Kinematic and mixing characteristics of vortex interaction induced by a vortex generator model: a numerical study

Wang, Ziang; Yu, Bin; Zhang, Bin; He, Miaosheng; Liu, Hong

doi:10.1007/s10483-021-2711-5

Cited by 4 publications

(1 citation statement)

References 49 publications

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“…The PS mixing behaviour in a vortical flow has been applied in the design of a lobed mixer (Waitz et al 1997) or a strut mixer (Vergine, Ground & Maddalena 2016), which generates the interacting streamwise vortices to enhance mixing (Wang et al 2021). It is noteworthy that the flow inside scramjet combustors invariably involves inhomogeneous compressible mixing.…”

Section: Introductionmentioning

confidence: 99%

On mixing enhancement by secondary baroclinic vorticity in a shock–bubble interaction

Zhang

et al. 2021

J. Fluid Mech.

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To investigate the intrinsic mechanism for mixing enhancement by variable-density (VD) behaviour, a canonical VD mixing extracted from a supersonic streamwise vortex protocol, a shock–bubble interaction (SBI), is numerically studied and compared with a counterpart of passive-scalar (PS) mixing. It is meaningful to observe that the maximum concentration decays much faster in a VD SBI than in a PS SBI regardless of the shock Mach number ( $Ma=1.22 - 4$ ). The quasi-Lamb–Oseen-type velocity distribution in the PS SBI is found by analysing the azimuthal velocity that stretches the bubble. Meanwhile, for the VD SBI, an additional stretching enhanced by the secondary baroclinic vorticity (SBV) production contributes to the faster-mixing decay. The underlying mechanism of the SBV-enhanced stretching is further revealed through the density and velocity difference between the light shocked bubble and the heavy ambient air. By combining the SBV-accelerated stretching model and the initial shock compression, a novel mixing time estimation for VD SBI is theoretically proposed by solving the advection–diffusion equation under a deformation field of an axisymmetric vortex with the additional SBV-induced azimuthal velocity. Based on the mixing time model, a mixing enhancement number, defined by the ratio of VD and PS mixing time further, reveals the contribution from the VD effect, which implies a better control of the density distribution for mixing enhancement in a supersonic streamwise vortex.

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Section: Introductionmentioning

confidence: 99%

On mixing enhancement by secondary baroclinic vorticity in a shock–bubble interaction

Zhang

et al. 2021

J. Fluid Mech.

Self Cite

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A circulation prediction model for ramp and vortex generator in supersonic flow: A numerical study

Wu¹,

He²,

Yu³

et al. 2022

Aerospace Science and Technology

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Mixing mechanisms in the view of mixing indicators: from passive-scalar mixing to variable-density mixing

Han,

Yu,

Liu

2023

MINA

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<abstract><p>Mixing is the basis of stable and efficient combustion in air-breathing power systems, and it is also an important problem in fluid mechanics, which has been extensively studied from various perspectives. The purpose of this review is to investigate mixing mechanisms based on two commonly-used mixing indicators, namely $ c^i $ ($ c $ refers to concentration, and $ i $ is either 1 or 2, indicating first- or second-order statistics), with a focus on passive-scalar (PS) and variable-density (VD) mixing. For PS mixing, the flow is not influenced by the mixing process. By using first-order statistics with concentration as the core, the PS mixing mechanisms on lamella structures can be described as stretching enhancing diffusion and promoting mixing. On the other hand, second-order statistics represented by the scalar dissipation rate can investigate mixing mechanisms on specific type of flow structures described by the invariants of velocity gradient tensors and the rotation of principal strain axis. As such, it has been found that strain-dominated flow structures can promote mixing, while rotation-dominated flow structures hinder it. For VD mixing, it has two distinct characteristics: flow changes due to baroclinic vorticity, and the inherent velocity divergence alters the mixing indicators. Studies using first-order statistics center on the mixing time in different types of VD flows, leading to the discovery of new phenomena. For instance, the second baroclinic vorticity can promote stretching in shock bubble interactions. Studies on second-order statistics for VD mixing have defined several mixing indicators from the component-transport equation, which have been utilized in phenomenological studies on VD mixing. This review aims to provide an overview of mixing phenomena, mixing indicators, and mixing mechanisms, and proposes research directions for understanding the mixing characteristics, flow structures, and their relationship with specific combustion phenomena particularly by second-order statistics.</p></abstract>

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Kinematic and mixing characteristics of vortex interaction induced by a vortex generator model: a numerical study

Cited by 4 publications

References 49 publications

On mixing enhancement by secondary baroclinic vorticity in a shock–bubble interaction

On mixing enhancement by secondary baroclinic vorticity in a shock–bubble interaction

A circulation prediction model for ramp and vortex generator in supersonic flow: A numerical study

Mixing mechanisms in the view of mixing indicators: from passive-scalar mixing to variable-density mixing

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