Influence of Gap Shape on Flow Characteristics of Highly Loaded Compressor Tandem Cascades

Gap shape is an important factor affecting the tandem cascade performance. This paper uses the gap expansion angle (K_b-b) to define gap shape and studies the effect of K_b-b on the two-dimensional flow field and flow characteristic near the endwall in a highly-loaded subsonic tandem cascade. By changing the incidence angle from -20 to 10^°, the K_b-b value increases, and the two-dimensional tandem cascade performance improves at positive incidence angles, while it descends at zero and negative incidence angles. Due to the influence of K_b-b on the camber of front and rear blades (RB), the optimal K_b-b should provide appropriate load distribution and sufficient gap flow strength. The corner stall more likely appears on the front blade near the endwall, which can suppress the flow separation on the rear blade to a certain extent. The K_b-b value near the endwall should be slightly larger than in the midspan to ensure a sufficient operating range for the front blade.