| Summary: | 博士 === 國立臺灣大學 === 機械工程學研究所 === 91 === This study aims at the deposition model applied in spray system, including the impact behavior of a droplet on the plate, and the movement and stick of the particle in the spraying combustion.
The stick, depostion, and splashing of a droplet impacting on surface is derived by theoretical analysis. The criterior of the stick for a droplet is a fucntion of We number, ie We=9.8. The deposition-splashing boundary equation is a function of the Weber number (We), the dimensionless maximum diameter ( ), and the contact angle ( ) on the substrate. The criterion of a liquid particle deposition or splashing is determined by the critical Weber number. The value of We is equal to 469.5 as comparing with experimental data. At the same time, the rebound model of the recoil process is established in this study. The gravity effect for can be neglect in sub-micro deposition. But, the diffusivity is also an important key of the deposition.
The 2-D turbulent spraying combustion code, which includes spray sizes distribution, droplet state criterion, droplet laws for interacting droplets, gas phase combustion model, modified turbulence model, multi-phase turbulent model, and turbulent droplet dispersion model was developed in this study. The SIMPLER and TDMA algorithm were used to solve two dimensional multi-phase elliptic-type equations. And, the simulation results were compared with the available experimental data in the case studies of swirling cold flow, two-phase swirling flow, evaporating and spraying flow, and swirling combustion flow. It was also examined by the commercial computational fluid dynamics (CFD-RC) to verify its prediction value. The results show that swirling number has a big effect on the regions of CTRZ and CRZ, the combustion mode of fuel droplets, the sizes distribution of droplets, and confined the movement of droplets. In addition, the stick effect of the wall was also detailed studied for the different swirling numbers.
|
|---|
