Study on the Atomization Gasification, Mixing and Combustuin Processes of Liquid fuel Jets in Supercritical Enironments

超临界环境液体燃料射流雾化气化、混合及燃烧过程研究

基本信息

批准号：
11650219
负责人：
UMEMURA Akira
金额：
$ 1.66万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Analyzes were made of characteristic processes involved in the combustion of sprays which are formed when liquid fuel is injected into the air whose thermodynamic state exceeds the critical point of the fuel. The following were found. ( 1) Despite the convectional belief that droplet auto-ignition delay time shortens monotonically with increasing pressure, it was found that the droplet auto-ignition delay time takes a peak at the ambient states near to the fuel critical point. This secular behavior is due to the influence of the phase equilibrium condition at droplet surface. Considering that current diesel engines operate at such condition, this knowledge addresses an interesting problem of finding an optimum spray condition for fast combustion. (2) Atomization is a keytechnology to spray combustion. However, the understanding of atomization mechanism involved in high-pressure sprays used in liquid rocket engines and diesel engines are very poor because optical observation is very difficult at high pressures. The current concept is based on the knowledge obtained from the experiments of water jet atomization at standard pressure. We examined the instability of jets with near-critical mixing surface and found a new instability mode with growth rate proportional to jet speed, which can make the liquid jetbroken into droplets with short spacing with the aids of hydrodynamic action. This finding theoretically bases the formation of dense sprays constituting of fine droplets at high pressures, if we regard a low-speed liquid jet as one of the liquid ligaments formed in the turbulent atomization process of an injected liquid. Furthermore, we studies (3) the mechanism of rapid flame propagation through combustible vortices formed in the process of turbulent mixing and (4) the modes of flame spreading between droplets for a various kind of sprays.

分析是针对喷雾剂燃烧的特征过程进行的，这些过程是在热力学状态超过燃料临界点的空气中形成的。找到以下内容。（1）尽管对流的信念是，液滴自动点火延迟时间随着压力的增加而单调缩短，但发现液滴自动点击延迟时间在接近燃油临界点的环境状态下达到顶峰。这种世俗的行为是由于液滴表面的相平衡条件的影响。考虑到当前的柴油发动机在这种情况下运行，该知识解决了一个有趣的问题，即为快速燃烧找到最佳的喷雾条件。（2）雾化是喷涂燃烧的键作。但是，对液态火箭发动机和柴油发动机中使用的高压喷雾剂涉及的雾化机制的理解非常差，因为在高压下，光学观察非常困难。当前的概念基于从标准压力下的水流雾化实验中获得的知识。我们检查了带有近临界混合表面的喷气机的不稳定性，并发现了一种与喷射速度成正比的增长速度的新不稳定性模式，这可以使液体喷射折断在液滴中具有短间距，并具有水动力动作的帮助。从理论上讲，这种发现是基于高压下细滴构成的密集喷雾剂的形成，如果我们将低速液体射流视为注射液体的湍流雾化过程中形成的液体韧带之一。此外，我们研究（3）通过在湍流混合过程中形成的可燃涡旋以及（4）在液滴之间散布的火焰模式以在各种喷雾剂之间扩散的火焰模式。