Direct numerical simulation of a supersonic turbulent boundary layer over a compression–decompression corner

Jian-nan, Duan; Li, Xin; Li, Xinliang; Liu, Hongwei

doi:10.1063/5.0052453

Cited by 27 publications

(6 citation statements)

References 43 publications

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“…profiles of fluctuations in various velocity components are plotted in figure 25( a ), which are qualitatively similar to those presented by Wu & Moin (2009) and Duan et al. (2021) for supersonic flat plate boundary layers. While all fluctuations display similar behaviour in both the geometries near the wall (), fluctuations attain higher amplitudes away from the wall in the notched geometry.…”

Section: Effect On Isolator Flowsupporting

confidence: 81%

Flow instabilities and impact of ramp–isolator junction on shock–boundary-layer interactions in a supersonic intake

2022

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Boundary layer instabilities and shock–boundary-layer interactions (SBLIs) critically affect the performance and safe operation of mixed-compression air intakes. We present a computational study anchored in companion experiments, to evaluate the multimodal mechanisms driving the dynamics of the external compression ramp flow and the cowl SBLI in a Mach $3$ intake. Boundary layer transition over the external ramp is first analysed through a global linear analysis, and the linear estimates are further validated through direct numerical simulations. The separation bubble over the ramp harbours three-dimensional stationary instabilities that induce transition, under the influence of secondary instabilities driven by the shear layer modes of the bubble. The interaction of the resulting turbulized boundary layer with the cowl shock at the ramp–isolator junction and its control through geometrical modification constitutes the second part of the study. We tested a faceted (baseline) and a notched (modified) junction design to evaluate its impact on the low-, mid- and high-frequency scales generated at the cowl SBLI region. In relation to the baseline case, the notched geometry effectively locks the separation point of the bubble, thus attenuating the upstream low-frequency breathing motion. The notch also energizes the midfrequency content through vortex shedding in a well-developed shear layer, which persists into the isolator, thus assisting in an efficient compression process through cross-stream mixing of near-wall flow. The isolator boundary layer in the notched design exhibits relatively lower static pressures and higher velocity fluctuations, which are conducive to improving the flow stability, unstart margin and efficiency of high-speed propulsion systems.

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Section: Effect On Isolator Flowsupporting

confidence: 81%

Flow instabilities and impact of ramp–isolator junction on shock–boundary-layer interactions in a supersonic intake

2022

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“…In the present DNS, an in-house high-order finite difference code (OpenCFD-SC) (Duan et al. 2021; Dang et al. 2022; Xu, Wang & Chen 2023 b ) is applied, and it has been used successfully in many supersonic/hypersonic SWTBLI studies (Zhu et al.…”

Section: Methodsmentioning

confidence: 99%

“…In the present DNS, an in-house high-order finite difference code (OpenCFD-SC) (Duan et al 2021;Dang et al 2022;Xu, Wang & Chen 2023b) is applied, and it has been used successfully in many supersonic/hypersonic SWTBLI studies (Zhu et al 2017;Duan et al 2021;Tong et al 2023). The DNS code solves the three-dimensional unsteady compressible Navier-Stokes equations in a generalized coordinate system via the high-order finite difference method.…”

Section: Numerical Schemementioning

confidence: 99%

Wall skin friction analysis in a hypersonic turbulent boundary layer over a compression ramp

