An Innovative Method for the Evaluation of Particle Deposition Accounting for Rotor/Stator Interaction

Abstract

Solid particle ingestion is one of the principal degradation mechanisms in the compressor and turbine sections of gas turbines. In particular, in industrial applications, the microparticles not captured by the air filtration system can cause deposits on blading and, consequently, result in a decrease in the compressor performance. This paper presents three-dimensional numerical simulations of the microparticle ingestion (0.15–1.50 μm) in a transonic axial compressor stage, carried out by means of a commercial computational fluid dynamic code. Particles of this size can follow the main air flow with relatively little slip, while being impacted by the flow turbulence. It is of great interest to the industry to determine which zones of the compressor blades are impacted by these small particles. Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separately from the continuous phase. A particular computational strategy is adopted in order to take into account the presence of two subsequent annular cascades (rotor and stator) in the case of particle ingestion. The proposed strategy allows the evaluation of particle deposition in an axial compressor stage, thanks to its capability of accounting for rotor/stator interaction. NASA Stage 37 is used as a case study for the numerical investigation. The compressor stage numerical model and the discrete phase model are set up and validated against the experimental and numerical data available in the literature. The blade zones affected by the particle impact and the kinematic characteristics of the impact of micrometric and submicrometric particles with the blade surface are shown. Both blade zones affected by the particle impact and deposition are analyzed. The particle deposition is established by using the quantity called sticking probability, adopted from the literature. The sticking probability links the kinematic characteristics of particle impact on the blade with fouling phenomenon. The results show that microparticles tend to follow the flow by impacting at full span with a higher impact concentration on the pressure side of rotor blade and stator vane. Both the rotor blade and stator vane suction side are only affected by the impact of smaller particles (up to 1 μm). Particular fluid dynamic phenomena, such as separation, shock waves, and tip leakage vortex, strongly influence the impact location of the particles. The kinematic analysis shows a high tendency of particle adhesion on the suction side of the rotor blade, especially for particles with a diameter equal to 0.15 μm.

A Mathematical Model of the Hydrodynamic Pressure Acting on a Turbine Runner Blade under the Rotor-Stator Interaction Based on the Quasi-Three-Dimensional Finite Element Method

“…ese abnormal pressure pulses can cause the runner blades to vibrate intensely, and this can cause fatigue cracks to develop in the runner blade, which can seriously endanger the operation of the unit [2]. erefore, it is necessary to study the hydrodynamic pressure acting on a runner blade under the rotorstator interaction in the process of studying the dynamic characteristics of a runner blade.…”

Quantitative computational fluid dynamic analyses of oil droplets deposition on vaneless diffusor walls of a centrifugal compressor

“…Meanwhile, the design parameters of the axial compressor also influenced the process of fouling formation, such as axial compressor chord length, solidity, roughness, and the number of stages . In addition, studies of the transport process of solid particles in an axial compressor and the kinematic characteristics of particle deposition were helpful in researching the mechanism of solid particle deposition.…”

Quantitative Computational Fluid Dynamics Analyses of Particle Deposition in a Heavy-Duty Subsonic Axial Compressor

“…In Ref. [10], Aldi et al analyze the microparticle ingestion in a transonic axial compressor stage. A particular computational strategy is adopted to take into account the presence of two subsequent annular cascades.…”