Effect of the nozzle holder on injected fuel temperature for experimental test rigs and its influence on diesel sprays

Abstract

One of the test boundary conditions whose control is necessary for both experimental and numerical studies about the automotive engines research field is the temperature of the fuel inside the injector body during the injection. However, it is a difficult parameter to be directly measured in a non-intrusive way due to the injector architecture and the nature of the standard experiments that are done to characterize sprays. An experimental analysis is performed in this work employing a continuous flow test chamber, normally used in the optical diagnosis of diesel sprays, in order to compare and characterize two different designs for the nozzle holder of the test rig. The first one consisted in an aluminum holder that coats the nozzle until its tip, while the second one is made of steel and only supports the nozzle without covering it from the environment. The employed methodology was to set the test rig at a wide range of thermodynamic conditions inside the vessel such as ambient temperature and density, and also the coolant temperature at the outlet of the injector casing for both cooling pieces. In this case, a dummy injector provided with a thermocouple was used to measure the tip temperature. In this way, correlations are obtained to estimate the injector body temperature out of the measurement points. Further experiments with a real single-hole diesel injector, controlling its tip temperature according to the previous results, are also discussed in this manuscript in order to analyze the effect of this parameter on the spray evaporation process. Liquid length at inert conditions and both ignition delay and lift-off length at reactive ones were measured employing the same test vessel. All those parameters showed to be shortened with an increment of injected fuel temperature, and the lower the ambient temperature, the stronger this influence is.

A numerical study of the effect of nozzle diameter on diesel combustion ignition and flame stabilization

“…This parameter is made up of the product of two terms. First, the rate of residence time per length unit (dt à =dl) is solved considering convective and diffusive contributions (equations (12) and (13)). Second, dl=df is obtained from the spatial gradient of f as projected along the direction defined by the velocity field (i.e.…”

“…The Spray A experiment, a single-hole nozzle injecting into a quiescent environment with thermodynamic conditions representative of CI engines, has allowed the development of an extensive database of experimental results. [8][9][10][11][12][13] On the simulation side, the single-hole nozzle experiment has enabled the comprehensive validation of the two-phase turbulent spray using both Lagrangian-Eulerian [14][15][16][17] and Eulerian 18,19 approaches.…”

Quantitative analysis of dribble volumes and rates using three-dimensional reconstruction of X-ray and diffused back-illumination images of diesel sprays

“…A description of the hightemperature facility can be found in recent works. 14,15 The optical configuration comprised a Photron SA-X2 camera equipped with a long-distance microscope lens. A diffusely illuminated background was achieved with a combination of a field lens and diffuser.…”

“…Consequently, images gathered are significantly sharper than continuous light source options. [12][13][14][15] In addition to optical measurements using visiblewavelength light, high-speed X-ray imaging has been used extensively to study the morphology of fuel injection sprays. 16 X-rays are highly penetrating in dense media, and scatter only weakly from liquid structures.…”

Comparative Analysis of the Features of Spraying a Heated Gas and Superheated Liquid Through Cylindrical Channels With Slices

“…Естественно, что управление этим процессом представляет чрезвычайный интерес для прикладной науки и инженеров-практиков, проектирующих технологическое оборудование. Так, например, в двигателестроении существует перманентная проблема управления структурой (формой) струи топлива, впрыскиваемой в камеру сгорания для достижения эффективного сжигания [5][6][7][8][9].…”