Study of the attenuation of waves propagating through fixed and rotating turbine blades
Notice bibliographique
Résumé
This paper deals with the prediction of the transmission and reflection coefficients of acoustic and entropy waves through a turbine. The two-dimensional analytical method of Cumpsty and Marble 5 for low frequencies, or compact row assumption, is extended to consider the enthalpy jump through a rotating blade. Numerical simulations of a rotor blade are used to validate the compact hypothesis and the extension of the theory. It is found that results are strongly dependent on the trailing edge condition used by Cumpsty and Marble 5 for the stator vane. Finally, the analytical method is used to reproduce the experimental data of Doyle and Matta. 7 Noise generated in the combustion chamber or by turbine blades propagates to the outlet of the engine through the downstream stator vanes and rotor blades. This propagation attenuates the acoustic emissions in the outlet, and should be thus considered when calculating combustion noise. At the same time, the acceleration and deceleration of entropy waves generated in the combustion chamber through non-uniform flows generates indirect noise, as shown by Marble and Candel, 16 which can contribute significantly to the total noise. 3,19,21 The propagation of acoustic and entropy waves through one-dimensional nozzle configurations has been studied in depth: Marble and Candel 16 proposed an analytical method to calculate the propagation of acoustic and entropy waves in a quasi-1D nozzle, based on the compact nozzle hypothesis. This hypothesis states that the wavelength of the perturbations is large compared to the axial extension of the nozzle, limiting the results to the low frequency range. Using the compact nozzle hypothesis the propagation of waves can be considered quasi-static and matching conditions can be written between both sides of the nozzle, corresponding to the mass, enthalpy and entropy conservation in a quasi-static regime. This analytical method can be used to calculate the attenuation of noise when acoustic waves propagate through a nozzle and at the same time to calculate the generation of indirect noise. Leyko et al. 15 used this analytical method to show that indirect combustion noise is relevant when considering typical aero-engine’s operational conditions. Experiments performed by Bake et al., 2 where an entropy wave was propagated through a nozzle, were explained both for the supersonic case with a shock wave 14 and for the subsonic case 8 using the compact nozzle hypothesis. The compact nozzle hypothesis has been extended both numerically 1,11 and analytically using asymptotic expansion methods. 9,24 Cumpsty and Marble 5 extended the one-dimensional analytical method to a fixed blade row. This extension takes into account the flow deviation imposed by the turbine blades and the cut-off frequencies of oblique acoustic modes present in real configurations. The method, based on the same compact hypothesis, uses similarly the mass, enthalpy and entropy equations to write the corresponding matching conditions. A fourth equation is obtained imposing the Kutta condition at the outlet of the blade. Using a matrix notation, the stages can be chained to obtain the transfer functions of a complete turbine. Recently, numerical simulations have been used to check the compact model and to analyse the errors made when considering
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 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) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| 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 ».