A numerical investigation of the dual performance characteristics of a small propeller fan using viscous flow calculations

Abstract

Dual performance characteristics of a small propeller fan are numerically investigated using viscous flow calculations. A performance test of the fan showed dual performance characteristics, i.e. radial type characteristics at low flow rates and axial type characteristics at high flow rates. The present work is aimed at investigating a sharp variation in the performance characteristics at low flow rates. The finite volume method is used to solve the continuity and Navier–Stokes equations in the flow domain around the fan. The performance parameters obtained from the calculations are compared with the measured values for the various flow rates. Comparisons between the predictions and the measurements indicate that the predicted results are in good agreement with the measured values and reasonably reproduce the sharp variations of the performance parameters at low flow rates. These comparisons show that the present numerical method is capable of resolving the performance characteristics with reasonable accuracy. At low flow rates, it has been found that the flow enters the fan in an axial direction and is discharged radially outward at the tip, which is much like the flow characteristics of a centrifugal fan. The centrifugal effect at low flow rates makes a significant difference in the performance characteristics of the fan.