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On stability of elastic domain during isothermal solid-solid phase transformationin a tube configuration

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Acta Mechanica Sinica 2012年第3期28卷 683-694页

作者： Liang dong Qing-Ping sun Department of Mechanical Engineering The Hong Kong University of Science and TechnologyClear Water Bay Hong Kong China

Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation （during loading） and vanishing （in unloading） of a high strain （martensite） domain. The two events are accompanied by a rapid stress drop/rise due to the formation/vanishing of do- main fronts. From a thermodynamic point of view, both are instability phenomena that occur once the system reaches its critical state. This paper investigates the stability of a shrink- ing cylindrical domain in a tube configuration during unload- ing. The energetics and thermodynamic driving force of the cylindrical domain are quantified by using an elastic inclu- sion model. It is demonstrated that the two domain fronts ex- hibit strong interaction when they come close to each other, which brings a peak in the total energy and a sign change in the thermodynamic driving force. It is proved that such domain front interaction plays an important role in control- ling the stability of the domain and in the occurrence of stress jumps during domain vanishing. It is also shown that the pro- cess is governed by two nondimensional length scales （the normalized tube length and normalized wall-thickness） and that the length scale dependence of the critical domain length and stress jump for the domain vanishing can be quantified by the elastic inclusion model.

关键词： Cylindrical elastic domain Stability of domain Domain front Critical domain length Stress jump ~ Ther-modynamic driving force

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

Direct numerical simulation of shock wave/boundary layer interaction controlled by steady microjet in a compression ramp

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Chinese Journal of Aeronautics 2024年第10期37卷 83-102页

作者： Ruoye XIAO dong sun Jian YU School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China State Key Laboratory of Aerodynamics Mianyang 621000China

Shock wave/boundary layer interaction in a 24°turning angle of the compression ramp at Mach number 2.9 controlled by steady microjet is investigated using direct numerical *** different jet spacings which are termed as sparse,moderate and dense are considered,and the induced vortex system and shock structures are compared.A moderate jet spacing configuration is found to generate counter-rotating vortex pairs that transport high-momentum fluid towards the vicinity of wall and strengthen the boundary layer to resist separation,reducing the separation *** dense jet spacing configuration creates a larger momentum deficit region,reducing the friction downstream of the *** of pressure and pressure gradient reveals that dense jet spacing configuration reduces the intensity of separation *** impact of varying jet spacings on the turbulent kinetic energy transport mechanism is also investigated by decomposing the budget terms in the transport ***,the spectral characteristics of the separation region are studied using power spectral density and dynamic mode decomposition methods,revealing that moderate jet spacing configuration suppresses low-frequency fluctuations in the separation region.

关键词： Shock wave/boundary layer interaction Compression ramp Steady microjet Different jet spacings Direct numerical simulation

STRESS HYSTERESIS AND DOMAIN EVOLUTION IN THERMOELASTIC TENSION STRIPS

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Acta Mechanica Solida Sinica 2009年第5期22卷 399-406页

作者： Liang dong Qingping sun Department of Mechanical Engineering The Hong Kong University of Science and Technology Hong Kong China

Martensite domain formation, evolution and annihilation are widely observed in stress-induced phase transformation of superelastic NiTi polycrystalline shape memory alloys. By the calculation of the thermodynamic driving force and the incorporation of friction kinetics of the interface, the domain morphology and its evolution were successfully simulated by the interface-tracking technique. The computational results agree well with the experimental observation of tensile strips. Based on theoretical and computational results, we discussed the effects of critical driving force and the existence of metastability on the transition between different domain patterns.

关键词： non-convex free energy friction kinetics hysteresis metastability interface-tracking technique domain evolution

Experimental Study on the Inlet Fogging System Using Two-Fluid Nozzles

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Journal of Thermal Science 2010年第2期19卷 132-135页

作者： Abhilash Suryan dong sun Kim Heuy dong Kim School of Mechanical Engineering Andong National University FMTRC Daejoo Machinery Co.

Large-capacity compressors in industrial plants and the compressors in gas turbine engines consume a considerable amount of power. The compression work is a strong fimction of the ambient air temperature. This increase in compression work presents a significant problem to utilities, generators and power producers when electric demands are high during the hot months. In many petrochemical process industries and gas turbine engines, the in- crease in compression work curtails plant output, demanding more electric power to drive the system. One way to counter this problem is to directly cool the inlet air. Inlet fogging is a popular means of cooling the inlet air to air compressors. In the present study, experiments have been performed to investigate the suitability of two-fluid nozzle for inlet fogging. Compressed air is used as the driving working gas for two-fluid nozzle and water at am- bient conditions is dragged into the high-speed air jet, thus enabling the entrained water to be atomized in a very short distance from the exit of the two-fluid nozzle. The air supply pressure is varied between 2.0 and 5.0 bar and the water flow rate entrained is measured. The flow visualization and temperature and relative humidity measurements are carried out to specify the fogging characteristics of the two-fluid nozzle.

