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Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper studied the selection and modification of the main pumps of the second pumping station of Huai'an by using CFD. The study analyzed the operation status of the main pumps and confirmed the necessity of reinforcement of the main pumps of the second pumping station of Huai'an. Selecting the main pumps for the second pumping station of Huai'an was carried out based on its operation data over these years, and the excellent hydraulic model of TJ05-ZL-02 was chosen. The hub ratio of the hydraulic model TJ05-ZL-02 is 0.4, while the original hub ratio of the second pumping station of Huai'an is 0.4667. Therefore, the hub ratio of the chosen hydraulic model must be modified. At the same time, to meet the requirements of diversion, drainage engineering of the second pumping station of Huai'an ensured that the pump model modified has the similar performance with the chosen hydraulic model, reduce the coefficient of flow and decrease the head of the high efficient area. First of all, this paper analyzed the influence of the main parameters including cascades dense degree and blade angle of each section on the hydraulic performance of axial-flow pumps. Which controlling the change of directions of the blade hydraulic performance. And use CFD to verify the hydraulic performance of the axial-flow pump when parameters changes. then decided the final retrofit design program. The feasibility of retrofitting program has been demonstrated through the numerical simulation of comparing the axial-flow pumps device before and after modification. Numerical simulation of the pump device adopts the standard k-ε model, and calculated the six flow point at 280, 300, 320, 340, 360 and 380 L/s, respectively. Finally, the experimental studies of the model pump showed that, model test performance curve trend was consistent with the numerical performance curve. According to flow-head curve , there is a little deviation in small flow area, and the flow-efficiency curve fit well, the performance of numerical simulation and experimental study has been mutual authentication. The head is in the range of 3.5 to 4.5 m, and the flow of 300 to 350 L/s after modification, which will fully meet the requirements of diversion, drainage and irrigation of the second pumping station of Huai'an for current and future. After modifications, the efficiency of axial-flow pumps device was over 70%, while the efficiency of the second pumping station of Huai'an initially was 68%, with nearly 20% increased, which play a huge role in increasing diversion performance and reducing cost. And the research shows that hub ratio of modified pump increasing may decline the overall performance of axial-flow pump, which indicates that there is the most optimal hub ratio for a specific speed of axial-flow pump,. It has very important significance for the optimal design of axial-flow pump hydraulic model and the large-scale pumping station renovation. [ABSTRACT FROM AUTHOR]

Hydropower is one of the most reliable source of green energy and is widely used to meet real-time electricity demand. The ever escalating energy demand and iterative development in hydropower have pushed the generation of hydropower towards a low lost-cost and more flexible state which can work in a wider hydrodynamic region without compromising its performance. So the research on multidisciplinary optimization of hydro turbine needs to be carried out. Francis-type turbine is attractive because the efficiency of the unit at its design point exceeds the other types. As mentioned above, with the needs of robust operation in wide region without compromising its performance, the Francis turbine runner has to be optimized under multidisciplinary constraints. Multidisciplinary optimization technology of Francis runners has always been a key point in the field of turbine research. The coupling strength of each variable is the basis for establishing a concise and efficient multidisciplinary optimization strategy. So in the multidisciplinary optimization of Francis runner, it is necessary to analyze the coupling strength of design variables. In this paper, based on the global relative sensitivity of design variables, a coupling strength analysis method of runner design variables has been presented. First, combing three-dimensional (3D) inverse design theory with curve parametric method, a parametric 3D inverse-design method has been developed to control the Francis runner geometry. According to this parametric 3D inverse-design method, the meridional flow passage and geometry of runner blade can be controlled by a set of discrete parameters. These parameters are treated as runner design variables. The hydraulic efficiency of turbine, the minimal pressure coefficient on runner blade and the maximum static stress of blade are selected as objective functions. Then the global relative sensitivity of each objective function to design variables is calculated by an improved Morris OAT method. Compared with the traditional Morris OAT method, an optimal Latin hypercube design technique is adopted in the improved method. The optimal Latin hypercube design technique has a better space filling property than the traditional one. So the sampling only needs to be done once, which reduces the time of global relative sensitivity analysis without compromising its precision. On the basis of the improved Morris OAT method, the speed of global relative sensitivity calculation is improved obviously. Secondly, the set which contains global relative sensitivity of design variables is treated as universe, and the semi-trapezoidal function in fuzzy mathematics is imported to quantify the membership of each variable to objective functions. After obtaining the membership of each variable, a judgment principle of variable's coupling strength is presented in this paper. According to this judgment principle, the coupling strength property of each design variable can be defined as strong coupling, middle coupling and weak coupling. Finally, based on the coupling strength of each design variable, the multidisciplinary optimization strategy of Francis runner is established. And then the multidisciplinary optimization of Francis runner can be carried out. In order to validate the coupling strength analysis method, an application case is presented in the paper. In that case, the design variables of a Francis turbine runner with the head of 200 m are chosen as the analysis object. From the analysis result, it can be found that only the coupling strength property of maximum thickness is weak coupling, and the others are middle coupling. According to the result, a multidisciplinary optimization strategy is established and used in the optimization of Francis turbine runner. After optimization, both the hydraulic performance and strength property of the optimized runner are improved, demonstrating the effectiveness of the coupling strength analysis method. In conclusion, the method proposed in this paper can be adopted to analyze the coupling strength of design variables of Francis runner. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the computational fluid dynamics (CFD) software, this paper studied the influence of the post guide vane under different sweep angles on the hydraulic performance of the axial flow pump device. The purpose was that through changing the angle of blade forward and back sweeping, the post guide vane could as much as possibly recover the velocity circulation of the impeller outlet, at the same time, the hydraulic loss of the guide vane could be not too large, so as to improve the hydraulic characteristics of the axial flow pump device. This paper used the Turbo-Grid software to build the model and carry out the mesh division of the post guide vane and the impeller, used the Pro/E software to build the models of the inlet straight pipe with water-guiding cone and the standard 60°outlet pipe, and then used the ICEM to carry out the structured-grid division. Then, the hydraulic property of the axial flow pump device was analyzed through the CFX software. There were 6 different post guide vane sweeping schemes, which were forward sweep 24°, forward sweep 16°, forward sweep 8°, 0°, back sweep 8°and back sweep 16°. Numerical simulation of the axial flow pump device adopted the standard κ-ε model, and each sweeping scheme of post guide vane had 8 flow points including 280, 300, 320, 340, 360, 380, 400 and 420 L/s. The influence of different post guide vane sweeping angles on the energy characteristics of the axial flow pump was analyzed under the design condition and the non-design condition. Then the hydraulic loss of the post guide vane and the outlet pipe was calculated and analyzed. Finally, the experimental study of the energy performance of the axial flow pump device was carried out. The results showed that, the test performance curve trend was consistent with the numerical simulation; the flow-head curve showed a little deviation under small flow, other parts fitted well, and the flow-efficiency curve did not fit so well, but the error between the test data and the numerical data was within 3% that was very small. The results from numerical simulation and experimental study had been mutually authenticated. The results of the study showed that: under small flow condition and near design condition, the energy performances of axial flow pump device of different sweep angles had comparatively large difference, on the other hand, the energy performances were almost the same under large flow condition; under the design condition, the flow separation of the airfoil tail of back sweep guide vane was very serious, and hydraulic loss of the guide vane was very large; the guide vane of forward sweep 16° could as much as possibly recover velocity circulation of the impeller outlet, also its hydraulic loss was the smallest. Therefore, the guide vane of forward sweep 16° has a good effect to improve the energy performance of the axial flow pump device. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)