Effect of grouped-hole nozzle geometry on the improvement of biodiesel fuel atomization characteristics in a compression ignition engine

Abstract

This paper describes the influence of grouped-hole nozzle geometry on the atomization characteristics of a biodiesel fuel. The effects of injection rate profile, spray evolution, droplet mean diameter, and mean velocity of the droplets are investigated in a highpressure injection system.A grouped-hole nozzle with 16 holes driven by piezo stack was used in the experiments and the obtained results are compared with those obtained using a single-hole nozzle with the same overall nozzle area. The effect of using a split fuel injection strategy on the spray atomization was analysed using a grouped-hole nozzle with 12 holes. The time-based injection rate profiles for a biodiesel fuel, i.e. the mass flowrate of the fuel injector nozzle were obtained from the pressure variation generated when the fuel was injected into a tube filled with fuel. The spray and atomization performance for biodiesel fuel injected through a grouped-hole nozzle were visualized and measured by a visualization system and droplet analyser system, respectively.It was revealed that the biodiesel injection rate profile from a single-hole nozzle with the same overall nozzle area shows a similar injection rate profile to that of the grouped-hole nozzle. The injection rate profiles for a split injection strategy are lower than for a single injection and the peak value of the second injection is lower than for the first injection. The Sauter mean diameter distributions of biodiesel from the grouped-hole nozzle have a larger diameter because the small droplets injected through the grouped-hole nozzle collide and coalesce with each other, which leads to an increase in droplet diameter. From these results, it can be concluded that the use of a grouped-hole nozzle and split injection strategy does not improve on the fuel atomization performance for biodiesel fuel for a single-hole nozzle.

Engine performance of a single cylinder direct injection diesel engine fuelled with blends of Jatropha Curcas oil and standard diesel fuel

“…However, the higher viscosity, density, and surface tension levels found may result in poor atomization characteristics, leading to a lower combustion pressure and rate of heat release in an internal combustion engine [22]. In this research, this behavior was not clearly observed and will be checked in further works.…”

Impact of Orifice Angle Configurations on the Droplet Atomization Enhancement of Diesel Fuel in a Group-Hole Nozzle

“…Parallel group-hole nozzle creates almost the same spray tip penetration compared with single-hole nozzle even it has a small orifice size (D) generally because the spray from each nozzle orifice compensates the spray momentum loss [16,17]. However, different orifice angles (0) such as converged or diverged must have infiuence on the spray tip penetration, spray velocity, and consequently, spray momentum.…”

“…However, although the effect of the group-hole nozzle geometry and distance between two orifices were revealed [14,15], the effect of nozzle orifice angles has not been under investigation. Especially, in aspect of droplet atomization characteristics, the effect of group-hole geometry on the droplet breakup characteristics is not clear whether it improves [3,6,14] or not [16,17].…”

Quantitative spray analysis of diesel fuel and its emulsions using digital image processing

“…Mie Scattering is another laser technique that has been used by [23][24][25][26][27] to investigate the characteristics of sprays generated by flash-boiling, pneumatic atomization, slit, piezo-electric, and port fuel injectors respectively. While Laser Induced Fluorescence (LIF) was used to visualize spray atomization [28][29], in addition to the Nd:YAG laser [14,21,[30][31][32][33][34][35][36][37] and other laser techniques mentioned in [12,[38][39][40][41][42][43][44][45][46][47][48]. Shadowgraphs are used as well in spray atomization investigations either individually [49][50][51][52] or accompanied by another optical technique such as laser-based techniques [25,28] and high speed camera [53].…”