Visualization Experimental Study On Agglomeration Of Diesel Exhaust Particulates Under Action Of Split-Stream-Rushing

Fine particulate matter from diesel exhaust can cause irreversible damage to human body.Current particulate control techniques are not effective in removing fine particulate matter from diesel exhaust.In order to solve the above problems,a new idea was proposed in this thesis,in which fine particulates can be firstly agglomerated and grown by split-stream-rushing,and then removed by conventional particle capture technology.Based on this idea,a split-stream-rushing agglomeration device of particulates was designed and manufactured.The internal flow field,the particle residence time and the particle agglomeration efficiency of the device were analyzed by the method of theoretical calculation,numerical simulation and experimental study.Firstly,the theoretical analysis of the force in the particle split-stream-rushing agglomeration device was carried out.Then,the internal flow field of the particle split-stream-rushing agglomeration device was studied,and the effects of different inlet velocity and rushing distance on the particle agglomeration characteristics were calculated by numerical simulation method.Finally,the effects of different rushing distance on particle residence time and particle agglomeration efficiency were studied by visualization experiment method,and the accuracy of simulation was verified.The main conclusions are as follows:(1)Split-Stream-Rushing can effectively reduce the air velocity and increase the residence time of the particles.(2)The agglomeration efficiency of the particles in the rushing cavity decreases as the particle size increases.For particles of the same size,the greater the air velocity,the lower the agglomeration efficiency.(3)Rushing distance is an important factor affecting the residence time of particles.The residence time of particles at 80 mm distance is longer than 70 mm distance and 90 mm distance,and at a wind speed of 20m/s,the residence time of particles at a rushing distance of 80 mm is the longest.(4)The rushing distance and air velocity are important factors that affect the effect of particle agglomeration.The larger the air velocity,the worse the effect of particle agglomeration;the particle agglomeration effect shows a trend of first decreasing and then increasing with the increase of the rushing distance,that is,80 mm The effect of particle agglomeration is the worst under the distance.