>\u00a0du\u00a0<a title=\"Rugosit\u00e9 relative du tuyau\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/relative-roughness-of-pipe\/\">tuyau<\/a>\u00a0.\u00a0Le\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-le-facteur-de-friction-de-darcy-definition\/\"><strong><span>facteur de friction<\/span><\/strong><\/a><span>\u00a0pour l&#8217;\u00e9coulement du fluide peut \u00eatre d\u00e9termin\u00e9 \u00e0 l&#8217;aide d&#8217;un\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/moody-diagram\/\"><strong><span>diagramme de Moody<\/span><\/strong><\/a><span>\u00a0.\u00a0Par exemple:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-turbulent-flow.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20491 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-turbulent-flow.png\" alt=\"coefficient de tra\u00een\u00e9e - \u00e9coulement turbulent\" width=\"357\" height=\"189\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-turbulent-flow.png\" \/><\/a><\/p>\n<p><span>La composante de friction de la\u00a0<\/span><strong><span>force de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0est donn\u00e9e par:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-skin-friction.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20492 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-skin-friction.png\" alt=\"force de tra\u00een\u00e9e - frottement de la peau\" width=\"345\" height=\"79\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-skin-friction.png\" \/><\/a><\/p>\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>Glissement de forme &#8211; Glissement de pression<\/span><\/h2>\n<p><strong><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/form-drag-pressure-drag-schema.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-20493 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/form-drag-pressure-drag-schema-300x288.png\" alt=\"tra\u00een\u00e9e de forme - tra\u00een\u00e9e de pression\" width=\"300\" height=\"288\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/form-drag-pressure-drag-schema-300x288.png\" \/><\/a><span>La tra\u00een\u00e9e de forme,<\/span><\/strong><span>\u00a0\u00e9galement appel\u00e9e\u00a0<strong>tra\u00een\u00e9e<\/strong>\u00a0de\u00a0<\/span><strong><span>pression,<\/span><\/strong><span>\u00a0r\u00e9sulte de la\u00a0<\/span><strong><span>forme<\/span><\/strong><span>\u00a0et de la\u00a0<\/span><strong><span>taille<\/span><\/strong><span>\u00a0de l&#8217;objet.\u00a0La\u00a0<\/span><strong><span>tra\u00een\u00e9e de pression<\/span><\/strong><span>\u00a0est proportionnelle \u00e0 la diff\u00e9rence entre les pressions agissant \u00e0 l&#8217;avant et \u00e0 l&#8217;arri\u00e8re du corps immerg\u00e9 et la zone frontale.\u00a0Ce type de force de tra\u00een\u00e9e est \u00e9galement une cons\u00e9quence int\u00e9ressante de l&#8217;\u00a0<\/span><strong><a title=\"\u00c9quation de Bernoulli - Principe de Bernoulli\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-lequation-de-bernoulli-principe-de-bernoulli-definition\/\"><span>effet de Bernoulli<\/span><\/a><span>\u00a0.\u00a0<\/span><\/strong><span>Selon le principe de Bernoulli, l&#8217;air en mouvement plus rapide exerce moins de\u00a0<\/span><a title=\"Qu'est-ce que la pression - Physique\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-pressure-physics\/\"><span>pression<\/span><\/a><span>\u00a0.\u00a0Cela provoque, qu&#8217;il peut y avoir une\u00a0<\/span><strong><span>diff\u00e9rence de pression<\/span><\/strong><span>\u00a0entre les surfaces de l&#8217;objet.\u00a0La taille g\u00e9n\u00e9rale et la forme du corps sont les facteurs les plus importants de la\u00a0<\/span><strong><span>tra\u00een\u00e9e de forme<\/span><\/strong><span>.\u00a0En g\u00e9n\u00e9ral, les corps ayant une section g\u00e9om\u00e9trique pr\u00e9sent\u00e9e plus grande auront une tra\u00een\u00e9e plus \u00e9lev\u00e9e que les corps plus minces.<\/span><\/p>\n<p><span>Comme le montre la figure, la force de tra\u00een\u00e9e provient de la diff\u00e9rence entre les pressions agissant \u00e0 l&#8217;avant et \u00e0 l&#8217;arri\u00e8re du corps immerg\u00e9.\u00a0Pour cette force peut \u00eatre calcul\u00e9e (dans ce cas) en utilisant simplement la d\u00e9finition de la pression comme:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/form-drag-drag-force.