Research on the Characteristics of Passage Center-line of Double-channel Impeller

A formula was deuced,which shows the relation between the outlet angle of center line of channel and wrap angle,variant coefficient,if variant Archimedes spiral is assumed the curve of center line of plate plane.It is the basis for controlling outlet angle of channel.Another formula was also derived for calculation the normal distance from points on the center line to outer diameter and cross-section area.By refer to the mathematic model of axial plane published in document,a numerical method was present for finding out the outlet point.Research for the method to draw 3-D passage center-line by CAD,compute the length of it and decide the split points position was also carried out.