Implementing the Digital Design Process for the Development of a Centrifugal Fan Impeller in the Undergraduate Engineering Curriculum

Abstract

For the past two years, Mechanical & Aerospace Engineering students at the University of Florida have been designing and manufacturing impellers for a centrifugal fan. The method is taught in our Thermo-Fluids Lab and Design class and involves using Euler's Turbomachine Equation and creating velocity diagrams to predict performance. A limitation of the Euler Turbomachine Equation is that it is based on a finite control volume analysis which prescribes blade angles at the entrance and exit of the impeller, but provides no information on the number or geometry of the blades within the impeller. Another limitation of the equation is that it assumes an infinite number of blades of zero thickness that results in uniform flow at the inlet and the exit, while a real impeller has a distinct velocity profile in between each blade that leads to losses not predicted by the equation. A Digital Design Process has evolved whereby students create an initial design using the Euler method, and then create a digital model using Solidworks, and then follow that up with a computational fluid dynamics (CFD) to optimize their design. After optimization, the students manufacture a prototype of their impeller using a 3-D printer, and then test the impeller in the lab fan performance apparatus. The results of their efforts as well as the issues involved in managing such a project with about 125 students per semester will be discussed in this paper.