In a centrifugal compressor, the leakage flow through the tip clearance generates the tip leakage vortex by the in- teraction with the main flow, and consequently makes the flow in the impeller passage more complex by...In a centrifugal compressor, the leakage flow through the tip clearance generates the tip leakage vortex by the in- teraction with the main flow, and consequently makes the flow in the impeller passage more complex by the inte- raction with the passage vortex. In addition, the tip leakage vortex interacts with the shock wave on the suction surface near the blade tip in the transonic centrifugal compressor impeller. Therefore, the detailed examination for the influence of the tip leakage vortex becomes seriously important to improve the aerodynamic performance cs- pccia｜ly for the transonic centrifugal compressor. In this study, the flows in the transonic centrifugal compressor with and without the tip clearance at the design condition were analyzed numerically by using the commercial CFD code. The computed results revealed that the tip leakage vortex induced by the high loading at the blade tip around the leading edge affected the loss generation by the reduction or the suppression of the shock wave on the suction surface of the blade.展开更多
The flow behavior in a typical arc welding process is very complex and features rapid melting and solidification. In this work, the flow in the melted region was determined by the effect of surface tension, viscosity,...The flow behavior in a typical arc welding process is very complex and features rapid melting and solidification. In this work, the flow in the melted region was determined by the effect of surface tension, viscosity, and gravity. Two-dimensional change of the geometry of the melted region was analyzed using the MPS （moving particle semi-implicit） method to melt a small upper plate in a hole at the center of a base plate. The relation between the initial geometry of the upper plate and the surface flatness after welding was calculated. The calculation results showed that the upper plate with a triangular notch at its center minimized the surface unevenness after welding. The depth of notch and thickness of the upper plate were optimized.展开更多
文摘In a centrifugal compressor, the leakage flow through the tip clearance generates the tip leakage vortex by the in- teraction with the main flow, and consequently makes the flow in the impeller passage more complex by the inte- raction with the passage vortex. In addition, the tip leakage vortex interacts with the shock wave on the suction surface near the blade tip in the transonic centrifugal compressor impeller. Therefore, the detailed examination for the influence of the tip leakage vortex becomes seriously important to improve the aerodynamic performance cs- pccia｜ly for the transonic centrifugal compressor. In this study, the flows in the transonic centrifugal compressor with and without the tip clearance at the design condition were analyzed numerically by using the commercial CFD code. The computed results revealed that the tip leakage vortex induced by the high loading at the blade tip around the leading edge affected the loss generation by the reduction or the suppression of the shock wave on the suction surface of the blade.
文摘The flow behavior in a typical arc welding process is very complex and features rapid melting and solidification. In this work, the flow in the melted region was determined by the effect of surface tension, viscosity, and gravity. Two-dimensional change of the geometry of the melted region was analyzed using the MPS （moving particle semi-implicit） method to melt a small upper plate in a hole at the center of a base plate. The relation between the initial geometry of the upper plate and the surface flatness after welding was calculated. The calculation results showed that the upper plate with a triangular notch at its center minimized the surface unevenness after welding. The depth of notch and thickness of the upper plate were optimized.
