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Effect of medium viscosity on performance conversion of pump as turbine |
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YANG Junhu,, LEI Lei, ZHANG Shuwei, MIAO Senchun,, YAN Jun
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In order to study the variation characteristics of performance conversion factors of pump and turbine with viscosity and specific speed, centrifugal pumps with five different specific speeds were chosen as pump and turbine. The flows in the turbines were numerically simulated at five different viscosities. Based on simulated results, the mathematical relationships such as head-flow rate and efficiency-flow rate are obtained with curve fitting. Then the head, efficiency and flow rate are decided at the best efficiency point where the slope of the efficiency curve with respect to flow rate is zero. Eventually, flow rate, head and efficiency conversion factors are calculated based on the flow rate, head and efficiency are at a viscosity higher than water and those at the viscosity of water are at best efficiency points. It is shown that medium viscosity has a greater influence on turbine performance, particularly, the hydraulic efficiency of turbine decreases evidently with increasing viscosity. At the same specific speed, the conversion factors rise with increasing viscosity. At the same viscosity, the conversion factors reduce generally with increasing specific speed. |
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2017 Vol. 35 (7): 553-557
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577 |
Structure of non-leakage diaphragm of reciprocating hydraulic diaphragm pump for slurry transportation |
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CHEN Li, CHEN Hongjun, GUAN Ruguang, FU Yihong, ZHANG Shunping
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Conventional reciprocating hydraulic diaphragm pumps usually are with a single-layer diaphragm structure to transport slurries. When the diaphragm ruptures, the leaked slurry can contaminate the hydraulic oil and subsequently damage to the hydraulic end components, eventually, increase the user maintenance costs. In order to eliminate this problem, a double-layer diaphragm structure without leakage is developed by studying the working principle of both the pump and the diaphragm and by analyzing the single-layer diaphragm structure, the rupture forms of diaphragm and the causes for rupture. Based on an analysis of design principle and working mechanism of the double-layer diaphragm, the pump with a double-layer diaphragm structure shows no any difference in the performance from the pump with a single-layer diaphragm, but also the drawback of the single-layer diaphragm is removed. A practical application proves that the double-layer diaphragm structure can completely meet the requirements on design under actual working conditions. Thus, such a structure is greatly valuable to study on the reciprocating hydraulic diaphragm pumps for slurry transportation, and also of significance to explore other similar diaphragm structures in a certain degree. |
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2017 Vol. 35 (7): 577-580
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