Wall temperature and bluntness effects on hypersonic laminar separation at a compression corner

Exposito, D.; Gai, S. L.; Neely, Andrew J.

doi:10.1017/jfm.2021.474

Cited by 9 publications

(12 citation statements)

References 69 publications

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“…This has been discussed in an earlier study (Exposito et al. 2021). Unfortunately, the numerical scheme adopted by Cassel et al.…”

Section: Resultssupporting

confidence: 57%

“…Another problem that has attracted the particular attention of researchers in recent years is the occurrence of wave-packets in the solutions of unsteady triple-deck equations at moderate scale angles in supersonic and hypersonic flows. Such an instability feature was first noted and discussed by Cassel, Ruban & Walker (1995) and subsequently explored by Fletcher, Ruban & Walker (2004), Logue, Gajjar & Ruban (2014) and also Exposito, Gai & Neely (2021). Despite these investigations, the precise nature of the breakdown in the solutions of unsteady triple-deck equations, whether they are physical or numerical, still remains unclear.…”

Section: Introductionmentioning

confidence: 84%

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A note on the appearance of wave-packets in steady-state triple-deck solutions of supersonic flow past a compression corner

2022

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This study is an attempt at solving steady-state triple-deck equations using the method of Bos & Ruban (Phil. Trans. R. Soc. Lond. A, vol. 358, issue 1777, 2000, pp. 3063–3073) for supersonic flow past a compression corner. This was motivated by the fact that in their above paper, they show solutions for scale angles up to 8, the highest obtained so far in the literature. However, we encountered a stationary wave-packet at the corner for scale angles 1.82 and 1.96, depending on the values of stretching factors. Our solutions are then compared with the steady-state solutions produced using the method of Logue, Gajjar & Ruban (Phil. Trans. R. Soc. A, vol. 372, issue 2020, 2014, 20130342), which do not show such wave-packets. These wave-packets do not appear to be the result of flow instability, as flow instabilities should only appear with unsteady equations (Cassel, Ruban & Walker, J. Fluid Mech., vol. 300, 1995, pp. 265–285). It is therefore suggested that the method of Bos & Ruban (Phil. Trans. R. Soc. Lond. A, vol. 358, issue 1777, 2000, pp. 3063–3073) produces these spurious wave-packets as a consequence of their numerical method. This has important implications in the interpretation of triple-deck solutions.

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“…This has been discussed in an earlier study (Exposito et al. 2021). Unfortunately, the numerical scheme adopted by Cassel et al.…”

Section: Resultssupporting

confidence: 57%

Section: Introductionmentioning

confidence: 84%

A note on the appearance of wave-packets in steady-state triple-deck solutions of supersonic flow past a compression corner

2022

Self Cite

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“…2004) or more recently to a numerical instability of the discretised problem by Exposito et al. (2021). A necessary condition for the instability described by (1.1) is that the flow is inflectional, and Cassel et al.…”

Section: Discussionmentioning

confidence: 99%

“…More recently, Exposito, Gai & Neely (2021) employed the method of Cassel et al. (1995) to look at the influence of the precise choice of ramp shape.…”

Section: Introductionmentioning

confidence: 99%

High-frequency instabilities in supersonic compression-ramp flow

2023

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We consider high Reynolds number supersonic flow over a compression ramp in the triple-deck formulation. Previous studies of compression-ramp stability have shown rapid growth of high-frequency disturbances in initial-value computations; however, no physical or numerical origin has yet been identified robustly. By considering linear perturbations to steady compression-ramp solutions, we show that instabilities observed in previous studies do not have a growth rate that is described by the integral eigenrelation of Tutty & Cowley (J. Fluid Mech., vol. 168, 1986, pp. 431–456) for a (long-wave) Rayleigh instability. We solve both the temporal and spatial instability problems in the limit of asymptotically large wavenumber $K$ (or equivalently frequency) and show that the growth rate of the instability remains $o(K)$ , being dominated by higher-order terms in the expansion at moderate ramp angles.

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“…2014; Pasquariello, Hickel & Adams 2017; Lusher & Sandham 2020), over-expanded nozzles (Martelli et al. 2017), compression ramps (Adams 2000; Ganapathisubramani, Clemens & Dolling 2007; Wu & Martin 2008; Priebe & Martin 2012; Exposito, Gai & Neely 2021; Helm, Martin & Williams 2021) and transonic normal shock waves (Pirozzoli, Bernardini & Grasso 2010; Burton & Babinsky 2012; Sartor et al. 2015; Karnick & Venkatraman 2017).…”

Section: Introductionmentioning

confidence: 99%

On wall pressure fluctuations in conical shock wave/turbulent boundary layer interaction

2023

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The structure and the frequency spectra of wall pressure fluctuations beneath a planar turbulent boundary layer interacting with a conical shock wave at Mach number $M_\infty =2.05$ and Reynolds number $\textit {Re}_\theta \approx 630$ (based on the upstream boundary layer momentum thickness) are examined to elucidate the effects of pressure gradient and flow separation on the characteristics of the wall pressure fluctuations, by exploiting a direct numerical simulation database. Upstream of the interaction, in the zero pressure gradient region, wall pressure statistics compare well with canonical compressible boundary layers in terms of fluctuation intensities and frequency spectra. Across the main interaction zone (APG1), the root-mean-square of wall pressure fluctuations becomes very large (corresponding to approximately 173.3 dB), with maximum increase approximately 12.7 dB from the incoming level. In the second adverse pressure gradient zone (APG2), the root-mean-square of wall pressure fluctuations attains a second peak (corresponding to $164.7$ dB), with an increase of 8.4 dB from the upstream level. Both the APG1 and APG2 regions feature a substantial fraction of flow reversal events, which are, however, scattered and interspersed with regions of attached flow. The wall pressure power spectral density exhibits a broadband and energetic low-frequency component associated with the global unsteadiness of the separation bubble/conical shock system. Analysis of the two-point correlations and wavenumber/frequency spectra of wall pressure fluctuations further suggests that the typical eddies become more elongated along the spanwise direction, as the flow in the separated region tends to escape the centreline, and the convection velocity is significantly reduced.

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Wall temperature and bluntness effects on hypersonic laminar separation at a compression corner

Abstract: Abstract

Cited by 9 publications

References 69 publications

A note on the appearance of wave-packets in steady-state triple-deck solutions of supersonic flow past a compression corner

A note on the appearance of wave-packets in steady-state triple-deck solutions of supersonic flow past a compression corner

High-frequency instabilities in supersonic compression-ramp flow

On wall pressure fluctuations in conical shock wave/turbulent boundary layer interaction

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