Internal Flow and Spray Characteristics of Pintle-Type Outwards Opening Piezo Injectors for Gasoline Direct-Injection Engines

Marchi, Andrea; Nouri, J. M.; Yan, Youyou; Arcoumanis, C.

doi:10.4271/2007-01-1406

Cited by 18 publications

(14 citation statements)

References 13 publications

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“…For this reason, during the evolution and development of the piezo type injector, the main emphasis was to identify, understand and prevent any type of instability like flapping and therefore enhancing the spray stability. The annular spray structure consists of a number of string and ligaments/droplets closely pacted together as was showm by close-up spray visualisation in [8][9][10] which was confirmed by the corresponding PDA measurements of [8 & 10] who showed the string spacing and the droplets size and velocity distribution downstream of the injector nozzle exit. They also showed the dependency of the overall spray cone angle with the back pressure was negligible.…”

Section: Introductionsupporting

confidence: 56%

“…The spray fluctuation, from RMS images, of Case1_2000rpm shows also a higher variation in the recirculation area and suggests an increase of instability with engine speed. As it was explained by [10], from the 2D Mie scattering images, the increase in engine speed resulted in a stronger recirculations, but at the same time caused them to become non-uniform and unstable. The angle analysis quantifies the above observations and shows that although the mean angle is the same (87.5°) in both cases, but an increase in STD can be observed at higher engine speed with a STD value of ±1.75° compare to ±1° at lower speed due to increased air motion and turbulence.…”

Section: Influence Of Engine Speedmentioning

confidence: 83%

“…This string-type structure originating at the nozzle exit has been previously observed in references [14] to [16], where it was argued that string formation could be the result of the interaction between the airflow and the injected liquid annular film. The source of this string-type spray structure was further investigated experimentally in references [17] and [18], where the presence of a very complex flow upstream of the nozzle seat was identified. The in-nozzle flow visualization revealed a two-phase flow with entrained air bubbles trapped downstream of the nozzle seat and initiating the formation of a string (filament-type) spray structure as it emerges from the nozzle exit.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spray stability of outwards opening pintle injectors for stratified direct injection spark ignition engine operation

Marchi

Nouri

Yan

et al. 2010

International Journal of Engine Research

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Citation: Marchi, A., Nouri, J. M., Yan, Y. & Arcoumanis, C. (2010). Spray stability of outwards opening pintle injectors for stratified direct injection spark ignition engine operation. International Journal of Engine Research, 11(6), pp. 413-437. doi: 10.1243/14680874JER605 This is the accepted version of the paper.This version of the publication may differ from the final published version. Abstract: The spray characteristics of three prototype piezo-electric pintle-type injectors was investigated under different operating conditions in an optical engine equipped with direct injection system and designed for spray-guided combustion concept. The pintle-type outward opening has the potential to overcome many of the typical problems related to spray-guided injection. Its hollow cone spray presents a better air utilization than the multi-hole with good penetration performance during early injection and a negligible dependence of the spray angle from the backpressure; the latter is essential for spray-guided approach to be successful as it fully depends on spray stability. The three prototype injectors are designed with different nozzle exit geometries for optimisation of the injectors for the most stable spray at all engine conditions. The emeringing fuel sprays, for single and double injection, were visualised using Mie scattering and a high speed CCD camera. The injectors' performance were assessed by constructing mean and RMS images at different operating conditions of injection pressures, back pressure, injector needle lift, and engine speed. From these images a through angle analysis were performed by comparing the mean, standard deviation, maximum and minimum spray cone angle at different conditions; the spray stability could be quantified by analysising the mean and RMS images and mean and RMS spray cone angles. Overall, the classification of the three prototypes has shown that the Inward Seal Band positive step design produces the most robust spray angle, which is ideally suited for stratified fuel mixture formation in spray-guided configurations for DISI engines. Permanent

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Section: Introductionsupporting

confidence: 56%

Section: Influence Of Engine Speedmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spray stability of outwards opening pintle injectors for stratified direct injection spark ignition engine operation

Marchi

Nouri

Yan

et al. 2010

International Journal of Engine Research

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“…According to manufacturing requirements, the absence of nozzle holes directly exposed to the combustion chamber environment makes the outward-opening design more robust [2] and cocking free, which may be a significant problem with multihole nozzles. Other attempts to investigate the injection performance and the spray characteristics in GDI systems with outward-opening injectors have been presented over the last few years [11,12]. These studies open an interesting field for future research *Corresponding author: School of Engineering and Mathematical Sciences, City University London, Northampton Square, London EC1V 0HB, UK.…”

Section: Introductionmentioning

confidence: 99%

Simulation of cavitation in outward-opening piezo-type pintle injector nozzles

Giannadakis

Papoulias

Theodorakakos³

et al. 2008

Proceedings of the Institution of Mechanical Engineers, Part D:

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The onset and development of cavitation in the annular needle seat passage of piezo-driven outward-opening pintle injector nozzles used with spray-guided direct-injection gasoline engines are studied using a Eulerian-Lagrangian computational fluid dynamics cavitation model. Cavitation is formed because of the fluid acceleration taking place at the needle sealing area and it has been found to be affected by its geometric details. Various submodels for nucleation and bubble formation, further bubble growth and collapse, as well as bubble break-up and transport are incorporated into the model. Qualitative model validation is performed against experimental data reported elsewhere in large-scale nozzle replicas, showing similar cavitation patterns to be formed. These consist of vapour pockets rather than a continuous vapour film and develop transiently in a rather chaotic manner around the circumferential needle sealing area, even under stationary geometry and fixed-flowrate conditions. Further transient effects associated with the fast opening and closing of the piezo-controlled needle valve are also presented.

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“…When the cavitation extends to the nozzle exit, the hydraulic flip is observed as air is entertained in the cavitation bubbles. The coexistence of cavitation bubbles and air entrainment is also confirmed by a study using a pintle‐type outwards‐opening gasoline injector .…”

Section: Fundamentals Of Cavitationmentioning

confidence: 95%

Cavitation in Diesel Fuel Injector Nozzles and its Influence on Atomization and Spray

2018

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In combustors, high‐pressure fuel injector nozzles are employed for liquid atomization and spray generation. The internal flow within nozzles, especially cavitation, plays an important role in promoting the breakup of liquid jets. The formation mechanism and evolvement of cavitation are reviewed and described. Different cavitation regimes were characterized experimentally and the positive effect of cavitation on liquid atomization was confirmed. Different empirical formulas correlating the discharge coefficient with fluid‐dynamical parameters are summarized. The applicability, advantages, and disadvantages of two popular computational models for flow modeling, i.e., the interface tracking model and the homogeneous equilibrium model, are reviewed. The effects of cavitation on the generated spray are discussed.

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Internal Flow and Spray Characteristics of Pintle-Type Outwards Opening Piezo Injectors for Gasoline Direct-Injection Engines

Abstract: ABSTRACT

Cited by 18 publications

References 13 publications

Spray stability of outwards opening pintle injectors for stratified direct injection spark ignition engine operation

Spray stability of outwards opening pintle injectors for stratified direct injection spark ignition engine operation

Simulation of cavitation in outward-opening piezo-type pintle injector nozzles

Cavitation in Diesel Fuel Injector Nozzles and its Influence on Atomization and Spray

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