Ultrafast X-ray study of multi-hole GDI injector sprays: Effects of nozzle hole length and number on initial spray formation

摘要: Abstract Nozzle hole design factors, such as length, diameter, position and number of nozzle holes, significantly alter the near-field jet flow following spray formation fuel injection nozzles. This study investigates effects various factors on multi-hole injectors for gasoline direct-injection (GDI) engines. The novelty this lies in intensive analysis breakup, dynamics droplet process that have rarely been characterized from previous studies by exploiting potentials synchrotron X-ray analysis. Among several length holes are investigated current paper first part. Four prototype nozzles, which different lengths numbers with a substantially low needle lift 35 μm, were used fundamental study. Single- multi-exposed phase-contrast images to characterize exit 30 mm downstream. emerging flows GDI highly turbulent perturbed immediately exit. decrease increased axial radial velocity an void fraction inside at It promoted breakup smaller more circular liquid ligaments/droplets when decreased, accompanied higher rate turbulence strength along axis. On other hand, increase decreased flow. led slower lower axis larger holes.