The Spray Structure of Air-Shrouded Dual-Stream Port Fuel Injectors With Different Air-Mixing Mechanisms

1998 ◽  
Vol 120 (1) ◽  
pp. 217-224
Author(s):  
F.-Q. Zhao ◽  
J.-H. Yoo ◽  
M.-C. Lai
Keyword(s):  
Mie Scattering ◽  
Spray Atomization ◽  
Spray Parameters ◽  
Radial Velocity Component ◽  
Fuel Injectors ◽  
Gasoline Engines ◽  
Spray Structure ◽  
Planar Laser ◽  
Air Mixing ◽  
Atomization Characteristics

An experimental study of the spray structure from air-shrouded dual-stream injectors with different air mixing mechanisms was carried out extensively to understand the spray characteristics of dual-stream port injectors for applications to four-valve gasoline engines. The injectors were tested under both steady and transient conditions at different injection pressures and air shrouding pressure differentials. The global spray structure was visualized using the planar laser Mie scattering technique and spray atomization processes were characterized by the phase-Doppler anemometry method. The experimental results showed that spray atomization characteristics are improved markedly by the air-shrouding technique and also strongly dominated by the air-mixing mechanisms. When the air flows into the injector tip mainly from the radial direction, two streams of the spray are forced to merge together and as a result a single-stream spray is formed. When the radial velocity component of the air is reduced and the air is made to mix well with the fuel inside the injector tip, however, the two streams of the spray are well separated over different injection conditions. Moreover, other spray parameters are also modified by the air shrouded into the injector, which must be optimized in order to achieve the best performance of the air-shrouded injector.

Effect of Air Movement to Spray Development of Rapeseed Oil in Diesel Engine

2014 ◽  
Vol 554 ◽  
pp. 479-483
Author(s):  
Azwan Sapit ◽  
Mohd Azahari ◽  
Mas Fawzi ◽  
Amir Khalid ◽  
Bukhari Manshoor
Keyword(s):  
Rapeseed Oil ◽  
High Speed ◽  
High Viscosity ◽  
Spray Atomization ◽  
Main Body ◽  
Mixing Process ◽  
Important Process ◽  
Air Movement ◽  
Air Mixing ◽  
Atomization Characteristics

Fuel-air mixing is important process in diesel combustion. Generally there a two air mixing strategy, which is slow fuel – fast air mixing and fast fuel – slow air mixing. Air movement inside the combustion chamber greatly affect the mixing process and made effective fuel air mixing possible. Biomass fuel needs great help of mixing to atomization because the fuel has high viscosity and high distillation temperature. This study investigates the effect of air movement to spray development and atomization characteristics of rapeseed oil (RO). Optical observation of RO spray was carried out using shadowgraph photography technique and also using high speed camera. The results show that fast air movement effectively promotes RO spray atomization, with the RO spray expand outward from the main body through the whole spray length, which suggests fuel dispersion due to fast air movement.

Effect of Wall Configuration on Atomization of Rapeseed Oil Diesel Spray Impinging on the Wall

2013 ◽  
Vol 315 ◽  
pp. 320-324 ◽  
Author(s):  
Azwan Sapit ◽  
Takashi Yano ◽  
Yoshiyuki Kidoguchi ◽  
Yuzuru Nada
Keyword(s):  
Rapeseed Oil ◽  
High Viscosity ◽  
Boundary Region ◽  
Spray Atomization ◽  
Important Process ◽  
Optical Images ◽  
Atomization Spray ◽  
Wall Impingement ◽  
Air Mixing ◽  
Atomization Characteristics

Fuel-air mixing is important process in diesel combustion. It has been well known that wall configuration of the piston affects spray atomization. Biomass fuel, that is viable alternative fuel for fossil one, needs great help of mixing to atomization because the fuel has high viscosity and high distillation temperature. This study investigates spray atomization characteristics of rapeseed oil (RO) when it impinges on the piston wall. Optical observation of RO spray was carried out using shadowgraph photography technique. The optical images and image analysis show that wall impingement effectively promotes RO spray atomization. Spray atomization is more sensitive to wall configuration for RO than diesel fuel. The wall that has flat floor at the bottom can improve atomization. It is necessary for RO spray to promote spray penetration followed by wall-impingement because long spray path offers wide spray boundary region to form droplets.

