To meet the increasingly stringent emission regulations nowadays, the quality of injection and spray must be high. The eccentric displacement of an injector needle during injection influences fuel flow characteristics within the nozzle (in-nozzle) and the injection and spray characteristics from the nozzle holes. In this study, the effect of the needle (within a double-layered eight-hole nozzle) on in-nozzle flow, injection and spray was analyzed and characterized. The model was validated by comparing simulation and experimental results from each hole (hole-to-hole). The hole-to-hole internal flow characteristics, injection characteristics, and spray characteristics under various needle eccentricities and radial displacements (needle deflections) were also analyzed. From the results, different asymmetric fuel flow characteristics were noted. Nozzle holes close to the needle deflection formed spray jets with wider cone angles and shorter penetration whereas nozzle holes at the opposite side of the needle deflection, formed spray jets with relatively smaller cone angle and higher penetration. As the needle lift got closer to the maximum lift, the effect of the eccentricity on in-nozzle fuel flow decreased. The direction of the needle eccentricity (needle deflection) dictated the flow dynamics within the holes which then affected the type of cavitation. The holes closer to the needle developed string type cavitation due to the formation of vortex flow in the nozzle. The eccentric effect of the needle was felt more by the lower layer nozzle holes than the upper layer holes.
PayriRBrachoGSorianoJA, et al. Nozzle rate of injection estimation from hole to hole momentum flux data with different fossil and renewable fuels. Fuel2020; 279: 118404.
2.
ZhangXHeZWangQ, et al. Effect of fuel temperature on cavitation flow inside vertical multi-hole nozzles and spray characteristics with different nozzle geometries. Exp Therm Fluid Sci2018; 91: 374–387.
3.
HanSKimJBaeC. Effect of air–fuel mixing quality on characteristics of conventional and low temperature diesel combustion. Appl Energy2014; 119: 454–466.
4.
LinneM. Imaging in the optically dense regions of a spray: a review of developing techniques. Prog Energy Combust Sci2013; 39(5): 403–440.
5.
CungKMoizAJohnsonJ, et al. Spray–combustion interaction mechanism of multiple-injection under diesel engine conditions. Proc Combust Inst2015; 35(3): 3061–3068.
6.
PrasetyaRSouAMoonS, et al. X-ray phase contrast imaging of cavitation and discharged liquid jet in nozzles with various sizes. At Sprays2019; 29(1): 59–78.
7.
PratamaRHHuangWMoonS. Unveiling needle lift dependence on near-nozzle spray dynamics of diesel injector. Fuel2021; 285: 119088.
8.
HuangWMoonSOhsawaK. Near-nozzle dynamics of diesel spray under varied needle lifts and its prediction using analytical model. Fuel2016; 180: 292–300.
9.
PayriRGimenoJVieraJP, et al. Needle lift profile influence on the vapor phase penetration for a prototype diesel direct acting piezoelectric injector. Fuel2013; 113: 257–265.
10.
OhnishiHYoshidaTArifukuT, et al. Characteristics of fuel discharge in multihole VCO nozzle. Trans Korean Soc Mech Eng B1995; 61: 1554–1559.
11.
KastengrenALTiloccoFZPowellCF, et al. Engine combustion network (ECN): measurements of nozzle geometry and hydraulic behavior. At Sprays2012; 22(12): 1011–1052.
12.
ZhangXLiuJWangJ. Effect of fuel and nozzle geometry on the off-axis oscillation of needle in diesel injectors using high-speed X-ray phase contrast imaging. J Instrum2016; 11(5): C05015.
13.
ZhangXMoonSGaoJ, et al. Experimental study on the effect of nozzle hole-to-hole angle on the near-field spray of diesel injector using fast X-ray phase-contrast imaging. Fuel2016; 185: 142–150.
14.
XueQSomSBattistoniM, et al. Three-dimensional simulations of the transient internal flow in a diesel injector: effects of needle movement. In: ILASS Americas, 25th annual conference on liquid atomization and spray systems, Pittsburgh, PA, May2013.
