Flow regime effects on non-cavitating injection nozzles over spray behavior

Abstract

This paper deals with the influence of flow regime (laminar, transition or turbulent) on the internal flow behavior, and how it affects the spray development in diesel nozzles. In particular, the research described here aims at studying and quantifying the internal flow regime effects on the spray behavior. With this purpose, internal flow results, based on mass flow rate and momentum flux measurements performed on three different tapered nozzles and which helped to determine the flow regime, has been taken into account as a point of departure for the spray behavior analysis. Thus, in this work, spray macroscopic visualization tests have been performed and analyzed which clearly revealed a change in the behavior of the angle and penetration of the spray related to the change of the flow nature. Moreover, with all the experimental data available, it has been possible to relate macroscopic parameters of the spray with those describing the internal flow (momentum and effective velocity) or the geometry of the nozzle (length or diameter) through correlations. A o Orifice outlet section area.C Spray penetration adjustment constant.C a Area Coefficient.D ef Effective diameter. r Inlet curvature radius.Re Reynolds number.S Spray penetration. ∆p Pressure drop across the nozzle.ρ a Discharge gas density.ρ f Fuel density.θ Spray angle.

Effect of turbulence model and inlet boundary condition on the Diesel spray behavior simulated by an Eulerian Spray Atomization (ESA) model

“…the threshold), the criteria used for its definition, etc. as noted by Payri et al (2011b). The spray penetration seems to be well predicted by all models but the RNG and Realizable k − models.…”

“…A very interesting result is the behavior of the penetration very short time after the start of injection given by the mass flow rate condition. This change in the slope is not present in the experimental curve because no measurements in the near field were made by Payri et al (2011b), notwithstanding other authors have experimentally observed it, for example, de la Morena (2011). Despite that, the behavior is similar to the experimental curve, maybe with slightly higher slope.…”

“…Figure 9 shows four different time steps. In each one, the upper part corresponds to the liquid mass fraction contour and the lower part to the experimental spray contour obtained via back-light illumination technique by Payri et al (2011b). The time of experimental images is about 150-180 µs delayed in order to compare images with the same penetration value.…”

“…Available data for such nozzle are: mass flow rate measurements, momentum flux experimental measurements and diffusive back-light spray visualization un-der non-cavitating and non-evaporative conditions. These measurements are presented and discussed in the work of Payri et al (2011bPayri et al ( , 2012. Only one experimental point of the whole test matrix corresponding to low injection pressure and high ambient density is selected to keep the number of simulations within a reasonable limit.…”

Analysis of combustion concepts in a newly designed two-stroke high-speed direct injection compression ignition engine

“…Mass flow rate and spray momentum flux were measured in a dedicated test rig [32][33][34][35] for the selected injection hardware at analogous test conditions using diesel and gasoline. The injection characteristics are required to be used as inputs of the detailed CFD calculations and also for the combustion analysis from the experimental information.…”