For sudden expansion pipes, experiments were carried ＇Out to study the cavitation inception for various enlargement ratios in high speed flows. The flow velocity of the prototype reaches 50 m/s in laboratory. The rel...For sudden expansion pipes, experiments were carried ＇Out to study the cavitation inception for various enlargement ratios in high speed flows. The flow velocity of the prototype reaches 50 m/s in laboratory. The relationship between the expansion ratio and the incipient cavitation number is obtained. The scale and velocity effects are revealed. It is shown that Keller＇s revised formula should be modified to calculate the incipient cavitation number when the forecasted velocity of the flows in the prototype exceeds the experimental velocity.展开更多
This work applies the Eulerian-Eulerian model in conjunction with the kinetic theory of granular flow and inter-particle collisions to study the characteristics of pressure recovery for a dilute gas-particle suspensio...This work applies the Eulerian-Eulerian model in conjunction with the kinetic theory of granular flow and inter-particle collisions to study the characteristics of pressure recovery for a dilute gas-particle suspension flowing through a pipe with a sudden expansion at a relatively higher solid loading.To do so,the numerical procedure was validated against experimental results for relatively small dilute phase flows in a pipe with a sudden expansion;a satisfactory agreement was obtained.Initially,the effect of the two significant numerical parameters namely,the speculairty coefficient and the coefficient of restitution for particle-particle collisions were investigated and then,for fixed combinations of these parameters the effect of particle-phase volume fraction,particle density,particle size,and inlet slip ratio were studied.It was concluded that pressure recovery diminishes as the speculairty coefficient increases and the particle-particle coefficient of restitution decreases.Pressure recovery was found to increase with increasing solid volume fraction for coarse particles whereas,for fine particles,a critical volume fraction is obtained above which pressure recovery reduces.An increase in slip ratio is found to diminish pressure recovery.Similarly,at relatively higher solid volume fractions,a critical diameter was found,above and below which pressure recovery decreases.展开更多
基金supported by the National Key Basic Research and Development Program of China (973 Program,Grant No.2007CB714105)the National Science and Technology Pillar Program of China (Grant No. 2008BAB29B04)+1 种基金the Science Foundation of Ministry of Education of China (Grant No.2008108111)the Program for New Century Excellent Talents in University (Grant No.NCET-08-0378)
文摘For sudden expansion pipes, experiments were carried ＇Out to study the cavitation inception for various enlargement ratios in high speed flows. The flow velocity of the prototype reaches 50 m/s in laboratory. The relationship between the expansion ratio and the incipient cavitation number is obtained. The scale and velocity effects are revealed. It is shown that Keller＇s revised formula should be modified to calculate the incipient cavitation number when the forecasted velocity of the flows in the prototype exceeds the experimental velocity.
文摘This work applies the Eulerian-Eulerian model in conjunction with the kinetic theory of granular flow and inter-particle collisions to study the characteristics of pressure recovery for a dilute gas-particle suspension flowing through a pipe with a sudden expansion at a relatively higher solid loading.To do so,the numerical procedure was validated against experimental results for relatively small dilute phase flows in a pipe with a sudden expansion;a satisfactory agreement was obtained.Initially,the effect of the two significant numerical parameters namely,the speculairty coefficient and the coefficient of restitution for particle-particle collisions were investigated and then,for fixed combinations of these parameters the effect of particle-phase volume fraction,particle density,particle size,and inlet slip ratio were studied.It was concluded that pressure recovery diminishes as the speculairty coefficient increases and the particle-particle coefficient of restitution decreases.Pressure recovery was found to increase with increasing solid volume fraction for coarse particles whereas,for fine particles,a critical volume fraction is obtained above which pressure recovery reduces.An increase in slip ratio is found to diminish pressure recovery.Similarly,at relatively higher solid volume fractions,a critical diameter was found,above and below which pressure recovery decreases.