Guo,

Zhang,

Zhu

et al. 2024

J. Fluid Mech.

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In this paper, direct numerical simulations in hypersonic turbulent boundary layers over a $24^{\circ }$ compression ramp at Mach 6.0 are performed. The wall skin friction and its spanwise non-homogeneity in the interaction region are analysed via the spectral analysis and drag decomposition method. On the compression ramp, the premultiplied spanwise energy spectrum of wall shear stress $\tau _{w}$ reveals two energetic spanwise length scales. One occurs in the region of $x/\delta _{ref}=0\unicode{x2013}3$ ( $x=0$ lies in the compression corner; $\delta _{ref}$ is the boundary layer thickness upstream of the interaction region) and is consistent with that of the large-scale streamwise vortices, indicating that the fluctuation intensity of $\tau _{w}$ is associated with the Görtler-type structures. The other one is observed downstream of $x/\delta _{ref}=3.0$ and corresponds to the regenerated elongated streaky structures. The fluctuation intensity of $\tau _{w}$ peaks at $x/\delta _{ref}=3.0$ , where both the above energetic length scales are observed. The drag decomposition method proposed by Li et al. (J. Fluid Mech., vol. 875, 2019, pp. 101–123) is extended to include the effects of spanwise non-homogeneity so that it can be used in the interaction region where the mean flow field and the mean skin friction $C_f$ exhibit an obvious spanwise heterogeneity. The results reveal that, in the upstream turbulent boundary layer, the drag contribution arising from the spanwise heterogeneity can be neglected, while this value on the compression ramp is up to 20.7 % of $C_f$ , resulting from the Görtler-type vortices. With the aid of the drag decomposition method, it is found that the main flow features that contribute positively to the amplification of $C_f$ and its rapid increase on the compression ramp includes: the density increase across the shock, the high mean shear stress and turbulence amplification around the detached shear layer and the Favre-averaged downward velocity towards the ramp wall. Compared with the spanwise-averaged value, $C_f$ and its components at the spanwise station where the downwash and upwash of the Görtler-type vortices occur reveal a spanwise variation exceeding 10 %.

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“…(2022) and Duan et al. (2021). Figure 1( a – c ) are given to show the instantaneous streamwise velocity, temperature and density fields.…”

Section: Basic Characteristics Of the Flowmentioning

confidence: 96%

“…The settings of simulation parameters are similar to the plate TBL in the compression ramp of Dang et al (2022) and Duan et al (2021). Figure 1(a-c) are given to show the instantaneous streamwise velocity, temperature and density fields.…”

Section: Simulation Parametersmentioning

confidence: 99%

Investigations on the turbulentnon-turbulent interface in supersonic compressible plate turbulent boundary layer

Su,

Long,

Wang

et al. 2024

J. Fluid Mech.

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The turbulent boundary layer (TBL) is a widely existing flow phenomenon in nature and engineering applications. Its strong mixing effect can achieve more sufficient material mixing, heat transport, etc. The understanding of the entrainment process and mechanism of irrotational fluids entering the turbulent region can be promoted by studying the geometric and dynamic characteristics of turbulent ${/}$ non-turbulent interfaces (TNTI). In compressible flow, it is unclear whether the properties of TNTI will change and whether the entrainment will show different features due to the influence of compressibility. Based on the direct numerical simulation results of supersonic compressible plate TBLs with Mach number of 2.9, the geometric and dynamic characteristics of TNTI are investigated in this paper. The interface is identified by the enstrophy method, and the height, thickness, fractal dimension, enstrophy transportation and entrainment characteristics of the interface are investigated. It is found that for the enstrophy transportation in a TBL, the contribution of compressibility-related terms accounts for approximately 13.4 % of the total enstrophy transportation, which tends to transfer the enstrophy of turbulence near the interface to both directions vertical to the interface. This promotes the expansion of the turbulent region towards the non-turbulent region, and the mean height, thickness and entrainment velocity are increased by approximately 3.7 %, 7.0 % and 8.5 %, respectively, while the fractal dimension is basically unaffected. Different from the incompressible flow, the contribution of the compressibility-related terms to the entrainment velocity is independent of the local curvature, and the intense entrainment process is more likely to occur on a highly curved concave surface.

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Direct numerical simulation of a supersonic turbulent boundary layer over a compression–decompression corner

Cited by 27 publications

References 43 publications

Flow instabilities and impact of ramp–isolator junction on shock–boundary-layer interactions in a supersonic intake

Flow instabilities and impact of ramp–isolator junction on shock–boundary-layer interactions in a supersonic intake

Wall skin friction analysis in a hypersonic turbulent boundary layer over a compression ramp

Investigations on the turbulentnon-turbulent interface in supersonic compressible plate turbulent boundary layer

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