| The regeneration process after cleaning dust as a filter material is one of the key technologies for bag dust removal.Pulse jet cleaning as the current mainstream cleaning method,dust shedding is coupled by a variety of factors,and its cleaning mechanism has not yet reached a consensus.It is necessary to explore a high-efficiency cleaning technology that integrates various influencing factors under the conditions of existing mechanism research,and it is necessary to break through the bottleneck of dust collector product innovation.The main driving force of pulse jet cleaning process is the pulsed airflow flowing through the nozzle.The existing mechanism research believes that the peak pressure difference inside and outside the filter bag is the key factor affecting the cleaning effect,and the cleaning process is affected by these rather than single influence.In order to balance the various influencing factors,improve the pulsed airflow intensity under existing conditions,and increase the filter bag response,this paper introduces the classic shock wave technology in the aerospace field,comprehensively enhances the cleaning mechanism involved.Based on the influence of various factors,the Laval nozzle based on Laval nozzle technology and the conventional nozzles of different profile types were designed to establish the pulse cleaning performance of different model nozzles.Numerical simulations and experimental studies were carried out.Finally,the effects of structural parameters of different cleaning systems on the cleaning performance were analyzed.The specific research contents and results are as follows:(1)In order to overcome the divergence mechanism of the cleaning mechanism and the influencing factors such as differential pressure and acceleration,an efficient cleaning technology using the supersonic Laval nozzle technology to realize the shock wave oscillation effect is proposed.The one-dimensional constant isentropic flow characteristics design based on variable cross section a new Laval nozzle.According to the geometric conditions and mechanical conditions of the nozzle design,Laval-type nozzle shrinkage section designed by quintic curve,the characteristic line method is designed to design the nozzle expansion section,and the Laval type nozzle suitable for the bag dust collector pulse jet cleaning system is obtained.(2)In order to verify the feasibility and effectiveness of the design nozzle,according to the structural characteristics and flow field characteristics of the pulse jet bag filter,the fluid dynamics model of pulse cleaning calculation for flow field analysis is constructed.The simulation results show that the flow through the design nozzle reaches an over-expanded state,which produces a shock wave oscillation effect.The computational fluid dynamics model and the transient dynamics model for unidirectional fluid-solid coupling analysis were used to compare the cleaning effects of the Laval nozzle and the conventional nozzle,and the actual ash loss in the pulse cleaning experiment was compared with Laval.The cleaning performance of the type nozzle and the conventional nozzle has the characteristics that the Laval type nozzle has more obvious effect on the cleaning of the long filter bag,and the efficiency of oneshot cleaning is up to 96%,which verifies the design scheme and the simulation result.(3)A calculation model of the blowpipe with 16 nozzle exit velocity and its flow deviation value as the evaluation index was established,and the uniformity of the jet flow of different profiles was studied.Preliminary optimization of the design nozzle,analysis of the influence of injection pressure and throat diameter on the cleaning performance of Laval nozzle.The effects of cross-section shape,blowing distance and nozzle diameter on the acceleration and maximum displacement of the filter bag were studied by using fluid-structure coupling technology.Through simulation analysis and discussion,it provides reference for the design of pulse dust cleaning system for bag filter. |
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