Entity

Time filter

Source Type


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. Source


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. Source


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. Source


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. Source


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. Source

Discover hidden collaborations