A new experimental method for studying the single droplet breakup mode of diesel-water composite droplet fuel

Abstract

Good atomization of the liquid phase fuel is a prerequisite for efficient combustion and micro-explosion can significantly increase the atomization. In order to study the influence of water content and ambient temperature on the breakup mode and combustion behavior of diesel-water composite droplet, a novel experimental method was proposed. Specifically, the required volume of water was placed at the end of the probe, and diesel was then dropped onto the outer surface of the water by free diffusion to form water-in-oil composite droplet. The experimental results indicated that compared with the combustion of pure diesel, the diesel-water composite droplet additionally experienced a fluctuating combustion stage, in which micro-explosion and puffing occurred. Water content and ambient temperature have dual effects on the breakup mode and combustion characteristics of composite droplet. When the water content exceeded 20%, the breakup mode of the droplet was converted from micro-explosion to puffing, which reduced the atomization performance of the fuel. The ignition time of the composite droplet was 50–60% lower than that of pure diesel, and the burnout time decreased by about 35%. The breakup mode of the droplet and the critical size results indicate that 10%water/90%diesel at 973 K is most conducive to combustion.