skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Influence of fuel properties on internal nozzle flow development in a multi-hole diesel injector

Abstract

Fuel phys­i­cal prop­er­ties are known to in­flu­ence in-noz­zle flow be­hav­ior, in turn af­fect­ing spray for­ma­tion in in­ter­nal com­bus­tion en­gines. A se­ries of 3D sim­u­la­tions was per­formed to model the in­ter­nal noz­zle flow in a five-hole mini-sac diesel in­jec­tor. The goal of the study was to eval­u­ate the be­hav­ior of two gaso­line-like fu­els (full-range naph­tha and light naph­tha) and com­pare them against n-Do­de­cane, se­lected from a palette used as a diesel sur­ro­gate. Sim­u­la­tions were car­ried out us­ing a multi-phase flow rep­re­sen­ta­tion based on the mix­ture model as­sump­tion with the Vol­ume of Fluid (VOF) method, and in­clud­ing cav­i­ta­tion ef­fects by means of the Ho­mo­ge­neous Re­lax­ation Model (HRM). Val­i­dated method­olo­gies from our pre­vi­ous stud­ies were em­ployed to ac­count for full nee­dle mo­tion. De­tailed sim­u­la­tions re­vealed the in­flu­ence of the fuel prop­er­ties on in­jec­tor per­for­mance, in­jected fuel en­ergy and propen­sity to cav­i­ta­tion. The three fu­els were com­pared with re­spect to global pa­ra­me­ters such as mass flow rate and area con­trac­tion co­ef­fi­cients, and lo­cal pa­ra­me­ters such as pres­sure and ve­loc­ity dis­tri­b­u­tion in­side the sac and ori­fices. Para­met­ric in­ves­ti­ga­tions were also per­formed to un­der­stand the fuel re­sponse to changes in the fuel in­jec­tion tem­per­a­ture, in­jec­tion pres­sure, and geom­e­try de­tails. Cav­i­ta­tion mag­ni­tude was ob­served to be stronglymore » as­so­ci­ated with the val­ues of sat­u­ra­tion pres­sure. Ow­ing to their higher volatil­ity, the two gaso­line-like fu­els were ob­served to cav­i­tate more than n-Do­de­cane across all the in­ves­ti­gated con­di­tions. While at full nee­dle lift cav­i­ta­tion was re­duced for all fu­els, dur­ing the in­jec­tion tran­sients the gaso­line-like fu­els showed more propen­sity to cav­i­tate in­side the ori­fice and seat re­gions. This is ex­pected to have a pro­found in­flu­ence on noz­zle ero­sion. Al­though full-range and light naph­tha have lower den­si­ties com­pared to n-Do­de­cane, ow­ing to their lower vis­cos­ity, the mass flow rate dif­fer­ences be­tween the naph­tha fu­els and n-Do­de­cane were small. In conclusion, the analy­sis of fuel en­ergy con­tent showed that the higher lower heat­ing value (LHV) of light naph­tha helped com­pen­sate for the slightly lower to­tal de­liv­ered mass.« less

Authors:
ORCiD logo [1];  [1];  [2];  [2];  [2]
  1. Argonne National Lab. (ANL), Lemont, IL (United States)
  2. Aramco Services Co., Novi, MI (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
Aramco Services Company; USDOE
OSTI Identifier:
1413755
Alternate Identifier(s):
OSTI ID: 1415657
Grant/Contract Number:
AC02-06CH11357; AC02- 06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Fuel
Additional Journal Information:
Journal Volume: 204; Journal Issue: C; Journal ID: ISSN 0016-2361
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; Cavitation; HRM; Internal Nozzle Flow; Naphtha; VOF; n-Dodecane

