Characteristics Of Flow Field Under The Action Of Paroxysmal Buoyant Jet And Side Suction Flow Based On Sensitivity Analysis

In industrial buildings,adding molten steel,slag dumping,and coal charging for coke oven operations,there are often sources of pollution that do not continuously release pollutants.Such pollution sources have the characteristics of intermittent emissions and large instantaneous emissions when releasing pollutants,which are called paroxysmal sources of pollution.Local ventilation system ventilation is effective for controlling the above pollution sources and is applicable to sites where there are sources of paroxysmal pollution.The side suction hood is a local exhaust device with a wide range of application,which can effectively control the source of paroxysmal pollution.At present,there are many researches on the steady-state floating jets for the steady-state pollution sources.There are still few researches on the characteristics of the flow field of the paroxysmal buoyant jets under the action of the paroxysmal buoyant jets and side suction.The control of the flow field characteristics of the paroxysmal buoyant jet under the action of the side suction flow is very important for the design of the parameters of the side exhaust hood and other local exhaust systems.In order to obtain the flow field characteristics of the paroxysmal buoyant jet under the action of the side suction,the numerical simulation model of paroxysmal jet flow under the side suction flow was first established.The accuracy of numerical simulation was verified by comparing the numerical simulation and experimental results.The influencing factors of the side suction cover collection efficiency were analyzed,and the global sensitivity analysis was performed on the factors affecting the side suction cover collection efficiency,and the primary and secondary relationship of the influence of the suction cover collection efficiency on each side was established.The results show that the horizontal distance between the side suction hood and the heat source,the pollutant emission speed,the amount of side suction hood exhaust,and the installation height of the side suction hood have a significant impact on the side suction hood collection efficiency.The pollution source heat source temperature has little effect on the side suction hood trapping efficiency.Secondly,based on the similarity theory,this paper constructs the experimental platform of the paroxysmal floating jet model and studies its flow field characteristics.The results show that the velocity field of the bursty jet flow presents a stepwise change of the burst over time.There is no obvious regularity of change in the axial temperature with time.The temperature of the edge control point at the long edge of the rectangular heat source has obvious step-by-step variation of the bursts over time.The temperature of the edge control point at the edge of the short edge does not have the obvious change law of the stepping burst with time.The concentration of pollutants in the flow field gradually increases with time.Then,based on the primary and secondary relationship of the influence of each factor on the efficiency of the suction hood on the side,the effect of the amount of side suction hood exhaust and the horizontal distance between the side suction hood and the heat source on the flow field characteristics of the paroxysmal buoyant jet was studied experimentally.The results show that when the exhaust volume of the side suction hood increases or the horizontal distance between the side suction hood and the heat source decreases,the attenuation gradients of the temperature field and concentration field in the flow field increase,and the ladder distribution phenomenon becomes more significant.And over time,more and more obvious changes in the pattern of step-like bursts occur,while the peak value of the burst response curve decreases.In a certain range of suction hood exhaust volume,the Paroxysmal pollutant exclusion ratio TCRRt shows a stepwise change of the burst pattern over time.The horizontal distance between the side suction hood and the heat source decreases,the Paroxysmal pollutant exclusion ratio TCRRt increases,and the Paroxysmal pollutant exclusion ratio TCRRt has a more obvious stepwise burst variation rule with time.Finally,the influence of the installation height of the side suction hood on the flow field characteristics of the paroxysmal buoyant jet was studied using numerical simulation methods.The results showed that the velocity field,temperature field and concentration field of pollutants in the buoyant jet flow under different installation heights of the side suction hoods showed a stepwise change of the bursts over time.At the same time,as the installation height of the suction hood increases,the speed value,temperature value,and pollutant concentration increase.Through the above theoretical analysis,experimental testing and numerical simulation studies,the characteristics of the flow field of paroxysmal buoyant jets under the action of paroxysmal buoyant jets and side suction flow are mastered,which provides a reference for the design and optimization of local exhaust systems.