Numerical investigations of aerodynamic characteristics in highly loaded tandem cascades with end-bend

Tandem cascades and end-bend blades can reduce compressor losses and promote energy conservation. In this study, a vortex model tailored for tandem cascades is proposed. Numerical investigations are conducted to elucidate the influence of end-bend heights and angles on aerodynamic characteristics. A quantitative assessment of the loss contribution for each vortex is provided based on loss weight coefficients. The findings demonstrate that end-bend angles exert a more pronounced impact on aerodynamic characteristics than end-bend heights. Although the implementation of end-bend increases the loss of the front blade trailing edge shedding vortex, it reduces losses by weakening the passage vortex and the rear blade trailing edge shedding vortex, resulting in a net decrease of the total loss. The end-bend blade optimizes the loading profile near the endwall, characterized by an expanded low-pressure zone behind the gap. A comparative analysis is performed among four tandem cascades: straight, curved, end-bend, and combined curved-end-bend. The correlation between losses, vortices, and topological structures is established by using topological analysis together with the vortex model. It is a crucial research methodology for elucidating the mechanisms of loss generation and vortex dynamics in tandem cascades with end-bend.