Large-scale structure and entrainment in the supersonic mixing layer

1995 ◽  
Vol 284 ◽  
pp. 171-216 ◽  
Author(s):  
N. T. Clemens ◽  
M. G. Mungal
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Large Scale ◽  
Mixture Fraction ◽  
Mixing Layer ◽  
Mie Scattering ◽  
Planar Laser ◽  
The Cross ◽  
Convective Mach Number ◽  
Stream Direction

Experiments were conducted in a two-stream planar mixing layer at convective Mach numbers,Mc, of 0.28, 0.42, 0.50, 0.62 and 0.79. Planar laser Mie scattering (PLMS) from a condensed alcohol fog and planar laser-induced fluorescence (PLIF) of nitric oxide were used for flow visualization in the side, plan and end views. The PLIF signals were also used to characterize the turbulent mixture fraction fluctuations.Visualizations using PLMS indicate a transition in the turbulent structure from quasi-two-dimensionality at low convective Mach number, to more random three-dimensionality for$M_c\geqslant 0.62$. A transition is also observed in the core and braid regions of the spanwise rollers as the convective Mach number increases from 0.28 to 0.62. A change in the entrainment mechanism with increasing compressibility is also indicated by signal intensity profiles and perspective views of the PLMS and PLIF images. These show that atMc= 0.28 the instantaneous mixture fraction field typically exhibits a gradient in the streamwise direction, but is more uniform in the cross-stream direction. AtMc= 0.62 and 0.79, however, the mixture fraction field is more streamwise uniform and with a gradient in the cross-stream direction. This change in the composition of the structures is indicative of different entrainment motions at the different compressibility conditions. The statistical results are consistent with the qualitative observations and suggest that compressibility acts to reduce the magnitude of the mixture fraction fluctuations, particularly on the high-speed edge of the layer.

Spray Atomization Study on Multi-Hole Nozzle for Direct Injection Gasoline Engines

2013 ◽  
Author(s):  
Motoyuki Abe ◽  
Ehara Hideharu ◽  
Soma Masahiro ◽  
Tohru Ishikawa
Keyword(s):  
Direct Injection ◽  
Spray Atomization ◽  
Gasoline Engines

Transient Fuel Spray Structure for Simulated Injection Strategies in Direct Injection, Spark Ignition Engines

2001 ◽  
Author(s):  
P. A. Hutchison ◽  
R. B. Wicker
Keyword(s):  
Flow Visualization ◽  
Cross Section ◽  
Direct Injection ◽  
Fuel Spray ◽  
Spark Ignition Engines ◽  
Rail Pressure ◽  
Fuel Injectors ◽  
Spray Structure ◽  
Image Velocimetry ◽  
Direct Injection Spark Ignition

Abstract For two production DISI fuel injectors, flow visualization and particle image velocimetry (PIV) were utilized to illustrate the effect of fuel rail pressure and in-cylinder density (using in-cylinder pressure) on instantaneous fuel spray structure. Studies were performed within a non-motored research cylinder for two fuel rail pressures (3 MPa and 5 MPa) and two in-cylinder pressures (2 atm and 6 atm). Instantaneous flow visualization demonstrated the effects of changes in fuel rail pressure and in-cylinder density on transient spray structure. Increased fuel rail pressure resulted in increased narrowing of the spray cross-section and increased spray penetration distance. Increased in-cylinder density produced sprays with increased narrowing of the spray cross-section and shorter penetration distances. Spray velocities were shown to increase with increased fuel rail pressure and decrease with increased in-cylinder density.

Experimental Investigation of Performance of an Air Blast Atomizer by Planar Laser Sheet Imaging Technique

2013 ◽  
Author(s):  
Cunxi Liu ◽  
Fuqiang Liu ◽  
Yanhui Mao ◽  
Yong Mu ◽  
Gang Xu
Keyword(s):  
Swirling Flow ◽  
Laser Sheet ◽  
Pollutant Emissions ◽  
Space Distribution ◽  
Imaging Method ◽  
Spray Cone ◽  
Air Blast ◽  
Fuel Distribution ◽  
Planar Laser ◽  
Air Mixing

It is widely recognized that the fuel/air mixing process is a critical factor in improving combustion efficiency and in minimizing pollutants such as NOx. Enhancement of fuel/air mixing can lead to lower pollutant emissions and greater efficiency. However, swirling flows in lean combustors play the role of fuel/air mixing and flame stability. The complex fluid dynamic phenomena encountered in swirling two-phase flow contribute to the difficulty in complete understanding the different processes occurring in combustors. Fortunately, Optical and laser-based visualization techniques available in our lab are important non-intrusive tools for visualizing flow process, especially for fuel injection and fuel/air mixing. To provide for a better understanding of effects of counter-rotating flow on droplets in atomization process, this study is a detailed characterization of the spray generated by an airblast atomizer by planar laser sheet imaging method. Optical facility for spray diagnostics with fuel Planar Laser Induced Fluorescence (fuel-PLIF) method for fuel distribution, and Particle Image Velocity (PIV) method for velocity of droplets, is used to evaluate the performance of an air-blast atomizer. The results show that the performance of secondary atomization is influenced by swirling flow and primary atomization simultaneously, the swirling flow exhibits significant influence on the droplet size and space distribution relative to that of primary atomization. The primary swirling air reopens the spray cone generated by pressure-swirl atomizer, and the secondary swirling air affects the fuel distribution by forming the recirculation zone. The results provide critical information for design and development of combustion chamber.

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