Analysis of the onset and evolution of a dynamic stall vortex on a periodic plunging aerofoil

Autor(es)

Miotto, Renato ; Wolf, William ; Gaitonde, Datta ; Visbal, Miguel

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF FLUID MECHANICS; v. 938, p. 29-pg., 2022-03-17.

Resumo

The onset and evolution of the dynamic stall vortex (DSV) are analysed by means of large eddy simulations of an SD7003 aerofoil undergoing periodic plunging motion in a transitional Reynolds number flow (Re = 6 x 10(4)). Interactions between upstream propagating Kelvin-Helmholtz instabilities and a shear layer formed at the leading edge trigger flow separation. The former appear to be related to acoustic waves scattered at the trailing edge due to initial vortex shedding. Two freestream Mach numbers (M-infinity = 0.1 and 0.4) are employed to examine the flow differences due to compressibility variations. The existence of a common timing for the acoustic perturbations in both flows suggests a possible Mach number invariance for the birth of the Kelvin-Helmholtz instability. Increasing compressibility, however, induces earlier spanwise fluctuations, higher flow three-dimensionality and a weaker and more diffuse DSV, which is formed further downstream of the leading edge and has lower residency time. In order to better characterize the onset of the DSV, two empirical criteria are assessed: the leading edge suction parameter and the chord-normal shear layer height. Results demonstrate a higher robustness of the latter with respect to Mach number variations. Modal decomposition, performed with both the classical dynamic mode decomposition (DMD) and its multi-resolution variant (mrDMD), highlights key trends and demonstrates the capacity of the mrDMD to extract physically meaningful flow structures related to the stall onset. Such detailed characterization of the shear layer can be used for a systematic exploration of flow control strategies for unsteady aerofoils. (AU)

• Processo FAPESP: 13/07375-0 - CeMEAI - Centro de Ciências Matemáticas Aplicadas à Indústria
• Beneficiário: Francisco Louzada Neto
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 17/10795-1 - Investigação de Escoamentos Compressíveis Turbulentos sobre Aerofólios Utilizando Simulações de Alta-Resolução
• Beneficiário: Renato Fuzaro Miotto
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 19/02335-6 - Investigação da física de escoamentos sobre aerofólios em estol dinâmico utilizando simulações de grandes escalas e técnicas de pós-processamento
• Beneficiário: Renato Fuzaro Miotto
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 21/06448-0 - Simulações numéricas de alta fidelidade aplicadas em aerodinâmica não-estacionária, turbulência e aeroacústica
• Beneficiário: William Roberto Wolf
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores - Fase 2