Effect of Leading Edge Erosion on the Tip Leakage Flow in a Compressor Cascade

Abstract

The interaction between tip leakage flow and passage flow in axial compressor blade rows creates complex flow mechanisms that impair flow stability. Caused by erosion of the compressor blades, these flow mechanisms become time-dependent. Especially, the compressor tip regions experience erosion-related surface loss owing to the particle-laden flow inside the engine. The corresponding reduction in chord length varies in height and leads to varying shapes of eroded compressor blades. It is likely that these impact the engine’s operability. The optical accessibility of flow structures in water was exploited by analyzing four blade tip geometries at different angles of incidence in a linear compressor cascade. The impact of these geometries on the tip flow structures is analyzed by observing the movement of inked fluid elements in space and time. Particle tracking velocimetry is used to obtain 3D trajectories of both stable and unstable flows. Whilst the non-eroded blade geometry shows stable vortex formation, a notable change in the flow characteristics is observed for particular erosion patterns. In these cases, the tip leakage flow exhibits unsteadiness, featuring fluctuations and unstable flow phenomena. A large blockage of the flow passage occurs due to a vortex breakdown.