Multi-objective Optimization Design of High-turning Tandem Cascade in Compressor
In order to carry out the optimization design of tandem cascade,the parametric modeling meth-od of tandem cascade based on superimposing thickness on camber line was developed,and the multi-ob-jective optimization design platform of tandem cascade based on Kriging surrogate model and NSGA-Ⅱoptimization algorithm was constructed.The high-turning blade profile with camber angle of 54.15° from the mid span of the last stage stator of a multi-stage axial compressor was taken as the prototype to perform the retrofit and multi-objective optimization design of tandem cascade.The sensitivity of geometric param-eters of tandem cascade was analyzed.Results show that the stagger angle of forward airfoil,axial over-lap,circumferential percent pitch and camber angle ratio have the most significant influence on the aero-dynamic performance of tandem cascade.Comparing with the prototype single-row cascade,the axial length of the optimized tandem cascade is shorter.The total pressure loss coefficient of the optimized tan-dem cascade is smaller and the static pressure ratio is larger than those of the prototype cascade at the same incidence angle.The available incidence angle range of the optimized tandem cascade is increased by 33.3％,and the total pressure loss coefficients are decreased by 39.1％,3.3％and 11.9％at inci-dence angles of-12°,-2° and 4° respectively.For the optimized tandem cascade,the load of forward airfoil is decreased and the load of aft airfoil is increased,the reasonable gap shape can weaken or sup-press the boundary layer separation,thus the aerodynamic performance within the full incidence range is increased.
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