Numerical study on deposition characteristics of non-spherical particles on flue gas turbine blades
WANG Yifan
XU Mingde
WANG Jianjun
XU Weiwei
ZHANG Hongyi
TIAN Lechen
SONG Haitao
FENG Menglong
Abstract：Objective Flue gas turbine is a core piece of energy-saving equipment in catalytic cracking systems.However,fouling on tur-bine blade surfaces poses significant risks to operational safety.Therefore,it is essential to conduct research on the structural mechanism of flue gas turbines.Previous studies have primarily focused on analyzing the chemical composition of fouling samples.Limited studies on the factors influencing particle deposition have often relied on cold-state experiments,leading to relatively low credibility.Using Fluent commercial software and a high-temperature deposition experimental platform,the study analyzes the factors affecting deposition.
Methods Firstly,based on the critical stress model and the protrusion element model,this paper developed a user-defined func-tion(UDF)to determine particle deposition on wall surfaces.The UDF was integrated into Fluent to simulate particle behavior under varying inlet air volumes and inlet particle concentrations.Secondly,high-temperature deposition experiments were con-ducted using an authentic flue gas turbine blade model and accurately calibrated installation angles.Experimental parameters were consistent with those in the numerical simulations,ensuring consistency and enabling validation of the simulation results.Thirdly,a laser particle size analyzer was used to compare the particle size distribution of inlet particles and deposited particles.
Results and Discussion Based on the UDF deposition model and high-temperature deposition experiments,the results were obtained.High-velocity zones were at the leading and trailing edges of the pressure surface of the flue gas turbine rotor blades.At the trailing edge of the pressure surface and the leading edge of the suction surface,the gas-phase velocity decreased sharply,causing inertial particle impact and potential blade erosion.When the gas phase reached the rotor blades,the flow area was reduced,causing an increase in velocity and a corresponding decrease in pressure.After passing through the rotor blades,the flow area expanded,causing the velocity to drop and the pressure to rise.This change formed a pressure gradient force that opposed the mainstream direction,leading to boundary layer separation and potential particle deposition.The pressure distribu-tion around the rotor blades exhibited systematic variation,with the highest pressure occurring at the leading edge of the pressure surface and gradually decreasing as it moved away from the blade.Conversely,the lowest pressure occurred at the leading edge of the suction surface and gradually increased away from the blade.A small low-pressure zone existed at the leading edge of the suction surface,resulting in a steep pressure gradient that destabilized fluid flow.In the presence of particles,this flow instabil-ity exacerbated blade erosion,increased surface roughness,and intensified particle deposition.Changes in inlet flow rates impacted both the deposition area and mass of non-spherical particles.The deposition area on the pressure surface gradually con-tracted from the entire surface to the central region,with an increase in deposition mass.On the suction surface,the deposition area expanded from the middle of the blade root towards the trailing edge,with the deposition mass also increasing as the flow rate rose.In contrast,variations in inlet particle concentration had minimal impact on the deposition area,but the deposition mass increased significantly with the increase in inlet particle concentration.Factors such as inlet flow rate,particle concentra-tion,and particle shape had little effect on size distribution range of deposited particles.
Conclusion Higher inlet flow rates and particle mass concentrations result in greater particle deposition mass,while the size dis-tribution of deposited particles remains unchanged.These findings provide a theoretical basis for studying the movement charac-teristics of catalyst particles in high-temperature flue gas,the interaction with blade surfaces,and deposition patterns.
Keywords：non-spherical particleflow diversionflue gas turbine
Publication Date：2025-05-01
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：18( 195-212 )