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20494 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/form-drag-drag-force.png\" alt=\"faire glisser - forcer la force\" width=\"199\" height=\"60\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/form-drag-drag-force.png\" \/><\/a><\/p>\n<p><span>\u00c9tant donn\u00e9 que la\u00a0<\/span><strong><a title=\"Perte de t\u00eate - Perte de pression\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/head-loss\/\"><span>perte de charge<\/span><\/a><span>\u00a0est \u00e0 peu pr\u00e8s proportionnelle au carr\u00e9 du d\u00e9bit<\/span><\/strong><span>\u00a0dans la plupart des flux d&#8217;ing\u00e9nierie, le\u00a0<\/span><strong><span>coefficient de tra\u00een\u00e9e total<\/span><\/strong><span>\u00a0peut \u00eatre d\u00e9termin\u00e9 en ajoutant simplement les coefficients de friction et de tra\u00een\u00e9e de pression:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20488 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\" alt=\"friction de la peau - tra\u00een\u00e9e de forme - coefficients\" width=\"308\" height=\"54\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\" \/><\/a><\/p>\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>Force de tra\u00een\u00e9e &#8211; \u00c9quation de tra\u00een\u00e9e<\/span><\/h2>\n<p><span>La\u00a0<\/span><strong><span>force de tra\u00een\u00e9e,\u00a0<\/span><\/strong><strong><span>F\u00a0<\/span><sub><span>D<\/span><\/sub><\/strong><span>\u00a0, d\u00e9pend entre autres de la\u00a0<\/span><a title=\"Qu'est-ce que la densit\u00e9 - Physique\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-density-physics\/\"><span>densit\u00e9<\/span><\/a><span>\u00a0du fluide, de la vitesse en amont et de la taille, de la forme et de l&#8217;orientation du corps.\u00a0Une fa\u00e7on d&#8217;exprimer cela est au moyen de l&#8217;\u00a0<\/span><strong><span>\u00e9quation de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0.\u00a0L&#8217;\u00a0<\/span><strong><span>\u00e9quation de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0est une formule utilis\u00e9e pour calculer la\u00a0<\/span><strong><span>force de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0subie par un objet en raison du mouvement \u00e0 travers un fluide.<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-formula.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20495 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-formula.png\" alt=\"force de tra\u00een\u00e9e - \u00e9quation de tra\u00een\u00e9e - formule\" width=\"261\" height=\"257\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-formula.png\" \/><\/a><\/p>\n<p><span>La zone de r\u00e9f\u00e9rence, A, est d\u00e9finie comme la zone de projection orthographique de l&#8217;objet sur un plan perpendiculaire \u00e0 la direction du mouvement.\u00a0Pour les objets creux, la zone de r\u00e9f\u00e9rence peut \u00eatre significativement plus grande que la zone de coupe transversale, mais pour les objets non creux, elle est exactement la m\u00eame qu&#8217;une zone de coupe transversale.<\/span><\/p>\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>Coefficient de tra\u00een\u00e9e &#8211; Caract\u00e9ristiques de tra\u00een\u00e9e<\/span><\/h2>\n<p><span>Comme il a \u00e9t\u00e9 \u00e9crit, les\u00a0<\/span><strong><span>caract\u00e9ristiques<\/span><\/strong><span>\u00a0de\u00a0<strong>tra\u00een\u00e9e<\/strong>\u00a0d&#8217;un corps sont repr\u00e9sent\u00e9es par le\u00a0<\/span><strong><span>coefficient de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0sans dimension\u00a0<strong>, C\u00a0<\/strong><strong><sub>D<\/sub><\/strong><strong>\u00a0,<\/strong>\u00a0d\u00e9fini comme:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-characteristics.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20496 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-characteristics.png\" alt=\"coefficient de tra\u00een\u00e9e - caract\u00e9ristiques\" width=\"266\" height=\"285\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-coefficient-characteristics.png\" \/><\/a><\/p>\n<p><span>La zone de r\u00e9f\u00e9rence, A, est d\u00e9finie comme la zone de projection orthographique de l&#8217;objet sur un plan perpendiculaire \u00e0 la direction du mouvement.\u00a0Pour les objets creux, la zone de r\u00e9f\u00e9rence peut \u00eatre significativement plus grande que la zone de coupe transversale, mais pour les objets non creux, elle est exactement la m\u00eame qu&#8217;une zone de coupe transversale.\u00a0Comme on peut le voir, le coefficient de tra\u00een\u00e9e est principalement fonction de la forme du corps et prend en compte \u00e0 la fois le frottement de la peau et la tra\u00een\u00e9e de forme.