Numerical Simulation Of Near Zone Flow Filed In Pulsed Turbulent Round Jet

Pulse bag filter use the pulse jet to clean dust, it is very important to study the flowcharacteristics of the pulse jet. Due to the influence of pulse jet, the filter bag of pulse bag filterwill be broken in the cleaning process, that makes an impact on the life of bag filter. Blowingdistance influences the time pulse jet reach the filter bag, which affects the result of dust cleaning.The temperature of the gas in pulse bag filter is higher than the temperature of pulse jet, whichinfluence the jet flow field in the progress of blowing. Because the injection system pulse bagfilter is composed of a plurality of nozzles, The influence between jets from different nozzles, andaffects the flow filed and entraining gas quantity. In this paper, different physical models werebuilt by Gambit software, and used the large eddy simulation technique in Fluent software toanalysis the flow field characteristics of near zone flow filed in pulsed turbulent round jet, and toanalysis the effects on the flow field of near zone flow filed in pulsed turbulent round jet withvarious factors, which provides the theoretical basis for the design of pulse bag filter’s dustcleaning system, and can lay the foundation for future optimization of bag filter and moreexcellent cleaning technology. therefore, it has the certain practical significance.First, this paper verified the feasibility of large eddy simulation (LES) method bycomparing numerical simulation and experiment. We build the physical model was consistentwith the experimental model of literature, used the large eddy simulation (LES) method tonumerical simulation, and found the conclusions were good agreement with experimental resultsof literature, so verified the feasibility of large eddy simulation (LES) method.Because the temperature of the gas in pulse bag filter is higher than the temperature of pulsejet, this paper studied the characteristics of flow field of turbulent round pulse jet into the differentthermal environment temperature, and the temperature were300K,400K,500K. The resultsshowed that in different ambient temperature, the characteristics of flow field of turbulentround pulse jet were different. When the entrance under the same condition, with the increasing of environmental temperature, the core length of jet gets longer, attenuation of the velocity onjet axis was slower, the velocity and turbulent kinetic energy along radius direction decayedand diffused slower. With the increasing of environmental temperature, the magnitude of thevelocity fluctuations and the maximum of power spectral density of the point becomes smallerwhich at the same distance to the tube’s nozzle on the axis. The environment temperature washigher, the flow field of the jet into the thermal environment was more stable.Secondly, in this paper, we studied the near zone flow filed characteristics of an array ofturbulent round pulse jets, and compared with jet in the same speed and boundary conditions. Theresults show that, core length of jet under the condition of an array of jets was longer thanthe single jet’s. Under the condition of array of jets, the magnitude of the velocity fluctuations andthe maximum of power spectral density of the point becomes smaller which at the same distanceto the tube’s nozzle on the axis than the single jet’s. Compared with the single jet condition, theflow field of the jet under the condition of an array of jets was more stable.In this article, we also studied the near zone flow filed characteristics of coaxial jet tube withthree different central jutting nozzles, and the lengths L of central jutting nozzle are2.5Di,5Di,7.5Di. Results indicate that, when the elongated length of central tube is2.5Di, the inner-jet’slength of the core plus length of the central jutting nozzle can effectively prolong theinner-jet’s blowing distance.With the increase of the length of the central jutting nozzle, the jet’slength of the core gets shorter.Finally, we studied the vibration problem of the filter bag under the action of the jet blowing.Under constant pressure, the filter bag’s forced vibration was related with filter bag’s elasticmodulus, length, radius, density, thickness, pressure, time and others. Vibration was a simpleharmonic motion, the frequency of vibration was proportional to the filter bag’s elastic modulus atthe power of1/2.The amplitude of vibration displacement associated with filter bag’s radius, lengthand elastic modulus, had nothing to do with the filter bag’s density, the filter bag’s radius andlength longer, the amplitude of vibration displacement larger. The elastic modulus of the filter baglarger, the amplitude of vibration displacement smaller. The amplitude of vibration accelerationhad nothing to do the filter bag’s elastic modulus, length of radius, associated with filter bag’sdensity,the filter bag’s density larger, the amplitude of vibration acceleration smaller. Providesconditions for the study of the flow characteristics of the jet under the vibrating boundaryconditions.