15.
BattistoniMXueQSomS, et al. Effect of off-axis needle motion on internal nozzle and near exit flow in a multi-hole diesel injector. SAE Int J Fuels Lubr2014; 7(1): 167–182.
16.
TorelliRSomSPeiY, et al. Influence of fuel properties on internal nozzle flow development in a multi-hole diesel injector. Fuel2017; 204: 171–184.
17.
TorelliRMatusikKENelliKC, et al. Evaluation of shot-to-shot in-nozzle flow variations in a heavy-duty diesel injector using real nozzle geometry. SAE Int J Fuels Lubr2018; 11(4): 1–17.
18.
SalvadorFJMartínez-LópezJRomeroJV, et al. Study of the influence of the needle eccentricity on the internal flow in diesel injector nozzles by computational fluid dynamics calculations. Int J Comput Math2014; 91(1): 24–31.
19.
WangCMoroAXueF, et al. The influence of eccentric needle movement on internal flow and injection characteristics of a multi-hole diesel nozzle. Int J Heat Mass Transf2018; 117: 818–834.
20.
PowellCFKastengrenALLiuZ, et al. The effects of diesel injector needle motion on spray structure. In: Proceedings of the ASME 2009 internal combustion engine division fall technical conference, Lucerne, Switzerland, 27–30 September 2009, pp.207–217. New York: ASME.
21.
GongHHuangWPratamaRH. Eccentric needle motion effect on spray dynamics of multi-hole diesel nozzle. SAE technical paper 2019-01-2281, 2019.
22.
ChiattiGChiavolaOPalazzoniM, et al. Diesel spray modeling under off-axis needle displacement. SAE technical paper 2015-01-0922, 2015.
23.
ChiavolaOPalmieriF. On a modified VCO nozzle layout for diesel common rail injectors under actual needle displacement. Energy Procedia2017; 126: 1027–1034.
24.
OdaTHiratsukaMGodaY, et al. Experimental and numerical investigation about internal cavitating flow and primary atomization of a large-scaled VCO diesel injector with eccentric needle. In: ILASS – Europe 2010, 23rd annual conference on liquid atomization and spray systems, Brno, Czech Republic, September2010.
25.
MoroALuoTWangC, et al. Eccentric needle displacement effect on spray formation from a multi orifice diesel injector. Heat Mass Transf2019; 55: 2623–2635.
26.
HuangWMoonSGaoY, et al. Eccentric needle motion effect on near-nozzle dynamics of diesel spray. Fuel2017; 206: 409–419.
27.
KimBParkS. Study on in-nozzle flow and spray behavior characteristics under various needle positions and length-to-width ratios of nozzle orifice using a transparent acrylic nozzle. Int J Heat Mass Transf2019; 143: 118478.
28.
BattistoniMSomSPowellCF. Highly resolved Eulerian simulations of fuel spray transients in single and multi-hole injectors: nozzle flow and near-exit dynamics. Fuel2019; 251: 709–729.
29.
PrasetyaRSouAOkiJ, et al. Three-dimensional flow structure and string cavitation in a fuel injector and their effects on discharged liquid jet. Int J Engine Res2021; 22(1): 243–256.
30.
GuanWHeZZhangL, et al. Investigations on interactions between vortex flow and the induced string cavitation characteristics in real-size diesel tapered-hole nozzles. Fuel2021; 287: 119535.
31.
WeiYFanLZhangH, et al. Experimental investigations into the effects of string cavitation on diesel nozzle internal flow and near field spray dynamics under different injection control strategies. Fuel2022; 309: 122021.
32.
SalvadorFJRuizSCrialesi-EspositoM, et al. Analysis on the effects of turbulent inflow conditions on spray primary atomization in the near-field by direct numerical simulation. Int J Multiph Flow2018; 102: 49–63.
