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Direct numerical simulation of impinging shock wave and turbulent boundary layer interaction over a wavy-wall

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Chinese Journal of Aeronautics 2021年第5期34卷 350-363页

作者： Fulin TONG Dong SUN xinliang li LHD Institute of MechanicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianvang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMicmyang 621000China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

The interaction of an impinging oblique shock wave with an angle of 30°and a supersonic turbulent boundary layer at Ma_(∞)=2.9 and Re_(θ)=2400 over a wavy-wall is investigated through direct numerical simulation and compared with the interaction on a flat-plate under the same flow conditions.A sinusoidal wave with amplitude to wavelength ratio of 0.26 moves in the streamwise direction and is uniformly distributed across the spanwise *** influences of the wavy-wall on the interaction,including the characterization of the flow field,the skin-friction,pressure and the budget of turbulence kinetic energy,are systematically *** region of separation grows slightly and decomposes into four *** peaks of skin-friction are observed at the rear part of the interaction *** low-frequency shock motion can be seen in the wall pressure *** of the turbulence kinetic energy budget indicate that both diffusion and transport significantly increase near the crests,balanced by an amplified dissipation in the near-wall *** orthogonal decomposition analyses show that the most energetic structures are associated with the separated shock and the shear layer over the *** the bubbles in the first two troughs are dominated by a low-frequency enlargement or shrinkage.

关键词： Direct numerical simulation Low-frequency unsteadiness Shock waves Turbulent boundary layer Wavy-wall

Characteristics of reattached boundary layer in shock wave and turbulent boundary layer interaction

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Chinese Journal of Aeronautics 2022年第6期35卷 172-185页

作者： Fulin TONG Junyi DUAN xinliang li State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China LHD Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

The reattached boundary layer in the interaction of an oblique shock wave with a flatplate turbulent boundary layer at Mach number 2.25 is studied by means of Direct Numerical Simulation(DNS).The numerical results are carefully compared with available experimental and DNS data in terms of turbulence statistics,wall pressure and skin *** coherent vortex structures are significantly enhanced due to the shock interaction,and the reattached boundary layer is characterized by large-scale structures in the outer *** space-time correlation of fluctuating wall shear stress and streamwise velocity fluctuation reveals that the structural inclination angle exhibits a gradual decrease during the recovery *** scale interactions are analyzed by using a twopoint amplitude modulation correlation.A possible mechanism is proposed to account for the strong amplitude modulation in the downstream ***,the mean skin-friction is decomposed to understand the physically informed *** the upstream Turbulent Boundary Layer(TBL),the contribution associated with the Turbulence Kinetic Energy(TKE)production is greatly amplified,while the spatial growth contribution induced by the pressure gradient largely inhibits skin-friction *** on bidimensional empirical mode decomposition,the turbulence kinetic energy production contribution is further split into different terms with specific spanwise length scales.

关键词： Amplitude modulation Shock wave Skin friction decomposition Structural inclination angle Turbulent boundary layer

Problems of the conventional BL model as applied to super/hypersonic turbulent boundary layers and its improvements

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Science China(Physics,Mechanics & Astronomy) 2011年第10期54卷 1889-1898页

作者： DONG Ming li xinliang Department of Mechanics Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin 300072China Key laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Turbulence modeling has played important roles in solving engineering problems. However, with the development of aero-space technology, turbulence modeling faces new challenges. How to further improve turbulence modeling for su-per/hypersonic flows is an urgent problem. Through analyzing a set of data resulting from DNS and experiments, it is foundthat some most popular models suffer from essential flaws, and can be hardly improved following the traditional mode ofthinking. On the contrary, the BL model, which is one of the simplest and widely-used models, can be further improved. In thispaper, through analyzing results from DNS data, the main cause of the inaccuracy in applying the BL model to supersonic andhypersonic turbulent boundary layers is found to have resulted from the mismatch between the location of the matching pointof the inner and outer layers of the BL model determined by the conventional way and those given by DNS. Improvement onthis point, as well as other improvements is proposed. Its effectiveness is verified through the comparison with DNS results.

关键词： turbulence modeling supersonic hypersonic turbulent boundary layer DNS BL model

DNS of a spatially evolving hypersonic turbulent boundary layer at Mach 8

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Science China(Physics,Mechanics & Astronomy) 2013年第7期56卷 1408-1418页

作者： liANG Xian li xinliang Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of Sciences

This paper reports the direct numerical simulation (DNS) for hypersonic turbulent boundary layer over a flat-plate at Ma∞ =8 with the ratio of wall-to-freestream temperature equal to 1.9, which indicates an extremely cold wall condition. It is primarily used to assess the wall temperature effects on the mean velocity profile, Walz equation, turbulent intensity, strong Reynolds analogy (SRA), and compressibility. The present high Mach number with cold wall condition induces strong compressibility effects. As a result, the Morkovin's hypothesis is not fully valid and so the classical SRA is also not fully consistent. However, some modified SRA is still valid at the far-wall region. It is also verified that the semi-local wall coordinate y* is better than conventional y+ in analysis of statistics features in turbulent boundary layer (TBL) in hypersonic flow.

