Analysis Research for Low Emission Spray Combustion via Fuel Injection Rate Control

本研究首先在共轨喷油系统的基础上开发了一种新型的燃油喷射系统。在此之前的发展，数值模拟代码，以估计该注射器内的主要基本部件的影响和估计的附加增压单元。因此，形成在针杆顶部的控制空间体积和位于控制空间中的入口/出口孔直径起重要作用，而共轨体积或共轨与喷射器之间的高压管的长度对喷射压力和喷射形状没有很大影响。最大喷油压力达到175 MPa。在喷油速率控制方面，通过系统控制程序实现了预喷、分段喷射和多次分段喷射。该系统连接到快速压缩机，并进行单次燃烧试验。实验表明，在所研究的压力范围内，随着喷射压力的增加，滞燃期沿着缩短，并且多次分喷中提前喷射的燃料使燃烧压力上升率增大。喷孔直径和孔数对燃烧室壁面热损失有明显影响。

A new fuel injection system was developed at first based on a common rail injection system in this research. Prior to this development, numerical simulation code was made in order to estimate the effects of main elementary parts within this injector and the estimation of the additional pressure booster unit. As a result, the control space volume which is formed at the top of the needle rod and the inlet/outlet orifice diameter which are located in the control volume play important parts, whereas the common rail volume or the length of high pressure tube between the common rail and the injector have no great influence on injection pressure and injection shape.By the construction of pressure booster, maximum fuel injection pressure has reached 175 MPa. And as to injection rate control, pilot injection, split injection and multiple divided injection were realized by means of the system control program. This system was attached to a rapid compression machine, and single shot combustion tests were performed. This experiment clarified that the ignition delay period is shortened along with the increase of injection pressure in the examined pressure range, and also earlier injection fuel in multiple divided injection made a higher combustion pressure rise rate.After this experiment, this combustion test apparatus was applied to estimate the heat loss phenomena-in diesel combustion. The heat loss to the combustion chamber wall was apparently affected by orifice diameter and hole number of the injector.