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non-equilibrium turbulent phenomena in the ?ow over a backward-facing ramp

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Applied Mathematics and Mechanics(English Edition) 2019年第2期40卷 215-236页

作者： Le FANG Hongkai ZHAO Weidan NI Jian FANG Lipeng LU Laboratoire de Mecanique Physique (LMP) Ecole Centrale de P'ekinBeihang University National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power Engineering Beihang University Scientific Computing Department Science and Technology Facilities Council (STFC)Daresbury Laboratory

non-equilibrium turbulence phenomena have raised great interests in recent years. Significant efforts have been devoted to non-equilibrium turbulence properties in canonical flows, e.g., grid turbulence, turbulent wakes, and homogeneous isotropic turbulence(HIT). The non-equilibrium turbulence in non-canonical flows, however, has rarely been studied due to the complexity of the flows. In the present contribution, a directnumerical simulation(DNS) database of a turbulent flow is analyzed over a backwardfacing ramp, the flow near the boundary is demonstrated, and the non-equilibrium turbulent properties of the flow in the wake of the ramp are presented by using the characteristic parameters such as the dissipation coefficient C and the skewness of longitudinal velocity gradient Sk, but with opposite underlying turbulent energy transfer properties. The equation of Lagrangian velocity gradient correlation is examined, and the results show that non-equilibrium turbulence is the result of phase de-coherence phenomena, which is not taken into account in the modeling of non-equilibrium turbulence. These findings are expected to inspire deeper investigation of different non-equilibrium turbulence phenomena in different flow conditions and the improvement of turbulence modeling.

关键词： non-equilibrium turbulence backward ramp direct numerical simulation(DNS)

non-equilibrium Plasma Assisted Combustion of Low Heating Value Fuels

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Journal of Thermal Science 2013年第3期22卷 275-281页

作者： Hongbin Hu Quanbin Song Yanji Xu Gang Li Chaoqun Nie Institute of Engineering Thermophysics Chinese Academy of Sciences

This paper describes the effects of non-equilibrium air plasma generated by a dielectric barrier discharge (DBD) on the combustion of low heating value fuels. The experimental results indicate that addition of a very small amount of energy to the air flow in the form of DBD significantly improves the flame stability. Moreover, main combustion characteristics such as flame propagation speed, combustion intensity and lean blow-off limits are also enhanced by the effect of plasma. Some active radicals such as excited O atom and excited N2 molecule are observed by spectrograph in the discharge area. Based on the results of numerical investigation we can conclude that these active radicals generated in discharge area can accelerate the production rate of active OH radical which plays a key role in the oxidation process of low heating value fuel, and thus the whole combustion process is accelerated.

关键词： Low heating value fuels non-equilibrium plasma Combustion stability Active radicals

non-equilibrium ignition criterion for magnetized deuterium–tritium fuel

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Nuclear Science and Techniques 2019年第4期30卷 132-142页

作者： E.Ghorbanpour A.Ghasemizad S.Khoshbinfar Department of Physics Faculty of Science University of Guilan

In this paper, non-equilibrium ignition conditions for magnetized cylindrical deuterium–tritium plasma in the presence of an axial magnetic field have been investigated. It is expected that temperature imbalance between ions and electrons as well as the axial magnetic field will relax the threshold of ignition ***, ignition conditions for this model are derived numerically involving the energy balance equation at the stagnation point. It has been derived using parametric space including electron and ion temperature(T_e, T_i), areal density(q R), and seed magnetic field-dependent free parameters of B/q, mB, and BR. For B/ρ 0.002 g cm^(-2), ρR> 0.25 g cm^(-2), and ρR > 0.02 g cm^(-2),respectively. The practical equilibrium conditions also addressed which is in good agreement with the corresponding one-temperature magnetized mode proposed in previous studies. Moreover, it has been shown that the typical criterion of BR ≥(6.13–4.64) × 10~5 G cm would be expectable. It is also confirmed that the minimum product of areal density times fuel temperature in equilibrium model is located in the range of T = 6–8 keV for all these free parameters, depending on the magnitude of the magnetic field. This is the entry point for the non-equilibrium model consistent with equilibrium model.

