An accurate estimation of the total pressure drop of a pipeline is important to the reliable design of a pneumatic conveying system. The present paper presents results from an investigation into the modelling of the p...An accurate estimation of the total pressure drop of a pipeline is important to the reliable design of a pneumatic conveying system. The present paper presents results from an investigation into the modelling of the pressure drop at a bend in the pneumatic conveying of fly ash. Seven existing bend models were used （in conjunction with solids friction models for horizontal and vertical straight pipes, and initial acceleration losses） to predict the total pipeline pressure drop in conveying fly ash （median particle diameter： 30 }zm; particle density： 2300 kg/m^3; loose-poured bulk density： 700 kg/m3） in three test rigs （pipelines with dimensions of 69 mm inner diameter （I.D.） × 168 m length; 105 mm I.D. × 168 m length; 69 mm I.D. × 554 m length）. A comparison of the pneumatic conveying characteristics （PCC） predicted using the seven bend models and experimental results shows that the predicted total pipeline PCC and trends depend on the choice of bend model. While some models predict trends that agree with the experimental results, other models predicted greater bend pressure drops for the dense phase of fly ash than for the dilute phase. Models of Pan, R. （1992）. Improving scale-up procedures for the design of pneumatic conveying systems. Doctoral dissertation, University of Wollongong, Australia, Pan, R., ＆ Wypych, P.W. （1998）. Dilute and dense phase pneumatic conveying of fly ash. In Proceedings of the sixth International Conference on Bulk Materials Storage and Transportation （pp. 183-189）, Wollongong, NSW, Australia and Chambers, A.J., ＆ Marcus, R.D. （1986）. Pneumatic conveying calculations. In Proceedings of the second International Conference on Bulk Materials Storage and Transportation （pp. 49-52）, Wollongong, Australia reliably predicted the bend losses for systems conveying fly ash over a large range of air flows.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the Department of Science and Technology(Government of India) for financial assistance provided under the Young Scientist Scheme(Grant No.SR/FTP/ETA-15/2011)
文摘An accurate estimation of the total pressure drop of a pipeline is important to the reliable design of a pneumatic conveying system. The present paper presents results from an investigation into the modelling of the pressure drop at a bend in the pneumatic conveying of fly ash. Seven existing bend models were used （in conjunction with solids friction models for horizontal and vertical straight pipes, and initial acceleration losses） to predict the total pipeline pressure drop in conveying fly ash （median particle diameter： 30 }zm; particle density： 2300 kg/m^3; loose-poured bulk density： 700 kg/m3） in three test rigs （pipelines with dimensions of 69 mm inner diameter （I.D.） × 168 m length; 105 mm I.D. × 168 m length; 69 mm I.D. × 554 m length）. A comparison of the pneumatic conveying characteristics （PCC） predicted using the seven bend models and experimental results shows that the predicted total pipeline PCC and trends depend on the choice of bend model. While some models predict trends that agree with the experimental results, other models predicted greater bend pressure drops for the dense phase of fly ash than for the dilute phase. Models of Pan, R. （1992）. Improving scale-up procedures for the design of pneumatic conveying systems. Doctoral dissertation, University of Wollongong, Australia, Pan, R., ＆ Wypych, P.W. （1998）. Dilute and dense phase pneumatic conveying of fly ash. In Proceedings of the sixth International Conference on Bulk Materials Storage and Transportation （pp. 183-189）, Wollongong, NSW, Australia and Chambers, A.J., ＆ Marcus, R.D. （1986）. Pneumatic conveying calculations. In Proceedings of the second International Conference on Bulk Materials Storage and Transportation （pp. 49-52）, Wollongong, Australia reliably predicted the bend losses for systems conveying fly ash over a large range of air flows.
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.
