Effect Of Positive Curved Blade On Aerodynamic Performance Of High-Turning Compressor Cascade

High stage load or high stage pressure ratio of the compressor system is one of the most important facts for an aircraft engine with thrust-weight ratio of 15~20 or higher. To reach higher pressure ratios with fewer stages, development of a highly-loaded blade by which flow can be highly turned is necessary. However, this will lead to aggravation of separation and increment of secondary loss in the compressor cascade. It is of high value to study the inner flow structure and loss increase mechanism and explore the method of lowering loss inside high turning compressor cascades.In this paper, a detailed experimental investigation was carried out in a low speed, large scale wind tunnel with four different compressor cascades composed of conventional straight blades, positive curved blades with curved angle of 15°, 20°, and 25°respectively. At design and off-design conditions, the cascade flow fields were measured by five-hole probe detailed, the static pressure was measured by tapping on the cascade surfaces and ink-trace flow visualizations is also conducted. To get details of flow field inside the cascades at design condition, numerical simulation was carried out by the commercial CFD software——FLUENT. Experimental and computational result shows that flow in the high turning compressor cascade is highly tridimensional. In the flow passage of Straight cascade, loss concentrates near endwalls and in the endwall corner region. There is weak reverse flow in the corner. In the case of positive curved cascade, compared with straight cascade, the loss near endwall decreases while increases near midspan; the blade loading is reduced at the endwall and increased at the midspan; the length of axial reverse pressure gradient is shorter near endwall and longer at midspan. Both of the two configurations can eliminate reverse flow in the endwall corner region and reduce the corner flow separation region notably. Spanwise C-shape static pressure distribution was established on the suction surface of all blades, and it is more intensive in positive curved blades.At design condition, the lowest mass-weighted average total pressure loss appears in the positive curved cascade with curve angle of 15°, and the highest...