Matching characteristic of tandem airfoil was researched by using numerical simulation.The forward and aft blade working characteristics were analyzed

and then

an attempt to optimize the blades with the controlled diffusion airfoil was made

by doing which a higher cascade performance was achieved.The result indicates that:the working status of forward blade changes obviously with the incidence

and the incidence range of whole stage almost depends on forward blade alone;aft blade incidence depends on the working status of forward blade deviation.Flow diffusion and turning in aft blade is weakened because of forward blade trailing edge's piling up

thus the working status of aft blade is improved on condition that the forward blade has large flow separations.Based on the analysis of tandem airfoil working characteristics

routine blade was replaced with controlled diffusion airfoil and a good result was achieved.