Experimental and Computational Investigation of a Quarter-Wave Resonator on a Large-Bore Marine Dual-Fuel Engine
Notice bibliographique
Résumé
<div class="section abstract"><div class="htmlview paragraph">Large pressure pulsations and a non-uniform distribution of charge air temperature along the intake manifold were detected on a large-bore marine Dual-Fuel engine. These two phenomena were found to impact negatively on the knock resistance of individual cylinders, when the engine is operated in gas-mode. As it happens with marine gas engines, the cylinder most prone to knocking drives the engine tuning for all the others, thus reducing the overall fuel conversion efficiency. In order to effectively tackle this issue, a comprehensive study was carried out, which included both experimental testing and fluid-dynamics simulation. A detailed GT-POWER 1D engine model was built, representing the laboratory 8L (i.e. inline eight-cylinder) engine configuration. The model was extensively correlated against measurements at different speeds and loads and it proved capable of closely reproducing both the pressure fluctuations and the temperature gradient along the intake manifold. Models for the other cylinder configurations (6L, 7L, 9L, 12V, 14V and 16V) were built scaling the validated 8L one. Linear acoustic analyses were then used to investigate the eigenvalues (natural frequencies) of the intake air path, for each engine variant. It was possible to infer that the second natural frequency of the intake volumes is to be considered as the main cause of the pressure fluctuations. The temperature gradient was on the other hand identified as a side-effect of the large pressure oscillations, as they increase locally the heat transfer coefficients between the charge air and the warm manifold walls. A quarter-wave resonator was designed, which was tuned on the resonance frequency to mitigate the pressure pulsations. For packaging reasons, it was decided to place the resonator inside the air receiver. As the resonator length was very close to the manifold’s one in some cylinder configurations, a bent resonator pipe was proposed. Its shape, cross-section and dimensions were investigated in detail and optimized by means of 1D and 3D CFD analyses. Eventually, tests on the 8L laboratory engine, fitted with the quarter-wave resonator of choice, supported the simulation results: pressure pulsations decreased by 40% and, after engine re-tuning, brake efficiency increased by 0.3% (absolute) at the same knock-margin.</div></div>
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
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 tête enseignante, 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 ».