Basic study for developing supercritical spray combustion simulator

超临界喷雾燃烧模拟器研制基础研究

基本信息

批准号：
04650173
负责人：
UMEMURA Akira
金额：
$ 1.28万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Numerical simulations were performed to examine the vaporization/cobustion characteristics for a liquid fuel droplet which was suddenly placed in an otherwise quiescent, inert/oxidizing gas at various status beyond the critical point of the fues. The vaporization/combustion characteristics were fully disclosed, together with their underlying physics. For a given ambient gas temperature, the minimum gasification/combustion time is achieved at such a pressure that the surface temperature which the droplet assumes immediately after its exposure to the hot inert gas or ignition coincides with the 'mixture' critical temperature. This pressure is far above the fuel critical pressure for a droplet gasifying in the ambient gas at a relatively low temperature, whereas the presence of flame shifts it very cose to the fuel critical pressure. Three modes of droplet vaporization were identified in the parameter space of ambient gas temperature and pressure ; (1) In the subcritical vaporization regi … More me, the droplet has the surface throughout its lifetime. (2) In the supercritical gasification regime, spatially continuous phase change occurs from the beginning. (3) Between them, there is the transient vaporization regime in which the transition from the sub-to-supercritical vaporization mode takes place.A generalized asymptotic theory was constructed to gain insight into the interactive droplet vaporization and combustion property in spray. At high pressures, a spray can be regarded as an ensemble of independent droplets pressures because the range of influence of each droplet is restricted within a short distance. A new numerical calculation method which incorporates the inherently unsteady droplet vaporization and combustion property was developed in order to transform a low-pressure spray combustion simulator at hand to a high-pressure one, in which the movements of a great number of droplets can be pursued in a Lagrangian way. Dynamic phenomena which would appear when the surface tension of droplet diminishes or vanishes were examined to approach the masked dynamic behaviors of sprays in supercritical conditions. Less

进行了数值模拟，以检查液体燃料液滴的分散/共生特性，该特性突然被放置在原本静止的，惰性/氧化的气体以外的各种状态，而不是燃料的临界点。分散/燃烧特性及其潜在物理学得到了充分披露。对于给定的环境气温，在压力下达到的最小气化/燃烧时间是在暴露于热惰性气体或点火后立即假设的表面温度与“混合物”临界温度一致的。该压力远远超过燃油的临界压力，即在相对较低的温度下在环境气体中液滴气体的压力，而火焰的存在将其非常依赖于燃料临界压力。在环境气体温度和压力的参数空间中鉴定出三种液滴色散模式；（1）在亚临界分散剂中……更多的我，液滴在其一生中具有表面。（2）在超临界气化制度中，从一开始就经常发生相变。（3）在它们之间，有一个过渡性分散性制度，其中发生了从子临界分散模式的过渡。建立了广义的渐近理论，以洞悉喷雾中的交互式液滴分散和混合物。高压，喷雾剂可以视为独立液滴压力的集合，因为每个液滴的影响范围在短距离内受到限制。开发了一种新的数值计算方法，该方法结合了遗传性不稳定的液滴色散和组合特性，以将手工的低压喷雾组合模拟器转换为高压液，其中可以以lagrangian的方式进行大量液滴的运动。当检查液滴的表面张力减小或消失以在超临界条件下接近喷雾的动态行为时，将会出现动态现象。较少的