| In recent years,with the rapid development of the economy and the increase of energy consumption,the pollution of harmful gases has become increasingly serious.The detection of harmful gases has become an important means to improve the regional environmental level,improve the quality of life,and protect human health.However,in dusty conditions where dust is widely dispersed,gas detection is often disturbed by dust particles.Under long-term detection,the detection accuracy of the instrument is greatly reduced,and the service life is also affected to varying degrees.The air pathway of the existing gas detection device is a pipeline structure,which has no filtering effect on the particulate matter in the dust-laden airflow,and a special filtering device is required to filter the particulate matter.In view of the problems that gas detection equipment is easily interfered by particulate matter under dusty conditions,and the existing filter device has high filtration pressure drop and cannot be reused,this study adopts the principle of engineering bionics,and draws on the effective characteristics of vegetation barriers to capture particulate matter and repeatable dust retention.By studying the macro and micro characteristics of leaves that are conducive to vegetation dust retention,the biomimetic elements of juniper’s striped thorn-shaped leaves,the grooves,ridges and trichomes of vegetation surface were extracted.12 structures of two types（I-type and N-type）of the dust-laden gas detection device are designed（I-L-blanks,I-L-leaves,I-S-leaves,I-L-grooves,I-S-grooves,I-H-grooves,N-B-grooves,N-S-grooves,N-B-ridges,N-S-ridges,N-B-trichomes,N-S-trichomes）,the bionic gas circuits were prepared by 3D printing technology.A filtration performance test bench was built.By comparing the concentration of particulate matter before and after the measured sample,the filtration efficiency and resistance pressure drop of the sample against the simulated particulate matter source under different airflow rates were tested,and the variation of the filtration performance of each sample with the airflow velocity was analyzed.Finally,the filtration process of the sample is numerically simulated and analyzed by the computational fluid dynamics simulation method,and the flow of particles in the sample and the changes of the air flow rate and the resistance pressure drop in the sample are obtained.The main conclusions are as follows:（1）Compared with the blank control group,the biomimetic structure of the collision surface of the biomimetic sample increased the probability of particle deposition.Increasing the channel length of the sample and the cross-sectional area of the collision surface can improve the filtration efficiency,but it is not as good as the effect obtained by increasing the tortuosity of the channel.All filter samples have high filtration efficiency for coarse particles.In general,the filtration efficiency of the N-type sample is greater than that of the I-type,and the pressure drop is smaller than that of the I-type.The filtration efficiency decreases with the increase of the dust-laden airflow velocity,and the pressure drop increases with the dust-laden airflow velocity.The resistance pressure drop of the N-type sample to the dust-laden airflow is very low,the minimum is 9Pa,the grooves and trichomes on the collision surface significantly improve the filtration efficiency.The N-S-grooves,N-S-trichomes and N-B-grooves structures have the best filtration efficiency,and the N-S-grooves,N-B-trichomes and N-B-grooves structures have the best quality factor.（2）By applying a coating on the collision surface inside the sample,the filtration efficiency of particles in the dust-laden airflow,especially the filtration efficiency of fine particles PM2.5,was further increased,but the pressure drop was also increased,resulting in a lower quality factor.After use,by cleaning the sample,its dust retention capacity can be restored,indicating that the design has good reusability.（3）The computational fluid dynamics simulation results show that the airflow is deflected and accelerated inside the sample,and the particles are deposited due to inertial collision with the wall surface.The biomimetic structure of the collision surface increases the deposition of particles.The airflow flows at a high speed in the lower part of the middle channel part of the N-type sample and collides with the wall,so a lot of particles are deposited on the lower wall of the middle pipe,and the resistance of the middle pipe of the N-type pipe to the air flow is also small.Therefore,increasing the meandering of the pipe can effectively improve the filtering performance of the filter device,and the most particles are deposited on the collision surface of N-S-grooves,N-S-trichomes and N-B-grooves. |
