VAPORIZATION AND IGNITION OF DENSE SPRAYS AT SUBCRITICAL AND SUPERCRITICAL PRESSURES
| Autor: | WEI-TANG CHIANG, 姜巍棠 |
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| Rok vydání: | 1994 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 82 In this dissertation, a mathematical model for computations of dense sprays at subcritical and supercritical pressures is developed. The concept of "sphere of influence" is applied to account for multi-droplet interaction. High-pressure effects are dealt with by solving both gas and liquid phase transient flows, as well as by including the effects of ambient gas solubility, property variation, thermodynamic nonideality, and transient diffusion. With dense spray vaporization, droplet lifetime is signifi- cantly prolonged at low initial ambient pressures, progressively decreasing as initial ambient pressures rise. From these results, it is summarized that the multi-droplet interaction is relatively weaker at high pressures. The studies of n-pentane dense spray ignition show that, at high pressures, the heterogeneous ignition can take place at a relatively smaller droplet size than it can at low pressures. Droplet vaporization and ignition of dense droplet clouds at sub- and super-critical conditions is also studied by solving the inner heterogeneous and outer homogeneous regions of a spherical cloud of monosized droplets. The results show that, at high pressures, less fuel vapor can be diffused to the cloud sur- roundings to cause ignition therein. The external group combust- ion mode is thus less likely for a cloud of droplets at high pre- ssures than it is for a cloud of droplets at low pressures with an equivalent spray density. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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