{"id":46185,"date":"2019-10-21T03:31:21","date_gmt":"2019-10-21T02:31:21","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/quest-ce-que-la-pression-negative-pression-de-vide-definition\/"},"modified":"2020-02-26T14:59:32","modified_gmt":"2020-02-26T13:59:32","slug":"quest-ce-que-la-pression-negative-pression-de-vide-definition","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-pression-negative-pression-de-vide-definition\/","title":{"rendered":"Qu&#8217;est-ce que la pression n\u00e9gative &#8211; Pression de vide &#8211; D\u00e9finition"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">Pression n\u00e9gative &#8211; Pression de vide. Lorsque la pression atmosph\u00e9rique locale est sup\u00e9rieure \u00e0 la pression dans le syst\u00e8me, on parle de pression de vide. G\u00e9nie thermique<\/div>\n<\/div>\n<div><\/div>\n<div><\/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>Quelle est la pression<\/span><\/h2>\n<p><strong><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Manometer-Pressure-Measurement.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-16368 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Manometer-Pressure-Measurement-235x300.png\" alt=\"manom\u00e8tre-pression-mesure\" width=\"235\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Manometer-Pressure-Measurement-235x300.png\" \/><\/a><span>La pression<\/span><\/strong><span>\u00a0est une mesure de la\u00a0<\/span><strong><span>force exerc\u00e9e<\/span><\/strong><span>\u00a0par unit\u00e9 de surface sur les limites d&#8217;une substance.\u00a0L&#8217;unit\u00e9 standard de\u00a0<\/span><strong><span>pression<\/span><\/strong><span>\u00a0dans le syst\u00e8me SI est le\u00a0<\/span><strong><span>Newton par m\u00e8tre carr\u00e9 ou pascal (Pa)<\/span><\/strong><span>\u00a0.\u00a0Math\u00e9matiquement:<\/span><\/p>\n<p><strong><span>p = F \/ A<\/span><\/strong><\/p>\n<p><span>o\u00f9<\/span><\/p>\n<ul>\n<li><strong><span>p est la pression<\/span><\/strong><\/li>\n<li><strong><span>F est la force normale<\/span><\/strong><\/li>\n<li><strong><span>A est l&#8217;aire de la fronti\u00e8re<\/span><\/strong><\/li>\n<\/ul>\n<p><span>Pascal est d\u00e9fini comme la force de 1N qui s&#8217;exerce sur la surface unitaire.<\/span><\/p>\n<ul>\n<li><strong><span>1 Pascal = 1 N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-60 lgc-tablet-grid-60 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\"><span>Cependant, pour la plupart des probl\u00e8mes d&#8217;ing\u00e9nierie, il s&#8217;agit d&#8217;une unit\u00e9 assez petite, il est donc pratique de travailler avec des multiples du pascal: le\u00a0<\/span><strong><span>kPa<\/span><\/strong><span>\u00a0, la\u00a0<\/span><strong><span>barre<\/span><\/strong><span>\u00a0et le\u00a0<\/span><strong><span>MPa<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<ul>\n<li><strong><span>1 MPa 10\u00a0<\/span><sup><span>6<\/span><\/sup><span>\u00a0N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<li><strong><span>1 bar 10\u00a0<\/span><sup><span>5<\/span><\/sup><span>\u00a0N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<li><strong><span>1 kPa 10\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<\/ul>\n<p><span>En g\u00e9n\u00e9ral, la pression ou la force exerc\u00e9e par unit\u00e9 de surface sur les limites d&#8217;une substance est caus\u00e9e par les\u00a0<\/span><strong><span>collisions<\/span><\/strong><span>\u00a0des\u00a0<\/span><strong><span>mol\u00e9cules<\/span><\/strong><span>\u00a0de la substance avec les limites du syst\u00e8me.\u00a0Lorsque les mol\u00e9cules frappent les murs, elles exercent des forces qui tentent de pousser les murs vers l&#8217;ext\u00e9rieur.\u00a0Les forces r\u00e9sultant de toutes ces collisions provoquent la\u00a0<\/span><strong><span>pression<\/span><\/strong><span>\u00a0exerc\u00e9e par un syst\u00e8me sur son environnement.\u00a0La pression en tant que\u00a0<\/span><a title=\"Propri\u00e9t\u00e9s \u00e9tendues et intensives\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/extensive-and-intensive-properties\/\"><strong><span>variable intensive<\/span><\/strong>\u00a0<\/a><span>est constante dans un syst\u00e8me ferm\u00e9.