In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measur...In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.展开更多
Gas holdup is one of the key parameters in flotation process. Gas holdup as measured by a differential pressure method was investigated and the relative errors compared to the average gas holdup from the volume expans...Gas holdup is one of the key parameters in flotation process. Gas holdup as measured by a differential pressure method was investigated and the relative errors compared to the average gas holdup from the volume expansion method. The errors were used to establish optimum measurement positions. The results show that the measurement position should be in the middle of the column and in the region half way from the center to the wall (the half-radius). The gas holdup along the axial direction is lower at the bottom and higher at the top of the floatation column. The gas holdup along the radial direction is lower near the wall and higher near the center of the flotation column. The average gas holdup measure- ment can be replaced by regional gas holdup values.展开更多
This paper performs a numerical simulation of three-dimensional flow field in a centrifugal compressor with long inlet and outlet pipes using CFX software.By arranging virtual probes at different positions in both inl...This paper performs a numerical simulation of three-dimensional flow field in a centrifugal compressor with long inlet and outlet pipes using CFX software.By arranging virtual probes at different positions in both inlet and outlet planes,the aerodynamic performance of the centrifugal compressor is measured and compared with each other.Then effects of measuring positions on measurement results are discussed.The results show that it will generate notable measuring errors of the pressure ratio and efficiency if the inlet total pressure is measured using a single-point probe.The inlet total pressure data can be accurate when they are measured using a 3-point rake.The outlet total pressure and total temperature data can not be accurate if they are respectively measured at one circumferential position even using a multi-point rake.Increasing tangential measuring positions at the outlet is effective to improve the test accuracy.When the outlet total pressure and total temperature are respectively measured at 3 tangential positions,the data can be almost accurate.展开更多
基金Projects(51808563,51925808)supported by the National Natural Science Foundation of ChinaProject(KLWRTBMC18-03)supported by the Open Research Fund of the Key Laboratory of Wind Resistance Technology of Bridges of ChinaProject(2017YFB1201204)supported by the National Key R&D Program of China。
文摘In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.
基金supports for this work provided by the NationalKey Technology R&D Program in the 11th Five-Year Plan of China(No. 2008BAB31B03)
文摘Gas holdup is one of the key parameters in flotation process. Gas holdup as measured by a differential pressure method was investigated and the relative errors compared to the average gas holdup from the volume expansion method. The errors were used to establish optimum measurement positions. The results show that the measurement position should be in the middle of the column and in the region half way from the center to the wall (the half-radius). The gas holdup along the axial direction is lower at the bottom and higher at the top of the floatation column. The gas holdup along the radial direction is lower near the wall and higher near the center of the flotation column. The average gas holdup measure- ment can be replaced by regional gas holdup values.
基金funded by Chinese Key Laboratory Fund,Grant No.9140C3310040705the National Natural Science Foundation of China,Grant No.50776004+1 种基金supported by the 111 Project,No.B07009973 Project,No.2007CB210103
文摘This paper performs a numerical simulation of three-dimensional flow field in a centrifugal compressor with long inlet and outlet pipes using CFX software.By arranging virtual probes at different positions in both inlet and outlet planes,the aerodynamic performance of the centrifugal compressor is measured and compared with each other.Then effects of measuring positions on measurement results are discussed.The results show that it will generate notable measuring errors of the pressure ratio and efficiency if the inlet total pressure is measured using a single-point probe.The inlet total pressure data can be accurate when they are measured using a 3-point rake.The outlet total pressure and total temperature data can not be accurate if they are respectively measured at one circumferential position even using a multi-point rake.Increasing tangential measuring positions at the outlet is effective to improve the test accuracy.When the outlet total pressure and total temperature are respectively measured at 3 tangential positions,the data can be almost accurate.
