Numerical and experimental study of particle deposition on inner wall of 180° bend

A proper representation of particle deposition in a bend is crucial because the unwanted deposition can compromise the efficiency of industrial processing equipment. In this paper, the gas flow in a 180° bend was simulated using Reynolds stress model (RSM) and measured by laser-Doppler velocimetry (LDV), and then deposition patterns on the inner wall of bends were experimentally studied under different inlet velocities, particle concentrations, bend curvature ratios and experimental materials. Preliminary results suggest that the deposition patterns under all variations of parameter values are basically alike: the deposition scope expands gradually from the top and bottom of inner wall, making the boundary line of stick-ash zone and non-stick-ash zone approximately like a parabola opening to the inflow. The particle concentration has a tremendous bearing on steady deposition time, but has little influence on inner wall deposition pattern (10–25 g/m3). Meanwhile, an increase in inlet velocity induces a reduction of deposition mass as well as sedimentary thickness. Compared with the particles before being conveyed, only particles with small diameter can deposit on the inner wall based on the analysis of deposition samples. Moreover, the relationship between deposition pattern and secondary flow as well as tangential velocity is also analyzed.