关键词： Evaporative Cooling Inlet Fogging Energy Savings Two-fluid Nozzles

Modeling and state of charge estimation of lithium-ion battery

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Advances in Manufacturing 2015年第3期3卷 202-211页

作者： Xi-Kun Chen dong sun School of Mechatronics Engineering and Automation Shanghai University

Modeling and state of charge （SOC） estimation of lithium-ion （Li-ion） battery are the key techniques of battery pack management system （BMS） and critical to its reliability and safety operation. An auto-regressive with exogenous input （ARX） model is derived from RC equivalent circuit model （ECM） due to the discrete-time characteristics of BMS. For the time-varying environmental factors and the actual battery operating conditions, a variable forgetting factor recursive least square （VFFRLS） algorithm is adopted as an adaptive parameter identifica- tion method. Based on the designed model, an SOC estimator using cubature Kalman filter （CKF） algorithm is then employed to improve estimation performance and guarantee numerical stability in the computational procedure. In the battery tests, experimental results show that CKF SOC estimator has a more accuracy estimation than extended Kalman filter （EKF） algorithm, which is widely used for Li-ion battery SOC estimation, and the maximum estimation error is about 2.3%.

关键词： Lithium-ion (Li-ion) battery Variable forgetting factor recursive least square (VFFRLS) Cubature Kalman filter (CKF) Extended Kalman filter (EKF)

ρ meson impact parameter distributions

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Chinese Physics C 2018年第6期42卷 37-43页

作者： Bao-dong sun Yu-Bing dong Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China School of Physics University of Chinese Academy of Sciences Beijing 100049 China Theoretical Physics Center for Science Facilities （TPCSF） CAS Beijing 100049 China

In this paper, the p meson impact parameter dependent parton distributions and the impact parameter dependent form factors are introduced and discussed. By employing a Gaussian form wave packet, we calculate the impac... 详细信息

关键词： ρ meson impact parameter distribution light-cone approach

Equation of state of initially liquid carbon monoxide and nitrogen mixture

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 599-606页

作者： YANG JinWen sun dong sun Yue SHI ShangChun Institute of Atomic and Molecular Physics Sichuan UniversityChengdu 610065China Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid PhysicsChinese Academy of Engineering PhysicsMianyang 621900China

The modified liquid perturbation variational theory and the improved vdW-1f model were applied to calculating the equation of the state of liquid CO-N2 mixture with the ratio of 1:1, 4:1 and 1:4, respectively, in the shock pressure range of 9-49 GPa. It was shown that the calculated result for CO-N2 mixture with the ratio of 1:1 is well consistent with the earlier experimental data. The thermodynamics equilibrium, chemical equilibrium and phase equilibrium were all considered in detail. It was found that Hugoniot of liquid CO-N2 mixture is moderately softened in the pressure range of 20-30 GPa and 30-49 GPa for different initial proportions, and that the Hugoniot is more softened in the latter pressure range, which means that the structural phase transition occurs near 20 GPa and 30 GPa. Since the shock pro-ductions may absorb a plenty of systematic energy, the shock temperature and pressure decline compared with the case of no chemical reaction. Pressures and temperatures increase gradually with the increase in the mole fraction of nitrogen composition. The results for the 1:1 CO-N2 mixture lie in the middle of two others. Therefore, it was shown that the modified Lorentz-Berthelor rule used in the scheme is effective to study shock-compression properties of liquid CO-N2 mixture under high temperatures and high pressures.

关键词： liquid mixtures carbon monoxide nitrogen equation of state liquid variational perturbation theory vdW-1f model

Detached-eddy simulations and analyses on new vortical flows over a 76/40° double delta wing

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Science China(Physics,Mechanics & Astronomy) 2013年第6期56卷 1062-1073页

作者： LI Qin sun dong ZHANG HanXin State Key Laboratory of Aerodynamics China and National Laboratory of CFD Beijing University of Aeronautics and Astronautics

Numerical simulations were performed on the massively separated flows of a 76/40° double delta wing using detached-eddy simulation(DES).A new type of cross-flow vortex is suggested.A vortex was initially generated near the junction of the strake and wing,which then moved towards the wing tip at certain wavelength and *** were made in detail on the mechanism of the generation of the cross-flow vortex,that is,the inviscid cross-flow instability which differs from that of the swept blunt ***-section topology of the cross-flow vortex is also investigated,and the wavelength of the vortex array and the characteristic frequency are *** analyses showed that the cross-flow vortices have an influence on the pressure distribution,which can cause a 10%-20% deviation from the averaged distribution.

关键词： double delta wing massively separated flows cross-flow instability vortex substructures DES