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Liu Y.,Dalian Maritime University | Liu X.,Harbin Power System Engineering and Research Institute | Li G.,Dalian Jiaotong University | Zhou L.,Tsinghua University
Advanced Powder Technology | Year: 2012

On the basis of the gas-particle Euler-Euler two-fluid approach, a new particle-particle Reynolds stress transportation model is proposed for closing the constitution equations of particle-laden-mixtures turbulent flows. In this model, binary particle-particle interaction originating from large-scale particle turbulent diffusions are fully considered in view of an extension closure idea of second-order-moment disperse gas-particle turbulent flows. The binary-particles turbulent flows with different density and same diameter are numerically simulated. The number density, the time-averaged velocity, the fluctuation velocity, the multiphase fluctuation velocity correlations, the normal and the shear Reynolds stress are obtained. Simulated results are in good agreement with experimental data. Binary mixture system has a unique transportation behavior with a stronger anisotropy due to particle inertia and multiphase turbulence diffusions. Fluctuation velocity correlation of axial-axial gas-particle is about twice larger than those of axial-axial particle-particle interaction. Moreover, both normal and shear Reynolds stress are redistributed. © 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.


Liu Y.,Dalian Maritime University | Liu P.,Dalian Maritime University | Jiang F.,Dalian Maritime University | Liu X.,Harbin Power System Engineering and Research Institute | Zhou L.,Tsinghua University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

To analyze the hydrodynamics of binary-particles gas-particle swirling flows, a binary-particles multi-unified second-order moment (MUSM) Reynolds stress equation was developed on the basis of single second-order-moment (USM) turbulence model. In this model, particle-particle and gas-particle two-phase fluctuation velocity correlation transportation were presented and their anisotropic characters were fully taken into account. Swirling gas-particle flow experiments data (Sommerfeld et al. 1992) were used to validate the model using reducing model and code of the mono-disperse particle gas-particle flows. Numerical simulations were performed for the gas-binary particles mixtures turbulent flows. Simulated results of the binary-particles with the different density and the same diameter are in good agreement with experimental data. Binary mixture system has a unique transportation behavior with a stronger anisotropy due to particle inertia and multiphase turbulence diffusions. Fluctuation velocity correlation of axial-axial gas-particle is about twice larger than those of axial-axial particle-particle interaction. Moreover, both normal and shear Reynolds stress are both redistributed. © 2012 Chinese Society for Electrical Engineering.


Liu Y.,Dalian Maritime University | Liu Y.,VTT Technical Research Center of Finland | Liu X.,Harbin Power System Engineering and Research Institute | Kallio S.,VTT Technical Research Center of Finland | Zhou L.,Tsinghua University
Advanced Powder Technology | Year: 2011

Based on the Eulerian-Eulerian two-fluid continuum approach, an improved unified second-order-moment two-phase turbulence model combining with the kinetic theory of particle collision frictional stress model is developed to simulate the dense gas-particle flows in downer, where the effective coefficient of restitution is incorporated into the particle-particle collision. The interaction term between gas and particle turbulence is fully taken into account by the transport equation of two-phase stress correlation. Hydrodynamics of high density particle flow, measured by Wang et al. [27] are predicted and the simulated results are in good agreement with experimental data. On the conditions of considering the realistic energy dissipation due to frictional stress, particle concentration and particle axial averaged velocity are closely the measured and they are better than without frictional stress model. Furthermore, the particle Reynolds stress is redistributed and the particle temperature is reduced. Effect of frictional stress leads to increase obviously the collision frequency at the outlet and inlet regions and the magnitude of frequency of particle collisions is 102. © 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.


Liu Y.,Dalian Maritime University | Liu X.,Harbin Power System Engineering and Research Institute | Li G.,Dalian Jiaotong University | Jiang L.,Beijing Institute of Spacecraft Environment Engineering
Energy Conversion and Management | Year: 2011

In this paper, a unified-second-order-moment two-phase turbulent model incorporating into the kinetic theory of granular flows for considering particle-particle collision (USM-θ) is proposed to study the turbulent gas-particle flows in swirl chamber. Anisotropy of gas-solid two-phase stress and the interaction between two-phase stresses are fully considered by constructing a two-phase Reynolds stress model and a transport equation of two-phase stress correlation. Sommerfeld et al. (1991) experimental data is used to quantitatively validate USM-θ and USM model for analysis the effects of particle-particle collision. Numerical predicted results show that time-averaged velocity and fluctuation velocity of gas and particle using particle temperature model are better than those of without particle temperature model. Maximum particle concentration and temperature located at thin shear layer adjacent to wall surface due to particle inertia. Small-scale particle fluctuation due to particle-particle collision is smaller than large-scale gas-particle turbulence fluctuation. Particle-particle collision leads to the redistribution dissipation of Reynolds stress and particle turbulence kinetic energy. © 2010 Elsevier Ltd. All rights reserved.


Li G.,Dalian Jiaotong University | Liu X.,Harbin Power System Engineering and Research Institute | Li T.,Beijing Institute of Spacecraft Environment Engineering
Composites Part B: Engineering | Year: 2013

Precise prediction on atomic oxygen undercutting by numerical simulation technique plays an importance role for long lifetime spacecraft design. A Monte Carlo mathematical model is presented to predict the undercutting process interaction between atomic oxygen and polyimide films of spacecraft in low earth orbital degree. In the meantime, the physical undercutting processes is described by tracing transportation particle approach on the basis of statistics. Simulated results showed that undercutting profiles with breaker patterns are in good agreement with flight experimental data for 43° and 28.5° orbit angle, as well as complicated effect factors are discussed in detail. Larger atomic oxygen fluence is favorable for producing more depth and width undercutting profiles and maximum depth is always larger than maximum width. Mass loss increased with the initial impact reaction probability increasing and decreased with the thermal assimilation coefficient going down. Especially for bigger orbit angle, the difference between depth and width are reduced due to the decrement of depth and the increment of width. © 2012 Published by Elsevier Ltd.


