In order to suppress the tip leakage vortex, a new tip clearance structure based on Gaussian function is proposed in this paper. Three tip clearance models with different Gaussian function amplitudes are designed. The SST-CC turbulence model is used to numerically analyze the effect of novel shaped tip clearance on tip leakage vortex, streamline, vortex intensity, turbulent kinetic energy and pressure. The results show that the new tip clearance structure has a cutting effect on the main tip leakage vortex and reduce the vortex intensity, but a new tip leakage vortex also appears. The energy loss caused by the new tip leakage vortex increases the turbulent kinetic energy of the flow field. The new tip clearance structure can reduce the low pressure area near the leading edge of the hydrofoil, increase the pressure. In addition, the biggest increase amplitude of lift-drag ratio is 1.12 %. This study can provide a new idea for the tip leakage vortex suppression and operation stability improvement of hydraulic machinery in practical engineering.

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The dynamic behavior of rotating machinery is crucial for researchers and manufacturers to understand precisely what happens inside the machines during operation. This paper presents a method for predicting the micromotion of the ring gear in an internal gear motor and pump. By solving the Reynolds equation and the motion equation, the ring gear orbit can be obtained. This mathematical model allows for the analysis of the effects of the geometric and operating parameters on the dynamic behavior of the internal gear motor and pump.

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The institutional affiliation on page 177 is corrected as follows: 1Faculty of Basic Sciences, University of Transport and Communications No.3 Cau Giay, Hanoi, 10000, Vietnam, hung.manh.nguyen@utc.edu.vn 2Faculty of Mechanical Engineering, University of Transport and Communications No.3 Cau Giay, Hanoi, 10000, Vietnam, phamhoamxd@utc.edu.vn

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