MPa Injection Pressure Research Articles

Atomization characteristics and prediction accuracy of LISA-DDB model for gasoline direct injection spray

In this paper, the spray atomization characteristics of a gasoline direct-injection injector were investigated experimentally and numerically. To visualize the developing spray process, a laser sheet method with a Nd :YAG laser was utilized. The microscopic atomization characteristics such as the droplet size and velocity distribution were also obtained by using a phase Doppler particle analyzer system at the 5 MPa of injection pressure. With the experiments, the calculations of spray atomization were conducted by using the KIVA code with the LISA-DDB breakup model. Based on the agreement with the experimental results, the prediction accuracy of LISA-DDB breakup model was investigated in terms of the spray shapes, spray tip penetration, SMD distribution, and axial mean velocity. The results of this study provides the macroscopic and microscopic characteristics of the spray atomization, and prediction accuracy of the LISA-DDB model.

Fibre orientation of fibre-reinforced PBT composites in injection moulding

The present study investigates the fibre orientation and distribution of 15 wt-% short fibrereinforced polybutylene terephthalate using both experimentation and computer-aided analysis. Filling time, melt temperature, mould temperature and packing pressure are chosen to be the controllable parameters that govern the injection-moulding process. The influence of injectionmoulding process parameters on the frozen–intermediate–core morphology is observed using scanning electron microscopy. The variations of frozen layer thickness are strongly affected by the injection-moulding parameters. The minimum is at a filling time of 3 s, a melt temperature of 240°C, a mould temperature of 90°C, and a packing pressure of 100% of the constant 42 MPa injection pressure for the mould with dimension 45 mm x 45 mm x 4.0 mm. The experimental results are used to validate the accuracy of the computer simulation in fibre orientation and distribution. Simulated and experimental results closely correspond to each other.

QUANTITATIVE MEASUREMENTS OF DIESEL FUEL SPRAY CHARACTERISTICS IN THE NEAR-NOZZLE REGION USING X-RAY ABSORPTION

The mass distribution of diesel fuel sprays close to the nozzle has been determined by using absorption techniques with a monochromatic, synchrotron X-ray beam. The measurements were highly quantitative, with a temporal resolution better than 1 ms. The radial mass distribution of the fuel can be well described by a Gaussian distribution near the nozzle. The calculated volume fraction of the fuel indicates that the so-called liquid core near the nozzle did not exist under the test conditions examined (20-80 MPa injection pressure, 0.3-0.6 ms injection duration). Rather, the bulk of the spray was composed of a liquid/gas mixture with liquid content not exceeding 50% by volume. The maximum-density region was found at the front edge of the sprays, where the fuel volume fraction can reach 80%, and was limited to a thin layer (1-2 mm) perpendicular to the spray axis. The penetration of the front edge was found to be nonlinear with respect to injection duration within 20 mm from the nozzle.

Effect of Injection Pressure on Atomization Characteristics of Fuel Spray in High-Pressure Gasoline Injector

This paper describes the macroscopic behavior and atomization characteristics of the high-pressure gasoline injector in direct-injection gasoline engine. The global spray behavior of fuel injector was visualized by shadowgraph technique. The atomization characteristics of gasoline spray such as mean diameter and mean velocity of droplet were measured by the phase Doppler particle analyzer system. In order to obtain the influence of fuel injection pressure, the macroscopic visualization and experiment of particle measurement on the fuel spray were investigated at 3,5 and 7 MPa of injection pressure under different surrounding pressure in the spray chamber. The results of this work show that the fuel injection pressure of gasoline injector in GDl engine has influence upon the mean droplet diameter, mean velocity of spray droplet, the spray tip penetration, and spray width under the elevated ambient pressure.