关键词： Magnetized plasma Two-temperature model Ion-electron non-equilibrium Axial magnetic field Ignition criteria

non-equilibrium and stochasticity influence the activation process of the yeast DNA damage pathway

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Science China(Physics,Mechanics & Astronomy) 2018年第2期61卷 76-79页

作者： ChenZi Jin XiaoDong Yan FangTing Li School of Physics Center for Quantitative Biology Peking University

Living cells are open systems that exist far away from a state of thermodynamical equilibrium. They utilize the high-grade chemical energy provided by food to produce ATP and re- lease ADP and Pi together with heat dissipation. Living cells exist in a non-equilibrium steady state （NESS）, they replicate themselves and respond to various environmental changes via signal transduction pathways. Because the majority of cells exist at room temperature, the stochasticity of chemical reac- tions in the cells is unavoidable. Recent research into fluores- cent proteins and microscopy techniques have enabled us to observe the dynamic process of mRNA and proteins in single living bacterial cells [1], and these have resulted in new in- sights into regulation mechanisms in molecular biology, i.e., in cellular signal transduction pathways.

关键词： non-equilibrium stochasticity influence DNA damage pathway

Three-dimensional non-equilibrium modeling of a DC multi-cathode arc plasma torch

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Plasma Science and Technology 2021年第7期23卷 98-109页

作者： Zelong ZHANG Cheng WANG Qiang SUN Weidong XIA Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230027People’s Republic of China Anhui Advanced Technology Research Institute of Green Building Hefei 230601People’s Republic of China

In this paper,a three-dimensional non-equilibrium steady arc model is used to investigate the temperature,velocity and electromagnetic field in multi-cathode arc torch,and the formation mechanism of a large-area,uniform and diffused arc plasma is *** numerical simulation results show that a large volume plasma region can be formed in the central region of the generator during *** this process,the maximum electron temperature appears near the cathode and in the central convergence region,while the maximum heavy particle temperature only appears in the central convergence *** phenomenon is consistent with the experimental arc *** the cathode tip,the arc column is in a contraction *** the area slightly away from the cathode,the six arc columns begin to join *** the plasma generator,there is a large-scale current distribution in all directions of X,Y and Z,forming a stable arc plasma with a wide range of *** calculated electron temperature distribution is in good agreement with the measured electron *** results suggest that the largearea diffused arc plasma in the multi-cathode arc torch is the combined effect of current distribution,convection heat transfer and heat conduction.

关键词： temperature uniformity numerical simulation non-equilibrium multiple cathode large-volume arc plasma

Analytical method of nonlinear coupled constitutive relations for rarefied non-equilibrium flows

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Chinese Journal of Aeronautics 2021年第2期34卷 136-153页

作者： Zhiqiang HE Zhongzheng JIANG Huangwei ZHANG Weifang CHEN School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China Department of Mechanical Engineering National University of SingaporeSingapore 117576Singapore

It is well known that Navier-Stokes equations are not valid for those high-Knudsen and high-Mach flows, in which the local thermodynamically non-equilibrium effects are dominant. To extend the non-equilibrium describing the ability of macroscopic equations, nonlinear Coupled Constitutive Relation(NCCR) model was developed from Eu’s generalized hydrodynamic equations to substitute linear Newton’s law of viscosity and Fourier’s law of heat conduction in conservation laws. In the NCCR model, how to solve the decomposed constitutive equations with reasonable computational cost is a key ingredient of this scheme. In this paper, an analytic method is proposed firstly. Compared to the iterative procedure in the conventional NCCR model, the analytic method not only obtains exact roots of the decomposed constitutive polynomials, but also preserves the nonlinear constitutive relations in the original framework of NCCR methods. Numerical tests to assess the efficiency and accuracy of the proposed method are conducted for argon shock structures, Couette flows, two-dimensional hypersonic flows over a cylinder and threedimensional supersonic flows over a three-dimensional sphere. These superior advantages of the current method are expected to render itself a powerful tool for simulating the hypersonic rarefied flows and microscale flows of high Knudsen number for engineering applications.

