Etude expérimentale des mécanismes d'atomisation effervescente. Application à la sécurité incendie dans les moteurs aéronautiques.
Notice bibliographique
Résumé
Fires are one of the most formidable risks in aviation because of the difficulties to fight them once airbone, as for example in confined spaces where the spread can be very fast. Halon1301 has been used for more than 50 years as extinguishing agent for aircraft engines, APU (Auxiliary Power Unit) and cargo fire protection. Halon1301 has specific properties for systems of fires engines protection. It has a low boiling point and high vapor pressure, which facilitates the mixture of the agent with the ventilation air in fire areas. In addition, its boiling point at -57,8°C and its ability to vaporize throughout the discharge are desirable physical properties. Because of changes in environmental regulation, it is necessary to replace Halon1301, the extinguishing agent currently present on aircraft engines fire protection systems. The use of this fluid has been banned by the Montreal (1994) and Kyoto (1998) protocols in industry, with the intent to reduce substances that deplete the ozone layer as well as greenhouse gases. Exemptions established by the European environmental Commission exist and are applied to the aeronautics field due to the lack of alternatives. For several years, Airbus has been working on the replacement of Halon1301 for engines and APU fire protection systems. Since 2003, several alternative agents to the Halon1301 have been identified. This study is dedicated to a fluid that appears as an environmentally friendly alternative: Novec1230. The most important difference between Halon1301 and Novec1230 is their physical phase. Indeed, Halon1301 is in gaseous state at all relevant conditions, while Novec1230 is a liquid below +49,2°C. At the cold temperature ventilation (negative temperature) or at ambient (+25°C), the agent will be liquid. The characteristics of evaporation (saturation curve) show that for these applications, we are in a two-phase flow with the presence of drops and gas. Gas-phase transport agent in every engine area is not a problem because it will be transported by the ventilation air flow. However, in the liquid phase, the efficient transport of the agent in the form of drops is more complex: If the drops are too large, they will tend to have a ballistic trajectory and will not reach all areas the engine. Therefore, the optimization of atomization of the agent becomes a central parameter for the design of the fire protection system. In the context of this project, a technology called effervescent atomization was considered. The principle is to dissolve a gas (in our case carbon dioxide, CO2), in the liquid agent Novec1230. Many adaptations of this technology are required to improve the performance of the atomization and subsequently the transport of the fire-extinguishing agent. The effervescent atomization process is a promising technology that offers potential improvements in terms of quality of atomization of the fluid and reduction of operating pressure. The goal of this project is to conduct theoretical and experimental research on the effervescent atomization process to identify the key parameters that influence the atomization.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,008 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».