Comparative Study of Blade Shape Design of Centrifugal Fan Impeller

For a centrifugal fan impeller the blade shape can be defined using two parameters: the blade angle and the blade width. There are different design methods depending on the assumption made on both the blade width and the blade angle. In this paper four design methods are presented: constant blade width and variable blade angle; hyperbolic blade width and variable blade angle; hyperbolic blade width and constant blade angle; linear blade width and variable blade angle. The sequential algorithm for solving the characteristic system of equations, which defines the blade geometry, is implemented in a MATLAB script file, for which principal code lines are explained. In the solving process of the characteristic system of equations for all four design methods considered, different relationships for relative velocity are obtained. The comparative graphical analysis of impeller blades obtained by all of the four design methods, as well as the blade geometry parameters is presented.