关键词： Knudsen number Microscale flow non-equilibrium nonlinear constitutive relations Rarefied gas

An Improved Three-Dimensional non-equilibrium Mixing Pool Model

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Chinese Journal of Chemical Engineering 1998年第4期6卷 70-76页

作者：曾爱武余国琮袁希钢天津大学化工研究中心天津

This paper presents an improved three-dimensional non-equilibrium mixing pool *** is a simplified form of the original model and is more practical for *** simulation re-sults show that the industrial scale distillation tray columns can be described closely by the *** effects of model parameters,such as the number of mixing pools,the point efficiencyand flow pattern,on separation are analyzed quantitatively.

关键词： three-dimensional non-equilibrium mixing pool model distillation backflow

Thermochemical non-equilibrium flow characteristics of high Mach number inlet in a wide operation range

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Chinese Journal of Aeronautics 2023年第12期36卷 164-184页

作者： Chunliang DAI Bo SUN Lianjie YUE Shengbing ZHOU Changfei ZHUO Changsheng ZHOU Jianyi YU School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China College of Aerospace Engineering Chongqing UniversityChongqing 400044China Beijing System Design Institute of Electro-mechanic Engineering Beijing 102308China

The high-temperature non-equilibrium effect is a novel and significant issue in the flows over a high Mach number(above Mach 8)air-breathing ***,this study attempts to investigate the high-temperature non-equilibrium flows of a curved compression two-dimensional scramjet inlet at Mach 8 to 12 utilizing the two-dimensional non-equilibrium RANS ***,the thermochemical non-equilibrium gas model can predict the actual high-temperature flows,and the numerical results of the other four thermochemical gas models are only used for comparative ***,the thermochemical non-equilibrium flow fields and work performance of the inlet at Mach 8 to 12 are ***,the influences of high-temperature non-equilibrium effects on the starting characteristics of the inlet are *** results reveal that a large separation bubble caused by the cowl shock/lower wall boundary layer interaction appears upstream of the shoulder,at Mach *** separation zone size is smaller,and its location is closer to the downstream area while the thermal process changes from frozen to non-equilibrium and then to *** the increase of inflow Mach number,the thermochemical non-equilibrium effects in the whole inlet flow field gradually strengthen,so their influences on the overall work performance of the high Mach number inlet are more *** vibrational relaxation or thermal non-equilibrium effects can yield more visible influences on the inlet performance than the chemical non-equilibrium *** inlet in the thermochemical non-equilibrium flow can restart more easily than that in the thermochemical frozen *** work should provide a basis for the design and starting ability prediction of the high Mach number inlet in the wide operation range.

关键词： non-equilibrium Scramjet inlet Starting ability Thermochemical Work performance

Numerical Analysis of MHD Accelerator with non-equilibrium Air Plasma

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Plasma Science and Technology 2012年第12期14卷 1110-1115页

作者： M.ANWARI H.H.QAZI SUKARSAN N.HARADA Electrical Engineering Department Umm Al-Qura University Faculty of Electrical Engineering Universiti Teknologi Malaysia Faculty of Electrical Engineering Universitas Islam "45" Bekasi Department of Electrical Engineering Nagaoka University of Technology

Magnetohydrodynamic （MHD） accelerator is proposed as a next generation propulsion system. It can be used to increase the performance of a propulsion system. The objective of this study is to investigate the performance of MHD accelerator using non-equilibrium air plasma as working gas. In this study, the fundamental performance of MHD accelerator such as flow performance and electrical performance is evaluated at different levels of applied magnetic field using I-D numerical simulation. The numerical simulation is developed based on a set of differential equations with MHD approximation. To solve this set of differential equations the MacCormack scheme is used. A specified channel designed and developed at NASA Marshall Space Flight Centre is used in the numerical simulation. The composition of the simulated air plasma consists of seven species, namely, N2, N, O2, O, NO, NO＋, and e-. The performance of the non-equilibrium MHD accelerator is also compared with the equilibrium MHD accelerator.

关键词： MHD accelerator Faraday type connection non-equilibrium air plasma