http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Influence of tip clearance on pressure fluctuations in an axial flow pump
Jianjun Feng,Xingqi Luo,Pengcheng Guo,Guangkuan Wu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4
Rotor-stator interaction in axial pumps can produce pressure fluctuations and further vibrations even damage to the pump system in some extreme case. In this paper, the influence of tip clearance on pressure fluctuations in an axial flow water pump has been investigated by numerical method. Three-dimensional unsteady flow in the axial flow water pump has been simulated with different tip clearances between the impeller blade tip and the casing wall. In addition to monitoring pressure fluctuations at some typical points, a new method based on pressure statistics was proposed to determine pressure fluctuations at all grid nodes inside the whole pump. The comparison shows that the existence of impeller tip clearance magnifies the pressure fluctuations in the impeller region, from the hub to shroud. However, the effect on pressure fluctuation in the diffuser region is not evident. Furthermore, the tip clearance vortex has also been examined under different tip clearances.
Yan Sina,Luo Xingqi,Feng Jianjun,Zhu Guojun,Zhang Lefu,Chen Senlin 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.1
In order to study the influence of inlet gas volume fraction (IGVF) on performance of a gas-liquid centrifugal pump, three-dimensional turbulent flow of a single-stage gas-liquid centrifugal pump has been simulated by using computational fluid dynamics (CFD). Both steady and unsteady simulations have been conducted for different inlet gas volume fraction conditions of the pump. The gas phase distribution, the internal flow field and pressure field of the pump were obtained with inhomogeneous two-fluid model. The result showed that many gas accumulation zones accompanied vortices appears in the impeller as IGVF increases, and surge would occur as IGVF reaches a certain value. The change of IGVF would change the magnitude and direction of the impeller radial force.
Like Wang,Xingqi Luo,Jinling Lu,Jianjun Feng,Guojun Zhu,Wei Wang,Kai Wang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9
Tidal energy is an important renewable energy that uses the potential energy created by the rising and falling of ocean tides to generate electricity. The tip leakage vortex (TLV) and cavitation caused by the tip leakage flow have adverse effects on the energy conversion efficiency and stable operation of the tubular turbine. The selection of the tip clearance shape is critical. Therefore, the effects of four different combinations of asymmetrical tip clearance shapes on the energy and cavitation characteristics of hydrofoils are studied in this paper. The results show that the TLV remains unchanged when tipwall and endwall are sinusoidal and cosine curve shaped, respectively. When tip clearance is the combination of a flat tipwall and a sinusoidal endwall, the lift-drag ratio decreases by 10.72 %. The high shear stress region of tipwall near leading edge decreases. The flow resistance of the leakage flow decreases, and the leakage flow becomes more serious. The cavitation volume is 2.5 times that under the original flat tip clearance. When tip clearance is the combination of a flat tipwall and a cosine endwall, and the lift-drag ratio increases by 9.67 %. The shear stress increases, the leakage flow decreases. The swirling strength around the center of the vortex core is weakened. The cavitation volume is 3.81, with a decrease of nearly 30 %. A proper asymmetrical tip clearance can effectively improve the energy performance and cavitation characteristics of hydrofoils. This study provides theoretical support for the design and optimization of hydraulic machine with tip clearance.