Numerical Simulation Of DPF Regeneration Characteristics Based On Fluid-thermal-structure Coupling And Grey Relational Analysis

With the national regulations on diesel engine emission becoming increasingly stringent,researchers are committed to improving the emission characteristics of internal combustion engines by studying the corresponding exhaust gas reprocessing technology.The Diesel Particulate Filter(DPF)has the simple structure,low cost and high efficiency and is considered the most effective means of collecting the Particulate Matter(PM)of exhaust carbon smoke.DPF can only accommodate a limited number of PM,and the corresponding regeneration process is required to restore the trapping capacity.At present,DPF regeneration is mainly realized by increasing the exhaust temperature of the engine and oxidizing PM.However,the back pressure generated by the carbon smoke distribution in THE DPF channel and the thermal damage caused by high temperature to solid body during the regeneration process become the difficulties in the application of DPF.Therefore,it is necessary to systematically study the velocity field,pressure field,temperature field and their correlation in the active regeneration of DPF.First,based on the actual physical process of active regeneration,a one-dimension and three-dimensional coupling model was established to carry out numerical simulation research on the regeneration process of different DPF carbon loads,focusing on the analysis of the influence of different loads on the fluid velocity,the capture efficiency of porous media,and the pore temperature and pressure drop.The results showed that the carbon load increased,the regeneration temperature and pressure drop increased,and the pressure drop presented bimodal distribution,while the regeneration time changed little.With the increase of wall permeability,the peak pressure drop and the capture efficiency of porous media are greatly reduced.The inlet flow rate increased,the difference of particle oxidation reaction and regeneration temperature decreased,and the regeneration time was shortened.Secondly,based on the theory of fluid mechanics,thermodynamics and solid mechanics,fluid-thermal-solid coupling model is set up,the DPF regeneration process of fluid-solid heat coupling simulation research,analysis of porous medium solid domain in the process of regeneration temperature distribution and stress,strain distribution,reveal different load quantity,inlet flow rate,the permeability of porous medium solid the influence law of stress and strain.The results show that the thermal stress is mainly distributed in the boundary of the two ends of the plug,and the deformation is mainly concentrated in the solid central region of the two ends of the plug.With the same carbon load,the local thermal stress can be reduced and the deformation trend can be suppressed by appropriately increasing the air intake flow.The permeability increases,the thermal stress increases,and the solid form variable increases.Finally,the multi-factor grey relational degree of pressure drop peak and thermal stress peak generated in the regeneration process is studied,and the influence of different parameters on the pressure drop peak and thermal stress peak is analyzed.The results show that the inlet flow rate has a significant influence on the pressure drop,while the carbon load has a significant influence on the thermal stress.In addition,the grey relational degree analysis method can be further used in the design and optimization of regeneration schemes.