Experimental study of second-mode wave on a flared cone at Mach 6

Liu, Xiaolin; Yi, Shihe; Xu, Xiwang; Shi, Yang; Ouyang, Tianci; Xiong, Haoxi

doi:10.1063/1.5103192

Cited by 32 publications

(5 citation statements)

References 14 publications

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“…Hot streaks, such as those visualized in the BAM6QT, were also detected, as shown in őgure 15 [185]. Liu et al [173] used the hypersonic quiet wind tunnel at the National University of Defense Technology [191] to investigate the nonlinear evolution of the second Mack mode on a ŕared cone and reported the existence of high-frequency harmonics.…”

Section: Flows Over Flared Conesmentioning

confidence: 92%

Görtler Instability and Transition in Compressible Flows

Xu,

Ricco,

Duan

2024

AIAA Journal

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We present a discussion on theoretical, experimental, and computational research studies on Görtler instability and the related transition to turbulence occurring in compressible boundary layers over concave surfaces. We first examine the theoretical results on primary and secondary instabilities, emphasizing the role of receptivity, the mechanism by which external agents, such as freestream fluctuations or wall roughness, act on a boundary layer to trigger Görtler vortices. We review experimental findings obtained from measurements in supersonic and hypersonic wind tunnels and discuss studies employing numerical methods, focusing on the direct numerical simulation approach. The research in these two last sections is surveyed according to the geometrical configuration, from simple concave walls to more complex surfaces of hypersonic vehicles. The experimental investigations have been successful in the visualizations of Görtler vortices, in the measurement of the wall-heat transfer in the transitional region, and in the computation of the Görtler-vortex growth rates, although detailed boundary-layer velocity measurements are still missing. Direct numerical simulations have confirmed instability results emerging from stability theories and revealed nonlinear interactions between Görtler vortices and other disturbances. The established initial-boundary-value receptivity theory can certainly benefit from more advanced experimental measurements, and receptivity results should be used in combination with direct numerical simulations. A major conclusion of our review is therefore that the understanding of Görtler vortices should be pursued by a combined methodology including theoretical analysis based on the receptivity formalism, direct numerical simulation, and experiments. Highly desirable outcomes of such endeavor are the prediction of the location and extension of the transition region, and a model for the transition process. We finally highlight further prospects and challenges on fundamental and applied research on Görtler instability and transition in compressible flows.

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Section: Flows Over Flared Conesmentioning

confidence: 92%

Görtler Instability and Transition in Compressible Flows

Xu,

Ricco,

Duan

2024

AIAA Journal

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“…which provides a measure of the quadratic interaction exhibited by the given triad of waves at frequencies of f 1 , f 2 and f 3 that satisfy the resonance wave matching requirement Hajj et al, 1997;Liu et al, 2019b). And a nonzero bispectrum value means that phase coupling may occur between f 1 , f 2 and f 3 .…”

Section: Spectral Methodsmentioning

confidence: 99%

“…The interaction between these frequencies of fluctuations, leading to a breakdown of the structure into smaller scales (Helland et al, 1985;Liu et al, 2019b;Zhu et al, 2020). Therefore, Figs.…”

Section: Bispectrummentioning

confidence: 97%

Evolution of turbulent kinetic energy during the entire sandstorm process

Liu

Shi

Zheng

2021

Preprint

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Abstract. An adaptive segmented stationary method for non-stationary signal is proposed to reveal the turbulent kinetic energy evolution during the entire sandstorm process observed at the Qingtu Lake Observation Array. Sandstorm which is a common natural disaster is mechanically characterized by a particle-laden two-phase flow experiencing wall turbulence, with an extremely high Reynolds number and significant turbulent kinetic energy. Turbulence energy transfer is important to the understanding of sandstorm dynamics. This study indicates that large-/very-large-scale coherent structures originally exist in the rising stage of sandstorms with a streamwise kinetic energy of 75 % rather than gradually forming. In addition to carrying a substantial portion of energy, the very-large-scale-motions are active structures with strong nonlinear energy transfer. These structures gain energy from strong nonlinear interaction. As sandstorm evolves, these large structures are gradually broken by quadratic phase coupling, with the energy fraction reducing to 40 % in the declining stage. The nonlinear process in the steady and declining stages weakens and maintains a balanced budget of energy. The systematic bispectrum results provide a new perspective for further insight of sandstorms.

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“…[3] In hypersonic flows, many experimental and numerical results have confirmed that the second mode is dominant in terms of the transition. [4][5][6][7][8] The surface temperature of a vehicle tends to remain constant over a long flight, but it may still have a certain temperature distribution. The thermal protection systems of such vehicles typically have elements with different heat conductivity and emissivity.…”

Section: Introductionmentioning

confidence: 99%

Effect of local wall temperature on hypersonic boundary layer stability and transition

Huang

2023

Chinese Phys. B

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Wall temperature significantly affects the stability and receptivity of the boundary layer. Changing the wall temperature locally may therefore be an effective laminar flow control technique. However, the situation is complicated when the wall temperature distribution is nonuniform, and previous experiments have found that local wall cooling may delay the onset of transition. In this paper, we attempt to clarify the physical mechanisms whereby the local wall temperature affects the transition and the stability of a hypersonic boundary layer. A numerical investigation of the disturbance evolution in a Mach-6 sharp cone boundary layer with local wall heating or cooling is conducted. Direct numerical simulations (DNS) are performed for the single-frequency and broadband disturbance evolution caused by random forcing. We vary the local wall temperature and the location of heating/cooling, and then use the eN method to estimate the transition onset. Our results show that local wall cooling amplifies high-frequency unstable waves while stabilizing low-frequency unstable waves, with local heating amplifying all unstable waves locally. The disturbance amplitude and second-mode peak frequency obtained by DNS agree well with previous experimental results. Local cooling/heating has a dual effect on the stability of the hypersonic boundary layer. For local cooling, while it effectively inhibits the growth of the low-frequency unstable waves that dominate the transition downstream, it also further destabilizes the downstream flow. In addition, while upstream cooling can delay the transition, excessive cooling may promote it; local heating always slightly promotes the transition. Finally, recommendations are given for practical engineering applications based on our results.

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Experimental study of second-mode wave on a flared cone at Mach 6

Cited by 32 publications

References 14 publications

Görtler Instability and Transition in Compressible Flows

Görtler Instability and Transition in Compressible Flows

Evolution of turbulent kinetic energy during the entire sandstorm process

Effect of local wall temperature on hypersonic boundary layer stability and transition

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