Effects of a Curved Surface of the Blade on the Performance Characteristics of Axial Flow Rotors

Abstract

The benefit of using a Computational Fluid Dynamics (CFD) technique is to predict the effects associated with non-radial stacking (NRS). Three-dimensional (3D) flow field for NRS blades of an axial turbomachine is studied. The non stacking line of the fan is provided by a curved surface by means of enlarging blade airfoil only at the base of the fan blade. The effectiveness of the NRS on the axial fan rotor of low-aspect-ratio was studied in two separate case studies a standard blade (SB) and a curved blade (CB). In developing a complete structured hexahedral mesh for the entire computational domain, comparative studies of CB and SB were conducted at the design and off-design flow rates. The structured mesh technique minimizes cell counts, cell skewness, and enables cost-effective CFD investigation. The results are presented in the form of local radial velocity, local ideal and total pressure rise of the outlet as well as the static pressure on the blade suction side. Specifically, it is pointed out that in the design point the CB rotor exhibits the highest efficiency for the most part of the entire span, whereas SB exhibits the lowest efficiency along the entire span. While in the off-design point, the CB rotor exhibits the highest efficiency at the blade hub only.