\u00a0Elle peut \u00e9galement d\u00e9pendre du\u00a0<\/span><a title=\"Le num\u00e9ro de Reynold\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\"><span>nombre de Reynolds<\/span><\/a><span>\u00a0et de la rugosit\u00e9 de surface.<\/span><\/p>\n<p><span>Lorsque les\u00a0<strong>coefficients de\u00a0<\/strong><\/span><strong><span>frottement<\/span><\/strong><span>\u00a0et de\u00a0<\/span><strong><span>tra\u00een\u00e9e de pression<\/span><\/strong><span>\u00a0sont disponibles, le\u00a0<\/span><strong><span>coefficient de tra\u00een\u00e9e total<\/span><\/strong><span>\u00a0est d\u00e9termin\u00e9 en les ajoutant simplement:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20488 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\" alt=\"friction de la peau - tra\u00een\u00e9e de forme - coefficients\" width=\"308\" height=\"54\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-form-drag-coefficients.png\" \/><\/a><\/p>\n<p><span>Aux faibles nombres de Reynolds, la tra\u00een\u00e9e est principalement due \u00e0\u00a0<\/span><strong><span>la tra\u00een\u00e9e de friction<\/span><\/strong><span>\u00a0.\u00a0C&#8217;est particuli\u00e8rement le cas pour les corps tr\u00e8s a\u00e9rodynamiques tels que les profils a\u00e9rodynamiques.\u00a0En revanche, \u00e0 un nombre de Reynolds \u00e9lev\u00e9, la chute de pression est importante, ce qui augmente la\u00a0<\/span><strong><span>tra\u00een\u00e9e de forme<\/span><\/strong><span> .<\/span><\/p>\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>Drag Force en g\u00e9nie nucl\u00e9aire<\/span><\/h2>\n<p><span>L&#8217;analyse de la\u00a0<\/span><strong><span>force de levage hydraulique<\/span><\/strong><span>\u00a0est l&#8217;une des analyses les plus importantes dans la conception d&#8217;un assemblage combustible et l&#8217;analyse de la compatibilit\u00e9 hydraulique des noyaux mixtes.\u00a0Les forces verticales sont induites par un \u00e9coulement ascendant \u00e0 grande vitesse \u00e0 travers le\u00a0<\/span><a title=\"Noyau du r\u00e9acteur\" href=\"https:\/\/www.reactor-physics.com\/what-is-reactor-core-definition\/\"><span>c\u0153ur<\/span><\/a><span>\u00a0du\u00a0<a title=\"Noyau du r\u00e9acteur\" href=\"https:\/\/www.reactor-physics.com\/what-is-reactor-core-definition\/\">r\u00e9acteur<\/a>\u00a0.\u00a0Le chemin d&#8217;\u00e9coulement du liquide de refroidissement du\u00a0<\/span><a title=\"R\u00e9cipient sous pression du r\u00e9acteur\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/reactor-pressure-vessel\/\"><span>r\u00e9acteur \u00e0<\/span><\/a><span>\u00a0travers la\u00a0<a title=\"R\u00e9cipient sous pression du r\u00e9acteur\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/reactor-pressure-vessel\/\">cuve<\/a>\u00a0du\u00a0<a title=\"R\u00e9cipient sous pression du r\u00e9acteur\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/reactor-pressure-vessel\/\">r\u00e9acteur<\/a>\u00a0serait:<\/span><\/p>\n<ul>\n<li>\n<figure id=\"attachment_14206\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-14206\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Continuity-Equation-Flow-Rate-min.png\"><img loading=\"lazy\" class=\"size-medium wp-image-14206 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Continuity-Equation-Flow-Rate-min-300x300.png\" alt=\"\u00c9quation de continuit\u00e9 - D\u00e9bits dans le r\u00e9acteur\" width=\"300\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Continuity-Equation-Flow-Rate-min-300x300.png\" \/><\/a><figcaption id=\"caption-attachment-14206\" class=\"wp-caption-text\"><span>Exemple de d\u00e9bits dans un r\u00e9acteur.\u00a0Il s&#8217;agit d&#8217;un exemple illustratif, les donn\u00e9es ne repr\u00e9sentent aucune conception de r\u00e9acteur.<\/span><\/figcaption><\/figure>\n<p><span>Le liquide de refroidissement p\u00e9n\u00e8tre dans la\u00a0<\/span><strong><span>cuve<\/span><\/strong><span>\u00a0du\u00a0<strong>r\u00e9acteur<\/strong>\u00a0au niveau de la buse d&#8217;entr\u00e9e et frappe contre le\u00a0<\/span><a title=\"Baril de base\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/core-barrel\/\"><span>baril de c\u0153ur<\/span><\/a><span>\u00a0.