In order to prolong the service life of multistage axial compressors, it is increasingly important to study the influence of blade surface roughness on the compressor performance. In this paper, a five-stage axial compressor of a real aero-engine was selected as the research object, and an equivalent gravel roughness model was used to model the roughness based on measured blade surface roughness data. Furthermore, the impact of blade surface roughness on the performance at design rotational speed was studied by full three-dimensional numerical simulation, and the mechanism of performance variation caused by the roughness was discussed combined with quantitative and flow field analyses. The results show that, when the blade surface roughness of all blades increases, the peak total efficiency decreases by approximately 0.4%, the blocking mass-flow decreases by approximately 0.3%, and the stable working range changes little. When the surface roughness of all rotor blades increases, the performance decline is close to that of all rotor and stator blades, and the variation in stator blade roughness has little effect on the compressor performance. Regarding the variation in roughness, the performance of the latter stage is more sensitive than that of the previous stage, and the decline in the performance of the fifth stage contributes the most to the total performance degradation of the compressor. Once the surface roughness of the fifth-stage rotor blade increases, the flow in the middle of the rotor blade deteriorates and the stage performance decreases obviously, which is the main reason for the decline in the overall performance.

The loss of cold air from the blade edge plates of the turbine has a negative impact on engine performance and safety. Using an experimental method, this paper investigates the effect of geometric and aerodynamic parameters on cold air leakage through pressure and mass flow measurements. Based on the results, it can be concluded that, with a change in sheet spacing, the proportion of bypass leakage and clearance leakage changes. At the same sheet spacing, the edge plate clearance is increased from 1 mm to 1.1 mm, resulting in a 30% increase of total leakage and a 25.7% increase of leakage equivalent mass flow. The edge plate clearance was increased from 1.1 mm to 1.2 mm, the total leakage increased by 19.2%, and the equivalent mass flow of leakage was 19%. The proportion of clearance leakage in the total leakage increased gradually for a given edge plate clearance. When the sheet spacing was 1 mm, bypass leakage accounted for 68% of the total leakage and was the primary source of leakage. The clearance leakage accounted for 83% of the total leakage with a plate spacing of 10 mm. When the sheet spacing is small, bypass leakage dominates; when it is large, clearance leakage dominates. The variation law of leakage with pressure, structural parameters and the ratio of sheet spacing to sealing slot length play an important role in the design of sealing structures.