Simulation of Fouling in Axial Flow Compressor Using a Throughflow Method

Abstract

Compressor fouling is a permanent concern for engine users, as it increases fuel consumption and decreases available useful power. Compressor performance can be restored provided certain measures are taken, e.g., regular washing of the flow path. The current study proposes a model that qualifies and, to a certain extent, quantifies compressor performance degradation attributable to fouling. The proposed model is built for the case of an axial flow compressor and it is embedded into a throughflow, streamline curvature tool called synthesis of correlations for the rapid assessment of turbomachine engine systems (SOCRATES). It is an integral model, integrated into the computational tool, that accounts separately for every effect that fouling introduces to the flow as the air passes through an axial compressor stage. In particular, the validity of the model is demonstrated on the NASA stage 37. Researchers in the past, studied the performance of this axial compressor stage, under cleaned and fouled conditions, using a commercial Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) code. Fouling in these numerical simulations is modeled based on a set of input values of surface roughness and the deposit’s layer thickness. The proposed model, receives the same set of inputs. The effect of blade surface roughness is introduced to the flow through the fouling profile loss factor and the modified deviation angle. The deposit’s layer thickness decreases the cascade throat surface area. Comparison of the results between the two computational tools, for a certain fouling scenario, showed a good qualitative and an adequate quantitative agreement. The proposed model makes SOCRATES as a computational tool attractive to engine users, who are in need of assessing the impact of compressor fouling on gas turbine engine performance.