Research On Particles Aggregation Around The Bluff Body Flow

Current coal soot emission control technology in many countries has reached a higher level,but for coal-burning flue gas in fine particle removal efficiency is still low,the ultrafine particles of the atmosphere caused environmental pollution.The people's governments at all levels and the relevant administrative departments in our country deeply understand the smoke fine particulate matter harmful to the environment and human health,and proposes some control coal-fired flue gas emissions standards and legal documents.But research in the ultrafine particle pollution control in China are still in research stage,hardly applied to industrial production equipment,for fine particle emissions control needs further research.In this paper,learned the existing dedusting technology and particle reunion,and the different particle reunion technologies are classified and existing scholar's research results very good interpretation of the advantages and disadvantages of different kinds of particle reunion technology,as well as indicated the research direction and implementation method in need of improvement.Through the summary of the research achievements of previous scholars,this article will further research on turbulence and vapor aggregation.Mainly using the PBM analysis the situation of particle aggregation in the step-back flow and bluff body flow.After analysis get the characteristics of aggregation.Firstly,the paper through adding the model of the particle reunion to compare with traditional turbulence model,observe the change of the vortex structure in flow field of the step-back flow to validate mathematical model.Secondly,the paper research the paritcle aggragation of the step-back flow.On the basis of the existing flue size building a simplified square pipe,the effects of interaction of particles aggregation was researched through changing spme factors including that particle volume fraction,particle diameter,fluid velocity,vopar content and bluff body size to simulate the gas-solid two phase flow.Results demonstrate that the optimal velocity conditions is 4~5m/s and the optimal vopar content is 0.05.Finally,the paper research the paritcle aggragation of the square bluff body including long and short square column sticking to wall,and comparing the effect of aggreation of square bluff body with the step-back flow.Concluded: because of the existence of the square column,around flow of second time reflex zone does not exist in the process,but in the presence of a large of one time backflow area.Under the same conditions the square column has the similar effect of the particle reunion with the step-back flow.Due to in the process of flow of the short square column have two kinds of vortex structure,the effect of particle collision and aggregation is better than the other two models.The optimal size is 120 mm.Short square column structure is simple and easily applied to engineering practice.