Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNG k-epsilon turbulence model. The flow was turbulent, incompressible and unsteady...Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNG k-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43 000. The working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model. Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera. The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good agreement with the numerical result.展开更多
In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine particles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course ...In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine particles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course of opening the gate. They constitute together the adhesion force of the sediment. Based on this viewpoint, this paper puts forward a formula for the effect of silt sediment on the lifting force. The formula includes gate weight, down-suction force, sealing rubber friction, plus-weight, water-column pressure, plus-silted-sediment weight and rolling(or sliding)-bearing friction. Finally, the verification results show that the formula has certain reliability and the calculation accuracy can meet the need of practical engineering.展开更多
Comparisons between the numerical predictions from a two-phase model and the experimental hydrodynamic data have been performed in fully developed gas-solid flows for FCC catalysts. The resultssuggested the existence ...Comparisons between the numerical predictions from a two-phase model and the experimental hydrodynamic data have been performed in fully developed gas-solid flows for FCC catalysts. The resultssuggested the existence of self-similar solid flux profiles at low solid fluxes. Non-uniformity in theradial solids fluxes was found with a high solid flowing mainly downward near the wall. The modelpredictions were reasonably caught up the experimental trends.展开更多
文摘Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNG k-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43 000. The working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model. Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera. The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good agreement with the numerical result.
基金Supported by Shandong Province Outstanding Young Scientist Award Fund(No.BS2014SF016)the National Natural Science Foundation of China(No.50979067)+1 种基金Ludong University Doctor Introduction Foundation(No.LY2014026 and No.LY2014028)the Open Research Fund Program of State Key Laboratory of Water Resources and Hydropower Engineering Science(No.2012B104)
文摘In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine particles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course of opening the gate. They constitute together the adhesion force of the sediment. Based on this viewpoint, this paper puts forward a formula for the effect of silt sediment on the lifting force. The formula includes gate weight, down-suction force, sealing rubber friction, plus-weight, water-column pressure, plus-silted-sediment weight and rolling(or sliding)-bearing friction. Finally, the verification results show that the formula has certain reliability and the calculation accuracy can meet the need of practical engineering.
文摘Comparisons between the numerical predictions from a two-phase model and the experimental hydrodynamic data have been performed in fully developed gas-solid flows for FCC catalysts. The resultssuggested the existence of self-similar solid flux profiles at low solid fluxes. Non-uniformity in theradial solids fluxes was found with a high solid flowing mainly downward near the wall. The modelpredictions were reasonably caught up the experimental trends.
