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The flow field resulting from injecting a gas jet into a crossflow confined in a narrow square duct has been studied under steady regime using schlieren imaging and laser Doppler velocimetry (LDV). This transparent duct is intended to simulate the intake port of an internal combustion engine fueled by gaseous mixture, and the jet is issued from a round nozzle. The schlieren images show that the relative small size of the duct would confine the development of the transverse jet, and the interaction among jet and sidewalls strongly influences the mixing process between jet and crossflow. The mean velocity and turbulence fields have been studied in detail through LDV measurements, at both center plane and several cross sections. The well-known flow feature formed by a counter rotating vortex pair (CVP) has been observed, which starts to appear at the jet exit section and persists far downstream contributing to enhancing mixing process.

The influence of spray-wall interaction on air entrainment in an unsteady non-evaporating diesel spray was studied using laser Doppler anemometry. The spray was injected into confined quiescent air at ambient pressure and temperature and made to impact on a flat wall. The air velocity component normal to a cylindrical surface surrounding the spray was measured during the entire injection period, allowing to evaluate the time history of the entrained air mass flow rate. The influence of wall distance and spray impingement angle on air entrainment characteristics has been investigated and the results indicate that the presence of a wall increases the entrained mass flow rate in the region close to the surface, during the main injection period. Normal impingement appears to produce stronger effects than oblique incidence at 30 and 45 deg. A qualitative explanation of the results is also proposed, based on the drop-gas momentum exchange mechanism.

The air entrainment in a transient non-evaporating diesel spray was studied using laser Doppler velocimetry, to provide information on the mixing properties in the near-field region extending to 160 nozzle diameters (40 mm). The spray was injected into confined quiescent air at ambient pressure and temperature. The air velocity component normal to a cylindrical surface surrounding the spray was measured during the entire injection period, allowing the instantaneous air mass flow rate and the entrainment rates to be evaluated as a function of time. Two injection conditions were examined and their influence on the entrainment quantified. In the near field zone investigated, the air entrainment in transient liquid jets appears to be lower than that in steady gaseous jets, but larger than that in steady liquid jets.

The effects of two types of intake ports on the in-cylinder bulk flow and turbulence structure were investigated in steady flow tests by using laser doppler anemometry. The results, obtained at constant mass flow-rate in a plane 15 mm or 0.19 bore diameters from the cylinder head, confirmed the expected differences in the tangential flow pattern, but revealed similarity in the axial velocity distribution characterized by a large recirculation zone (RZ) attached to the inlet valve. In both cases the turbulence was found higher, more inhomogeneous and more non-isotropic in the regions of positive axial flow than in the RZ. Localized highly turbulent conditions have been identified and characterized as a consequence of bi-modal probability distribution functions (pdf) of velocity and aperiodic oscillations from one velocity regime to another.