<\/span><\/li>\n<li><span>Le baril de noyau force l&#8217;eau \u00e0 couler vers le bas dans l&#8217;espace entre la paroi de la cuve du r\u00e9acteur et le\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/core-barrel\/\"><span>baril de noyau<\/span><\/a><span>\u00a0, cet espace est g\u00e9n\u00e9ralement connu sous le nom de\u00a0<\/span><strong><span>tuyau de descente<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>Depuis le fond de l&#8217;enceinte sous pression, le flux est invers\u00e9 \u00e0 travers le c\u0153ur afin de traverser les\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/\"><span>assemblages combustibles<\/span><\/a><span>\u00a0, o\u00f9 la temp\u00e9rature du liquide de refroidissement augmente au fur et \u00e0 mesure qu&#8217;il traverse les crayons combustibles.<\/span><\/li>\n<li><span>Enfin, le liquide de refroidissement du r\u00e9acteur plus chaud p\u00e9n\u00e8tre dans la r\u00e9gion interne sup\u00e9rieure, o\u00f9 il est achemin\u00e9 par la buse de sortie dans les jambes chaudes du circuit primaire et se dirige vers les\u00a0<\/span><strong><a title=\"G\u00e9n\u00e9rateur de vapeur\" href=\"https:\/\/www.nuclear-power.com\/steam-generator\/\"><span>g\u00e9n\u00e9rateurs de vapeur<\/span><\/a><span>\u00a0.<\/span><\/strong><\/li>\n<\/ul>\n<p><span>Les assemblages combustibles sont maintenus par l&#8217;\u00a0<\/span><strong><span>ensemble de structure de guidage sup\u00e9rieur<\/span><\/strong><span>\u00a0, qui d\u00e9finit le haut du noyau.\u00a0Cet assemblage est en acier inoxydable et a de nombreux usages.\u00a0L&#8217;ensemble de structure de guidage sup\u00e9rieure exerce une\u00a0<\/span><strong><span>force axiale<\/span><\/strong><span>\u00a0sur les assemblages combustibles (\u00e0 travers des ressorts dans la buse sup\u00e9rieure), d\u00e9finissant ainsi la position exacte de l&#8217;assemblage combustible dans le noyau.\u00a0La\u00a0bride d&#8217;\u00a0<\/span><strong><span>assemblage de la structure de guidage sup\u00e9rieure<\/span><\/strong><span>\u00a0est maintenue en place et pr\u00e9charg\u00e9e par la bride de t\u00eate de fermeture RPV.\u00a0L&#8217;ensemble de structure de guidage sup\u00e9rieure guide et prot\u00e8ge \u00e9galement\u00a0<\/span><a title=\"Barres de commande\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/control-rods\/\"><span>les<\/span><\/a><span>\u00a0ensembles de\u00a0<a title=\"Barres de commande\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/control-rods\/\">barres de commande<\/a>\u00a0et l&#8217;instrumentation int\u00e9gr\u00e9e.<\/span><\/p>\n<p><span>La force d&#8217;appui requise de l&#8217;\u00a0<\/span><strong><span>ensemble de structure de guidage sup\u00e9rieure<\/span><\/strong><span>\u00a0sur les assemblages combustibles doit \u00eatre calcul\u00e9e avec beaucoup de soin.\u00a0Une force d&#8217;appui insuffisante peut entra\u00eener la\u00a0<\/span><strong><span>lev\u00e9e de l&#8217;assemblage combustible<\/span><\/strong><span>\u00a0, d&#8217;autre part, une force d&#8217;appui excessive peut entra\u00eener un\u00a0<\/span><strong><span>cintrage de l&#8217;assemblage combustible<\/span><\/strong><span>\u00a0, ce qui est \u00e9galement inacceptable.<\/span><\/p>\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>Exemple: force de tra\u00een\u00e9e &#8211; coefficient de tra\u00een\u00e9e &#8211; faisceau de carburant<\/span><\/h2>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Diameter-Fuel-Channel.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-20407 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Diameter-Fuel-Channel-254x300.png\" alt=\"Diam\u00e8tre hydraulique - Canal de carburant\" width=\"254\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Hydraulic-Diameter-Fuel-Channel-254x300.png\" \/><\/a><span>Calculer la\u00a0<\/span><strong><span>tra\u00een\u00e9e<\/span><\/strong><span>\u00a0de\u00a0<strong>frottement<\/strong>\u00a0d&#8217;une\u00a0<\/span><strong><span>barre de combustible unique \u00e0 l&#8217;<\/span><\/strong><span>\u00a0\u00a0int\u00e9rieur d&#8217;un c\u0153ur de r\u00e9acteur en fonctionnement normal (d\u00e9bit de conception).\u00a0Supposons que ce crayon de combustible fait partie d&#8217;un faisceau de combustible avec le r\u00e9seau de combustible rectangulaire et que ce faisceau de combustible ne contient pas de grilles d&#8217;espacement.\u00a0Sa hauteur est\u00a0<\/span><strong><span>h = 4 m<\/span><\/strong><span>\u00a0et la vitesse d&#8217;\u00e9coulement du c\u0153ur est constante et \u00e9gale \u00e0\u00a0<\/span><strong><span>V\u00a0<\/span><\/strong><strong><sub><span>c\u0153ur<\/span><\/sub><\/strong><strong><span>\u00a0= 5 m \/ s.