Quantitative CFD Analyses of Particle Deposition on a Transonic Axial Compressor Blade: Part II -- Impact Kinematics and Particle Sticking Analysis

In heavy-duty gas turbines, the micro-particles not captured by the air filtration system can cause fouling and, consequently, a performance drop of the compressor. This paper presents three-dimensional numerical simulations of the micro-particle ingestion (0 – 2 µm) on an axial compressor rotor carried out by means of a commercial computational fluid dynamic code. Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separately from the continuous phase. The NASA Rotor 37 is considered as a case study for the numerical investigation. The compressor rotor numerical model and the discrete phase model were previously validated by the authors in the first part of this work. The kinematic characteristics (velocity and angle) of the impact of micrometric and sub-micrometric particles with the blade surface of an axial transonic compressor are shown. The blade zones affected by particle impact were extensively analyzed and reported in the first part of this work, forming the starting point for the analyses shown in this paper. The kinematic analysis showed a high tendency of particle adhesion on the suction side, especially for the particles with a diameter equal to 0.25 µm. Fluid dynamic phenomena and airfoil shape play a key role regarding particle impact velocity and angle. This work has the goal of combining, for the first time, the kinematic characteristics of particle impact on the blade with fouling phenomenon by the use of a quantity called sticking probability adopted from literature. From these analyses, some guidelines for a proper management of the power plant (in terms of filtration and washing strategies) are highlighted.