Conversion from Free-Form Surface to Ruled Surface of Centrifugal Compressor Impellers

Abstract

At present, there are several conversion methods exist, which are based on cutter fixing at a point on the blade surface to swing around the blade surface, searching for a position where the error between the cutter and the free-form surface is the smallest. They rarely take into account the benefit from searching cutter position along the blade’s tangential direction, and ignore the possible optimal cutter position from such search. In this paper, we propose a new cutter search method that allows this tangential swing in additional to meridional plane swing of the cutter in searching for the optimal position of the cutter. The mathematics of the method is described, and two different centrifugal compressor impellers with free-form blade surfaces are employed as test cases. The results show that this method can well convert the free-form surfaces of the impeller blades into ruled surfaces.