Optical Diagnostics for Gasoline Direct Injection Engines

This work investigates nanoparticles formation process in light-duty gasoline direct-injection engines operated in homogeneous combustion. The analysis specifically focuses on the contribution of particles in the range of 10–23 nm, which are expected to be taken into account in future emission regulations. Experiments were carried out on a single-cylinder 0.4-L displacement gasoline direct-injection optical engine. Exhaust gases were analyzed by means of a commercial device (DMS500) to obtain a quantitative measurement of the particulates number and size. Optical diagnostics (broadband color imaging and liquid phase laser-induced fluorescence) were employed to correlate the exhaust measurements to the in-cylinder physical phenomena. The main leverages to control soot particulates formation were investigated. The engine temperature was found to have a significant impact during the entire warm-up phase on the global particulates number and also on the relative contribution of the 10–23 nm range to the total particulates number. Injection phasing has also a primary role in the formation of particulates in the small range of the spectrum when operating in mild stratified combustion mode. On the other hand, an increased in-cylinder aerodynamic (e.g. combined swirl-tumble motion) has a positive impact in reducing global particulates number but also causes an increase of the 10–23 nm relative contribution. Optical diagnostics helped establishing a relationship between the detection of liquid film, the consequent pool fires and the exhaust gas measurements. The evaporation of the liquid film detected on the injector nozzle and the intake valve right after the injection appears to be decisive for the formation of nanoparticles in pool-fire mode. The experimental results indicate that when pool fires were detected, the particulates number increased drastically in the whole range of the spectrum including the 10–23 nm range. Authors relate this effect to in-homogeneities in the fuel-mixing field induced by the evaporation of the liquid film.

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Investigation of Cycle-to-Cycle Variations of In-Cylinder Processes in Gasoline Direct Injection Engines Operating With Variable Tumble Systems

10.4271/2004-01-0044 ◽

2004 ◽

Cited By ~ 14

Author(s):

J. Fischer ◽

A. Velji ◽

U. Spicher

Keyword(s):

Direct Injection ◽

Gasoline Direct Injection ◽

Direct Injection Engines

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Fuel Pressure Increase up to 50 MPa for Gasoline Direct-injection Engines

MTZ worldwide ◽

10.1007/s38313-018-0044-2 ◽

2018 ◽

Vol 79 (7-8) ◽

pp. 50-55 ◽

Cited By ~ 2

Author(s):

Felix Eitel ◽

Jörg Schäfer ◽

Achim Königstein ◽

Christof Heeger

Keyword(s):

Direct Injection ◽

Gasoline Direct Injection ◽

Pressure Increase ◽

Direct Injection Engines

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Simulation of Coarse Droplet and Liquid Column Formed around Nozzle Outlets Due to Valve Wobble of a Gasoline Direct Injection Injector

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4039808 ◽

2018 ◽

Vol 140 (10) ◽

Author(s):

Eiji Ishii ◽

Yoshihito Yasukawa ◽

Kazuki Yoshimura ◽

Kiyotaka Ogura

Keyword(s):

Surface Tension ◽

Particulate Matter ◽

Direct Injection ◽

Gasoline Direct Injection ◽

Fuel Spray ◽

Direct Injection Engines ◽

Fuel Injectors ◽

Multiple Injections ◽

Fuel Mixtures ◽

Opening And Closing

The generation of particulate matter (PM) is one problem with gasoline direct-injection engines. PM is generated in high-density regions of fuel. Uniform air/fuel mixtures and short fuel-spray durations with multiple injections are effective in enabling the valves of fuel injectors not to wobble and dribble. We previously studied what effects the opening and closing of valves had on fuel spray behavior and found that valve motions in the opening and closing directions affected spray behavior and generated coarse droplets during the end-of-injection. We focused on the effects of valve wobbling on fuel spray behavior in this study, especially on the behavior during the end-of-injection. The effects of wobbling on fuel spray with full valve strokes were first studied, and we found that simulated spray behaviors agreed well with the measured ones. We also studied the effects on fuel dribble during end-of-injection. When a valve wobbled from left to right, the fuel dribble decreased in comparison with a case without wobbling. When a valve wobbled from the front to the rear, however, fuel dribble increased. Surface tension significantly affected fuel dribble, especially in forming low-speed liquid columns and coarse droplets. Fuel dribble was simulated while changing the wetting angle on walls from 60 to 5 deg. We found that the appearance of coarse droplets in sprays decreased during the end-of-injection by changing the wetting angles from 60 to 5 deg.

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