Measurement of Diesel Spray Impingement and Fuel Film Characteristics Using Refractive Index Matching Method

2007 ◽  
Author(s):  
Bo Yang ◽  
Jaal Ghandhi
Keyword(s):  
Refractive Index ◽  
Diesel Spray ◽  
Matching Method ◽  
Fuel Film ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Spray Impingement ◽  
Film Characteristics

scholarly journals Effect of engine conditions and injection timing on piston-top fuel films for stratified direct-injection spark-ignition operation using E30

2019 ◽  
Vol 21 (2) ◽  
pp. 302-318 ◽  
Author(s):  
Carl-Philipp Ding ◽  
David Vuilleumier ◽  
Namho Kim ◽  
David L Reuss ◽  
Magnus Sjöberg ◽  
...  
Keyword(s):  
Refractive Index ◽  
Direct Injection ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Injection Timing ◽  
Fuel Film ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Wall Wetting ◽  
Direct Injection Spark Ignition

Mid-level ethanol/gasoline blends can provide knock resistance benefits for stoichiometric spark-ignition engine operation, but previous studies have identified challenges associated with spray impingement and wall wetting, leading to excessive particulate matter emissions. At the same time, stratified-charge spark-ignition operation can provide increased thermal efficiency, but care has to be exercised to avoid excessive in-cylinder soot formation. In support of the use of mid-level ethanol/gasoline blends in advanced spark-ignition engines, this study presents spray and fuel-film measurements in a direct-injection spark-ignition engine operated with a 30 vol.%/70 vol.% ethanol/gasoline blend (E30). Crank-angle resolved fuel-film measurements at the piston surface are conducted using two different implementations of the refractive index matching technique. A small-angle refractive index matching implementation allows quantification of the wetted area, while a large-angle refractive index matching implementation enables semi-quantitative measurements of fuel-film thickness and volume, in addition to fuel-film area. The fuel-film measurements show that both the amount of fuel deposited on the piston and the shape of the fuel-film patterns are strongly influenced by the injection timing, duration, intake pressure, and coolant temperature. For combinations of high in-cylinder gas density and long injection duration, merging of the individual spray plumes, commonly referred to as spray collapse, can cause a dramatic change to the shape and thickness of the wall fuel films. Overall, the study provides guidance to engine designers aiming at minimizing wall wetting through tailored combinations of injection timings and durations.

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