Study On Properties Of Aggregated Spheres

Particles involves in many domains such as nature, engineering application and scientific research. However, the particles we encounter are not just monomer in actual application, they usually appear as aggregate because there is molecular interaction between the particles. There are kinds of aggregates such as smoky fog, soot, mill dust, paint layers etc. The orientation of every particle in the aggregate can be random, so every particle can be simplified as spherical particle. Therefore, the radiative properties of spherical aggregates should be studied firstly when studying the real particles radiative problems, which can offer more exact radiative properties of particles for the study on radiative transfer.In this dissertation, a particular summary on the study of aggregate particles is given. Then, we discussed the method to compute the radiative properties of aggregate. The formula for radiative properties of spherical aggregate is elaborated in this dissertation. And then we use Generalized Multiparticle Mie-solution (GMM) to calculate. In the condition of the same size parameter, but different constituent radius and different distance between constituent spheres, the extinction coefficients and scattering coefficients of aggregates were calculated. Analyzed the result, we can find that the radiative properties of the aggregates are equal when the aggregates are in the same size parameter and also the radio of the distance are equal to the radio of the constituent radius. Furthermore, the aggregates with the same size parameter were calculated in the condition of the same constituent radius as 0.1μm but with variational distance between constituent spheres. The results were compare with that calculated by independent scattering. We found that there is differentia between the two different cases. When the distance between the two particles is larger, the differentia is smaller. Then when we studied the radiative properties of aggregates composed of different numerary particles, we found that the more of the constituent spheres, the larger differentia of the radiative properties between the two cases.Based on the radiative properties of aggregates obtained above, the influence of aggregates on radiative transfer in multi-disperse system is investigated and the results are compared with equivalent spherical system. With the study of the influence of aggregate-effect on radiative transfer, we found that there is obvious differentia between the two temperature fields. The maximum relative error is approach 20%. So we cann't neglect the interaction between particles when we calculate the temperature field of the particles system composed of aggregates.