Design On The Novel Cascade Impactor And Its Verification Of Capacity

Aerosols affect greatly on the environment pollution, climate change and human health. Cascade impactors have been widely applied as aerosols collectors, which separate and collect aerosols according to their air dynamic diameters being based on the theory of inertia impaction. The cascade impactors can obtain different diameter particles on different collect stage to provide samples for the subsequent physical and chemical analyses in order to know their composition and source. Thesis work is mainly focused on the design of the novel cascade impactor and its verification of capacity.1. Basic concept and the harm of aerosols have been reviewed. Then the new trend of aerosol research and the main methods for sampling and analyzing aerosols are introduced.2. Based on the theories of aerodynamics and inertial impaction, the working principles of cascade impactors have been discussed.3. The calculated method of the nozzle diameter in the single stage sampler with given flow rate and cut diameter of aerosol particles is proposed, and the corresponding program is compiled. The influence of designing parameters on the impactor cut diameters is discussed. After that, a way to decrease the designing error of nozzle is proposed. 4. Establishing designing programs for cascade impactor. Proposing a series of designing principles according to discussion for machining precision of cascade impactor. According the above principles, proposing new designing methods, which can short the designing time and obtain better designing result. Then, the optimum method for decreasing the designing errors is suggested.5. Some problems of the present cascade impactor have been improved. The performance tests using different methods have been carried out for the present multi-impactors. Experimental results reveal that the sampling system separates particles successfully according their dimensions and fulfill the demand to analyze chemical composition of aerosol particles and the relationship with morphology.6. Adding a 2.5(m cutting stage to be consonant with international standards and re-designing each cutter of cascade impactors. A new seven stage multi-impactor with the cut diameter of 10(m, 5(m, 2.5(m, 1.0(m, 0.5(m, 0.25(m, 0.1(m has been machined.7. Improving the apparatus of single-disperse-aerosol, testifying its collecting performance and achievement on the introducing of single-disperse -aerosol. It can provide the single aerosol particles for further analysis of their diameter.