New Model to Predict Water Droplets Erosion Based on Erosion Test Curves: Application to On-Line Water Washing of a Compressor

Abstract

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 μm 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.

Numerical Prediction of Long-Term Droplet Erosion and Washing Efficiency of Axial Compressors Through the Use of a Discrete Mesh Morphing Approach

“…Every time a droplet hits a solid surface, a UDF developed by the authors [19] and containing the WDE model presented in Refs. [15,18], is activated. The erosion model was developed for stainless steel targets and it is based on the experiments reported in Refs.…”

“…5 Incubation energy as a function of the impact-to-critical velocity ratio. Experimental data (squares [16], triangles [17]) and proposed fitting curve [15]. the injector mass flow rate, the amount of simulated water mass (m inj,sim ) multiplied by F 1 .…”

“…To study the effect of water droplet erosion (WDE) in Ref. [15], we developed an erosion model based on experiments available in the open literature [16,17]. The WDE model was applied to several compressor blade geometries in the past [15,[18][19][20][21].…”

“…[15], we developed an erosion model based on experiments available in the open literature [16,17]. The WDE model was applied to several compressor blade geometries in the past [15,[18][19][20][21]. In all these simulations, the computation of the erosion mechanism was carried out by assuming that the profile did not change due to the erosion itself thus neglecting the variation in the fluid flow due to the profile modification.…”

Comparative Life Cycle Assessment of Different Gas Turbine Axial Compressor Water Washing Systems

“…For a better efficiency of cleaning it is recommended to periodically perform both on-line and off-line washes. Recently, it has been demonstrated the effectiveness of a new High Flow On-line Water Wash [2]: by maintaining the GT axial compressors efficiency almost constant in time, HFOLWW permits to decrease the fuel consumption needed to balance the efficiency losses to get the required power, eventually reducing CO2 emission [2][3][4][5].…”