Trajectories of Ash Particles Through a Coal-Burning Gas Turbine

A three-dimensional algorithm was previously developed to compute more accurate particle trajectories through turbomachinery blade rows. The capabilities of this algorithm are demonstrated in this paper with trajectory analyses through a coal-burning gas turbine developed by the Bureau of Mines. This five-stage axial turbine contains three-dimensional variations in both the geometry and the gas flow field that have a significant effect upon the trajectories of small (10 micron) coal ash particles. The trajectory analyses performed through the first three blade rows describe particle motion similar to that implied by the erosion patterns observed after testing. Particle impacts are predicted in the regions of the blade surfaces that experienced erosion. Particle impact characteristics of angle and velocity correlate qualitatively with the relative amounts of erosion observed among different regions of the blade surfaces.