\u00a0Il n&#8217;est vraiment pertinent que dans les syst\u00e8mes liquides ou gazeux.<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-40 lgc-tablet-grid-40 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/What-is-Pressure.png\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-16371 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/What-is-Pressure-300x129.png\" alt=\"Quelle est la pression\" width=\"300\" height=\"129\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/What-is-Pressure-300x129.png\" \/><\/a><\/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>Pression manom\u00e9trique n\u00e9gative &#8211; Pression de vide<\/span><\/h2>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/absolute-vs.-gauge-pressure.png\"><img loading=\"lazy\" class=\"alignright size-full wp-image-16281 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/absolute-vs.-gauge-pressure.png\" alt=\"pression absolue vs manom\u00e9trique\" width=\"388\" height=\"247\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/absolute-vs.-gauge-pressure.png\" \/><\/a><strong><span>Pression manom\u00e9trique n\u00e9gative &#8211; Pression de vide.\u00a0<\/span><\/strong><span>Lorsque la pression atmosph\u00e9rique locale est sup\u00e9rieure \u00e0 la pression dans le syst\u00e8me, le terme\u00a0<\/span><strong><span>pression de vide<\/span><\/strong><span>\u00a0est utilis\u00e9.\u00a0Un vide parfait correspondrait \u00e0 une pression nulle absolue.\u00a0Il est certes possible d&#8217;avoir une pression manom\u00e9trique n\u00e9gative, mais pas possible d&#8217;avoir une pression absolue n\u00e9gative.\u00a0Par exemple, une pression absolue de 80 kPa peut \u00eatre d\u00e9crite comme une pression manom\u00e9trique de -21 kPa (c&#8217;est-\u00e0-dire 21 kPa en dessous d&#8217;une pression atmosph\u00e9rique de 101 kPa).<\/span><\/p>\n<p><em><span>p\u00a0<\/span><\/em><em><sub><span>vide<\/span><\/sub><\/em><em><span>\u00a0= p\u00a0<\/span><\/em><em><sub><span>absolu;\u00a0atm<\/span><\/sub><\/em><em><span>\u00a0&#8211; p\u00a0<\/span><\/em><em><sub><span>absolu<\/span><\/sub><\/em><\/p>\n<p><span>Par exemple, les\u00a0<\/span><span>turbines<\/span><span>\u00a0\u00e0\u00a0vapeur\u00a0\u00e0 condensation\u00a0\u00a0(dans\u00a0<a title=\"Centrale nucl\u00e9aire\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/\">les centrales nucl\u00e9aires<\/a>\u00a0) \u00e9vacuent la\u00a0<a title=\"Propri\u00e9t\u00e9s de Steam - Qu'est-ce que Steam\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-steam-proprietes-de-steam-definition\/\">vapeur<\/a>\u00a0\u00e0 une pression bien inf\u00e9rieure \u00e0 la pression atmosph\u00e9rique\u00a0<\/span><span>(par exemple \u00e0 0,08 bar ou 8 kPa ou 1,16 psia)\u00a0<\/span><span>et dans un \u00e9tat partiellement condens\u00e9.\u00a0En unit\u00e9s relatives, il s&#8217;agit d&#8217;une pression manom\u00e9trique n\u00e9gative d&#8217;environ &#8211; 0,92 bar, &#8211; 92 kPa ou &#8211; 13,54 psig.<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n<div><\/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<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Pression n\u00e9gative &#8211; Pression de vide. Lorsque la pression atmosph\u00e9rique locale est sup\u00e9rieure \u00e0 la pression dans le syst\u00e8me, on parle de pression de vide. G\u00e9nie thermique Quelle est la pression La pression\u00a0est une mesure de la\u00a0force exerc\u00e9e\u00a0par unit\u00e9 de surface sur les limites d&#8217;une substance.\u00a0L&#8217;unit\u00e9 standard de\u00a0pression\u00a0dans le syst\u00e8me SI est le\u00a0Newton par m\u00e8tre &#8230; <a title=\"Qu&#8217;est-ce que la pression n\u00e9gative &#8211; Pression de vide &#8211; D\u00e9finition\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-pression-negative-pression-de-vide-definition\/\" aria-label=\"En savoir plus sur Qu&#8217;est-ce que la pression n\u00e9gative &#8211; Pression de vide &#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 la pression n\u00e9gative - Pression de vide - D\u00e9finition<\/title>\n<meta name=\"description\" content=\"Pression n\u00e9gative - Pression de vide. 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