关键词： DNS compressibility effects turbulent boundary layer

Effects of dimensional wall temperature on velocity-temperature correlations in supersonic turbulent channel flow of thermally perfect gas

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Science China(Physics,Mechanics & Astronomy) 2019年第6期62卷 64-74页

作者： XiaoPing Chen xinliang li ZuChao Zhu Key Laboratory of Fluid Transmission Technology of Zhejiang Province Zhejiang Sci-Tech University Key Laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences

Direct numerical simulations of temporally evolving supersonic turbulent channel flows of thermally perfect gas are conducted at Mach number 3.0 and Reynolds number 4800 for various values of the dimensional wall temperature to study the influence of the latter on the velocity-temperature correlations. The results show that in a fully developed turbulent channel flow, as the dimensional wall temperature increases, there is little change in the mean velocity, but the mean temperature decreases. The mean temperature is found to be a quadratic function of the mean velocity, the curvature of which increases with increasing dimensional wall temperature. The concept of "recovery enthalpy" provides a connection between the mean velocity and the mean temperature, and is independent of dimensional wall temperature. The right tails of probability density function of the streamwise velocity fluctuation grows with increasing dimensional wall temperature. The dimensional wall temperature does not have a significant influence on the Reynolds analogy factor or strong Reynolds analogy(SRA). The modifications of SRA by Huang et al. and Zhang et al. provide reasonably good results, which are better than those of the modifications by Cebeci and Smith and by Rubesin.

关键词： direct numerical simulation velocity-temperature correlation supersonic flow channel flow thermally perfect gas strong Reynolds analogy

Direct numerical simulation of passive scalar in decaying compressible turbulence

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Science China(Physics,Mechanics & Astronomy) 2004年第1期47卷 52-63页

作者： li xinliang FU Dexun MA Yanwen State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

The passive scalars in the decaying compressible turbulence with the initial Reynolds number (defined by Taylor scale and RMS velocity) Re=72, the initial turbulent Mach numbers (defined by RMS velocity and mean sound speed) Mt=0.2—0.9, and the Schmidt numbers of passive scalar Sc=2—10 are numerically simulated by using a 7th order upwind difference scheme and 8th order group velocity control scheme. The computed results are validated with different numerical methods and different mesh sizes. The Batchelor scaling with k -1 range is found in scalar spectra. The passive scalar spectra decay faster with the increasing turbulent Mach number. The extended self-similarity (ESS) is found in the passive scalar of compressible turbulence.

关键词： passive scalar, decaying compressible turbulence, direct numerical simulation.

Decomposition of mean skin friction in incident shock wave/turbulent boundary layer interaction flows at Mach 2.25

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Chinese Journal of Aeronautics 2023年第9期36卷 178-194页

作者： Junyi DUAN Fulin TONG xinliang li Hongwei liU LHD Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China

The evolution characteristics of the mean skin friction beneath the supersonic turbulent boundary layer that interacts with incident shock waves at Mach 2.25 are analyzed using Direct Numerical Simulation(DNS). The separated and attached boundary layers in the interaction region that respectively correspond to 33.2° and 28° incident shock angles are considered. The mean skin friction recovery rate for the separated boundary layer is much gentler and distinctly less than that for the attached case where the skin friction completes its recovery within one boundary layer thickness. The novel mean skin friction decomposition method for compressible flows proposed by the recent research is applied in the interaction region to investigate the internal evolution characteristics quantitatively. The results reveal that the three decomposition components are distinctly unequal between the two cases. The contributions of the turbulent motions at different scales to the associated term are focused on using empirical mode decomposition technology. It indicates that the outer large-scale structures dominate separation and reattachment regions, while contributions from inner small-scale structures are limited. In contrast, contributions from the outer largescale structures are dramatically reduced in the attached case, which results in the outer large-scale and inner small-scale motions being of equal importance.

关键词： Compressible flow Boundary layers Direct numerical simulation Shock waves Skin friction Turbulent flow

Low Infrared Emissivity and Strong Stealth of Ti-Based MXenes

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Research 2022年第4期2022卷 147-153页

作者： xinliang li Minghang li Xin li Xiaomeng Fan Chunyi Zhi Department of Materials Science and Engineering City University of Hong Kong83 Tat Chee AvenueKowloonHong Kong 999077China Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi'an710072China

Advanced scenario-adaptable infrared(IR)stealth materials are crucial for creating localized closed thermal *** emissivity over the broadest possible band is expected,as is superior mechanical ***,we report a series of Ti-based MXenes with naturally low emissivity as ideal IR shielding *** a wavelength ranging from 2.5 to 25μm,Ti_(3)C_(2)T_(X) film delivers an average emissivity of 0.057 with the lowest point of *** a low emissivity coupled with outstanding structural shaping capability is beyond the current *** reflection-dominated mechanism is ***,some intriguing scenarios of IR stealth for wearable electronic devices and skin thermal control are *** finding lights an encouraging path toward next-generation IR shielding by the expanding MXene family.

关键词： wear Infrared Strong

DNS of compressible turbulent boundary layer around a sharp cone

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 699-714页

作者： li xinliang FU DeXun MA YanWen State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100080China

Direct numerical simulation of the turbulent boundary layer over a sharp cone with 20° cone angle (or 10° half-cone angle) is performed by using the mixed seventh- order up-wind biased finite difference scheme and sixth-order central difference scheme. The free stream Mach number is 0.7 and free stream unit Reynolds number is 250000/inch. The characteristics of transition and turbulence of the sharp cone boundary layer are compared with those of the flat plate boundary layer. Statistics of fully developed turbulent flow agree well with the experimental and theoretical data for the turbulent flat-plate boundary layer flow. The near wall streak-like structure is shown and the average space between streaks (normalized by the local wall unit) keeps approximately invariable at different streamwise locations. The turbulent energy equation in the cylindrical coordinate is given and turbulent en-ergy budget is studied. The computed results show that the effect of circumferen-tial curvature on turbulence characteristics is not obvious.

关键词： direct numerical simulation boundary layer transition sharp-cone turbulent kinetic energy budget