| As an advanced flow field measurement technique, the PIV technology was widely applied in the area of complex flow field measurement because of the characteristics of non-interference, high spatial resolution, whole flow field and transient measurement. In this paper, the PIV technology was applied in three typical flow field measurements that is the gasoline spray field, the in-cylinder flow field of engine and the burble field of sediment in a water channel.In the spray experiment, much comparison and research were taken in the spray characteristics of the swirl injector with the diameter of 0.35mm and the double-jet holes injector of 2×0.22mm. It shows that the spray of swirler forms a significant injection cone angle, the quality of spray of the swirler is obviously better than the double-jet holes, the penetration length of swirler is shorter than latter, but the spray of the double-jet holes is focused on the central line of injection, and is faster and longer than the former. The features of two injectors are completely in coincidence with the theories of the liquid film jet and cylinder jet. And it also shows that the spray quality of swirler is much better than traditional multi-holes injector if it's larger.The study of distribution maps of velocity vectors, vorticities and turbulent intensities show that the distribution of high speed particles of the swirler is totally more divergent, and high speed particles of double-jet holes are distributed more on the central line that is in coincidence with its concentration distribution; the distributions of vorticity and turbulent intensity to the double-jet holes are concentrated on the peripheral of the shape of spray that is opposite to the distributions of velocity and concentration and the distribution of turbulent intensity of the swirler is not as well as the former. These conclusions are helpful to study the process of gasoline spray and oil-air mixture.In the engine experiment, the evolvement of the turbulent ILS produced by the intake-stroke and the compress-stroke on the cross-section in the cylinder were studied. It analyzed that the two ILS curves produced by y-direction velocity component along x and y directions reached peak value synchronously at the 150°CA, meanwhile, the total-ILS of the whole flow field also reached peak value, approaching 4.0mm; The y-direction velocity component became the major factor to influence the alteration of the totle ILS produced by the whole flow field. In the water channel experiment, the set-dimension models such as small plastic sphere were used to simulate the sand grains and use the PIV to measure the burble field of the models in a water channel in order to get the speed characteristics of the wake flow. The reasults are useful for the corresponding numerical simulation. |
