Combustion of Transient Gas Fuel Jet and Process of Entrainment of Ambient Air into Jet

瞬态气体燃料射流的燃烧及环境空气夹带进入射流的过程

基本信息

批准号：
06650248
负责人：
YOSHIYAMA Sadami
金额：
$ 1.34万
依托单位：
Okayama 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：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

It is well known that the process of mixture formation in direct injection engine such as diesel engine has great influence on the combustion in the cylinder. It is very important to understand the entrainment process of amibient air into the jet or spray in detail. However, few studies have been done on the entrainment process. The fuel injected into the cylinder with high pressure and high temperature in a diesel engine evaporates and goes through with entraining the ambient air. Therefore, for understanding the phenomena easily, a gas was injected for the reason of ignoring the evaporation process and the entrainment process is investigated under the amibient air with atmospheric pressure and room temperature.In this study, a laser sheet was passed through the cross section of the jet that contained the jet axis or was perpendicular to the jet axis. The instantaneous image of the transient jet and the movement of the ambient air were visualized with fine particles and micro-balloons … More , respectively. A path line method for micro-balloons utilizing a CCD shutter camera was applied for obtaining the air mass entrained into a transient gas jet approximately. In the case of the flame, which was formed by igniting the hydrogen jet at the initiation of the jet, the air flowed into the jet was as the same sa in the jet without combustion. However, the rate of air flowed into the jet per unit surface area was smaller and decreased with time. When the timing of the ignition was delayd after the initiation of the jet injection, the combustible mixture was formed in advance and the air flowed into the jet increased because of turbulent diffusion due to the rapid combustion.It is also said that the combustible mixture increases in impinging on a wall because of turbulent diffusion. The same method was applied to the jet impinging on a flat wall in order to inveatigate the entrainment of the ambient air into the jet. As a result, the air mass flowed into the jet impinging on a flat wall increased after the impingement for a while, but was almost the same when the time passed more and more even in the injection period. It was found that the rolled up region near the jet tip casused the ambient air flow into the jet. The compact structures that would correspond to the scale of the vortex were disposed regularly near the rolled up region. Less

众所周知，柴油机等直喷式发动机中混合气的形成过程对气缸内的燃烧影响很大，详细了解环境空气进入射流或喷雾的过程非常重要。关于夹带过程的研究很少。在柴油机中，在高压和高温下喷射到气缸中的燃料会蒸发并夹带周围的空气。因此，为了容易理解这一现象，我们喷射了一种气体。的原因在大气压力和室温的环境空气下，忽略蒸发过程和夹带过程。在这项研究中，激光片穿过包含射流轴线或垂直于射流轴线的射流横截面。瞬态射流的瞬时图像和环境空气的运动分别通过细颗粒和微气球进行可视化。利用 CCD 快门相机的微气球路径线方法来获取空气质量。在喷射开始时点燃氢气喷射而形成火焰的情况下，流入喷射中的空气与未燃烧的喷射中的情况相同。当喷射开始后延迟点火时间时，单位表面积流入射流的空气量较小，并且随着时间的推移而减少，因为可燃混合气提前形成，流入射流的空气量增加。的由于快速燃烧而产生湍流扩散。据说，由于湍流扩散，可燃混合物对墙壁的撞击会增加。同样的方法也适用于撞击平坦墙壁的射流，以研究环境空气的夹带。结果，流入撞击平坦墙壁的射流的空气质量在撞击一段时间后增加，但当喷射时间越来越均匀时，空气质量几乎相同。研究发现，喷射尖端附近的卷起区域导致周围空气流入射流，与涡流规模相对应的紧凑结构在卷起区域附近规则地布置。