33.
SalvadorFJPastorJMDe la MorenaJ, et al. Computational study on the influence of nozzle eccentricity in spray formation by means of Eulerian Σ - Y coupled simulations in diesel injection nozzles. Int J Multiph Flow2020; 129: 103338.
34.
ZhangLHeZGuanW, et al. Simulations on the cavitating flow and corresponding risk of erosion in diesel injector nozzles with double array holes. Int J Heat Mass Transf2018; 124: 900–911.
35.
ZhouXLiTWeiY, et al. Scaling liquid penetration in evaporating sprays for different size diesel engines. Int J Engine Res2020; 21(9): 1662–1677.
36.
NsikaneDMVogiatzakiKMorganRE, et al. Novel approach for adaptive coefficient tuning for the simulation of evaporating high-speed sprays injected into a high-temperature and high-pressure environment. Int J Engine Res2020; 21: 1162–1179.
37.
TheodorakakosAStrotosGMitroglouN, et al. Friction-induced heating in nozzle hole micro-channels under extreme fuel pressurisation. Fuel2014; 123: 143–150.
38.
StrotosGKoukouvinisPTheodorakakosA, et al. Transient heating effects in high pressure diesel injector nozzles. Int J Heat Fluid Flow2015; 51: 257–267.
39.
MoroAZhouQXueF, et al. Comparative study of flow characteristics within asymmetric multi hole VCO and SAC nozzles. Energy Convers Manag2017; 132: 482–493.
40.
XueFLuoFCuiH, et al. Numerical analyses of transient flow characteristics within each nozzle hole of an asymmetric diesel injector. Int J Heat Mass Transf2017; 104: 18–27.
41.
WangCAdamsMLuoT, et al. Hole-to-hole variations in coupled flow and spray simulation of a double-layer multi-holes diesel nozzle. Int J Engine Res2021; 22: 3233–3246.
42.
JinTSunYWangC, et al. The influence of needle eccentric motion on hole-to-hole injection characteristics of a two-layered eight-hole diesel injector. J Eng Gas Turbine Power2021; 143(10): 101005.
43.
RöllALuoFO’ConnellN, et al. Hydraulic stability of micro injections using a two-layered 8-hole solenoid injector with PODE. Fuel2021; 297: 120748.
44.
LuoFJiangSMoroA, et al. The development of a data acquisition system for measuring the injection rate of a multihole diesel injector. Sens Actuators A Phys2017; 261: 166–176.
45.
WuXDengJCuiH, et al. Numerical simulation of injection rate of each nozzle hole of multi-hole diesel injector. Appl Therm Eng2016; 108: 793–797.
46.
ZhouLYDongSFCuiHF, et al. Measurements and analyses on the transient discharge coefficient of each nozzle hole of multi-hole diesel injector. Sens Actuators A Phys2016; 244: 198–205.
47.
LuoTJiangSMoroA, et al. Measurement and validation of hole-to-hole fuel injection rate from a diesel injector. Flow Meas Instrum2018; 61: 66–78.
48.
TongLTianyuJYuS, et al. Numerical research on influence of structural parameters of common-rail injector on injection rate of each nozzle hole. Flow Meas Instrum2022; 85: 102158.
49.
LuoFSunYMoroA, et al. Measurement and analysis of injection characteristics among each nozzle hole within a heavy-duty diesel engine. Flow Meas Instrum2021; 79(101942): 101942.
50.
GuoLYangL. Experimental study on injection quantity of each hole of common rail injector. In: SAECCE2021- IEE016, 2021, pp.641–647.
51.
WatanabeHNishikoriMHayashiT, et al. Visualization analysis of relationship between vortex flow and cavitation behavior in diesel nozzle. Int J Engine Res2015; 16(1): 5–12.
52.
WangCAdamsMJinT, et al. An analytical model of diesel injector’s needle valve eccentric motion. Int J Engine Res2022; 23: 469–481.
