In order to examine both primary and secondary erosion of turbomachines, two examples were studied: the impeller of a centrifugal compressor and the stationary straight infinite cascade. The first example was examined when particulates of large diameters bombarded its internal surface, thus providing a primary erosion pattern. An inviscid flow is assumed since the trajectories of large diameter particles are slightly influenced by viscous effects. Tracing these trajectories for silica and alumina particles defined four areas on the internal surfaces of the impeller which experienced the highest rate of material removal due to the successvie impacts. The viscous model of a centrifugal compressor is also under investigation by the authors.

The stationary infinite cascade of a typical turboexpander was subjected to fine particulate impacts. These fine particles were greatly influenced by both the viscous effects and secondary flow. Thus three-dimensional viscous flow was defined experimentally using a laser-Doppler anemometer (LDA). The pressure surface, especially the turning section, suffered from the highest erosion damage. These results compared favorably with the experimental results of the Ruston and Hornsby turbine operating with Greta Coal. The erosion rates of the first stage Ruston Turbine after 124.8 hours of operation showed similar results.

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