Citation Formats

Torelli, Roberto, Som, Sibendu, Pei, Yuanjiang, Zhang, Yu, and Traver, Michael. Influence of fuel properties on internal nozzle flow development in a multi-hole diesel injector. United States: N. p., 2017. Web. doi:10.1016/j.fuel.2017.04.123.
Torelli, Roberto, Som, Sibendu, Pei, Yuanjiang, Zhang, Yu, & Traver, Michael. Influence of fuel properties on internal nozzle flow development in a multi-hole diesel injector. United States. doi:10.1016/j.fuel.2017.04.123.
Torelli, Roberto, Som, Sibendu, Pei, Yuanjiang, Zhang, Yu, and Traver, Michael. Wed . "Influence of fuel properties on internal nozzle flow development in a multi-hole diesel injector". United States. doi:10.1016/j.fuel.2017.04.123.
@article{osti_1413755,
title = {Influence of fuel properties on internal nozzle flow development in a multi-hole diesel injector},
author = {Torelli, Roberto and Som, Sibendu and Pei, Yuanjiang and Zhang, Yu and Traver, Michael},
abstractNote = {Fuel phys­i­cal prop­er­ties are known to in­flu­ence in-noz­zle flow be­hav­ior, in turn af­fect­ing spray for­ma­tion in in­ter­nal com­bus­tion en­gines. A se­ries of 3D sim­u­la­tions was per­formed to model the in­ter­nal noz­zle flow in a five-hole mini-sac diesel in­jec­tor. The goal of the study was to eval­u­ate the be­hav­ior of two gaso­line-like fu­els (full-range naph­tha and light naph­tha) and com­pare them against n-Do­de­cane, se­lected from a palette used as a diesel sur­ro­gate. Sim­u­la­tions were car­ried out us­ing a multi-phase flow rep­re­sen­ta­tion based on the mix­ture model as­sump­tion with the Vol­ume of Fluid (VOF) method, and in­clud­ing cav­i­ta­tion ef­fects by means of the Ho­mo­ge­neous Re­lax­ation Model (HRM). Val­i­dated method­olo­gies from our pre­vi­ous stud­ies were em­ployed to ac­count for full nee­dle mo­tion. De­tailed sim­u­la­tions re­vealed the in­flu­ence of the fuel prop­er­ties on in­jec­tor per­for­mance, in­jected fuel en­ergy and propen­sity to cav­i­ta­tion. The three fu­els were com­pared with re­spect to global pa­ra­me­ters such as mass flow rate and area con­trac­tion co­ef­fi­cients, and lo­cal pa­ra­me­ters such as pres­sure and ve­loc­ity dis­tri­b­u­tion in­side the sac and ori­fices. Para­met­ric in­ves­ti­ga­tions were also per­formed to un­der­stand the fuel re­sponse to changes in the fuel in­jec­tion tem­per­a­ture, in­jec­tion pres­sure, and geom­e­try de­tails. Cav­i­ta­tion mag­ni­tude was ob­served to be strongly as­so­ci­ated with the val­ues of sat­u­ra­tion pres­sure. Ow­ing to their higher volatil­ity, the two gaso­line-like fu­els were ob­served to cav­i­tate more than n-Do­de­cane across all the in­ves­ti­gated con­di­tions. While at full nee­dle lift cav­i­ta­tion was re­duced for all fu­els, dur­ing the in­jec­tion tran­sients the gaso­line-like fu­els showed more propen­sity to cav­i­tate in­side the ori­fice and seat re­gions. This is ex­pected to have a pro­found in­flu­ence on noz­zle ero­sion. Al­though full-range and light naph­tha have lower den­si­ties com­pared to n-Do­de­cane, ow­ing to their lower vis­cos­ity, the mass flow rate dif­fer­ences be­tween the naph­tha fu­els and n-Do­de­cane were small. In conclusion, the analy­sis of fuel en­ergy con­tent showed that the higher lower heat­ing value (LHV) of light naph­tha helped com­pen­sate for the slightly lower to­tal de­liv­ered mass.},
doi = {10.1016/j.fuel.2017.04.123},
journal = {Fuel},
number = C,
volume = 204,
place = {United States},
year = {Wed May 31 00:00:00 EDT 2017},
month = {Wed May 31 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 31, 2018
Publisher's Version of Record