<\/span><\/strong><\/p>\n<p><span>Suppose que:<\/span><\/p>\n<ul>\n<li><span>le diam\u00e8tre ext\u00e9rieur du rev\u00eatement est:\u00a0<\/span><strong><span>d = 2 xr\u00a0<\/span><\/strong><strong><sub><span>Zr, 1<\/span><\/sub><\/strong><strong><span>\u00a0= 9,3 mm<\/span><\/strong><\/li>\n<li><span>le pas des goupilles de combustible est:\u00a0<\/span><strong><span>p = 13 mm<\/span><\/strong><\/li>\n<li><span>la\u00a0<\/span><a title=\"Rugosit\u00e9 relative du tuyau\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/relative-roughness-of-pipe\/\"><span>rugosit\u00e9 relative<\/span><\/a><span>\u00a0est\u00a0<\/span><strong><span>\u03b5 \/ D = 5 \u00d7 10\u00a0<\/span><\/strong><strong><sup><span>-4<\/span><\/sup><\/strong><\/li>\n<li><span>la\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-density-physics\/\"><span>densit\u00e9<\/span><\/a><span>\u00a0du fluide\u00a0est:\u00a0<\/span><strong><span>\u03c1 = 714 kg \/ m\u00a0<\/span><\/strong><strong><sup><span>3<\/span><\/sup><\/strong><\/li>\n<li><span>la vitesse d&#8217;\u00e9coulement du c\u0153ur est constante et \u00e9gale \u00e0\u00a0<\/span><strong><span>V\u00a0<\/span><\/strong><strong><sub><span>c\u0153ur<\/span><\/sub><\/strong><strong><span>\u00a0= 5 m \/ s<\/span><\/strong><\/li>\n<li><span>la\u00a0<\/span><a title=\"Qu'est-ce que la temp\u00e9rature - Physique\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-temperature-physique-definition\/\"><span>temp\u00e9rature<\/span><\/a><span>\u00a0moyenne\u00a0du liquide de refroidissement du r\u00e9acteur est:\u00a0<\/span><strong><span>T en\u00a0<\/span><\/strong><strong><sub><span>vrac<\/span><\/sub><\/strong><strong><span>\u00a0= 296 \u00b0 C<\/span><\/strong><\/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-spacer\"><\/div>\n<h2><span>Calcul du nombre de Reynolds<\/span><\/h2>\n<p><span>Pour calculer le\u00a0<\/span><a title=\"Le num\u00e9ro de Reynold\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\"><span>nombre de Reynolds<\/span><\/a><span>\u00a0, nous devons savoir:<\/span><\/p>\n<ul>\n<li><span>le diam\u00e8tre ext\u00e9rieur du rev\u00eatement est:\u00a0<\/span><strong><span>d = 2 xr\u00a0<\/span><\/strong><strong><sub><span>Zr, 1<\/span><\/sub><\/strong><strong><span>\u00a0= 9,3 mm<\/span><\/strong><span>\u00a0(pour calculer le diam\u00e8tre hydraulique)<\/span><\/li>\n<li><span>le pas des goupilles de combustible est:\u00a0<\/span><strong><span>p = 13 mm<\/span><\/strong><span>\u00a0\u00a0(pour calculer le diam\u00e8tre hydraulique)<\/span><\/li>\n<li><span>la viscosit\u00e9 dynamique de l&#8217;eau satur\u00e9e \u00e0 300 \u00b0 C est:\u00a0<\/span><strong><span>\u03bc = 0,0000859 Ns \/ m\u00a0<\/span><\/strong><strong><sup><span>2<\/span><\/sup><\/strong><\/li>\n<li><span>la densit\u00e9 du fluide est:\u00a0<\/span><strong><span>\u03c1 = 714 kg \/ m\u00a0<\/span><\/strong><strong><sup><span>3<\/span><\/sup><\/strong><\/li>\n<\/ul>\n<p><strong><span>Le diam\u00e8tre hydraulique, D\u00a0<\/span><\/strong><strong><sub><span>h<\/span><\/sub><\/strong><span>\u00a0, est un terme couramment utilis\u00e9 pour g\u00e9rer le d\u00e9bit dans\u00a0<\/span><strong><span>des tubes et canaux non circulaires<\/span><\/strong><span>\u00a0.\u00a0Le\u00a0<\/span><strong><span>diam\u00e8tre hydraulique du canal de carburant<\/span><\/strong><span>\u00a0,\u00a0<\/span><em><span>D\u00a0<\/span><\/em><em><sub><span>h<\/span><\/sub><\/em><span>\u00a0, est \u00e9gal \u00e0\u00a0<\/span><strong><span>13,85 mm<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>Voir aussi:\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/internal-flow\/hydraulic-diameter-2\/\"><span>Diam\u00e8tre hydraulique<\/span><\/a><\/p>\n<p><span>Le\u00a0<\/span><strong><span>nombre de Reynolds<\/span><\/strong><span>\u00a0\u00e0 l&#8217;int\u00e9rieur du canal de carburant est alors \u00e9gal \u00e0:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/reynolds-number-example.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20412 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/reynolds-number-example.png\" alt=\"nombre de reynolds - exemple\" width=\"593\" height=\"78\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/reynolds-number-example.png\" \/><\/a><\/p>\n<p><span>Cela satisfait pleinement les\u00a0<\/span><a href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-quun-ecoulement-turbulent-definition\/\"><strong><span>conditions turbulentes<\/span><\/strong><\/a><span>\u00a0.<\/span><\/p>\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>Calcul du coefficient de friction cutan\u00e9e<\/span><\/h2>\n<p><strong><span>Le facteur de frottement<\/span><\/strong><span>\u00a0pour un \u00e9coulement turbulent d\u00e9pend fortement de la\u00a0<\/span><strong><span>rugosit\u00e9 relative.