This paper presents a unified slip model for axial, radial, and mixed-flow impellers. The core assumption of the model is that the flow deviation or slip velocity at impeller exit is mainly originated from the blade l...
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ISBN:
(纸本)9780791844021
This paper presents a unified slip model for axial, radial, and mixed-flow impellers. The core assumption of the model is that the flow deviation or slip velocity at impeller exit is mainly originated from the blade loading near the discharge of an impeller and its subsequent relative eddy in the impeller passage. The blade loading is estimated and then used to derive the slip velocity using Stodola's assumption. The final form of the slip factor model can be successfully related to Carter's rule [1] for axial impellers and Stodola's [2] slip model for radial impellers, making the case for this model to be applicable to axial, radial, and mixed-flow impellers. Unlike conventional slip factor models for radial impellers, the new slip model suggests that the flow coefficient at the impeller exit is an important variable for the slip factor when there is significant blade turning at the impeller discharge. This explains the interesting off-design trends for slip factor observed from experiments, such as the rise of the slip factor with flow coefficient in the Eckardt A impeller [3]. Extensive validation results for this new model are presented in this paper. Several cases are studied in detail to demonstrate how this new model can capture the slip factor variation at the off-design conditions. Furthermore, a large number of test data from more than 90 different compressors, pumps, and blowers were collected. Most cases are radial impellers, but a few axial impellers are also included. The test data and model predictions of the slip factor are compared at both design and off-design flow conditions. In total, over 1,650 different flow conditions are evaluated. The unified model shows a clear advantage over the traditional slip factor correlations, such as the Busemann-Wiesner model [4], when off-design conditions are considered.
作者：
zhao ChaoyangXin ZhouGuiqin Wangxuwen BingFreshwater Fisheries Research Center
Chinese Academy of Fishery Sciences Wuxi 214081China Wuxi Fishery College
Nanjing Agricultural University Wuxi 214081 China Wuxi Fishery College Nanjing Agricultural University Wuxi 214081 China College of Animal Science and Technology Jilin Agricultural University Changchun 130118 China Freshwater Fisheries Research Center Chinese Academy of Fishery Sciences Wuxi 214081China
Remote ischemic postconditioning (RIP) refers to an ischemia conducted in a distant organ that protects against a prior ischemia in another organ. We tested whether RIP protects against focal ischemia in the rat brain...
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Remote ischemic postconditioning (RIP) refers to an ischemia conducted in a distant organ that protects against a prior ischemia in another organ. We tested whether RIP protects against focal ischemia in the rat brain. Stroke was generated by a permanent occlusion of the left distal middle cerebral artery combined with a 30-min occlusion of the bilateral common carotid arteries (CCA) in male rats. After CCA release, RIP was generated by three cycles of 15-min occlusion/15-min release of the left-hind femoral artery. The results showed that rapid RIP performed immediately after CCA release reduced infarction by 67% measured at 2 days after stroke. In addition, delayed RIP initiated as late as 3 h, but not 6 h, still robustly reduced infarction by 43% 2 days after stroke. RIP's protective effect was abolished by injecting the protein synthesis inhibitor, cycloheximide, and the afferent nerve blocker, capsaicin, suggesting that RIP blocks ischemic injury by modulating protein synthesis and nerve activity. Nevertheless, rapid RIP did not reduce infarction size 2 months after stroke while it ameliorated the outcome of the behavioral test. In conclusion, RIP attenuates brain injury after focal ischemia. (C) 2009 Elsevier B.V. All rights reserved.
The design parameters and the operational aspects ofmine water disposal project in Fengxi Xinyu coalmine were *** primary disposal process included neutralization,coagulation settling and mechanical filtration process...
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The design parameters and the operational aspects ofmine water disposal project in Fengxi Xinyu coalmine were *** primary disposal process included neutralization,coagulation settling and mechanical filtration process,and reverse osmosis (RO) process for desalination were used to treatmine water with high-turbidity,high-hardness and *** results showed that the pretreatedmine water could be used for washing coal,and the quality of permeate liquid of RO for water with milk excelled the national standards for drinking *** water source was supplied to the coalmine,the recycle ofmine water was resource engineering practice.
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