Spray flow structure from twin-hole diesel injector nozzles

Abstract

a b s t r a c tTwo techniques were used to study non-evaporating diesel sprays from common rail injectors which were equipped with twin-hole and single-hole nozzles for comparison. To characterise the sprays, high speed optical imaging and X-ray radiography were used. The former was performed at the Laboratory for Turbulence Research in Aerospace and Combustion (LTRAC) at Monash University, while the latter was performed at the 7-BM beamline of the Advanced Photon Source (APS) at Argonne National Laboratory. The optical imaging made use of high temporal, high spatial resolution spray recordings on a digital camera from which peripheral parameters in the initial injection phase were investigated based on edge detection. The X-ray radiography was used to explore quantitative mass distributions, which were measured on a point-wise basis at roughly similar sampling rate. Three twin-hole nozzles of different subtended angles and a single-hole nozzle were investigated at injection pressure of 1000 bar in environments of 20 bar back pressure. Evidence of strong cavitation was found for all nozzles examined with their C D ranging from 0.62 to 0.69. Penetration of the twin-hole nozzles was found to lag the single-hole nozzle, before the sprays merged. Switching in hole dominance was observed from one twin-hole nozzle, and this was accompanied by greater instability in mass flow during the transient opening phase of the injectors.

Experimental investigation on the effect of injector hole number on engine performance and particle number emissions in a light-duty diesel engine

“…Increasing hole number with decreasing hole size was found to greatly affect the fuel conversion efficiency because these factors resulted in a reduced spray penetration. 6,18,19 It has also been reported that a very high hole number results in flame-flame interference among sprays from neighboring holes. 4,20…”

“…Increasing hole number with decreasing hole size was found to greatly affect the fuel conversion efficiency because these factors resulted in a reduced spray penetration. 6,18,19 It has also been reported that a very high hole number results in flame-flame interference among sprays from neighboring holes. 4,20 In recent past, many researchers have shifted their focus toward optical engine as it is an extraordinary tool for in-detail comprehension of the combustion process and visualization of combustion propagation which cannot be obtained from metal engines.…”

Computational assessment of temperature variations through calibrated orifices subjected to high pressure drops: Application to diesel injection nozzles

“…Sayin et al [4] investigated the influence of the injector hole number on the engine performance and emissions, whereas Gavaises [5] and the authors [6] tried to gain insight on the role of cavitation on the fuel spray mixing capabilities through an analysis of the effect of the hydro erosion. As a result, for instance, new nozzle concepts have been suggested by the authors in the form of elliptical orifices [7] or convergent-divergent orifices [8], whereas other researchers analyzed the possibility of including twin-hole nozzles in diesel injection systems [9], reporting their lower penetration when compared to the equivalent single hole nozzles. As far as the injection conditions are concerned, Wang et al [10] analyzed the effect of increasing the injection pressure on the soot formation, whereas Gumus et al [11] linked this property to the engine emissions.…”

Experimental study of spray analysis for Palmarosa biodiesel‐diesel blends in a constant volume chamber

“…The time incorporated normal brightness was reduced with an increase in injection pressure. Other researches focus on the spray characteristics using semiphenomenological model, 21 Numerical simulation and CFD at low injection pressure, 22 Laser-induced exciplex fluorescence, 23 Air entrainment analysis using quasi-steady jet theory, 24 X-ray and highspeed visual imagery methods, 25 shock wave analysis by Schlieren imaging method, 26,27 multi-hole nozzle by X-ray phase-Contrast Imagery method, 28,29 Hybrid atomizer, 30 and Preheating of high viscosity fuel. 31 However, it is required to investigate biodiesel blends' spray properties due to their greater surface tension.…”