\u00a0<\/span><\/strong><span>Il est d\u00e9termin\u00e9 par l&#8217;\u00e9quation de Colebrook ou peut \u00eatre d\u00e9termin\u00e9 \u00e0 l&#8217;aide du\u00a0<\/span><a title=\"Diagramme Moody\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/moody-diagram\/\"><strong><span>diagramme de Moody<\/span><\/strong><\/a><span>\u00a0.\u00a0Le\u00a0<\/span><strong><span>graphique de Moody<\/span><\/strong><span>\u00a0pour\u00a0<\/span><strong><span>Re = 575 600<\/span><\/strong><span>\u00a0et\u00a0<\/span><strong><span>\u03b5 \/ D = 5 x 10\u00a0<\/span><\/strong><strong><sup><span>-4<\/span><\/sup><\/strong><span>\u00a0renvoie les valeurs suivantes:<\/span><\/p>\n<ul>\n<li><span>le\u00a0<\/span><a title=\"Facteur de friction Darcy\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-le-facteur-de-friction-de-darcy-definition\/\"><strong><span>facteur de friction de Darcy<\/span><\/strong><\/a><span>\u00a0est \u00e9gal \u00e0\u00a0<\/span><strong><span>f\u00a0<\/span><\/strong><strong><sub><span>D<\/span><\/sub><\/strong><strong><span>\u00a0= 0,017<\/span><\/strong><\/li>\n<li><span>le\u00a0<\/span><a title=\"Facteur de friction de ventilation\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/fanning-friction-factor\/\"><strong><span>facteur de friction Fanning<\/span><\/strong><\/a><span>\u00a0est \u00e9gal \u00e0\u00a0<\/span><strong><span>f\u00a0<\/span><\/strong><strong><sub><span>F<\/span><\/sub><\/strong><strong><span>\u00a0= f\u00a0<\/span><\/strong><strong><sub><span>D<\/span><\/sub><\/strong><strong><span>\u00a0\/ 4 = 0,00425<\/span><\/strong><\/li>\n<\/ul>\n<p><span>Le coefficient de frottement cutan\u00e9 est donc \u00e9gal \u00e0:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-coefficient-example.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20533 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-coefficient-example.png\" alt=\"coefficient de frottement cutan\u00e9 - exemple\" width=\"377\" height=\"186\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/skin-friction-coefficient-example.png\" \/><\/a><\/p>\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>Calcul de la force de tra\u00een\u00e9e<\/span><\/h2>\n<p><span>Pour calculer la\u00a0<\/span><strong><span>force de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0, nous devons savoir:<\/span><\/p>\n<ul>\n<li><span>le coefficient de frottement cutan\u00e9, qui est:\u00a0<\/span><strong><span>C\u00a0<\/span><\/strong><strong><sub><span>D, frottement<\/span><\/sub><\/strong><strong><span>\u00a0= 0,00425<\/span><\/strong><\/li>\n<li><span>l&#8217;aire de la surface de la broche, qui est:\u00a0<\/span><strong><span>A = \u03c0.dh = 0,1169 m\u00a0<\/span><\/strong><strong><sup><span>2<\/span><\/sup><\/strong><\/li>\n<li><span>la\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-density-physics\/\"><span>densit\u00e9<\/span><\/a><span>\u00a0du fluide\u00a0, qui est:\u00a0<\/span><strong><span>\u03c1 = 714 kg \/ m\u00a0<\/span><\/strong><strong><sup><span>3<\/span><\/sup><\/strong><\/li>\n<li><span>la vitesse d&#8217;\u00e9coulement du c\u0153ur, constante et \u00e9gale \u00e0\u00a0<\/span><strong><span>V\u00a0<\/span><\/strong><strong><sub><span>c\u0153ur<\/span><\/sub><\/strong><strong><span>\u00a0= 5 m \/ s<\/span><\/strong><\/li>\n<\/ul>\n<p><span>\u00c0 partir du\u00a0<\/span><strong><span>coefficient de friction de<\/span><\/strong><span>\u00a0la\u00a0<strong>peau,<\/strong>\u00a0qui est \u00e9gal au\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/fanning-friction-factor\/\"><strong><span>facteur de friction de Fanning,<\/span><\/strong><\/a><span>\u00a0nous pouvons calculer la composante de friction de la\u00a0<\/span><strong><span>force de tra\u00een\u00e9e.\u00a0<\/span><\/strong><span>La force de tra\u00een\u00e9e est donn\u00e9e par:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-example.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20534 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-example.png\" alt=\"force de tra\u00een\u00e9e - exemple\" width=\"452\" height=\"72\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/drag-force-example.png\" \/><\/a><\/p>\n<p><span>En supposant qu&#8217;un assemblage combustible puisse avoir, par exemple, 289 goupilles combustibles (assemblage combustible 17&#215;17), la\u00a0<\/span><strong><span>composante frictionnelle<\/span><\/strong><span>\u00a0de la\u00a0<\/span><strong><span>force de tra\u00een\u00e9e<\/span><\/strong><span>\u00a0est alors de l&#8217;ordre de\u00a0<\/span><strong><span>kilonewtons<\/span><\/strong><span>\u00a0.