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In this work, three Engine Combustion Network (ECN) single-hole nozzles with the same nominal characteristics have been tested under a wide range of conditions measuring spray penetration and spreading angle. n-dodecane has been injected in nonevaporative conditions at different injection pressures ranging from 50 to 150 MPa and several levels of ambient densities from 7.6 to 22.8 kg/m 3 . Nitrogen and Sulphur Hexafluoride (SF 6 ) atmospheres have been explored and,in the first case, a temperature sweep from 300 to 550 K at constant gas density has been executed. Mie scattering has been used as the optical technique by employing a fast camera, whereas image processing has been performed through a home-built Matlab code. Differences in spray penetration related to spray orifice diameter, spreading angle and start of injection transient have been found for the three injectors. Significant differenceshave been obtained when changing the ambient gas, whereas ambient temperature hardly affects the spray characteristics up to 400 K. However, a reduction in penetration has been observed beyond this point, mainly due to the sensitivity limitation of the technique as fuel evaporation becomes important. The different behavior observed when injecting in different gases could be explained due to the incomplete momentum transfer between spray droplets and entrained gas, together with the fact that there is an important change in speed of sound for the different gases, which affects the initial stage of the injection.

Elsevier Molina, S.; Salvador Rubio, FJ.; Carreres Talens, M.; Jaramillo, D. (2014). A computational investigation on the influence of the use of elliptical orifices on the inner nozzle flow and cavitation development in diesel injector nozzles. Energy Conversion and Management. 79:114-127. doi:10.1016/j.enconman.2013.12.015. THE INFLUENCE OF THE USE OF ELLIPTICAL ORIFICES ON THE INNER NOZZLE FLOW AND CAVITATION DEVELOPMENT IN DIESEL INJECTOR A COMPUTATIONAL INVESTIGATION ON

The influence of using biodiesel fuels on the hydraulic behavior of a solenoid operated common rail injection system has been explored by means of a one-dimensional model. This model has been previously obtained, including a complete characterization of the different components of the injector (mainly the nozzle, the injector holder and the electrovalve), and extensively validated by means of mass flow rate results under different conditions. After that, both single and multiple injection strategies have been analyzed, using a standard diesel fuel and rapeseed methyl ester (RME) as working fluids. Single long injections allowed the characterization of the hydraulic delay of the injector, the needle dynamics and the discharge capability of the couple injector-nozzle for the two fuels considered. Meanwhile, the effect of biodiesel on main plus post injection strategies has been evaluated in several aspects, such as the separation of the two injections or the effect of the main injection on the post injection fueling. Finally, a modification in the injector hardware has been proposed in order to have similar performances using biodiesel as the original injector configuration using standard diesel fuel.

ElsevierSalvador Rubio, FJ.; Gimeno, J.; Carreres Talens, M.; Crialesi Esposito, M. (2016). Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part I: Experimental mass flow rate measurements and discussion. Energy Conversion and Management. 114:364-375. doi:10.1016/j.enconman.2016.02.042.Salvador, F.J., Gimeno, J., Carreres, M., Crialesi-Esposito, M., "Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part I: Experimental mass flow rate measurements and discussion". 31Results show an important influence of the fuel temperature, especially at low injection pressure. A 32 low injection temperature results in a lower stationary mass flow rate, whereas injection duration is 33 also reduced. These results will be explained mainly through the fuel properties variation induced 34 by temperature, together with the ballistic nature of the injector used for the study.

COMPARISON OF MICROSAC AND VCO DIESEL INJECTOR NOZZLES IN TERMS ABSTRACT 23A computational study focused on the inner nozzle flow and cavitation phenomena has been 24 reported in this paper in order to investigate the two most common types of diesel injector nozzles 25 at the present: microsac and valve covered orifice (VCO). The geometrical differences among both 26 types of nozzles are mainly located at the needle seat, upstream of the discharge orifices. In the 27 case of microsac nozzles there is a small volume upstream of the discharge orifices which is not 28 present in VCO nozzles. Due to these geometrical differences among both type of nozzles, 45One of the main conclusions of this study is the higher influence of the needle on the mass flow, 46 momentum and injection velocity results for the VCO nozzle as compared to the microsac one.

Cavitation phenomenon has a strong influence on the internal flow and spray development in diesel injector nozzles. Despite its importance, there are lots of aspects which remain still unclear, especially at partial needle lifts when the injector is in the opening and closing phases. For that reason, the current paper is focused on the influence of the needle lift on the internal flow in a diesel nozzle. This study has been carried out with 3D simulations at high injection pressure (160 MPa) using a homogeneous equilibrium model implemented in OpenFOAM to model cavitation phenomenon.The nozzle has been simulated with LES methods at six different needle lifts (10, 30, 50, 75, 100 and 250 μm), providing relevant information about the evolution of the internal flow, the turbulence development (vorticity, turbulence-cavitation interaction and turbulent structures) and the flow characteristics in the nozzle outlet (mass flow, momentum flux and effective velocity) with the needle position.

An experimental and computational study of an increasingly used third-generation common-rail injection system with a piezo actuator has been carried out. A complete characterization of the different elements of the system, both geometrically and hydraulically, has been performed in order to describe its behaviour. The information obtained through the characterization has been used to create a one-dimensional model that has been implemented in the commercial software AMESim and extensively validated against experimental data. The results of the validation demonstrate the model ability to predict the injection rate of the injector with a high level of accuracy, therefore, constituting a powerful tool in order to carry out further studies of this type of injection system.