Multiphase Phenomena in Diesel Fuel Injection Systems

Karathanassis, Ioannis K.; Koukouvinis, Phoevos; Gavaises, E.

doi:10.1007/978-981-15-0335-1_8

Cited by 3 publications

(1 citation statement)

References 73 publications

(82 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5,7,19,37 XPCI has been also used to identify the detailed flow structures in nozzle replicas associated with the off-axis location of a needle valve relative to hole entrance, which gives rise to complex vortex (string) cavitation and cloud shedding. [38][39][40][41] However, the actual 3-D movement of the needle within injectors varies from injector to injector and thus, shot-to-shot and injector-to-injector variations can be expected.…”

Section: Introductionmentioning

confidence: 99%

An analytical model of diesel injector’s needle valve eccentric motion

Wang

Moro

Jin

et al. 2021

International Journal of Engine Research

Self Cite

View full text Add to dashboard Cite

Past experimental studies have shown that the needle valve of high-pressure diesel injectors undergoes lateral movement and deformation, while the continuous increase in injection pressure enlarges the gap of the needle valve assembly. Two different analytical models, considering or omitting this change are presented here, linking the geometries of the needle valve assembly with the magnitude of needle valve tip lateral movement. It is found that the physical dimensions of the needle valve assembly and the injection pressure have a significant impact on the radial displacement of the needle. For example, for nominal clearances between the needle guidance and the needle valve of about 1–3 μm, the magnitude of the radial movement of the needle tip could reach tens of microns. The model that takes into account the variation of the gap between the needle guide and needle valve is found to give predictions closer to the experimental results.

show abstract

Section: Introductionmentioning

confidence: 99%

An analytical model of diesel injector’s needle valve eccentric motion

Wang

Moro

Jin

et al. 2021

International Journal of Engine Research

Self Cite

View full text Add to dashboard Cite

show abstract

Combined visualisation of cavitation and vortical structures in a real-size optical diesel injector

et al. 2020

View full text Add to dashboard Cite

A high-speed flow visualisation set-up comprising of combined diffuse backlight illumination (DBI) and schlieren imaging has been developed to illustrate the highly transient, two-phase flow arising in a real-size optical fuel injector. The different illumination nature of the two techniques, diffuse and parallel light respectively, allows for the capturing of refractive-index gradients due to the presence of both interfaces and density gradients within the orifice. Hence, the onset of cavitation and secondary-flow motion within the sac and injector hole can be concurrently visualised. Experiments were conducted utilising a diesel injector fitted with a single-hole transparent tip (ECN spray D) at injection pressures of 700–900 bar and ambient pressures in the range of 1–20 bar. High-speed DBI images obtained at 100,000 fps revealed that the orifice, due to its tapered layout, is mildly cavitating with relatively constant cavity sheets arising mainly in regions of manufacturing imperfections. Nevertheless, schlieren images obtained at the same frame rate demonstrated that a multitude of vortices with short lifetimes arise at different scales in the sac and nozzle regions during the entire duration of the injection cycle but the vortices do not necessarily result in phase change. The magnitude and exact location of coherent vortical structures have a measurable influence on the dynamics of the spray emerging downstream the injector outlet, leading to distinct differences in the variation of its cone angle depending on the injection and ambient pressures examined. Graphic abstract

show abstract