Studies on fuel spray characteristics of a rotating fuel injector and its effect on performance and emission in a direct injection diesel engine

Abstract

Diesel engines are used extensively due to higher performance, better fuel efficiency and low maintenance. The major drawback of them is that they emit sufficiently higher NOx and particulate matter. The fuel injection parameters, and spray characteristics have a major role in combustion and emission formation. A conventional injector produces spray mainly along the axial direction, which results in poor mixing of air and fuel. The current study aims to minimise this poor mixing issue, by developing a rotating injector by functionally modifying the existing three-orifice injector, to enable injector rotation. A modified fuel injection system is developed to accommodate a rotating fuel injector with sleeve. The rotating injector provides an angular momentum to the fuel, establishing a co-swirl motion to the fuel and modifying the spray characteristics. The spray images were observed using a high-resolution camera. A comparison and analysis of the spray characteristics is carried out using image processing techniques. A detailed comparison of conventional injection systems with two, three and five orifice injectors, a Common Rail Direct Injection system, and a rotating injection system was made, by default single hole injector have low spray area compare then other injectors. OpenCV Python code is used for spray edge detection, colour thresholding of images, spray angle determination and cross-sectional fuel dispersion area calculations. The overall spray cone angle is greater for the rotational direct Injection system. The rotating injection spray is found to disperse over a wider angle, with almost negligible air gap and over a greater cross-sectional area. The rotation of the injector reduces local high concentration of the fuel, improve the homogeneity of the fuel-air mixture.