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Analysis on secondary instability of shear layer based on the concept of phase synchronization

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Theoretical & Applied Mechanics Letters 2014年第6期4卷 31-34页

作者： Wubing Yang Qing Shen Qiang Wang Xiangjiang Yu China Academy of Aerospace Aerodynamics

A concept of phase synchronization point is proposed, and then a model is built using this concept to explain secondary instabilities. This model has been used to determine the conditions of K- and H-type secondary instabilities, which are coincident with the conditions published in literatures. It also can be used to analyze other secondary instability phenomena. For example, the numerical results validate the analysis results in the case of 1/3rd subharmonic mode secondary instability. Furthermore, the numerical results indicate that the spanwise wave number of 3D disturbance has significant effect on the secondary instability.

关键词： shear layer secondary instability 3D disturbance numerical simulation

Transitional wave configurations between Type Ⅲ and Type Ⅳ oblique-shock/bow-shock interactions

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Chinese Journal of Aeronautics 2023年第3期36卷 96-106页

作者： Jun PENG Shuai LI Fan YANG Mingyue LIN Guilai HAN Zongmin HU State Key Laboratory of High-temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China The System Design Institute of Mechanical-Electrical Engineering Beijing 100854China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

The interactions of oblique/bow shock waves are the key flow phenomena restricting the design and aerothermodynamic performance of high-speed *** Ⅲ and Type Ⅳ Shock/Shock Interactions(SSIs)have been extensively investigated,as such interactions can induce abnormal aerodynamic heating problems in hypersonic flows of *** transition process between these two distinct types of shock/shock interactions remains *** the present study,a subclass of shock/shock interaction configuration is revealed and defined as Type Ⅲ*** Ⅲa interaction can induce much more severe aerodynamic heating than a Type Ⅳ interaction which was ever reported to be the most serious in *** intense aerodynamic heating observed in this configuration highlights a new design point for the thermal protection system of hypersonic vehicles.A secondary Mach interaction between shock waves in the supersonic flow path of a Type Ⅲ configuration is demonstrated to be the primary mechanism for such a subclass of shock/shock interaction configuration.

关键词： Shock interactions Transitional configuration Aerodynamic heating shear layer Mach interaction

Simulation of shear layers interaction and unsteady evolution under different double backward-facing steps

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Theoretical & Applied Mechanics Letters 2020年第4期10卷 224-229页

作者： Fang Deng Guilai Han Zonglin Jiang State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100049China School of Engineering Science Chinese Academy of SciencesBeijing 100049China

High-order accurate schemes are employed to numerically simulate the interaction of a supersonic jet and a co-directional supersonic inflow. A double backward-facing step model is proposed to investigate the interaction between the jet shear layer and the supersonic inflow shear layer. It is found that due to the interaction of the shear layer, a secondary jet is injected into the recirculation zone at the intersection of the two shear layers. The secondary jet produced by the interaction of the two shear layers has a periodicity because of shear layers interaction. The distinction in the shape of double backward-facing steps will induce changes in the period of the secondary jet. The analysis and discussion of the periodicity of the secondary jet are mainly focused in this letter.

关键词： shear layer Interaction Unsteady evolution Jet Numerical simulation

Intermittent Bursts in the Boundary Plasma of HT-7

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Plasma Science and Technology 2010年第4期12卷 401-407页

作者：颜宁徐国盛张炜常加峰明廷凤丁斯晔章文扬韩效锋 Institute of Plasma Physics Chinese Academy of Sciences

Intermittent characteristics of turbulence induced by coherent structures （blobs） was clearly observed in the ion saturation current signal, density fluctuation, particle flux and heat flux in HT-7. It is obvious that ion saturation current signal has deviated from Gaussian distribution and the skewness （S） and flatness （K） of signal increase radially outwards in the scrape-off layer （SOL）. Using conditional analysis （CA）, asymmetric character of the intermittent bursts are demonstrated. Owing to the radial propagation of the coherent structures, the particle density profile in SOL is non-exponential and flat outwards from the last close flux surface （LCFS）. It is found around LCFS that the large burst fluctuations （above 2.5 rms） are responsible for about 50% of the total particle transport. Burst events move radially outwards with Ee ~ B velocity, and the blob size can be calculated as 5r ~ V^rc. Our experiment shows that the blob size, life time and drift velocity experienced a pronounced decorrelation in the shear layer. The electrostatic Reynolds stress components become very strong and show a radially steep gradient in the proximity of the shear layer. These experimental findings may imply that the coherent structures are titled by the developed shear flow in the E × B shear layer.

