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RISS 인기검색어
- 검색키워드
- 저자 : Daoxing Ye (검색결과 3 건)
- 무료
- 기관 내 무료
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Daoxing Ye,Xide Lai,Yimin Luo,Anlin Liu 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.10
A mathematical model for the flowrate and rotation speed of RCP during idling was established. The numerical calculation method and dimensionless method were used to analyze the flow, head, torque and pressure and speed changes under idle conditions. Regularity, using the Q criterion vortex identification judgment method combined with surface flow spectrum morphology analysis to diagnose the vortex dynamic characteristics on RCP blade. On impeller blade, there is two oscillations in the pressure ratio on pressure surface in blade outlet region. The velocity on the suction surface is two times more oscillating than the inlet of blade, and there is an intersection with the velocity ratio curve on pressure surface. On blade of guide vane, the pressure ratio increases along the inlet to outlet direction, and the speed ratio decreases with the increase of idle time. There is a vortex that rotates counterclockwise on the suction surface, and the streamline on the suction surface of blade is subjected to the entrainment and blocking action of the vortex creates a large reverse flow in the main flow region. There are two vortices at the outlet of guide vane suction side and the vortices are in opposite directions.
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Xide Lai,Daoxing Ye,Bo Yu,Xiaoming Chen,Yaguang Heng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1
Pressure pulsations are an important factors that cause unstable phenomena such as vibration and noise in the reactor coolant pump (RCP), which is much more complex than inside a general mixed-flow pump due to its structure and actual operating conditions. It is necessary to figure out its characteristics at different operating conditions in order to meet the high requirements of reliability and safety in both design and operation phases. Pressure pulsations inside the impeller and diffuser vanes was carefully investigated by using 3D unsteady flow simulations of the completed pump at 5 operating conditions. To seek the relationship between the pressure pulsations characteristics and operating conditions, the timedomain and frequency-domain characteristics of pressure pulsations at different locations inside the RCP were analyzed. It has been shown that the dominant frequency of pressure pulsations is mainly governed by the blade-passing frequency due to rotor-stator interaction (RSI) between the impeller and diffuser vanes at all operating conditions, and the amplitude of pressure pulsations mainly depends on the operating discharges. The influence on the peak amplitude of its higher harmonics can be neglected when operating at the design discharge, but cannot be negligible for operating at the smaller discharge. The behavior of pressure pulsations at the inlet of the impeller in circumferential direction is not the same and more intensive on the suction side than the pressure side of a blade at different operating conditions, but it is almost the same at the outlet of the impeller as the interaction between the impeller and diffuser vanes. The maximum amplitude of pressure pulsations mainly depends on the operating discharge and reaches the smallest level at the design operating condition. Due to geometric features of the spherical casing, the vortex flow inside the spherical casing leads to the highly irregular and unsteady pressure pulsations inside flow channel of the impeller and diffuser under the smaller discharge operating conditions, and the amplitude of pressure pulsations in higher frequencies increases with the decreasing of the operating discharge. The amplitude of pressure pulsations inside the whole flow channel distinctly increases when the RCP is operating at the extreme small operating discharge. The spherical casing does have influence on the pressure pulsations inside the impeller and diffuser vanes, the effect is stronger under smaller discharge operating conditions than at larger ones.
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Qingjiang Xiang,Jun Liu,Daoxing Ye,Xikun Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2
The barrel of a firefighting water cannon, which is in the form of S-shaped curved tube of varying cross section, would affect the hydraulic performance of the generated water jet. Numerical simulations were conducted to study the effects of installing a splitter plate in the tube with different placement forms and different offset distances. The hydraulic performance of the barrel is assessed using different parameters, including axial velocity uniformity and secondary flow intensity. The results showed that the turbulent fluctuation at the outlet is greatly reduced after the splitter plate is installed. The energy loss induced by the splitter plate in single form is significantly smaller than that in separated form. The outlet velocity achieves better uniformity when the splitter plate is placed near the inlet than near the outlet. Due to the presence of splitter plate, the magnitude of both vortex flux and swirling intensity is small, indicating that secondary flow is relatively weak. The obtained results provide guidance for the design of splitter plate in the barrel of firefighting water cannon.
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