Prediction of Performance of a Variable-Pitch Axial Fan with Forward-Skewed Blades

For a single-stage variable-pitch axial fan, the aerodynamic performance and through flow with and without blade skewing are examined numerically. Simulated results show that the total pressure rise and efficiency increase by 2.99% and 0.16%, respectively, with the best forward-skewed angle of theta = 3 degrees at the design conditions. At the blade pitch angles of beta = 29 degrees and 35 degrees, the total pressure rises and efficiency of the fan with theta = 3.0 degrees under the highest efficiency point change by -0.55%, -0.53% and 1.39%, 2.11%, respectively. At design and off-design conditions, the forward-skewed blades mitigate tip leakage and delay the emergence of separation flow at the blade root, these benefits are higher at the higher blade pitch angle. The theta = 3.0 degrees forward skew effectively raises the stage performance of the impeller and guide vanes.