In-Cylinder Tumble Flow Characteristics and Implications for Fuel/Air Mixing in Direct Injection Gasoline Engines

2003 ◽  
Author(s):  
Holger Lienemann ◽  
John S. Shrimpton
Keyword(s):  
Direct Injection ◽  
Flow Characteristics ◽  
Gasoline Engines ◽  
Air Mixing

scholarly journals Characterization of a Novel Porous Injector for Multi-Lean Direct Injection (M-LDI) Combustor

2017 ◽  
Author(s):  
Jianing Li ◽  
Umesh Bhayaraju ◽  
San-Mou Jeng
Keyword(s):  
Air Temperature ◽  
Mass Fraction ◽  
Direct Injection ◽  
Flame Temperature ◽  
Gaseous Fuel ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Porous Tube ◽  
Lean Direct Injection ◽  
Air Mixing

A generic novel injector was designed for multi-Lean Direct Injection (M-LDI) combustors. One of the drawbacks of the conventional pressure swirl and prefilming type airblast atomizers is the difficulty of obtaining a uniform symmetric spray under all operating conditions. Micro-channels are needed inside the injector for uniformly distributing the fuel. The problem of non-uniformity is magnified in smaller sized injectors. The non-uniform liquid sheet causes local fuel rich/lean zones leading to higher NOx emissions. To overcome these problems, a novel fuel injector was designed to improve the fuel delivery to the injector by using a porous stainless steel material with 30 μm porosity. The porous tube also acts as a prefilming surface. Liquid and gaseous fuels can be injected through the injector. In the present study, gaseous fuel was injected to investigate injector fuel-air mixing performance. The gaseous fuel was injected through a porous tube between two radial-radial swirling air streams to facilitate fuel-air mixing. The advantage of this injector is that it increases the contact surface area between the fuel-air at the fuel injection point. The increased contact area enhances fuel-air mixing. Fuel-air mixing and combustion studies were carried out for both gaseous and liquid fuel. Flame visualization, and emissions measurements were carried out inside the exit of the combustor. The measurements were carried out at atmospheric conditions under fuel lean conditions. Natural gas was used as a fuel in these experiments. Fuel-air mixing studies were carried out at different equivalence ratios with and without confinement. The mass fraction distributions were measured at different downstream locations from the injector exit. Flame characterization was carried out by chemiluminescence at different equivalence ratios and inlet air temperatures. Symmetry of the flame, flame length and heat release distribution were analyzed from the flame images. The effects of inlet air temperature and combustion flame temperature on emissions was studied. Emissions were corrected to 15% O2 concentration. NOx emissions increase with inlet air temperature and flame temperature. Effect of flame temperature on NOx concentration is more significant than effect of inlet air temperature. Fuel-air mixing profile was used to obtain mass fraction Probability Density Function (pdf). The pdfs were used for simulations in Chemkin Pro. The measured emissions concentrations at the exit of the injector was compared with simulations. In Chemkin model, a network model with several PSRs (perfectly stirred reactor) were utilized, followed by a mixer and a PFR (plug flow reactor). The comparison between the simulations and the experimental results was investigated.

Numerical Simulation of Transient Flow Inside Nozzle on Gasoline Direct Injection Engine

2012 ◽  
Vol 466-467 ◽  
pp. 1237-1241
Author(s):  
Yan Hua Wang ◽  
Shi Chun Yang ◽  
Yun Qing Li
Keyword(s):  
Kinetic Energy ◽  
Transient Flow ◽  
Direct Injection ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Turbulence Kinetic Energy ◽  
Gasoline Direct Injection ◽  
Injection Hole ◽  
Gasoline Direct Injection Engine ◽  
Nozzle Configuration

To achieve transient flow characteristics at exit of nozzle orifice on gasoline direct injection engine, two phase Euler-Euler schemes was used to simulate the internal flow of the swirl nozzle. Different flow characteristics were calculated in the simulation. Different kinds of nozzle configuration were studied. Cavitaion and swirl flow occured in the nozzles. Injection hole configuration matters more than area variation of swirl tangential slot to discharge coefficient of the studied nozzle. Discharge coefficient changes a little along the injection hole length. The area of the swirl tangrntial slot plays an important throttling action in nozzle internal flow. Smaller area of swirl tangential slot generates larger degree cavitation but smaller mean injection velocity. Turbulence kinetic energy changes with the time of cavitation and swirl field occurring and the nozzle configuration. Before the appearance of cavitation, smaller inclination angle of orifice can generate more turbulence kinetic energy. After that moment, turbulence kinetic energy varies with different configuration. Along injection hole length, turbulence kinetic energy obviously varies. These flow characteristics affect primary atomization and will be as input for next spray simulation. They are also applied to design reference for injection nozzle.

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

2008 ◽  
Vol 222 (10) ◽  
pp. 1895-1910 ◽  
Author(s):  
E Giannadakis ◽  
D Papoulias ◽  
A Theodorakakos ◽  
M Gavaises
Keyword(s):  
Bubble Growth ◽  
Large Scale ◽  
Direct Injection ◽  
Bubble Formation ◽  
Needle Valve ◽  
Transient Effects ◽  
Cavitation Model ◽  
Gasoline Engines ◽  
Opening And Closing ◽  
Vapour Film

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.

Cavitation in Fuel Injection Systems for Spray-Guided Direct Injection Gasoline Engines

2007 ◽  
Author(s):  
D. Papoulias ◽  
E. Giannadakis ◽  
N. Mitroglou ◽  
M. Gavaises ◽  
A. Theodorakakos
Keyword(s):  
Fuel Injection ◽  
Direct Injection ◽  
Gasoline Engines

Effects of intake swirl on the fuel/air mixing and combustion performance in a lateral swirl combustion system for direct injection diesel engines

Fuel ◽  
2021 ◽  
Vol 286 ◽  
pp. 119376
Author(s):  
Yanlin Chen ◽  
Xiangrong Li ◽  
Shuainan Shi ◽  
Qingxu Zhao ◽  
Dong Liu ◽  
...  
Keyword(s):  
Diesel Engines ◽  
Direct Injection ◽  
Combustion System ◽  
Combustion Performance ◽  
Swirl Combustion ◽  
Air Mixing ◽  
Intake Swirl
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