\u00a0De plus, cette force de tra\u00een\u00e9e provient uniquement du frottement de la peau sur le faisceau de combustible.\u00a0Mais l&#8217;assemblage combustible PWR typique contient d&#8217;autres composants, qui influencent l&#8217;hydraulique de l&#8217;assemblage combustible:<\/span><\/p>\n<ul>\n<li><strong><span>Barres de combustible<\/span><\/strong><span>\u00a0.\u00a0Les crayons combustibles contiennent le carburant et les poisons combustibles.<\/span><\/li>\n<li><strong><span>Buse sup\u00e9rieure<\/span><\/strong><span>\u00a0.\u00a0Fournit le support m\u00e9canique de la structure d&#8217;assemblage combustible.<\/span><\/li>\n<li><strong><span>Buse inf\u00e9rieure<\/span><\/strong><span>\u00a0.\u00a0Fournit le support m\u00e9canique de la structure d&#8217;assemblage combustible.<\/span><\/li>\n<li><strong><span>Grille d&#8217;espacement<\/span><\/strong><span>\u00a0.\u00a0Assure un guidage pr\u00e9cis des crayons combustibles.<\/span><\/li>\n<li><strong><span>Guide tube de d\u00e9 \u00e0 coudre<\/span><\/strong><span>\u00a0.\u00a0Tube vide pour barres de contr\u00f4le ou instrumentation in-core.<\/span><\/li>\n<\/ul>\n<p><span>Comme il a \u00e9t\u00e9 \u00e9crit, le deuxi\u00e8me composant de la force de tra\u00een\u00e9e est la tra\u00een\u00e9e de forme.\u00a0<\/span><strong><span>La tra\u00een\u00e9e de forme,<\/span><\/strong><span>\u00a0\u00e9galement appel\u00e9e\u00a0<strong>tra\u00een\u00e9e<\/strong>\u00a0de\u00a0<\/span><strong><span>pression,<\/span><\/strong><span>\u00a0r\u00e9sulte de la\u00a0<\/span><strong><span>forme<\/span><\/strong><span>\u00a0et de la\u00a0<\/span><strong><span>taille<\/span><\/strong><span>\u00a0de l&#8217;objet.\u00a0La\u00a0<\/span><strong><span>tra\u00een\u00e9e de pression<\/span><\/strong><span>\u00a0est proportionnelle \u00e0 la diff\u00e9rence entre les pressions agissant \u00e0 l&#8217;avant et \u00e0 l&#8217;arri\u00e8re du corps immerg\u00e9 et la zone frontale.<\/span><\/p>\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>Chute de pression &#8211; assemblage de carburant<\/span><\/h2>\n<p><span>En g\u00e9n\u00e9ral, la\u00a0<strong>chute de pression<\/strong>\u00a0totale de\u00a0<\/span><strong><span>l&#8217;assemblage combustible<\/span><\/strong><span>\u00a0est form\u00e9e par la chute de friction du faisceau de combustible (en fonction de\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/major-head-loss-friction-loss\/relative-roughness-of-pipe\/\">la rugosit\u00e9 relative<\/a>\u00a0des crayons combustibles, du\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/reynolds-number\/\">nombre de reynolds<\/a>\u00a0, du\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/internal-flow\/hydraulic-diameter-2\/\">diam\u00e8tre hydraulique<\/a>\u00a0,\u00a0etc.) et d&#8217;autres chutes de pression des \u00e9l\u00e9ments structurels (buse sup\u00e9rieure et inf\u00e9rieure, grilles d&#8217;espacement ou grilles de m\u00e9lange ).<\/span><\/p>\n<p><span>En g\u00e9n\u00e9ral, il n&#8217;est pas si simple de calculer les chutes de pression dans les assemblages combustibles (en particulier les grilles d&#8217;espacement) et il appartient au\u00a0<\/span><strong><span>savoir-faire<\/span><\/strong><span>\u00a0cl\u00e9\u00a0de certains fabricants de carburants.\u00a0La plupart du temps, les chutes de pression sont mesur\u00e9es dans\u00a0<\/span><strong><span>des boucles hydrauliques exp\u00e9rimentales<\/span><\/strong><span>\u00a0, plut\u00f4t que calcul\u00e9es.<\/span><\/p>\n<p><span>Les ing\u00e9nieurs utilisent le\u00a0<\/span><a title=\"Coefficient de perte de pression - PLC\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/head-loss\/pressure-loss-coefficient-plc\/\"><strong><span>coefficient de perte de pression<\/span><\/strong><\/a><span>\u00a0,\u00a0<\/span><strong><span>PLC<\/span><\/strong><span>\u00a0.\u00a0Il est not\u00e9 K ou\u00a0<\/span><strong><span>\u03be<\/span><\/strong><span>\u00a0\u00a0(prononc\u00e9 \u00abxi\u00bb).\u00a0Ce coefficient caract\u00e9rise\u00a0<\/span><a title=\"Perte de t\u00eate - Perte de pression\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/bernoullis-equation-bernoullis-principle\/head-loss\/\"><span>la perte<\/span><\/a><span>\u00a0de charge d&#8217;un certain syst\u00e8me hydraulique ou d&#8217;une partie d&#8217;un syst\u00e8me hydraulique.\u00a0Il peut \u00eatre facilement mesur\u00e9 dans les boucles hydrauliques.