Experimental study of the injection conditions influence over n-dodecane and diesel sprays with two ECN single-hole nozzles. Part II: Reactive atmosphere

Abstract

a b s t r a c tThe second part of this experimental analysis, presented in this paper, seeks to go deep on the characterization of the Spray C and Spray D nozzles from the Engine Combustion Network, investigating the penetration of fuel spray at reacting conditions alongside characteristic parameters of combustion such as ignition delay and lift-off length. Both ECN mono-orifice injectors have similar nozzle flow capacity but different conicity degrees and corner sharpness, being Spray C more susceptible to cavitate. Schlieren imaging technique was employed to quantitatively measure reactive penetration and ignition delay, while lift-off length was identified through OH ⁄ chemiluminescence. As in the inert part of this research, n-dodecane and commercial diesel were selected for the tests, thereby the effect of the fuel properties in the measured parameters was analyzed. Also, once again the concept of R-parameter, defined as the penetration derivative respect to the square root of time was calculated to delve into the penetration behavior. The experiments were performed in a constant pressure-flow facility able to reproduce engine-like thermodynamic conditions. Results revealed that R-parameter evolution can be divided in four stages: an inert zone, a 'bump', a 'valley' part and a quasi-steady one that overlaps the previous inert part. Those stages are highly governed by ambient temperature and oxygen concentration. Nozzle geometry and fuel properties demonstrated to have a noteworthy influence on all measured parameters.

Experimental study of the injection conditions influence over n-dodecane and diesel sprays with two ECN single-hole nozzles. Part I: Inert atmosphere

“…The employed optical setup allows both Schlieren and DBI high-speed to be recorded simultaneously. The second half of this research covers the analysis of those injectors, but in reactive conditions, measuring combustion parameters as well as ignition delat and lift-off length, and will be presented in a further document [28].…”

Spray/wall interaction analysis on an ECN single-hole injector at diesel-like conditions through Schlieren visualization.

“…Several 'free-jet' experiments have been carried out previously in the test rig [7]- [9], [19]. However, for this type of tests involving a wall obstructing the free path of the jet, it was necessary to design a system to reliably support the wall at determined angles and distances from the injector tip achieved with high accuracy.…”

“…A way to express the spreading in a time-independent form and to compare its behavior with the well-known one of the free penetration, is to convert it in terms of its time squared root derivative ∂S(t)/∂√t, as have been made in previous works with the free penetration under the name of R-parameter [9], [19]. In those works, was demonstrated how, accordingly with literature, the steady spray vapor penetration of an inert spray is proportional to the time raised to the power of 0.5, making possible to obtain a constant value referred to as R-parameter, independent of the time and of the penetration evolution.…”

“…It is an axial single-hole Bosch 3-22 injector with an outlet diameter of 192 µm [18], a k-factor of 1.5 whose rounded nozzle entrance and a convergent shape is oriented to avoid the cavitation phenomenon. The geometrical features of the Spray D can be found on the ECN webpage [15] and it has been hydraulically characterized in previous studies [9], [19], [20]. The injection setup consisted of a conventional Common-Rail system, which is mainly constituted by a standard rail with pressure regulator and a high pressure volumetric Bosch CP3 pump which is driven by an electric motor.…”

Analytical characterization of the Aegle marmelos pyrolysis products and investigation on the suitability of bio‐oil as a third generation bio‐fuel for C.I engine

“…The comprehensive combustion of engine fuel is indicated by the amount of CO 2 emission [38]. However, the inadequate combustion of the fuel indicated by the higher amount of CO emission.…”