Reducing Hydrocarbons and Odor in Diesel Exhaust by Fuel Injector Design

Ford, H. S.; Merrion, David F.; Hames, R. J.

doi:10.4271/700734

Cited by 39 publications

(5 citation statements)

References 3 publications

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“…In Valve Covered Orifice (VCO) injectors the needle closes the nozzle's inlet so that fuel from the sac cannot enter the chamber. Such designs can minimize emissions [3] [4]. However, the presence of a sac is important to equalize to the pressure of the fuel at the nozzle inlets.…”

Section: Introduction Backgroundmentioning

confidence: 99%

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

Papadopoulos¹,

Aleiferis²

2015

SAE Int. J. Engines

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The design of a Diesel injector is a key factor in achieving higher engine efficiency. The injector's fuel atomisation characteristics are also critical for minimising toxic emissions such as unburnt Hydrocarbons (HC). However, when developing injection systems, the small dimensions of the nozzle render optical experimental investigations very challenging under realistic engine conditions. Therefore, Computational Fluid Dynamics (CFD) can be used instead. For the present work, transient, Volume Of Fluid (VOF), multiphase simulations of the flow inside and immediately downstream of a real-size multi-hole nozzle were performed, during and after the injection event with a small air chamber coupled to the injector downstream of the nozzle exit. A Reynolds Averaged Navier-Stokes (RANS) approach was used to account for turbulence. Grid dependency studies were performed with 200k-1.5M cells. Both k- and k- SST models were considered in the validation process, with the k- SST found to predict better the injector's flow rate. The cavitation models of Schnerr-Sauer and the Zwart-GerberBelamri were employed for validation against optical data of cavitation in a simplified nozzle geometry obtained from the literature. The Schnerr-Sauer model was in better agreement with the experiments, hence this model was subsequently employed for the real injector simulations. The motion of the injector needle was modeled by a dynamic grid methodology. An injection pressure of 400 bar was applied at the inlet of the injector. Two outlet pressures were examined, 60 bar and 1 bar. The results showed that the flow was far from steady-state during the injection event and that hysteresis existed between the needle opening and closing phases. This indicated the importance of transient simulations, contrary to widely-used steady state simulations at fixed needle lifts. The two outlet pressures resulted in very different final states of the flowfield in the nozzle. Specifically, the nozzle ended up either full of liquid fuel at the end of injection or full of air after most of the fuel had been ejected into the chamber downstream. These predictions highlighted phenomena that can increase HC emissions due to fuel leakage, as well as processes that may be linked to different formation mechanisms of nozzle deposits.

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Section: Introduction Backgroundmentioning

confidence: 99%

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

Papadopoulos¹,

Aleiferis²

2015

SAE Int. J. Engines

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“…The possibility to control injection rate and sprays characteristics, that have been the key points in the achievement of the above targets, have increased the interest of car manufacturers in the study of unsteady sprays produced by electronically controlled injectors. Previous studies have shown the effect of cavitation and hydraulic flip on the atomization process of high pressure diesel sprays [1], and the effect of the sac volume on the spray characteristics [2,4]. The characteristics of high-pressure VCO nozzles have also been investigated in a previous study [3,5] and strong hole-to-hole variation in the spray characteristics were observed for all the operating conditions presented.…”

Section: Introductionmentioning

confidence: 83%

An Experimental Study of High Pressure Nozzles in Consideration of Hole-to-Hole Spray Abnormalities

Risi¹,

Colangelo²,

Laforgia³

2000

SAE Technical Paper Series

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The present study focuses on the causes of dissimilarity in the flow structures of sprays produced by different holes of the same direct injection highpressure diesel nozzle. To assess the effect of nozzle geometry on the transient spray structure, photographs of the spray plumes produced by VCO, mini-sac and reduced sac nozzles at different delays from the start of injection were acquired. Injected fuel volume, feeding pressure, injection duration, spray penetration and cone angle were measured for all the investigated nozzles. A statistical analysis of the acquired images and data showed that sprays from the same hole were highly repeatable even with clear hole-to-hole variation of the spray structure. In particular, for the three investigated nozzle geometries the effect of nozzle flow rate, hole inlet and outlet diameter, needle geometry and working time under engine conditions were investigated. Microscope pictures of the nozzle holes were also acquired. Measurements showed that no correlation exists between spray structure and micro-defects in the holes geometry caused by drilling operations in the range of the investigated conditions (injection pressure ranging between 40 and 140 MPa). Whereas a strong dependence on needle dynamics and on the eccentricity between the nozzle and the needle due to asymmetric feeding conditions was observed. A deterioration of the nozzle performances after a fatigue test of about 100 hour running in engine was observed for all the investigated nozzles due to the deposition of carbon particles on the interior wall of the nozzle holes.

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“…The quality of the operation of diesel fuel injectors depends heavily on whether the problem of injector needle hanging is eliminated or at least reduced. Several factors that facilitate the occurrence of this phenomenon are [32][33][34]:…”

Section: Injector Precision Pairsmentioning

confidence: 99%

Investigations of the Usefulness of Dilatometric Methods in the Diagnostics of Combustion Engines

Idzior

Karpiuk

2021

Energies

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Due to rapidly progressing development in the field of materials used in the automotive industry, research methods enabling the validation of the properties of materials used in specific applications, e.g., engines, are gaining importance. One such method is dilatometry, which belongs to a branch of physics dealing with methods of measuring the thermal expansion of bodies. It includes assessment study of the dependence of body measurements on external conditions. The authors propose that dilatometric methods could be used to diagnose damage and the causes of engine damage that has already occurred. This is a novel approach in diagnostic methods. The aim of the paper was to validate the proposed method for diagnosing of combustion engine components. Two cases of malfunction of this type of device are presented. In the first case, the subject of research is needle-nozzle holder precision pairs used in engines with a power of 150 kW. The main achievement of the research is revealing the occurrence of different thermal expansion values of the materials in the individual nozzle holders, with specific needles in particular causing adverse changes in clearances between these elements. The other case involved tests with respect to engine pistons. The proposed test method allows for a very accurate and relatively quick determination of the degree of damage to their surface. The conducted research confirms the usefulness of dilatometric methods in diagnosing combustion engines—their application makes it possible to determine the causes for the formation of the irregularities. The presented results are promising and enable further development of the methods and their implementation not exclusively with regard to internal combustion engines.

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Reducing Hydrocarbons and Odor in Diesel Exhaust by Fuel Injector Design

Cited by 39 publications

References 3 publications

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

Numerical Modelling of the In-Nozzle Flow of a Diesel Injector with Moving Needle during and after the End of a Full Injection Event

An Experimental Study of High Pressure Nozzles in Consideration of Hole-to-Hole Spray Abnormalities

Investigations of the Usefulness of Dilatometric Methods in the Diagnostics of Combustion Engines

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