Numerical investigation of the effect of fuel injection mode on spray/wall interaction and emission formation in a direct injection diesel engine at full load state

Jafarmadar, Samad; Shafee, Sina; Barzegar, Ramin

doi:10.2298/tsci1004039j

Cited by 8 publications

(8 citation statements)

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“…The injection rate shapes were set based on boot length and boot pressure, and a trade-off relation between NO x and soot emissions for long boot length and high boot pressure was found. Jafarmadar et al 16 studied the effect of three injection rate modes on combustion process in a diesel engine using a three-dimensional CFD model. They found that using the ramp injection rate shape can slightly retard the combustion process and improve combustion performance; meanwhile, lower NO x and soot emissions were found compared to the boot and rectangle injection modes.…”

Section: Introductionmentioning

confidence: 99%

Effect of fuel injection rate shapes on mixture formation and combustion characteristic in a free-piston diesel engine generator

Han

Yuan

et al. 2018

Advances in Mechanical Engineering

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The free-piston engine generator is a new power machinery, which removes the crank-shaft mechanism. This article aims to study the impact of different injection rate shapes (left triangle, rectangle, and right triangle) on the free-piston engine generator spray and combustion characteristics. An iteration numerical model was established and validated by experiment. The results reveal that there is a positive correlation between injection rate and evaporation rate, and the faster evaporation rate is more conducive to total evaporated fuel mass. The left triangle and rectangle injection modes have the better level of atomization and mixing in the early injection due to stronger turbulent kinetic energy, longer penetration, and smaller Sauter mean diameter, while the right triangle has opposite results, which impairs the mixture formation, and its higher injection pressure in the late injection duration causes more impinged fuel mass. Moreover, the temperature, pressure, peak heat release rate, and indicated thermal efficiency for the left triangle are greater than the other two injection modes. Therefore, for the free-piston engine generator, faster injection rate in the early injection stage enables to improve the fuel evaporation, atomization, and mixing processes, meanwhile enhances the level of isochoric heat release around top dead center, resulting in higher indicated thermal efficiency.

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Section: Introductionmentioning

confidence: 99%

Effect of fuel injection rate shapes on mixture formation and combustion characteristic in a free-piston diesel engine generator

Han

Yuan

et al. 2018

Advances in Mechanical Engineering

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“…The spray/wall interaction model used in this simulation was based on the spray/wall impingement model [22] which has previously been utilized by authors to investigate effects of fuel injection mode and spray impingement on diesel combustion [1,2]. The Shell auto--ignition model was used for modeling of the auto ignition [23].…”

Section: Model Descriptionmentioning

confidence: 99%

“…The other approach which has become a dominant factor in the engine research in the recent years is the application multi-dimensional CFD codes which can gain insight into the in-cylinder flow field and combustion process by solving the governing flow field and species transport equations [1,2]. The other approach which has become a dominant factor in the engine research in the recent years is the application multi-dimensional CFD codes which can gain insight into the in-cylinder flow field and combustion process by solving the governing flow field and species transport equations [1,2].…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics simulation of the combustion process, emission formation and the flow field in an in-direct injection diesel engine

Barzegar¹,

Shafee²,

Khalilarya³

2013

THERM SCI

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In the present paper, the combustion process and emission formation in the Lister 8.1 I.D.I Diesel engine have been investigated using a Computational Fluid Dynamics (CFD) code. The utilized model includes detailed spray atomization, mixture formation and distribution model which enable modeling the combustion process in spray/wall and spray/swirl interactions along with flow configurations. The analysis considers both part load and full load states. The global properties are presented separately resolved for the swirl chamber (pre-chamber) and the main chamber. The results of model verify the fact that the equal amount of the fuel is burned in the main and pre-chamber at full load state while at part load the majority of the fuel is burned in the main chamber. Also, it is shown that the adherence of fuel spray on the pre-chamber walls is due to formation of a stagnation zone which prevents quick spray evaporation and plays an important role in the increase of soot mass fractions at this zone at full load conditions. The simulation results, such as the mean in-cylinder pressure, heat release rate and exhaust emissions are compared with the experimental data and show good agreement. This work also demonstrates the usefulness of multidimensional modeling for complex chamber geometries, such as in I.D.I Diesel engines, to gain more insight into the flow field, combustion process and emission formation

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“…The shorter the injection duration, the higher the proportion of the ramping part. In the case of a small fuel injection quantity with a short injection duration, the injection rate shape always tends to be triangular [11,12], whose spray mixing characteristics are quite different from that of the commonly used injection rate shapes, like the square, boot or rectangle [9,10,13]. Besides, the advanced innovation of piezoelectric injectors makes a significant contribution to the extremely fast needle response time [14,15], meaning it is easer for diesel engines to adopt highly defined injection rate shapes to improve their performance.…”

mentioning

confidence: 95%

Investigation on an Injection Strategy Optimization for Diesel Engines Using a One-Dimensional Spray Model

2019

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Common rail systems have been widely used in diesel engines due to the stricter emission regulations. The advances in injector technology and ultrahigh injection pressure greatly promote the development of multiple-injection strategy, leading to the shorter injection duration and more variable injection rate shape, which makes the mixing process more significant for the formation of pollutant emission. In order to study the mixing process of diesel sprays under variable injection rate shapes and find the optimized injection strategy, a one-dimensional spray model was modified in this paper. The model was validated by the measured spray penetrations based on shadowgraphy experiments with the varying injection rate. The simulations were performed with five injection rate shapes, triangle, ramping-up, ramping-down, rectangle and trapezoid. Their spray penetrations, entrainment rates and equivalence ratios along spray axial distance are compared. The potentials of multiple-injection and gas-jet after end-of-injection (EOI) to improve mixing process and emission reduction are discussed finally. The results indicated that ramping-up injection rate obtains the highest entrainment rate after EOI, and it needs 1.5 times of injection duration for the entrainment wave to arrive at the spray tip. For the other four injection rates, the sprays can be treated as a steady-like state, needing twice of injection duration from EOI to the time the entrainment wave reaches the spray tip. The multiple-injection with proper injection rate shape enhanced the entrainment rate, and the gas-jet after EOI affected the mixture distribution and entrainment rate in spray tail under ramping-down injection rate.

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Numerical investigation of the effect of fuel injection mode on spray/wall interaction and emission formation in a direct injection diesel engine at full load state

Cited by 8 publications

References 1 publication

Effect of fuel injection rate shapes on mixture formation and combustion characteristic in a free-piston diesel engine generator

Effect of fuel injection rate shapes on mixture formation and combustion characteristic in a free-piston diesel engine generator

Computational fluid dynamics simulation of the combustion process, emission formation and the flow field in an in-direct injection diesel engine

Investigation on an Injection Strategy Optimization for Diesel Engines Using a One-Dimensional Spray Model

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