\u00a0Le coefficient de perte de charge peut \u00eatre d\u00e9fini ou mesur\u00e9 pour les deux tuyaux droits et en particulier pour\u00a0<\/span><a title=\"Perte de t\u00eate mineure - Pertes locales\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/fluid-dynamics\/minor-head-loss-local-losses\/\"><strong><span>les pertes locales (mineures)<\/span><\/strong><\/a><span>\u00a0.<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/PLC-Pressure-loss-coefficient-equations.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-20526 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/PLC-Pressure-loss-coefficient-equations.png\" alt=\"PLC - Coefficient de perte de pression - \u00e9quations\" width=\"339\" height=\"375\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/PLC-Pressure-loss-coefficient-equations.png\" \/><\/a><\/p>\n<p><span>En utilisant les donn\u00e9es de l&#8217;exemple mentionn\u00e9 ci-dessus, le\u00a0<\/span><strong><span>coefficient de perte de pression<\/span><\/strong><span>\u00a0(seulement le frottement du tuyau droit) est \u00e9gal \u00e0\u00a0<\/span><strong><span>\u03be = f\u00a0<\/span><sub><span>D<\/span><\/sub><span>\u00a0L \/ D\u00a0<\/span><sub><span>H<\/span><\/sub><span>\u00a0= 4,9<\/span><\/strong><span>\u00a0.\u00a0Mais le coefficient global de perte de pression (y compris les grilles d&#8217;espacement, les buses sup\u00e9rieure et inf\u00e9rieure, etc.) est g\u00e9n\u00e9ralement environ trois fois plus \u00e9lev\u00e9.\u00a0Cet automate (\u00a0<\/span><strong><span>\u03be = 4,9<\/span><\/strong><span>\u00a0) provoque que la chute de pression est de l&#8217;ordre de ( en\u00a0utilisant les entr\u00e9es pr\u00e9c\u00e9dentes)\u00a0<\/span><strong><span>Dp\u00a0<\/span><sub><span>friction<\/span><\/sub><\/strong><span>\u00a0= 4,9 x 714 x 5\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0\/2 =\u00a0<\/span><strong><span>43,7 kPa<\/span><\/strong><span>\u00a0(sans grilles, embouts sup\u00e9rieur et inf\u00e9rieur d&#8217;\u00a0espacement).\u00a0Un PLC r\u00e9el environ trois fois plus \u00e9lev\u00e9 signifie un\u00a0<strong><sub>carburant\u00a0<\/sub><\/strong><\/span><strong><span>\u00a0\u0394p<\/span><\/strong><span>\u00a0environ trois fois plus \u00e9lev\u00e9\u00a0.<\/span><\/p>\n<p><span>La perte de charge globale du r\u00e9acteur,\u00a0<strong><sub>r\u00e9acteur<\/sub><\/strong><\/span><strong><span>\u00a0\u0394p<\/span><\/strong><span>\u00a0, doit comprendre:<\/span><\/p>\n<ul>\n<li><span>descente et fond de r\u00e9acteur<\/span><\/li>\n<li><span>plaque de support inf\u00e9rieure<\/span><\/li>\n<li><span>assemblage de combustible comprenant des grilles d&#8217;espacement, des buses sup\u00e9rieure et inf\u00e9rieure et d&#8217;autres composants structurels &#8211;\u00a0\u00a0<\/span><strong><span>\u0394p\u00a0<\/span><sub><span>fuel<\/span><\/sub><\/strong><\/li>\n<li><span>ensemble de structure de guidage sup\u00e9rieur<\/span><\/li>\n<\/ul>\n<p><span>En cons\u00e9quence, la perte de charge globale du r\u00e9acteur &#8211;\u00a0\u00a0<strong><sub>r\u00e9acteur<\/sub><\/strong><\/span><strong><span>\u00a0\u0394p<\/span><\/strong><span>\u00a0est g\u00e9n\u00e9ralement de l&#8217;ordre de centaines de kPa (disons 300 &#8211; 400 kPa) pour les param\u00e8tres de conception.<\/span><\/p>\n<\/div>\n<\/div>\n<p>&nbsp;<\/p>\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>Qu&#8217;est-ce que la r\u00e9sistance \u00e0 l&#8217;air et aux fluides?\u00a0En dynamique des fluides et en a\u00e9rodynamique, la tra\u00een\u00e9e est une force agissant \u00e0 l&#8217;oppos\u00e9 du mouvement relatif de tout objet en mouvement.\u00a0G\u00e9nie thermique Qu&#8217;est-ce que la tra\u00een\u00e9e en physique &#8211; R\u00e9sistance \u00e0 l&#8217;air et aux fluides En\u00a0dynamique des fluides\u00a0, la\u00a0tra\u00een\u00e9e\u00a0est une force agissant \u00e0 l&#8217;oppos\u00e9 du &#8230; <a title=\"Quelle est la r\u00e9sistance &#8211; R\u00e9sistance \u00e0 l&#8217;air et aux fluides &#8211; D\u00e9finition\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quelle-est-la-resistance-resistance-a-lair-et-aux-fluides-definition\/\" aria-label=\"En savoir plus sur Quelle est la r\u00e9sistance &#8211; R\u00e9sistance \u00e0 l&#8217;air et aux fluides &#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>Quelle est la r\u00e9sistance - R\u00e9sistance \u00e0 l&#039;air et aux fluides - D\u00e9finition<\/title>\n<meta name=\"description\" content=\"Quelle est la r\u00e9sistance - R\u00e9sistance \u00e0 l&#039;air et aux fluides. 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