Based on the redesign requirement of stator blade with high critical inlet Mach number of a highly-loaded axial flow fan

the performance contrast experiment of prototype single cascade and redesign tandem cascade was presented. The improvement effect of tandem cascade at high inlet Mach number was also evaluated by analyzing the internal flow field parameters of both types of cascade.Results show that the tandem cascade has significant advantages in reducing flow loss and increasing compression capacity than the single cascade. Compared with the single cascade

the total pressure loss coefficient and the static pressure ratio of the tandem cascade reduced by 19% and enhanced by 3.1%

respectively. Accordingly

the flow blockage phenomena of the single cascade at original design condition are eased basically. The front blade can restrain the boundary layer development on suction surface of the rear blade of the tandem cascade

thus the rear blade has good operating performance.