Sedimentation is one of the key technical problems present throughout feasibility demonstration,design,construction,and operation of the Three Gorges Project.Since the Three Gorges Reservoir(TGR)began impoundment oper...Sedimentation is one of the key technical problems present throughout feasibility demonstration,design,construction,and operation of the Three Gorges Project.Since the Three Gorges Reservoir(TGR)began impoundment operation in 2003,important progress has been made in sedimentation and regulation technologies through systematic research and practices.This paper reveals the asynchronous propagation pattern of flood and sediment peak inflows,sediment movement in the backwater area during drawdown period,sediment flocculation,and sediment deposition that compromises the flood control reservoir storage,and puts forward new sediment regulation techniques,including sediment peak discharge regulation during flood season,siltation reduction in the backwater area during drawdown period,dynamic adjustment of the reservoir level during flood season,and joint sediment regulation in cascade reservoirs.A real-time monitoring,forecasting and dynamic regulation platform for water and sediment inflow in the TGR was developed;a new mode of dynamic sediment regulation called“regulating sediment for greater benefits”is proposed,which addresses the constraints of sedimentation on the optimal operation of TGR.By enabling more flexible operation,this mode improves the process and pattern of sedimentation,ensures the safety of reservoir operation,and significantly augments the comprehensive benefits of the TGR.展开更多
Invert traps are used to trap sewer solids flowing into a sewer drainage system, The performance of the invert trap in an open rectangular channel was experimentally and numerically analysed using field sewer solids c...Invert traps are used to trap sewer solids flowing into a sewer drainage system, The performance of the invert trap in an open rectangular channel was experimentally and numerically analysed using field sewer solids collected from a sewer drain. Experiments showed that the free water surface rises over the central opening （slot） of the invert trap, which reduces the velocity near the slot and allows more sediment to be trapped in comparison with the case for the fixed-lid model （assuming closed conduit flow with a shear-free top wall） used by earlier investigators. This phenomenon cannot be modelled using a closed conduit model as no extra space is provided for the fluctuation of the water surface, whereas this space is provided in the volume of fluid （VOF） model in the form of air space in ANSYS Fluent 14.0 software. Additionally, the zero atmospheric pressure at the free water surface cannot be modelled in a fixed-lid model. In the present study, experimental trap efflciencies of the invert trap using field sewer solids were fairly validated using a three-dimensional computational fluid dynamics model （VOF model） coupled with a stochastic discrete phase model. The flow field （i.e., velocities） predicted by the VOF model were compared with experimental velocities obtained employing particle image velocimetry. The water surface profile above the invert trap predicted by the VOF model was found to be in good agreement with the experimentally measured profile. The present study thus showed that the VOF model can be used with the stochastic discrete phase model to well predict the performance of invert traps.展开更多
文摘Sedimentation is one of the key technical problems present throughout feasibility demonstration,design,construction,and operation of the Three Gorges Project.Since the Three Gorges Reservoir(TGR)began impoundment operation in 2003,important progress has been made in sedimentation and regulation technologies through systematic research and practices.This paper reveals the asynchronous propagation pattern of flood and sediment peak inflows,sediment movement in the backwater area during drawdown period,sediment flocculation,and sediment deposition that compromises the flood control reservoir storage,and puts forward new sediment regulation techniques,including sediment peak discharge regulation during flood season,siltation reduction in the backwater area during drawdown period,dynamic adjustment of the reservoir level during flood season,and joint sediment regulation in cascade reservoirs.A real-time monitoring,forecasting and dynamic regulation platform for water and sediment inflow in the TGR was developed;a new mode of dynamic sediment regulation called“regulating sediment for greater benefits”is proposed,which addresses the constraints of sedimentation on the optimal operation of TGR.By enabling more flexible operation,this mode improves the process and pattern of sedimentation,ensures the safety of reservoir operation,and significantly augments the comprehensive benefits of the TGR.
文摘Invert traps are used to trap sewer solids flowing into a sewer drainage system, The performance of the invert trap in an open rectangular channel was experimentally and numerically analysed using field sewer solids collected from a sewer drain. Experiments showed that the free water surface rises over the central opening （slot） of the invert trap, which reduces the velocity near the slot and allows more sediment to be trapped in comparison with the case for the fixed-lid model （assuming closed conduit flow with a shear-free top wall） used by earlier investigators. This phenomenon cannot be modelled using a closed conduit model as no extra space is provided for the fluctuation of the water surface, whereas this space is provided in the volume of fluid （VOF） model in the form of air space in ANSYS Fluent 14.0 software. Additionally, the zero atmospheric pressure at the free water surface cannot be modelled in a fixed-lid model. In the present study, experimental trap efflciencies of the invert trap using field sewer solids were fairly validated using a three-dimensional computational fluid dynamics model （VOF model） coupled with a stochastic discrete phase model. The flow field （i.e., velocities） predicted by the VOF model were compared with experimental velocities obtained employing particle image velocimetry. The water surface profile above the invert trap predicted by the VOF model was found to be in good agreement with the experimentally measured profile. The present study thus showed that the VOF model can be used with the stochastic discrete phase model to well predict the performance of invert traps.