Yang W.,Nanjing University of Aeronautics and Astronautics | Liu X.,Harbin Power System Engineering and Research Institute | Li G.,Dalian Jiaotong University | Zhang J.,Nanjing University of Aeronautics and Astronautics
International Journal of Thermal Sciences | Year: 2012

Experimental investigations on the film cooling characteristics of parallel-inlet film holes are carried out. There are four kinds of film hole arrangements: one-row, two-row(staggered arrangement), two-row(aligned arrangement) and three-row arrangement. Experimental results show that film hole arrangement and blowing ratios have great effects on film cooling effectiveness and heat transfer coefficient(HTC). Film cooling effectiveness is increased with the increase of blowing ratios, but the HTC is decreased with the increment of blowing ratio. The film cooling effectiveness of single-row film hole(d = 7 mm) is the best of all test pieces. As for staggered arrangement design, its HTC is larger than that of aligned arrangement at the same position. In addition, the HTC is increased with the decrement diameter of film hole for all kinds of film hole arrangement patterns. For film cooling, a smaller HTC means a better film cooling effectiveness. © 2012 Elsevier Masson SAS. All rights reserved.


Li G.,Dalian Jiaotong University | Liu X.,Harbin Power System Engineering and Research Institute
Acta Astronautica | Year: 2010

A new multi-local linear model based on the TkakgiSugeno approach is presented to carry out controlling of a nonlinear unsteady system and to make a design of inverted pendulum fuzzy controller. Nonlinear multi-variance behaviors are transformed to a multi-local linear model using a fuzzy approximation method, which is used to implement control steadily and rapidly for the global system. Detailed investigations on dynamic behaviors of inverted pendulum under reduced-gravity space environments are performed using Simulink simulations. Results showed that stabilization of an inverted pendulum is greatly affected by reduced-gravity conditions and effects of θ angle variation are the largest. When θ is greater than 1.571 rad threshold value, balances will be lost under earth, lunar and microgravity conditions. Furthermore, microgravity is favorable for keeping balance status. An appropriate compensation controlling provided by the presented fuzzy controller can keep a better balance for inverted pendulum. © 2010 Elsevier Ltd. All rights reserved.


Liu Y.,Dalian Maritime University | Liu X.,Harbin Power System Engineering and Research Institute | Li G.,Dalian Jiaotong University | Li T.,Beijing Institute of Spacecraft Environment Engineering
Applied Surface Science | Year: 2010

Atomic oxygen undercutting effect of the protective polymer film in low earth orbit space environment is a potential threat to vulnerable long duration exposure facility. A Monte Carlo computational model is developed to simulate the interactions between atomic oxygen undercutting course with polyimide film. Physical process of the atomic oxygen undercutting, the definition of parameters, the affected by atomic oxygen fluence, orbit angle, protection coating thickness and thermal assimilation and the additive anti-undercutting components as well as a new three-dimensional reaction probability are discussed in detail. Simulated results are in good agreement with flight experimental data. With the increment of the atomic oxygen fluence, all the undercutting profiles, the depth and the width increased. Maximum undercutting depth is always larger than maximum undercutting width and the larger thermal assimilation coefficient causes the smaller undercutting damage. Using three-dimensional reaction probability, maximum depth decreased by approximately 20% than that of 28.5° orbit angle. © 2010 Elsevier B.V. All rights reserved.


Yang W.,Nanjing University of Aeronautics and Astronautics | Li X.,Dalian University of Technology | Liu X.,Harbin Power System Engineering and Research Institute
Journal of Mechanical Science and Technology | Year: 2013

An experiment was designed at the curving section of a combustion chamber to study the effects of cooling effectiveness on impingement-reversed convection film cooling with and without pin fins. Numerical simulations were also carried out. The effectiveness of compound cooling increased with the rise in blowing ratio. With regard to the effect of the pin fins, impingement pin fin-reversed convectionfilm cooling was more effective than the method without pin fins, particularly for smaller blowing ratio conditions. The number and arrangement of fin pin rows had a small effect on cooling efficiency under the same blowing ratio value. Simulation results agreed well with experimental data and could be used to optimize basic design. © 2013 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.


Pan X.,Dalian Maritime University | Liu X.,Harbin Power System Engineering and Research Institute | Li G.,Dalian Jiaotong University | Li T.,Beijing Institute of Spacecraft Environment Engineering
Acta Astronautica | Year: 2011

A unified second-order-moment gasparticle two-phase turbulent model incorporated with kinetic theory of granular flows (USM-θ) is developed to study the particle dispersion behavior of dense gasparticle flows in horizontal channel with 6.96 μm wall roughness and with earth, lunar and microgravity environments, respectively. Anisotropy of gas and particle two-phase stresses and the interaction between two-phase stresses are fully considered by constructing two-phase Reynolds stress model and the transport equation of two-phase stress correlation. The flow behavior of particles in a horizontal channel of Kussin and Sommerfeld [12] experiments is numerically simulated. Results show that the reduced gravity conditions affect the particle concentration distribution, particle velocity and fluctuation velocity, particle temperature, axialaxial fluctuation velocity correlation of gas and particle and particle collision frequency. Under microgravity conditions, particle temperature and collision frequency are much less than those of earth and lunar gravity. Compared with earth gravity, anisotropic of two-phase flow and sedimentation are weaker. © 2010 Elsevier Ltd. All rights reserved.

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