A computational study on the flow behavior of a gas-solid injector by Eulerian approach was carried out. The gas phase was modeled with k-ε turbulent model and the particle phase was modeled with kinetic theory of gr...A computational study on the flow behavior of a gas-solid injector by Eulerian approach was carried out. The gas phase was modeled with k-ε turbulent model and the particle phase was modeled with kinetic theory of granular flow. The simulations by Eulerian two-fluid model （TFM） were compared with the corresponding results by discrete element method （DEM） and experiments. It was showed that TFM simulated results were in reasonable agreement with the experimental and DEM simulated results. Based on TFM simulations, gas-solid flow pattern, gas velocity, particle velocity and the static pressure under different driving jet velocity, backpressure and convergent section angle were obtained. The results showed that the time average axial gas velocity sharply decreased and then slightly increased to a constant value in the horizontal conveying pipe. The time average axial particle velocity increased initially and then decreased, but in the outlet region of the convergent section the particle velocity remarkably increased once more to the maximal value. As a whole, the static pressure distribution change trends were found to be independent on driving gas velocity, backpressure and convergent section angle. However, the static pressure increased with increase of convergent section angle and gas jet velocities. The difference of static pressure to backpressure increased with increasing backpressure.展开更多
Based on the Fliigge shell theory, equations of motion of ring-stiffened thin-walled cylindrical shells conveying fluid are developed with the aid of the Hamilton＇s principle. Analysis is carried out on the vibration...Based on the Fliigge shell theory, equations of motion of ring-stiffened thin-walled cylindrical shells conveying fluid are developed with the aid of the Hamilton＇s principle. Analysis is carried out on the vibration and stability of the ring-stiffened shells conveying fluid, and the effects of fluid velocity, the Young modulus, the size, and the number of the ring stiffeners on the natural frequency and the instability characteristics are examined. It is found that stiffeners can reduce the number of circumferential waves for the fundamental mode, and increase the shell＇s natural frequency, and thus the critical fluid velocity. For the number of longitudinal half waves being equal to one, the natural frequency and the corresponding critical fluid velocity are the largest for the internal-ring stiffened shell and are the smallest for the symmetrical-ring stiffened shell. The natural frequencies and the corresponding critical fluid velocity predicted by the established model increase with the increase in the Young modulus, the size, or the number of the stiffeners.展开更多
A problem of wave propagation in submerged pipe conveying fluid is discussed in this paper. Three different fluid-pipe models are considered: the pipe conveying non-viscous fluid immersed in still fluid, the pipe conv...A problem of wave propagation in submerged pipe conveying fluid is discussed in this paper. Three different fluid-pipe models are considered: the pipe conveying non-viscous fluid immersed in still fluid, the pipe conveying non-viscous fluid considering hydrostatic pressure and the pipe conveying viscous fluid considering hydrostatic pressure. The Fliiggle shell model and the hydrostatic pressure considered as the static prestress are introduced for the description of pipe and external/internal fluids. The effects of steady viscous forces are obtained by using the time-mean Navier-Stokes equations, and the perturbation pressures can be determined by means of potential flow theory. The wave dispersion curves of a submerged pipe conveying fluid are obtained numerically by considering the coupling conditions. The effects of internal fluid velocity and hydrostatic pressure on phase velocity are also discussed.展开更多
基金Supported by the National High Technology Research and Development Program of China （2006AA05A103）, the National Natural Science Foundation of China （50706007）, Foundation of Graduate Creative Program of Jiangsu （CX08B-060Z）, and the Foundation for Excellent Ph.D. Thesis of Southeast University. ACKNOWLEDGEMENTS The authors also expressed sincere gratitude to Professors M. Horio, B. Leckner, A. Kane and E.J. Anthony for constructive advice during their visiting period in Southeast University, which contributed to our research.
文摘A computational study on the flow behavior of a gas-solid injector by Eulerian approach was carried out. The gas phase was modeled with k-ε turbulent model and the particle phase was modeled with kinetic theory of granular flow. The simulations by Eulerian two-fluid model （TFM） were compared with the corresponding results by discrete element method （DEM） and experiments. It was showed that TFM simulated results were in reasonable agreement with the experimental and DEM simulated results. Based on TFM simulations, gas-solid flow pattern, gas velocity, particle velocity and the static pressure under different driving jet velocity, backpressure and convergent section angle were obtained. The results showed that the time average axial gas velocity sharply decreased and then slightly increased to a constant value in the horizontal conveying pipe. The time average axial particle velocity increased initially and then decreased, but in the outlet region of the convergent section the particle velocity remarkably increased once more to the maximal value. As a whole, the static pressure distribution change trends were found to be independent on driving gas velocity, backpressure and convergent section angle. However, the static pressure increased with increase of convergent section angle and gas jet velocities. The difference of static pressure to backpressure increased with increasing backpressure.
基金supported by the National Natural Science Foundation of China (No. 50908094)the Ph. D. Programs Foundation of Ministry of Education of China (No. 20100142120071)the Natural Science Foundation of Hubei Province (No. 2010CDB02204)
文摘Based on the Fliigge shell theory, equations of motion of ring-stiffened thin-walled cylindrical shells conveying fluid are developed with the aid of the Hamilton＇s principle. Analysis is carried out on the vibration and stability of the ring-stiffened shells conveying fluid, and the effects of fluid velocity, the Young modulus, the size, and the number of the ring stiffeners on the natural frequency and the instability characteristics are examined. It is found that stiffeners can reduce the number of circumferential waves for the fundamental mode, and increase the shell＇s natural frequency, and thus the critical fluid velocity. For the number of longitudinal half waves being equal to one, the natural frequency and the corresponding critical fluid velocity are the largest for the internal-ring stiffened shell and are the smallest for the symmetrical-ring stiffened shell. The natural frequencies and the corresponding critical fluid velocity predicted by the established model increase with the increase in the Young modulus, the size, or the number of the stiffeners.
文摘A problem of wave propagation in submerged pipe conveying fluid is discussed in this paper. Three different fluid-pipe models are considered: the pipe conveying non-viscous fluid immersed in still fluid, the pipe conveying non-viscous fluid considering hydrostatic pressure and the pipe conveying viscous fluid considering hydrostatic pressure. The Fliiggle shell model and the hydrostatic pressure considered as the static prestress are introduced for the description of pipe and external/internal fluids. The effects of steady viscous forces are obtained by using the time-mean Navier-Stokes equations, and the perturbation pressures can be determined by means of potential flow theory. The wave dispersion curves of a submerged pipe conveying fluid are obtained numerically by considering the coupling conditions. The effects of internal fluid velocity and hydrostatic pressure on phase velocity are also discussed.
