Numerical Investigation of Asymmetric Separation Vortices over Slender Body by RANS/LES Hybrid Simulation

Inaba, Ryoji; Nishida, Hiroyuki; Nonomura, Taku; Asada, Keiichi; Fujii, Kozo

doi:10.2322/tastj.10.pe_89

Cited by 3 publications

References 20 publications

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Unified mechanisms for separation control around airfoil using plasma actuator with burst actuation over Reynolds number range of 103–106

et al. 2020

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We conduct large-eddy simulations of separated airfoil flows with control by a dielectric-barrier-discharge plasma actuator over a wide range of Reynolds numbers. The Reynolds numbers based on the chord length (Re) are set at Re = 5.0 × 103, 1.0 × 104, 6.3 × 104, 2.6 × 105, and 1.6 × 106. These Reynolds numbers cover most of the conditions used in the previous studies on separation control by a plasma actuator. The burst frequency nondimensionalized by the chord length and freestream velocity (F+) is used as the computational parameter, and the effective burst actuation and control mechanisms at each Reynolds number condition are investigated. With regard to cases without the control, the flows separate near the leading edge in the laminar state at the Reynolds number range of 103–105, and a substantial turbulent separation occurs at the Reynolds number of 1.6 × 106. Separation control with a high burst frequency [F+ ≃ O(10)] can cause early flow reattachment through the promotion of turbulent transition of a separation shear-layer for Re = 6.3 × 104 and 2.6 × 105. Flow reattachment is mainly caused by momentum entrainment into the boundary layer by fine-scale turbulent vortices. On the other hand, the large-scale spanwise vortices play an important role at F+ = 1 for Re = 1.0 × 104 and 1.6 × 106. In these cases, the dynamics of the spanwise vortices show similar behavior and the pairing of these vortices significantly contributes to the separation control by increasing the momentum entrainment. The optimum value of F+ changes with a Reynolds number. In contrast, when a nondimensional burst frequency based on the characteristics of the separation shear-layer (Fθs) is considered, a high lift-to-drag ratio is found at Fθs≃O(10−2) for all Reynolds numbers. This demonstrates that one of the effective burst frequencies is closely related to the scale of the separation shear-layer, especially for the spanwise vortex shed from the separation shear-layer.

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Unified mechanisms for separation control around airfoil using plasma actuator with burst actuation over Reynolds number range of 103–106

et al. 2020

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Wind Tunnel Testing and Numerical Analysis on Angle-of-Attack 60º Side-Force Characteristics of Double-Cone Reusable Rocket

Takagi¹,

MUTO²,

Kitamura³

et al. 2022

JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCE

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Stability of Vortex Symmetry at Flow Separation From Slender Bodies and Control by Local Gas Heating

Shalaev

2024

Vortex Dynamics - Theoretical, Experimental and Numerical Approaches [Working Title]

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A new approach to describe the asymmetry vortex state occurrence for the separated flow over slender bodies is presented. On the basis of the proposed model, a criterion of the asymmetry origin for conical bodies is found using catastrophe theory. Main properties of the transition to an asymmetric state are studied on the basis of the local analysis, the flow characteristics near the critical saddle point. Using the obtained criterion and the new model, numerical calculations of turbulent boundary layer are made to estimate an effectiveness of global flow structure control methods using local plasma discharge or surface heating. The qualitative confirmation of presented numerical results was done by experiments.

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Numerical Investigation of Asymmetric Separation Vortices over Slender Body by RANS/LES Hybrid Simulation

Cited by 3 publications

References 20 publications

Unified mechanisms for separation control around airfoil using plasma actuator with burst actuation over Reynolds number range of 103–106

Unified mechanisms for separation control around airfoil using plasma actuator with burst actuation over Reynolds number range of 103–106

Wind Tunnel Testing and Numerical Analysis on Angle-of-Attack 60º Side-Force Characteristics of Double-Cone Reusable Rocket

Stability of Vortex Symmetry at Flow Separation From Slender Bodies and Control by Local Gas Heating

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