Session: 36-04 Water, Icing, and Lubricant Deposition

Paper Number: 83033

83033 - Numerical Prediction of Long Term Droplet Erosion and Washing Efficiency of an Axial Compressors Through the Use of a Discrete Mesh Morphing Approach 

Fouling and erosion phenomena are between the main causes of performance deterioration in axial compressors. They are due to solid particles ingestion that can stick on the blades, eventually provoking erosion, hence altering the blades geometry and affecting the aerodynamic performances. Online water washing of compressors is commonly used to reduce performance deterioration due to blade fouling. Since this kind of washing is applied when the machine is close to its full load, injected droplets are strongly accelerated when they reach the rotor blades and they can themselves induce undesirable phenomena like erosion. Numerical simulations permit to reproduce the complex two-phase field dynamics. However, since usually simulations of erosion process do not account for the change in target geometry, they cannot be used to evaluate the whole long term process. For this purpose, a simulation tool was developed by some of the authors to evaluate the erosion of fans due to long time exposition to solid particles. Here, the technique was implemented in Ansys Fluent and it was adopted to study the evolution of erosion of an axial compressor subject to water washing. Prediction of erosion process in industrial applications helps to better schedule maintenance operations to predict the blade life, and in particular to optimize the washing process.

Numerical simulations were carried out considering droplets injection and transport from the compressor inlet to the first stage rotor blades. Simulation were performed on the whole machine to account for the asymmetric distribution of the spray injectors as of the machine struts, IGV and rotor blades. The simulations are carried out by adopting the k-ε realizable turbulence model with standard wall functions, coupled with the discrete-phase model used to track injected droplets motion. Droplets-wall interaction is also accounted for by adopting the Stanton-Rutland model which defines a droplet impact outcome (deposit, rebound, splashing), depending on the impact conditions. Moreover, an erosion model developed by the authors was implemented in a User Defined Function (UDF) to evaluate the material removal induced by the droplets injection. To increase the computation efficiency, geometry modification due to erosion is not considered for every erosive impacts but for discrete steps for which the mesh alteration is assumed to influence the aerodynamic field. The erosion model permits to evaluate the material removal which is converted into nodal mesh displacement used as an input by a secondary UDF which governs the mesh morphing.  Results show how erosion due to water washing evolves in time motivating the adoption of such an approach.

Presenting Author: Giuliano Agati Sapienza Università di Roma

Presenting Author Biography: NA

Authors:

Giuliano Agati Sapienza Università di Roma
Domenico Borello Sapienza Università di Roma
Francesca Di Gruttola Sapienza Università di Roma
Domenico Simone University of Brasilia
Franco Rispoli Sapienza Università di Roma
Alessio Castorrini Università della Basilicata
Serena Gabriele Baker Hughes
Paolo Venturini Dipartimento di Meccanica e Aeronautica, 'Sapienza