Erosion Study in Turbomachinery Affected by Coal Ash Particles. Final Report

摘要

Small particle trajectories approaching the test specimen in an erosion tunnel are analtyically determined. The two-dimensional equations of motion are solved for a spherical particle under the sole influence of aerodynamic drag. The two-dimensional gradients of gas properties in the flow field are determined by a numerical solution of the equations describing a compressible inviscid fluid. At one inlet condition, the trajectories are computed for coal ash particles of various sizes approaching test specimens at several orientations. Trends are identified in the approaching characteristics that may be related to the observed erosion. The results indicate that for ash particles with diameters less than 10 microns, significant numbers are deflected away from the specimen. These particles would otherwise impact the specimen if they had more inertia to resist the turning effect of the flow field. For ash particles with diameters less than 30 microns, those which do impact the specimen do so over a wide range of incident angles quite different from the angle between the specimen surface and the tunnel axis and at lower velocities than those at the test section inlet.