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • Cited by 1
  • The needle shutdown of fuel injectors leads to an undesired fuel dribble that forms unburned hydrocarbons and decreases the engine thermal efficiency in modern engines. Understanding of the fuel dribbling process is of great importance to establish its minimization strategy for optimal use of conventional fuels. However, the detailed needle dynamics and in- and near-nozzle flow characteristics governing the fuel dribble process have not been thoroughly understood. In this study, the needle dynamics, in- and near-nozzle flow characteristics and fuel dribble of a mini-sac type three-hole diesel injector were investigated using a highspeed X-ray phase-contrast imaging technique at different injectionmore » pressures. The results showed that an increase in injection pressure increased the flow evacuation velocity at the needle close that induced a more intense fuel cavitation and air ingestion inside the nozzle. The fuel dribbling process showed a high shot-toshot deviation. A statistical analysis of 50-shot results exhibited two breakup modes of fuel dribble determined by the flow evacuation velocity at the needle close and presence of air ingestion. In the first mode, the fast breakup with a short residence time of fuel dribble occurred. Meanwhile, the dripping of undisturbed liquid column with a long residence time of fuel dribble occurred in the second mode. An increase in injection pressure increased the population of the first mode due to more intense air ingestion that primarily caused by an increase in needle closing speed other than an increase in peak injection velocity. Based on the results, the formation mechanism and control strategies of the fuel dribble from modern diesel injectors were discussed.« less
  • Fuel atomization and vaporization process play a critical role in determining the engine combustion and emission. The primary near-nozzle breakup is the vital link between the fuel emerging from the nozzle and the fully atomized spray. In this study, the near-nozzle spray characteristics of diesel injector with different umbrella angle (UA) were investigated using high-speed X-ray phase-contrast imaging and quantitative image processing. A classic ‘dumbbell’ profile of spray width (SW) composed of three stages: opening stage, semisteady stage and closing stage. The SW peak of two-hole injectors was more than twice of that of single-hole injector at the opening andmore » closing stages, corresponding to the hollow-cone spray. This indicated the vortex flow was formed with the increase of the UA. The higher injection pressure had little influence on the SW while led to earlier breakup closer to the nozzle. Significant fuel effect on the SW at higher needle lift was found. However, this effect could be neglect at lower needle lift due to the leading role of internal flow and cavitation on the near-field spray characteristics. In addition, the morphology-based breakup process was observed, which highlighted the important effect of internal flow on the spray development. The possibility of using hollow-cone spray in diesel injector was also discussed.« less
  • Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. The study of cavitation in realistic injectors is challenging, both theoretically and experimentally, since the associated two-phase flow field is turbulent and highly complex, characterized by large pressure gradients and small orifice geometries. We report herein a computational investigation of the internal nozzle flow and cavitation characteristics in a diesel injector. A mixture based model in FLUENT V6.2 software is employed for simulations. In addition, a new criterion for cavitation inception based on the total stress is implemented, and its effectiveness inmore » predicting cavitation is evaluated. Results indicate that under realistic diesel engine conditions, cavitation patterns inside the orifice are influenced by the new cavitation criterion. Simulations are validated using the available two-phase nozzle flow data and the rate of injection measurements at various injection pressures (800-1600 bar) from the present study. The computational model is then used to characterize the effects of important injector parameters on the internal nozzle flow and cavitation behavior, as well as on flow properties at the nozzle exit. The parameters include injection pressure, needle lift position, and fuel type. The propensity of cavitation for different on-fleet diesel fuels is compared with that for n-dodecane, a diesel fuel surrogate. Results indicate that the cavitation characteristics of n-dodecane are significantly different from those of the other three fuels investigated. The effect of needle movement on cavitation is investigated by performing simulations at different needle lift positions. Cavitation patterns are seen to shift dramatically as the needle lift position is changed during an injection event. The region of significant cavitation shifts from top of the orifice to bottom of the orifice as the needle position is changed from fully open (0.275 mm) to nearly closed (0.1 mm), and this behavior can be attributed to the effect of needle position on flow patterns upstream of the orifice. The results demonstrate the capability of the cavitation model to predict cavitating nozzle flows in realistic diesel injectors and provide boundary conditions, in terms of vapor fraction, velocity, and turbulence parameters at the nozzle exit, which can be coupled with the primary breakup simulation.« less