Enhancement of disturbance wave amplification due to the intrinsic three-dimensionalisation of laminar separation bubbles

Autor(es)

Rodriguez, D. ^[1] ; Gennaro, E. M. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Fed Fluminense, Dept Mech Engn, Grad Program Mech Engn PGMEC, Lab Theoret & Appl Mech LMTA, Niteroi, RJ - Brazil

^[2] Sao Paulo State Univ UNESP, Campus Sao Joao da Boa Vista, Sao Joao Da Boa Vista, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: AERONAUTICAL JOURNAL; v. 123, n. 1268, p. 1492-1507, OCT 2019.
• Citações Web of Science: 1

Resumo

Previous studies demonstrated that laminar separation bubbles (LSBs) in the absence of external disturbances or forcing are intrinsically unstable with respect to a three-dimensional instability of centrifugal nature. This instability produces topological modifications of the recirculation region with the introduction of streamwise vorticity in an otherwise purely two-dimensional time-averaged flows. Concurrently, the existence of spanwise inhomogeneities in LSBs have been reported in experiments in which the amplification of convective instability waves dominates the physics. The co-existence of the two instability mechanisms is investigated herein by means of three-dimensional parabolised stability equations. The spanwise waviness of the LSB on account of the primary instability is found to modify the amplification of incoming disturbance waves in the linear regime, resulting in a remarkable enhancement of the amplitude growth and a three-dimensional arrangement of the disturbance waves in the aft portion of the bubble. Present findings suggest that the oblique transition scenario should be expected in LSBs dominated by the convective instability, unless high-amplitude disturbances are imposed. (AU)

• Processo FAPESP: 14/24782-0 - Estudo da origem da não-estacionariedade de bolhas de separação laminar não-forçadas
• Beneficiário: Elmer Mateus Gennaro
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/01586-0 - Instabilidade de escoamentos separados em aplicações aeronáuticas
• Beneficiário: Elmer Mateus Gennaro
• Modalidade de apoio: Auxílio à Pesquisa - Regular