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Dong L.,Jiangsu University | Dai C.,Jiangsu University | Tang X.-C.,Jiangsu Zhenhua Pump Industry Manufacturing Co.
Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics | Year: 2015

A mesh quality improvement strategy combining OPS and topological optimization was firstly putted forward to overcome the existing defect that can't improve bad elements with all their vertices on the boundary in OPS. According to the sharing form of edge (or face) and its adjacent element, the approach applied different topological optimization methods. The topological correlation of mesh after optimization rather than the element quality in connected region was considered. In this way, this kind of element was transformed into non-full-boundary element. Examples show that the approach shows better advantage in boundary and whole mesh quality than OPS. Numerical results show that comparing with Freitag algorithm, the proposed algorithm is more successful in eliminating poor dihedral angles at both extremes. And the combined algorithm shows better advantage on boundary and entire quality improvement for centrifugal pump over OPS. ©, 2015, Editorial Office of Chinese Journal of Computational Mechanics. All right reserved. Source

Dong L.,Jiangsu University | Dai C.,Jiangsu University | Zhang Y.,Anhui Sanlian Pump Industry Co. | Xiao J.,Jiangsu University | And 2 more authors.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2015

Mesh quality influences numerical accuracy and computational efficiency directly in CFD. In order to improve the quality of mesh on solid boundaries in a centrifugal pump greatly, an optimization-based smoothing algorithm is proposed. In this algorithm, a new mesh quality metric is employed, and an error function is derived by transforming the metric. The total error function of the mesh is the sum of the error in every element, and adopted as the objective function of the optimization. Furthermore, in the objective function, the qualities of the mesh on and off the boundaries are involved, a weight coefficient is also included to control the quality of the mesh on the boundaries. The Broyden Fletcher Goldfarb Shanno algorithm is applied to transform the global minimization to a series of local minimization to enhance the computational efficiency. A practical example shows that the proposed algorithm can improve the mesh quality considerably; moreover not only the quality of the mesh on the boundaries but also the overall quality of all the mesh can be upgraded with the increasing weight coefficient as well. ©, 2015, Editorial Department of Journal of Drainage and Irrigation Machinery Engineering. All right reserved. Source

Wang X.-L.,Jiangsu University | Jiang D.-L.,Jiangsu Zhenhua Pump Industry Manufacturing Co. | Yu Z.-J.,Jiangsu Zhenhua Pump Industry Manufacturing Co. | Dai L.,Jiangsu Zhenhua Pump Industry Manufacturing Co.
Reneng Dongli Gongcheng/Journal of Engineering for Thermal Energy and Power | Year: 2011

By using a CFD (computational fluid dynamics) numerical simulation method, studied was the law governing the pressure and gas-liquid two phase distribution inside the impeller of a marine centrifugal pump at various cavitation allowances. It has been found that the numerical simulation results share an identical variation tendency with the test results and the average absolute error is approximately 0. 15 m. In the stealth cavitation stage, the air bubbles are only produced and burst in a very small local area on the back at the inlet of the blades and no relatively big cavitation destruction to the impeller is caused. In the partial vortex cavitation stage, a low speed vortex zone exists on the back of the blades close to the outlet of the impeller and its size and distribution law is relating to the transversal section of the volute. In the vortex cavitation stage, a hollow cavity exists in the passage between the low speed vortex zone and the volute. The existence of the low speed vortex zone and hollow cavity may influence the stability of the flow speed inside the volute, producing a very big pressure pulsation and furthermore causing a relatively big noise and vibration to the marine centrifugal pump. Source

Quan L.-G.,Jiangsu Zhenhua Pump Industry Manufacturing Co. | Xu H.-M.,Jiangsu Zhenhua Pump Industry Manufacturing Co. | Lu J.-X.,Jiangsu Zhenhua Pump Industry Manufacturing Co. | Zhuang W.-J.,Jiangsu Zhenhua Pump Industry Manufacturing Co.
Reneng Dongli Gongcheng/Journal of Engineering for Thermal Energy and Power | Year: 2011

By using the Reynolds number time-average equation and the dual-equation turbulent flow model, in combination with the SIMPLEC algorithm, numerically simulated was the three-dimensional non-compressible turbulent flow field inside a centrifugal pump. Furthermore, the internal pressure distribution and pulsations at various monitoring points were obtained. On the basis of the simulation, an outer characteristic experiment was conducted, proving that the simulation results are correct. The research results show that the asymmetry of the volute makes the flow inside the centrifugal pump be of asymmetrical and non-steady characteristics, and force the pressure to change periodically at the frequency of the rotating blades. At the rated flow rate, the pressure fluctuation amplitude at the monitoring points is smaller than that under off-design operating conditions. Source

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