| Turbomachinery mainly refers to a kind of energy conversional mechine that depends on the impeller and the working fluid continuous flow through the blade of the impeller, has a very prominent position and plays a vital role in the development of national economy and national defense. However, a period of time for the pneumatic, materials, manufacturing, and other technical limitations, especially for the lack of large actuarial capacity, innovation and development of turbomachinery has been constrained, there is a larger gap between developed countries in some key areas. With the rapid rise of computer technology, the development of turbomachinery is coming to a new spring, because there are a large number of advanced parametric CAD and CFD flow analysis softwares have arisen, and make the computer numerical simulation experiment instead of a physical prototype testing possible, which significantly reduced the development of turbomachinery design cycle and cost, but also makes it possible to accelerate new product development.There are mainly two parts of this paper. Firstly, using the traditional thermal design method combined with advanced CFD numerical simulation technology, for a freight locomotive which requires the centrifugal cooling fan with the performance of large flow and high total pressure, this paper uses an innovative oblique hub disk structure, independently researchs and designs a new type of forward multi-blade centrifugal cooling fan impeller. This new mechine, compared to the same type of imported fans with the same dimensions, has increased the total pressure 11.8% in the condition of 25.5% speed lower, entirely replaces the imported fan to carry out localization successfully. At present, the independent design of new high total pressure and large flow centrifugal cooling fan wiht oblique hub disk and forward type multi-blade impeller has been replaced the imported fan loading into operation.Secondly, based on the study of the fan localization design, further using the advanced CFD numerical simulation and optimization software NUMECATM/Design3D, this paper analyzes the performance response of the independently design parametric AP1000 RCP mix-flow impeller hydraulic model from the four aspects of the blade installation angle of the inlet and outlet,the form of blade inlet edge,impeller outlet diameter and the blade thickness variation along the flow lines. Taking all factors then, it has established the multi-objective optimization function model which sets improving efficiency and reducing the head as the optimization objective to optimize the impeller performance. Finally it has obtained an excellent imperller hydraulic model than the original by the efficiency increases and the head meets the design requirements, espespecially the critical cavitation number decreased about 21.86% which making the pump cavitation performance improved significantly after the optimization. Beyond the optimization of the hydraulic performance,it has a finite element analysis of structural strength in the base of the optimized impeller, and ultimately obtained that the optimized impeller model not only has an excellent hydraulic performance, but also a good structural strength that fully meet the safety of the RCP requirements.All the above work benefits from the research and design methods of turbomechinery being continuous innovating and developing which makes a reference for future research work,especially for carring out the local process of the core technology of the RCP research,design and manufacturing is significant.
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