Macroscopic and Microscopic Characteristics of a GDI Spray Under Various Thermodynamic Conditions

Abstract

Article Macroscopic and Microscopic Characteristics of a GDI Spray Under Various Thermodynamic Conditions Jian Li 1, Lulu Li 1, Rujie Xiao 1, Yuanfei Liang 1, Shuyi Qiu 2, and Xuesong Li 2,* 1 SAIC GM Wuling Automobile Co., Ltd., 18 Hexi Rd, Liunan District, Liuzhou 545001, China 2 School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China * Correspondence: xuesonl@sjtu.edu.cn     Received: 12 June 2023 Accepted: 9 August 2023 Published: 28 August 2023   Abstract: Gasoline direct injection (GDI) is the most common and advanced fuel supply strategy for gasoline engines. The fuel atomization quality and fuel/air mix degree determine the subsequent combustion efficiency and emissions. However, the engine works in complex conditions which have numerous thermodynamic boundary conditions, and the characteristics of fuel atomization also change accordingly. It is necessary to clarify the influence of various thermodynamic conditions on the GDI spray. In this work, three different types of optics diagnostic methods were utilized to capture the macroscopic and microscopic characteristics of a commercial GDI injector spray under various thermodynamic boundary conditions. Specifically, Mie-scattering photography was employed to get the macroscopic parameters; planar Mie-scattering photography was utilized to get the spray pattern; phase Doppler interferometry (PDI) was used to get the microscopic characteristic, i.e., the droplet size distributions. It is found from this study that higher injection pressure, lower ambient pressure, and lower ambient temperature would lead to longer penetration and larger plume width. Lower ambient pressure and higher ambient temperature would cause a smaller spray pattern. Higher injection pressure, lower ambient pressure, and higher ambient temperature would result in smaller droplet sizes.