The 'multi-point design' approach for single airfoils in aeronautical engineering is introduced into the optimal design for diffuser cascades of centrifugal compressors. Genetic algorithms are used to solve the multi-point problem. The proposed approach is applied to a 'two-point design' of a real diffuser cascade. The numerical results show that a group of optimal blade profiles can be obtained, from which the designer can select performance compromises for the two given design condition points.

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The centrifugal impeller with arbitrary surface blades is a very important component in automobile, ships, and aircraft industry, and it is one of the most difficult parts to process. Focusing on the machining efficiency improvement, combining the geometric advantages of ruled surface and arbitrary surface, and utilizing the efficient and accurate advantages of flank machining and point machining, this article presents a novel and targeted tool-path generation method and algorithm for five-axis flank machining of centrifugal impeller with arbitrary surface blades. In light of specific characters of different surfaces, the analyses of two different impeller blades are proposed first, the more characteristic and complex geometrical structures of the arbitrary blade are achieved. In rough machining, an approximate ruled surface blade is obtained, and a simple channel is achieved; the flank milling of the centrifugal impeller with ruled surface blades is achieved relative to the point milling of the centrifugal impeller with arbitrary surface blades; and the triangle tool path planning method is added in this process to save the machining time and cost collectively. Furthermore, in semi-finish machining, the approximate sub-ruled blade surfaces are calculated, and a new flank milling method of the sub-ruled blade surfaces is achieved; a new solution for tool interference is achieved in this process and the generation of non-interference tool paths becomes easy. Machining experiments of two different impellers are presented as a test of the proposed methods.

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This article presents an efficient tool path generation method for five-axis machining of a difficult machined centrifugal impeller. Geometry of centrifugal impeller is analyzed, and the inherent low efficiency of the machining of difficult machined centrifugal impeller is obtained. The tool path curves which are calculated by the most common isoparametric method are shown to testify the waste in machining. The new type machining layers are calculated, and the new machining regions are achieved. The new tool path curves in each new machining region are calculated, and they are sparser and triangular. For the inherent low machining efficiency of difficult machined centrifugal impeller, the machining time can be greatly reduced just by the optimizing tool path generation method in this article. Numerical simulation and a real test impeller are presented as the test of the proposed method.