Abstract
Due to much lower cost of development and production, circular arc blades are often applied to axial flow fans. However, compared with NACA 65 profile, circular arc blades have higher losses, which are caused by the formation of separation bubbles or complete separation at the leading edge. Therefore, it is necessary to identify a specific geometry of leading edge, which can reduce the separation bubbles or complete separation. In this article, circular arc blades with different leading edges are examined by numerical method. The numerical investigations were performed with Reynolds numbers of [Formula: see text] and [Formula: see text]. All examinations were performed for different incidence angles. The influence of the sidewall on the flow loss and behavior is taken into account. In this article, the influence of leading edge geometry and Reynolds number on the flow losses is shown. The occurrence of flow behavior such as separation bubbles at the leading edge, secondary flow, and corner stall is shown and discussed. The flow structure on the blade and the corresponding sidewall region is illustrated with numerical streamline figures.
Highlights
Due to the resource shortage, many blade profiles have been designed and tested to develop a blade with high efficiency, for example, the well proven and explored NACA profiles (National Advisory Committee for Aeronautics).[1]
The z and Db of original circular arc blade have a good agreement between numerical and experimental methods
Circular arc blades with different leading edges are investigated by numerical method
Summary
Due to the resource shortage, many blade profiles have been designed and tested to develop a blade with high efficiency, for example, the well proven and explored NACA profiles (National Advisory Committee for Aeronautics).[1]. In order to reduce the manufacturing costs, an alternative approach is circular arc blade. The flow losses of circular arc blade is higher than NACA 65 profile. It is necessary to find a way to reduce the flow losses of circular arc blade by investigating the flow structure, aerodynamic quality values, and different profile geometries. The losses of a turbine blade can be divided into profile loss and secondary flow loss. The profile loss is caused by the growth of the boundary layer on the blade and the formation of separation bubbles. The secondary flow loss is caused by the friction of the blade and sidewall. In this article, the flow behavior such as secondary flow and separation bubbles are investigated
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