Experimental Study on the Adhesive Fuel Features of Inclined Wall-Impinging Spray at Various Injection Pressure Levels in a Cross-Flow Field

Abstract

The wall-impingement phenomenon significantly impacts mixture formation, combustible performance, and pollutant release in DISI engines. However, there is insufficient knowledge regarding the behavior of fuel adhesion. Thus, here, we examine adhesive fuel features at various injection pressure levels (5 and 10 MPa) in a cross-flow field (0 to 50 m/s). The RIM optical method was employed to track the expansion and distribution of fuel adhesion. As a result, adhesive fuel features such as area, mass, thickness, and lifetime were assessed. Postprocessing image analysis reveals that fuel adhesion was consistently thinner at the edge region. With increased injection pressure, the cross flow led to a rise in the fuel-adhesion area and mass; however, small changes in pressure did not affect adhesive thickness. Adhesive thickness significantly decreased in the cross flow, indicating enhanced evaporation potential. Furthermore, lifetime prediction was conducted to quantitatively evaluate the impact of cross flow and injection pressure upon fuel adhesion, which could be calculated by examining the decreasing trend in adhesive area. Results show that the lifetime was dramatically reduced with higher cross-flow velocity, and slightly decreased with lower injection pressure. Under injection pressure of 10 MPa, the adhesive lifetime in the cross-flow field of 50 m/s was reduced by 77.5% compared with the static flow field (0 m/s). The experimental results provide corresponding guidance for low-carbon fuel utilization and emission reduction in DISI engines.

Thermal Load Analysis of Piston Damaged by Wall-Wetting Combustion in a Heavy-Duty Diesel Engine

“…Therefore, the dynamics of wall films, such as wall film formation, propagation, and breakup, require further investigation. Wall film during spray impinging can be quantitatively measured using laser-induced fluorescence and Mie scattering methods, and film thickness has been measured using low-speed refractive index matching in a constant volume chamber [2,3]. Recently, impinging spray characteristics, including impinging distance, wall angle, wall temperature, injection pressure, and fuel mass, have been fully investigated [4][5][6][7][8][9][10].…”

“…Adjusting the injection parameters is the common way to improve the fuel atomization quality. Although increasing the injection pressure is conducive to shortening the lifetime of fuel adhesion [3], ignition instability may occur with the increase in injection pressure under the condition of low temperature [8]. Scholars have simulated the characteristics of fuel film formation and spray impinging under cold conditions and the influence and law of spray-wall impinging distance on ignition and combustion morphology in low-temperature environments [11][12][13][14].…”