NEW MODEL TO PREDICT WATER DROPLETS EROSION BASED ON EROSION TEST CURVES: APPLICATION TO ON-LINE WATER WASHING OF A COMPRESSOR

摘要

Here, a new model for predicting the water droplet erosion (WDE) from online water washing in compressors is developed and its results are discussed in comparisons with a baseline model. The model development started with the analysis of existing WDE models as well as pertinent experimental campaigns aiming at extracting a comprehensive erosion model able to account for the influence of droplet velocity and diameter, impact angle, surface roughness and hardness on the erosion phenomena. The new approach is applied to the study of WDE for droplets of 100 urn diameter in a gas turbine compressor and the predictions are compared with those of the Springer model. Even if the two models (Springer's and ours) return qualitatively similar results, the erosion prediction is strongly different as in Springer model the erosion rate is four time higher than in the present model. This difference is attributed to the oversimplification of Springer model that does not account for any of the parameters that are relevant for the water erosion such as surface hardness and roughness as well as for a different treatment of the incubation period. Furthermore, to analyze the effect of all the main quantities affecting WDE process, several simulations were performed. Droplets diameter is found to be the key parameter, in determining the erosion rate. Reducing the diameter one can reduce erosion from online water washing. Surface hardness is also very important, while surface roughness can be relevant depending on the time frame one is interested at.