SPOD analysis of noise-generating Rossiter modes in a slat with and without a bulb seal

Autor(es)

Himeno, Fernando H. T. ^[1] ; Souza, Daniel S. ^[2] ; Amaral, Filipe R. ^{[3, 1]} ; Rodriguez, Daniel ^[4] ; Medeiros, Marcello A. F. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Aeronaut Engn, Av Trabalhador Sao Carlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[2] UNESP Sao Paulo State Univ, Av Profa Isette Correa Fontao 505, BR-13876750 Sao Joao Da Boa Vista, SP - Brazil

^[3] Aeronaut Inst Technol, Praca Marechal Eduardo Gomes 50, BR-12228900 Sao Jose Dos Campos, SP - Brazil

^[4] Univ Politecn Madrid, TSIAE UPM Sch Aeronaut, Plaza Cardenal Cisneros 3, Madrid 28040 - Spain

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF FLUID MECHANICS; v. 915, MAR 18 2021.
• Citações Web of Science: 0

Resumo

The slat represents an important airframe noise source as it extends over almost the entire aircraft wingspan. Most studies of slat noise consider idealized geometries. However, for practical applications, several elements are installed on its cove, such as bulb seals to avoid direct contact with the main wing surface. Previous investigations of an unswept and untapered MD30P3ON airfoil reported that the flow dynamics and the corresponding acoustic noise are very sensitive to the presence and location of the bulb seal. For certain locations a second recirculation bubble is created inside the slat cove and the acoustic narrowband peaks are intensified. The present paper shows that the two-bubble topology promotes the recirculation of turbulence within the slat cove. Spectral proper orthogonal decomposition analysis based on the radiated pressure intensity is used to identify the flow structures responsible for sound generation. Even though the recirculating turbulence is mostly incoherent, it interacts with the coherent Kelvin-Helmholtz vortices in the initial part of the mixing layer. Then, vortex merging and straining lead to the formation of complex vortex clusters. Our results show that the origin and evolution of these clusters are consistent with Rossiter's mechanism responsible for the narrowband peaks. The enhanced recirculation accelerates the cluster evolution leading to wider clusters and lower-frequency Rossiter modes. (AU)

• Processo FAPESP: 16/02970-5 - Estudo computacional do efeito aeroacústico de um selo localizado na cova do eslate e análise através de técnica POD
• Beneficiário: Fernando Henrique Tadashi Himeno
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 06/52568-7 - Aeronave silenciosa: uma investigação em aeronáutica
• Beneficiário: Julio Romano Meneghini
• Modalidade de apoio: Auxílio à Pesquisa - Parceria para Inovação Tecnológica - PITE
• Processo FAPESP: 19/02203-2 - Estudo de problemas inversos em turbulência e aeroacústica utilizando análise de resolvente
• Beneficiário: Filipe Ramos do Amaral
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 18/02542-9 - Estudo numérico de pacotes de onda sobre placa plana com rugosidade
• Beneficiário: Fernando Henrique Tadashi Himeno
• Modalidade de apoio: Bolsas no Brasil - Doutorado