Flip buckets are commonly used to discharge flow away from a hydraulic structure into the downstream to dissipate energy.A new leak-floor flip bucket is presented,making the ski-jump water jet a typical long-narrow na...Flip buckets are commonly used to discharge flow away from a hydraulic structure into the downstream to dissipate energy.A new leak-floor flip bucket is presented,making the ski-jump water jet a typical long-narrow nappe.Based on the model experiments and numerical simulation,the flow pattern,formation process and mechanism of the leak-floor flip bucket are studied.The results show that cross section flow shape develops from the"Y-type"to"|-type",and this is because the natural pressure difference is generated when water flows through the leak-floor area and moves transversely from both sides to the center.Different from the slit-type flip bucket with sidewall contraction,the leak-floor flit bucket makes the water jet narrow and long without high pressure on the side walls of the flip bucket.Under the same jet length condition,the maximum sidewall pressure of the slit-type is 4.67 times that of the leak-floor flip bucket.The effects of flow discharge on the jet length are less significant for the leak-floor bucket than for the slit-type bucket.展开更多
The energy dissipation is a key index in the evaluation of energy dissipation elements.In the present work,a flip bucket with a slot,called the slot-type flip bucket,is theoretically and experimentally investigated by...The energy dissipation is a key index in the evaluation of energy dissipation elements.In the present work,a flip bucket with a slot,called the slot-type flip bucket,is theoretically and experimentally investigated by the method of estimating the energy dissipation.The theoretical analysis shows that,in order to have the energy dissipation,it is necessary to determine the sequent flow depth h1 and the flow speed V1 at the corresponding position through the flow depth h2 after the hydraulic jump.The relative flow depth h2/ho is a function of the approach flow Froude numberFro,the relative slot widthb/Bo,and the relative slot angleθ/β.The expression for estimating the energy dissipation is developed,and the maximum error is not larger than 9.21%.展开更多
Numerical modeling of hydraulic phenomenon by computational fluid dynamic （CFD） approaches is one of the main parts in the high cost hydraulic structure studies. In this paper, using Flow 3D as CFD commercial tool, ...Numerical modeling of hydraulic phenomenon by computational fluid dynamic （CFD） approaches is one of the main parts in the high cost hydraulic structure studies. In this paper, using Flow 3D as CFD commercial tool, the cavitation phenomenon was assessed along spillway＇s flip bucket of the Balaroud dam. Performance of numerical modeling was compared to the physical model, which was constructed to this purpose. During numerical modeling, it was found that RNG turbulence model is a suitable performance for modeling the cavitation. Physical modeling shows that minimum cavitation index is about 0.85 and minimum cavitation index based on Flow 3D results is about 0.665, which was related to the flood discharge with return period of 10000 years. The main difference between numerical and physical modeling is related to the head of velocity, which is considered in physical modeling. Results of numerical simulation show that occurrence of cavitation based on cavitation index equal to 0.25 is not possible along the spillway.展开更多
The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Frou...The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Froude number for the flow choking to occur in those flip buckets. The error of the present method relative to the experimental data is less than 5%. The results show that, the Froude number for the flow choking to occur is related to the contraction ratio and the contraction angle of the flip buckets. When the flow choking occurs, the upper jet trajectory decreases and the lower one is almost not affected, and the dynamic pressures on the bottom and the sidewalls increase due to the flow profile rising on the flip buckets.展开更多
In the present work,a slot-type flip bucket with separated flows,called SFS-type flip bucket,is developed,and flow regime and energy dissipation are experimentally investigated.Comparing with the circular-shaped or sl...In the present work,a slot-type flip bucket with separated flows,called SFS-type flip bucket,is developed,and flow regime and energy dissipation are experimentally investigated.Comparing with the circular-shaped or slot-type flip bucket buckets,the present SFS-type flip bucket has better flow regime and larger energy dissipation since the three branches of the flows are separated through the outlet of the flip bucket.Meanwhile,the energy dissipation for this flip bucket is estimated.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51379138&51179113)Sichuan Province Funds for Distinguished Young Scientists(Grant No.2013JQ0007)
文摘Flip buckets are commonly used to discharge flow away from a hydraulic structure into the downstream to dissipate energy.A new leak-floor flip bucket is presented,making the ski-jump water jet a typical long-narrow nappe.Based on the model experiments and numerical simulation,the flow pattern,formation process and mechanism of the leak-floor flip bucket are studied.The results show that cross section flow shape develops from the"Y-type"to"|-type",and this is because the natural pressure difference is generated when water flows through the leak-floor area and moves transversely from both sides to the center.Different from the slit-type flip bucket with sidewall contraction,the leak-floor flit bucket makes the water jet narrow and long without high pressure on the side walls of the flip bucket.Under the same jet length condition,the maximum sidewall pressure of the slit-type is 4.67 times that of the leak-floor flip bucket.The effects of flow discharge on the jet length are less significant for the leak-floor bucket than for the slit-type bucket.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51579076,51479057)
文摘The energy dissipation is a key index in the evaluation of energy dissipation elements.In the present work,a flip bucket with a slot,called the slot-type flip bucket,is theoretically and experimentally investigated by the method of estimating the energy dissipation.The theoretical analysis shows that,in order to have the energy dissipation,it is necessary to determine the sequent flow depth h1 and the flow speed V1 at the corresponding position through the flow depth h2 after the hydraulic jump.The relative flow depth h2/ho is a function of the approach flow Froude numberFro,the relative slot widthb/Bo,and the relative slot angleθ/β.The expression for estimating the energy dissipation is developed,and the maximum error is not larger than 9.21%.
文摘Numerical modeling of hydraulic phenomenon by computational fluid dynamic （CFD） approaches is one of the main parts in the high cost hydraulic structure studies. In this paper, using Flow 3D as CFD commercial tool, the cavitation phenomenon was assessed along spillway＇s flip bucket of the Balaroud dam. Performance of numerical modeling was compared to the physical model, which was constructed to this purpose. During numerical modeling, it was found that RNG turbulence model is a suitable performance for modeling the cavitation. Physical modeling shows that minimum cavitation index is about 0.85 and minimum cavitation index based on Flow 3D results is about 0.665, which was related to the flood discharge with return period of 10000 years. The main difference between numerical and physical modeling is related to the head of velocity, which is considered in physical modeling. Results of numerical simulation show that occurrence of cavitation based on cavitation index equal to 0.25 is not possible along the spillway.
基金Project supported by the National Natural Science Foundation of China(Grant No.51179056)the PAPD(Grant No.3014-SYS1401)the Fundamental Research Funds for the Central Universities of China(Grant No.2014B03114)
文摘The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Froude number for the flow choking to occur in those flip buckets. The error of the present method relative to the experimental data is less than 5%. The results show that, the Froude number for the flow choking to occur is related to the contraction ratio and the contraction angle of the flip buckets. When the flow choking occurs, the upper jet trajectory decreases and the lower one is almost not affected, and the dynamic pressures on the bottom and the sidewalls increase due to the flow profile rising on the flip buckets.
基金Project supported by the National Natural Science Foundation of China(Grant No.51579076).
文摘In the present work,a slot-type flip bucket with separated flows,called SFS-type flip bucket,is developed,and flow regime and energy dissipation are experimentally investigated.Comparing with the circular-shaped or slot-type flip bucket buckets,the present SFS-type flip bucket has better flow regime and larger energy dissipation since the three branches of the flows are separated through the outlet of the flip bucket.Meanwhile,the energy dissipation for this flip bucket is estimated.
