Predicting Erosion in a Counter-Rotating Fan under Different Operating Conditions

Counter-rotating fans (CRFs) represent an effective solution for ventilation in tunnels and mines. However, these systems are particularly vulnerable to erosion in dusty environments. The present study investigated the dynamics of dust particles and erosion by examining various factors, including blade staggering, inter-space between front rotor (FR) and rear rotor (RR), airflow rate, and dust concentration. The analysis employed a Lagrangian particle tracking code, incorporating probabilistic models for particles release positions, sizes, and rebound. The finite element method (FEM) allowed the tracking of particles and determining the impact conditions necessary in evaluating the local erosion rates. The sizes of particles varied from 0.1 to 100 microns, with concentrations ranging from 0.1 to 0.5mg/m3, to replicate areas affected by Saharan dust. To mimic regions of mining activities, concentrations were adjusted to range between 1 and 3mg/m3. The FR experienced heavy impacts, resulting in erosion along the leading edge (LE) of the blades, as well as on the upper two-thirds of the pressure side (PS) and at the tip of blades. Additionally, significant erosion was observed over a strip of the suction side (SS) extending from the LE. The RR exhibited erosion patterns over three-quarters of PS, with erosion rates exceeding double those in the FR. Erosion patterns were influenced by several factors, including particle concentration, flow conditions, stagger angles, inter-space, and the position of the RR blade against that of the FR. A comprehensive understanding of these factors is essential for monitoring erosion progression and selecting suitable protective coatings.