Blade Lean and Tip Leakage Flows in Highly Loaded Compressor Cascades

Blade lean has been intensively utilized in axial compressors. In this study, three families of highly loaded compressor cascades featuring different aspect ratios (AR) with different levels of blade lean were designed and simulated with and without tip clearance. The influences of blade lean on corner separation and tip leakage flow (TLF) were investigated. Results show that blade lean can exert spanwise pressure gradient confined to the fore part, spanwise mass flow rate re-distribution exhibiting differently at fore and rear part of blade, and stage reaction variations. AR has a significant influence on blade lean. With the increase of AR, corner separation grows significantly and requires a higher lean level to be controlled. TLF eliminates corner separation of linear cascades but also increases the loss of leaned cascades; blade lean introduces 22% higher tip leakage mass flow, but exhibits 43% (blade M) and 38% (blade E) lower tip leakage loss. The flow mechanism can be mainly accounted by the reduction of bulk flow velocity, tip leakage velocity and the velocity difference near leading edge (LE). High AR cascade induces re-distribution of TLF along blade chord and reduces leakage loss compared with low AR counterpart.