Based on systematic experiments on the influence of air entrainment on rock block stability in plunge pools impacted by high-velocity jets,this study presents adaptations of a physically based scour model.The modifica...Based on systematic experiments on the influence of air entrainment on rock block stability in plunge pools impacted by high-velocity jets,this study presents adaptations of a physically based scour model.The modifications regarding jet aeration are implemented in the Comprehensive Scour Model(CSM),allowing it to reproduce the physical-mechanical processes involved in scour formation concerning the three phases;namely,water,rock,and air.The enhanced method considers the reduction of momentum of an aerated jet as well as the decrease of energy dissipation in the jet diffusive shear layer,both resulting from the entrainment of air bubbles.Block ejection from the rock mass depends on a combination of the aerated time-averaged pressure coefficient and the modified maximum dynamic impulsion coefficient,which was found to be a constant value of 0.2 for high-velocity jets in deep pools.The modified model is applied to the case of the observed scour hole at the Kariba Dam,with good agreement.展开更多
Air pollution caused by particles with small size has been a global concern because of threats to human health.A feasible way to remove these super fine suspended particles is using electrostatic precipitation technol...Air pollution caused by particles with small size has been a global concern because of threats to human health.A feasible way to remove these super fine suspended particles is using electrostatic precipitation technology.Herein,the PIV was used to measure the particle velocity distribution.By analyzing the particle motion trend in high electric field,a process of particle charging loss was observed.This phenomenon cannot be explained by current particle charging theories.Our conclusions may improve the understanding of particle charging processes.展开更多
文摘Based on systematic experiments on the influence of air entrainment on rock block stability in plunge pools impacted by high-velocity jets,this study presents adaptations of a physically based scour model.The modifications regarding jet aeration are implemented in the Comprehensive Scour Model(CSM),allowing it to reproduce the physical-mechanical processes involved in scour formation concerning the three phases;namely,water,rock,and air.The enhanced method considers the reduction of momentum of an aerated jet as well as the decrease of energy dissipation in the jet diffusive shear layer,both resulting from the entrainment of air bubbles.Block ejection from the rock mass depends on a combination of the aerated time-averaged pressure coefficient and the modified maximum dynamic impulsion coefficient,which was found to be a constant value of 0.2 for high-velocity jets in deep pools.The modified model is applied to the case of the observed scour hole at the Kariba Dam,with good agreement.
基金supported by the National Natural Science Foundation of China(Grant No.51107095)
文摘Air pollution caused by particles with small size has been a global concern because of threats to human health.A feasible way to remove these super fine suspended particles is using electrostatic precipitation technology.Herein,the PIV was used to measure the particle velocity distribution.By analyzing the particle motion trend in high electric field,a process of particle charging loss was observed.This phenomenon cannot be explained by current particle charging theories.Our conclusions may improve the understanding of particle charging processes.
