The flow field of 3D （three-dimensional） wall-jet is investigated. Jet-blast from airplane is simulated by wall-jet setup using a sonic nozzle at a laboratory scale. Farfield velocity and fluctuation distributions a...The flow field of 3D （three-dimensional） wall-jet is investigated. Jet-blast from airplane is simulated by wall-jet setup using a sonic nozzle at a laboratory scale. Farfield velocity and fluctuation distributions are measured by using X-type hot wire anemometer at four measurement planes. As a result, the flow properties of streamwise component are consistent with data which are obtained in previous researches. The secondary flow is also measured on each measurement plane. Reynolds stresses, v＇v＇ and w＇ w＇, are analyzed from the fluctuation of the secondary flow. The law of similarity is observed in the dimensionless distributions of mean velocity and fluctuation. However, the distributions in nearer field （i.e., in the measurement plane at X/D = 100） tend to disobey the similarity law, especially in the cases of fluctuation. It seems that jet-blast is not fully developed by reaching X/D = 100. The experimental results are compared with computational results which are obtained by CFD （computational fluid dynamics） with SST （shear-stress transport） turbulence model. And it is shown that the results by the simulation with SST turbulence model do not follow the similarity law. The present database of the Reynolds stresses is critically important for development of a new turbulence model of RANS （reynolds-averaged navier-atokes） simulations on wall-jet.展开更多
To focus on the key scientific problem of process control of dynamic catastrophe of high dams,presented for the first time are the modelling theory of liquid-gas-solid tri-phase coupling of the air-cushion isolation c...To focus on the key scientific problem of process control of dynamic catastrophe of high dams,presented for the first time are the modelling theory of liquid-gas-solid tri-phase coupling of the air-cushion isolation control of high dams and its numerical simulation method,and theoretical description of the complicated dynamics problem of the tri-phase coupling-thermodynamics state-material-contact bi-nonlinearity,as well as the simulation analysis of the key effects of dynamic catastrophe of the air-cushion isolated high dam engineering.The analytic solution of plane-wave with rigid-dam body was created.The simulation comparison of dynamic catastrophe processes of 305 m Jinping arch dam with and without seismic control was carried out,and the results were basically in agreement with that obtained from the large shaking table tests,and verify each other.The entire air-chamber and optimized air-cushion with varying thickness were presented to develop a optimization method.The large shaking table tests of the isolated dam model,which is satisfied with the basic dynamic similarity relations,were performed for the first time.The test data seemed to be convincing and were in agreement with the dynamic simulation results of the tested model,thereby providing an experimental verification to the simulation theory and method.The combination experiments of theoretical model and physical model demonstrated that the hydrodynamic pressure of high arch dams can be reduced by more than 70% as well as the first and third principle stresses of the dam body reduced by more than 20%-30%,thereby the global anti-seismic capacity of the high dam being improved significantly.The results have shown that the air-cushion isolation is the prior developing direction of structural control technology of high concrete dams.展开更多
文摘The flow field of 3D （three-dimensional） wall-jet is investigated. Jet-blast from airplane is simulated by wall-jet setup using a sonic nozzle at a laboratory scale. Farfield velocity and fluctuation distributions are measured by using X-type hot wire anemometer at four measurement planes. As a result, the flow properties of streamwise component are consistent with data which are obtained in previous researches. The secondary flow is also measured on each measurement plane. Reynolds stresses, v＇v＇ and w＇ w＇, are analyzed from the fluctuation of the secondary flow. The law of similarity is observed in the dimensionless distributions of mean velocity and fluctuation. However, the distributions in nearer field （i.e., in the measurement plane at X/D = 100） tend to disobey the similarity law, especially in the cases of fluctuation. It seems that jet-blast is not fully developed by reaching X/D = 100. The experimental results are compared with computational results which are obtained by CFD （computational fluid dynamics） with SST （shear-stress transport） turbulence model. And it is shown that the results by the simulation with SST turbulence model do not follow the similarity law. The present database of the Reynolds stresses is critically important for development of a new turbulence model of RANS （reynolds-averaged navier-atokes） simulations on wall-jet.
基金supported by the National Natural Science Foundation of China (Grant No. 90715026)
文摘To focus on the key scientific problem of process control of dynamic catastrophe of high dams,presented for the first time are the modelling theory of liquid-gas-solid tri-phase coupling of the air-cushion isolation control of high dams and its numerical simulation method,and theoretical description of the complicated dynamics problem of the tri-phase coupling-thermodynamics state-material-contact bi-nonlinearity,as well as the simulation analysis of the key effects of dynamic catastrophe of the air-cushion isolated high dam engineering.The analytic solution of plane-wave with rigid-dam body was created.The simulation comparison of dynamic catastrophe processes of 305 m Jinping arch dam with and without seismic control was carried out,and the results were basically in agreement with that obtained from the large shaking table tests,and verify each other.The entire air-chamber and optimized air-cushion with varying thickness were presented to develop a optimization method.The large shaking table tests of the isolated dam model,which is satisfied with the basic dynamic similarity relations,were performed for the first time.The test data seemed to be convincing and were in agreement with the dynamic simulation results of the tested model,thereby providing an experimental verification to the simulation theory and method.The combination experiments of theoretical model and physical model demonstrated that the hydrodynamic pressure of high arch dams can be reduced by more than 70% as well as the first and third principle stresses of the dam body reduced by more than 20%-30%,thereby the global anti-seismic capacity of the high dam being improved significantly.The results have shown that the air-cushion isolation is the prior developing direction of structural control technology of high concrete dams.
