Semi-empirical model for the engine liquid fuel sheet formed by the oblique jet impinging onto a plate

Abstract

Operating conditions and fuel properties are important to the atomization quality, which is an inevitable problem that the liquid fuel has to face, specifically for new alternative fuels. One of the recognized atomization methods is the liquid sheet formed by the oblique fuel jet or spray impinging onto a plate in a direct injection (DI) engine. In this paper, a series of experiments that deal with the sheet, are carried out under different operating conditions. Meanwhile, a semi-empirical model fitted for new alternative fuels is established to predict the shape and the size of the sheet. The predictions of the model are in good agreement with the experimental data. Based on the experiments and predictions, the specific effect of the dynamic viscosity, the surface tension, the impingement velocity and the impingement angle on the sheet were analyzed, respectively. It is found that the sheet consists of a thin liquid layer and a thick rim which connects the outer and the inner border lines. With the decrease of the dynamic viscosity, the size of both the outer and inner border lines of the sheet will non-linearly increase. The gradient of the size of the border lines is decreased with the increase of the dynamic viscosity. With the decrease of the surface tension coefficient, the size of the border lines will gradually increase. The size of the border lines will linearly increase with the increasing impingement velocity. With the increase of the impingement angle, the border lines will gradually become circles. The semi-empirical model that is established with reasonable assumptions, can help fuel developers to assess the potential atomization quality of their new fuels.