| Efficiency is one of the most important performance index of centrifugal pump. Hydraulic loss in pressurized water chamber is high when centrifugal pump works, which affects badly on centrifugal pump working efficiency. Diffuser of pressurized water chamber is the primary pass through parts of centrifugal pump. From diffuser inlet section to outlet section, there are two changes that the sectional area expands continuously and the sectional shape changes gradually from irregular to regular. Traditional design method of diffuser just pays attention to its sectional shape variation and ignores the influence of hydraulic loss caused by sectional area enlargement on pump hydraulic performance. Therefore, this paper takes pressurized water chamber diffuser as research emphases, through theoretical analysis, numerical simulation and experimental study, performs precisely investigations for influence of diffuser sectional area change regulations of pressurized water chamber on centrifugal pump. The key work and relevant results are as follows:1. Analyze research progress of centrifugal pump pressurized water chamber and the theory of numerical simulation for centrifugal pump. Perform numerical simulation for carrier pump IS50-32-125 and by this means point out the detailed method of modeling and meshing for fluid domain of centrifugal pump in order to present the whole process of numerical simulation for centrifugal pump.2. Perform theoretical analyses and calculating for hydraulic loss in pressurized water chamber of centrifugal pump. Put forward the ‘L’ regulation which the diffuser sectional area of pressurized water chamber expands uniformly and the ‘U’ and ‘N’ regulations which the diffuser sectional area of pressurized water chamber expands non-uniformly. Through analyses and calculations, present the mathematical model of realizing pressurized water chamber of semicircle inlet diffuser sectional area change according to the three regulations and the way of realizing pressurized water chamber of arbitrary-shaped inlet diffuser sectional area change according to the three regulations.3. Select 3 model pumps and perform numerical simulation for each diffuser sectional area change regulations(‘L’, ‘U’ and ‘N’) in design condition. Analyses of external characteristic and internal characteristic based on numerical simulation results indicate in design condition, ‘L’ diffuser sectional area change regulation is the best pattern. Compared with ‘U’ diffuser sectional area change regulation, the head of delivery of 3 model pumps raises optimally 1.26% and averagely 0.74%, and efficiency of 3 model pumps raises optimally 0.62% and averagely 0.51%.4. For the 3 model pumps, perform numerical simulation in large rate of flow and small rate of flow. Summarize 3 model pumps’ performance curves in the condition of diffuser sectional area change according to the three regulations. Analyses of velocity vector of internal flow field and performance curves feature indicate that hydraulic loss in pressurized water chamber is higher in the method of diffuser’s traditional design. The influence of three diffuser sectional area change regulations on centrifugal pump is incongruous in different working conditions, but the head of delivery and efficiency of model pumps are higher when diffuser sectional area changes according to ‘L’ on the whole. That’s to say centrifugal pump performance is the best when diffuser sectional area of pressurized water chamber expands uniformly.5. Based on the results of numerical simulation, perform experimental study for model pump which diffuser sectional area of pressurized water chamber expands uniformly. Results show that the head of delivery of centrifugal pump raises 1.14% and efficiency raises 0.52% in design condition. The conclusions of numerical simulation research and experimental study are identical, which states clearly the methods of investigations are reasonable and the conclusions are dependable. |
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