Nozzle Exit Flow Characteristics for Square-edged and Rounded Inlet Geometries

Kent, J. C.; Brown, Gordon M.

doi:10.1080/00102208308923615

Cited by 37 publications

(23 citation statements)

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“…This increase is continuous and has an asymptotic theoretical maximum value (for an infinite Reynolds number). As outlined by other researchers in the literature, the variation law for the discharge coefficient with the Reynolds number depends strongly on the orifice geometry [13], [17], [18], [19], [20]. In Figure 4, a correlation for the discharge coefficient as a function of Reynolds number obtained from the experimental data has also represented.…”

Section: Mass Conservation Equation Leads Tomentioning

confidence: 92%

Using one-dimensional modeling to analyse the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Detailed injection system model

Payri

Salvador²,

Martí-Aldaraví³

et al. 2012

Energy Conversion and Management

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A combined experimental and computational investigation has been performed in order to evaluate the influence of physical properties of biodiesel on the injection process in a common-direct injection system with second generation solenoid injectors. For that purpose, after a complete characterization of the system, which involved mechanical and hydraulic characterization, a one-dimensional model has been obtained and extensively validated. Simulations have then been performed with a standard Diesel and a 100% rape methyl ester (RME) biodiesel which allowed a comparison and analysis of the dynamic response of the injector to be done. Different injection strategies involving main injection and main plus post-injection have been used to explore the impact of the use of biodiesel on the performance and stability of solenoid injectors.As far as the dynamic response of the injector is concerned, the results obtained have clearly shown that the use of biodiesel affects the dynamic response of the needle, especially at low injection pressures. The behavior of the system under multi-injection strategies (main plus post injection) has been also evaluated determining for different operating conditions (injection pressures and backpressures) the minimum dwell time between injections to assure a stable behavior in the injection process (mass flow rate).Important differences have been found between biodiesel and standard diesel in this critical parameter at low injection pressures, becoming less important at high injection pressure. Finally, a modification on the injector hardware has been proposed in order to compensate these differences.

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Section: Mass Conservation Equation Leads Tomentioning

confidence: 92%

Using one-dimensional modeling to analyse the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Detailed injection system model

Payri

Salvador²,

Martí-Aldaraví³

et al. 2012

Energy Conversion and Management

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show abstract

“…Another important observation from Figure 5 is that pressure losses are not far from being proportional to P rail , because the different curves tend to be horizontal lines 4 . This result indicates that pressure losses in the injector (P rail − P sac ) are more or less proportional to the pressure drop in the nozzle orifice (P sac − P back ), even if the pressure losses are not negligible.…”

Section: Pressures Losses Calculation Algorithmmentioning

confidence: 99%

“…For this reason, different methods to lowering pollutant emissions are currently under investigation. One of the explored methods when dealing with diesel engines is the injector nozzle geometry [4][5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Characterization of the pressure losses in a common rail diesel injector

López

Salvador

Garza

et al. 2012

Proceedings of the Institution of Mechanical Engineers, Part D:

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A methodology to characterise the pressure losses in quasi-steady conditions (i.e. at full needle lift) of common rail diesel injectors was developed. The aim was to quantify the error when experimental results of nozzle internal flow are compared with CFD results, where pressure losses are usually neglected. The proposed methodology is based mainly on experimental tests that are complemented with some approximate calculations, based on the physics of the phenomenon, to take into account the effect of the needle deformation.The results obtained in the work lead to two important conclusions: on the one hand, that it is dangerous to extrapolate results relative to the injection (internal flow, spray atomization, spray penetration..) and combustion processes from low permeability nozzles (e.g. single-hole nozzles) to high permeability nozzles (e.g. multi-hole nozzles), and, on the other hand, that the comparison of these results between experiments and CFD simulations should be carried out carefully, because the pressure losses in the injector can be high under certain conditions. Finally, people working on the study of the injection and/or combustion processes, through experiments or simulations, will find here some interesting information to better know the actual injection pressure to be used in their analysis and/or simulations.

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“…The main reason for this effect is that the nozzle geometry has an influence on the internal flow and on the spray characteristics, particularly on the atomization [10,11] and mixing [12,13] processes. This is the main reason why there are lots of studies analyzing the effect of nozzle geometry on its internal and external flow [14,15]. One of the aspects the nozzle geometry has an influence on is the appearance or not of the cavitation phenomenon.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive study on the effect of cavitation on injection velocity in diesel nozzles

López

Salvador

Garza

et al. 2012

Energy Conversion and Management

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Arregle, JJP. (2012). A comprehensive study on the effect of cavitation on injection velocity in diesel nozzles. Energy Conversion and Management. 64:415-423. doi:10.1016/j.enconman.2012.03.032. A comprehensive study on the effect of cavitation on injection velocity in diesel nozzles AbstractResults when testing cavitating injection nozzles show a strong reduction in mass flow rate when cavitation appears (the flow is choked), while the momentum flux is reduced to a lesser extent, resulting in an increase in effective injection velocity. So as to better understand the origin of this increase in effective injection velocity, the basic equations for mass and momentum conservation were applied to an injection nozzle in simplified conditions. The study demonstrated that the increase in injection velocity provoked by cavitation is not a direct effect of the latter, but an indirect effect. In fact, the vapor appearance inside the injection hole produces a decrease in the viscosity of the fluid near the wall. This leads to lower momentum flux losses and to a change in the velocity profile, transforming it into a more "top hat" profile type. This change in the profile shape allows explaining why the momentum flux reduction is not so important compared to that of the mass flow rate, thus explaining why the effective injection velocity increases.

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Nozzle Exit Flow Characteristics for Square-edged and Rounded Inlet Geometries

Cited by 37 publications

References 0 publications

Using one-dimensional modeling to analyse the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Detailed injection system model

Using one-dimensional modeling to analyse the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Detailed injection system model

Characterization of the pressure losses in a common rail diesel injector

A comprehensive study on the effect of cavitation on injection velocity in diesel nozzles

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