Development of Micro-Diesel Injector Nozzles via Mems Technology and Effects on Spray Characteristics

Abstract

Micro-machined diesel injector nozzles have been designed, fabricated and used with commercially produced diesel injection systems in the study of spray dynamics. Such a system, properly designed, may improve spray behavior in DI diesel engines due to improved atomization and fuel-air mixing.In this work, fourteen micro-planar orifice nozzles were fabricated using the MEMS (Micro-Electro-Mechanical-Systems) technique. Circular orifice diameters were varied from 40 to 260 microns and the number of orifices was varied from one to 169. Three plates with noncircular orifices were also fabricated to examine the effect of orifice shape on spray characteristics. These nozzles were then attached to commercial injectors and the associated injection systems were used for the spray experiments.Given these novel injection systems, jet spray characteristics of micro-planar orifice nozzles were investigated experimentally using optical diagnostic techniques in a pressurized constant volume cylindrical chamber. Local drop sizes were measured by the laser diffraction technique, and average drop sizes of the whole sprays were measured by the light extinction * Corresponding author : Address : 295 Roger Adams Laboratory, Box C-3, 600 South Mathews Avenue, Urbana, IL 61801, USA Tel: +1-217-333-5233 E-mail address: sbaik@scs.uiuc.edu 1 technique. Current test results show expected qualitative trends in spray kinematics and drop sizes, but quantitative magnitudes of the behavior are less dependent on orifice geometry than first anticipated. Droplet coalescence among adjacent sprays were apparent for the multiple orifice nozzles because all the orifices were aligned in the same direction with limited spacing.Non-planar configurations are under development and may show improved performance.

Effect of Injector Nozzle Holes on Diesel Engine Performance

“…Numerous studies have suggested that decreasing the injector nozzle orifice diameter is an effective method on increasing fuel air mixing during injection (Baik, 2001). Smaller nozzle holes have found to be the most efficient at fuel/air mixing primarily because the fuel rich core of the jet is smaller.…”

Adaptive collision meshing and satellite droplet formation in spray simulations

“…The TAB model (O'Rourke and Amsden, 1987) is employed in the simulation of the experiment by Arai and Saito (1999), since the injected droplet Weber number was slightly greater than 6. In the simulation of the high-speed non-evaporating spray by Baik et al (2003), the WAVE model (Reitz, 1987) is used to describe both the primary atomization and droplet secondary breakup. The model by Zhou and Leschziner (1991) is employed to describe droplet dispersion due to turbulence.…”

“…The performance of the collision mesh on a high-speed non-evaporating spray is assessed using the experiment by Baik et al (2003). The effect of the satellite droplet model on the prediction of spray characteristics is also explored using this experiment.…”

“…To assess the capability of the adaptive collision mesh on realistic sprays, the experiments by Baik et al (2003) on high-speed non-vaporizing sprays in a constant volume chamber and at room temperature were simulated using the adaptive collision mesh. Then the improved satellite droplet model was applied to the same simulation to explore it effect on the prediction of spray characteristics.…”

Estudio, Modelado e Implementación Paralela de Sistemas Celulares Utilizados en Microfabricación

“…Entre los dispositivos basados en tecnología MEMS destacan los sensores de presión [81], acelerómetros [82], sensores de flujo de gas [83], microactuadores [84] o microinyectores [85]. La industria basada en MEMS ha sufrido un crecimiento continuo [86].…”