LAUSR

The supersonic through-flow variable-pitch tandem fan offers significant potential to expand the acceptable inflow range of the fan. However, owing to its higher degree of freedom, the adjustment relationship between the front and rear blades needs further clarification. This study uses numerical simulations to explore the adjustment and loss mechanisms of the rear blade stagger angle in a variable-pitch tandem cascade across different operating modes. In the transonic mode, cascade performance changes monotonically with the rear blade stagger angle. A larger stagger angle can significantly reduce the shock boundary layer interaction on the suction side of the rear blade, while weakening the maximum boost capacity of the cascade. In the supersonic through-flow mode, the favorable pressure gradient enables the rear blade to operate at a smaller positive incidence, improving its flow turning ability and alignment between the inlet metal angle of the rear blade and the inflow angle of the front blade under positive incidence conditions. In the high-speed windmilling mode, it is crucial to achieve a balance between the separation at the trailing edge of the suction side of the rear blade and the shock-induced separation on the pressure side. Notably, the optimal trend of the rear blade stagger angle adjustment in these two modes shows an inverse relationship.