Research On Automatic Design Optimization Of Axial Flow Impeller

To improve the overall performance, reduce the cost, and shorten the design period is an important target of the design of axial flow pumps. The impeller is the heart of a water pump and the main origin of its behavioral efficiency, stability of the operation and the anti-cavitation performance. Therefore, to automate the optimum design of impellers can help to improve the performance of axial flow pumps.This dissertation combines the numerical optimum technology with the advanced CFD simulation technique, replaces designers'experience by mathematical models for controlling of the blade design direction. Finally a platform for automation of the optimum design of axial flow pump impellers is built in this paper. The platform which based on the multidisciplinary optimization software iSIGHT takes the existing axial-flow impeller model as the research object, and analyses the automation of the optimum design of it. These studies mainly consist of the following aspects:First, use CFX (fluid analyze software) to simulate the internal flow field of the impeller model under the design condition by the solution of the Navier Stokes equation and the standard k-εturbulence model. Then, calculate the characteristic parameters of the impeller model as the initial value for the next optimum design.Second, determine the distribution of the cascade solidity and the airfoil setting angle of ten profiles of the blade's development direction. Then run the program OPTPUMP.exe to generate the discrete points' data of the blade profiles, which can build parameterized modeling of the initial blade. The cascade solidity of each profile of the blade is parameterized by the cascade solidity of the blade tip and the multiple of the cascade solidity of the blade root. The airfoil setting angle of each profile of the blade is fitted with second polynomials. These provide the design variables for the automatic optimization design of the follow-up work.Third, the TurboGrid and CFX are integrated in iSIGHT. The automatic optimum design platform for axial flow impeller was established, in which the parameterization modeling, mesh, flow computation and numerical optimization are combined together. Then the automatic optimum design for the initial blade under the design condition was carried out. The optimum objective is maximum the efficiency of the blade, and the constraints are the head and the NPSH of the blade. Compared with the initial blade, the performances of the optimized blade are improved obviously. The results show that this automatic optimum design method is feasible and effective.