Study of Visualization Experiment on the Influence of Injector Nozzle Diameter on Diesel Engine Spray Ignition and Combustion Characteristics

Yuanzhi Tang,Zhiyuan Hu,Yunhua Zhang,Liang Fang,Chengguan Wang,Pi-Qiang Tan,Diming Lou

doi:10.3390/en13205337

Abstract

The elementary research of spray and combustion is of great significance to the development of compactness of modern diesel engines. In this paper, three injectors with different nozzle orifice diameters (0.23 mm, 0.27 mm and 0.31 mm) were used to study the diesel spray, ignition and flame-wall impingement visualization experiment. This paper studied the influence of different nozzle sizes on the trends of spray, ignition and flame diffusion under the flame-wall impinging combustion and used the flame luminosity to characterize the soot generation in combustion. By analyzing the quantitative data, such as spray penetration, ignition delay, flame area and flame luminosity systematically, it was shown that the smaller nozzle benefitted diesel combustion to some extent. The 0.23 mm nozzle injector in these experiments had the best fuel-air mixing effect under 800 K. The length of the spray liquid under the 0.23 mm nozzle condition was 19% and 23% shorter than that of 0.27 and 0.31 mm, respectively. Smaller orifice size of the nozzle can help to reach the gas ignition conditions more effectively. Without liquid fuel impingement, the simple flame-wall impingement will not change the trend of the nozzle influence on combustion. The total amount of accumulated soot according to the approximate luminosity spatial integral calculation in the combustion process was reduced by 37% and 43% under 0.27 mm and 0.23 mm nozzles, respectively, which is favorable for the clean combustion of diesel engines.

Highlights

Diesel engines have been widely used in various fields for the features of low fuel consumption, high torque, reliability and durability, and have been used in more than two-thirds of highway passenger and freight transportation
The spray experiment conditions were consistent with actual diesel engine working conditions
In the construction of the small-size diesel engine structure, the injector with small-orifice nozzle can decrease the liquid penetration effectively, avoid the deterioration of combustion caused by the liquid-wall impingement and lead to a smaller high temperature combustion area to reduce the generation of soot

Summary

Introduction

Diesel engines have been widely used in various fields for the features of low fuel consumption, high torque, reliability and durability, and have been used in more than two-thirds of highway passenger and freight transportation. The diesel engine will still play a key role in the world for a long time. The combustion of the direct injection (DI) diesel engine will always be the research focus because of its severe emissions like PM (Particulate Matter) pollutants [1]. Soot is the main component of diesel PM pollutants. The formation process or the nucleation of elementary carbon particles occurs mostly in areas with worse mixture during combustion. The atomization degree of fuel spray and the quality of fuel and gas mixture directly determines the formation of soot in the latter combustion process [2,3], and the structural parameters of the fuel injection system and combustion chamber are one of the important factors that affect the fuel-air mixing of diesel engine [4]

Methods

Results

Conclusion