关键词： intermittent bursts coherent structures skewness and flatness blob size drift velocity decorrelation shear layer Reynolds stress

RESEARCH ON THE EFFECT OF PARTICLE OF TWO-DIMENSIONAL shear FLOW

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Applied Mathematics and Mechanics(English Edition) 2000年第8期21卷 855-860页

作者：林建忠石兴余钊圣 Department of Mechanics Zhejiang University Hangzhou P R China Hangzhou Institute of Applied Engineering Hangzhou P R China

The two-way coupling model was adopted to study the! two-dimensional gas-solid mixing layer. The flow was simulated by pseudo-spectral method and particles were traced with Lagrangian method. It is found that the concentration and the Stokes number of the particles have distinct effect on the flow not only accounting for the influence of the flow on the particles, but also the particles' counteraction on the flow. The particles accelerate the dispersion of the vorticity and inhibit the variance of the flow and diminish the intensity of the coherent structure. The lifetime of the vortex is shortened. The pattern of particles' distribution is similar to the results from one-way coupling model.

关键词： gas-solid flow shear layer coherent structures two-way coupling

STUDY ON THE FUEL AIR MIXING INDUCED BY A SHOCK WAVE PROPAGATING INTO A H_2-AIR INTERFACE

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Applied Mathematics and Mechanics(English Edition) 2001年第4期22卷 460-467页

作者：徐胜利岳朋涛韩肇元 Department of Modern Mechanics University of Science and Technology of China Hefei P R China

2nd-order upwind TVD scheme was used to solve the laminar, fully Navier-Stokes equations. The numerical simulations were done on the propagation of a shock wave with Ma(s) = 2 and 4 into a hydrogen and air mixture in a duct and a duct with a rearward step. The results indicate that a swirling vortex: may be generated in the lopsided interface behind the moving shock. Meanwhile, the complex shock system is also formed in this shear flow region. A large swirling vortex is produced and the fuel mixing can be enhanced by a shock wave at low Mach number. But in a duct with a rearward step, the shock almost disappears in hydrogen for Mns = 2. The shack in hydrogen will become strong if Ma(s) is large. Similar to the condition of a shock moving in a duct full of hydrogen and air, a large vortex cart be formed in the shear flow region. The large swirling vortex even gets through the reflected shock and impacts on the lower wall. Then, the distribution of hydrogen behind the rearward step is divided into two regions. The transition from regular reflection to Mach reflection was observed aswell in case Ma(s) = 4.

关键词： shock wave swirling vortex shear layer fuel mixing numerical simulation

Simulation of Heat Transfer Characteristics in Channel with Square Rib Under Uniform and Turbulent Inlet Conditions

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第5期36卷 845-855页

作者： LI Heng YU Ting WANG Duo ZU Yingqing XU Hongyi Department of Aeronautics and Astronautics Fudan University

The detailed flow structures and closely-related heat transfer characteristics are investigated along the wall of a cooling channel with rib tabulator by *** typical Reynolds numbers defined by the rib height are set at 200,500,1300,and the Mach numbers is 0.2,*** inlet boundary conditions,including the uniform and the fully-developed turbulent conditions,are used to study the turbulence effects on the characteristics of heat transfer in the vicinity of rib and *** show that the local Nusselt number increases when the Reynolds number rises from 200 to *** lower Reynolds number,the turbulent inlet condition generates more tangible heat transfer *** higher Reynolds number,however,the uniform inlet condition contributes more to the convective heat transfer *** paper discovers that the high Nusselt number has a consistent correlation with the positive and negative sign alteration of the shear layer on the wall,which satisfactorily explains the mechanisms of heat transfer enhancement due to the flow.

关键词： convective heat transfer turbulent inflow condition rortex method shear layer

Effect of turbulence intensity on airfoil flow:numerical simulations and experimental measurements

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Applied Mathematics and Mechanics(English Edition) 2011年第8期32卷 1029-1038页

作者：李韵武王庶王健平米建春 Department of Mechanics and Aerospace Engineering State Key Laboratory on Turbulence and Complex Systems College of Engineering Peking University

The effect of the turbulence intensity of the oncoming stream on the aerodynamic characteristics of the NACA-0012 airfoil is investigated by a direct numerical simulation. The numerical results are found to be consistent with the experimental measurements. Based on the finite spectral QUICK scheme, the simulation gets the high accuracy results. Both the simulation and the experiment reveal that the airfoil stall does not exist for the low turbulence intensity, however, occurs when the turbulence intensity increases sufficiently. Besides, the turbulence intensity has a significant effect on both the airfoil boundary layer and the separated shear layer.

关键词： finite spectral method turbulence intensity boundary layer shear layer lift force drag force airfoil stall

THE EFFECTS OF TURBULENCE ON THE AERODYNAMIC PROPERTIES OF TWO-DIMENSIONAL RECTANGULAR PRISMS(Ⅱ)——ELASTICALLY SUPPORTED CASE

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Acta Mechanica Sinica 1989年第2期5卷 118-124页

作者： Sun Yawei (Department of Mechanics,Peking University) Department of Mechanics Peking University Beijing China

The effects of turbulence on the aerodynamic properties,especially surface-pressure spectra and vortex-induced vibrations,of two-dimensional rectangular prisms with slenderness ratios of 2 and 4 are investigated *** attention is given to turbulence integral scale ef- fects from the view-point of energy distribution in frequency domain.

关键词： vortex-induced vibration turbulence shear layer Karman vortex