3-D CFD Analysis of the Combustion Process in a DI Diesel Engine using a Flamelet Model

2000 ◽  
Author(s):  
H. Bensler ◽  
F. Bühren ◽  
E. Samson ◽  
L. Vervisch
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Cfd Analysis ◽  
Flamelet Model ◽  
Di Diesel Engine

Applying the Representative Interactive Flamelet Model to Evaluate the Potential Effect of Wall Heat Transfer on Soot Emissions in a Small-Bore DI Diesel Engine

2001 ◽  
Author(s):  
Carl Hergart ◽  
Norbert Peters
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Wide Spectrum ◽  
Turbulent Flame ◽  
Combustion Process ◽  
Heat Losses ◽  
Wall Heat Transfer ◽  
Two Phase ◽  
Flamelet Model ◽  
Di Diesel Engine

Abstract Due to the wide spectrum of turbulent and chemical length- and time scales occurring in a HSDI diesel engine, capturing the correct physics and chemistry underlying combustion poses a tremendous modeling challenge. The processes related to the two-phase flow in a DI diesel engine add even more complexity to the total modeling effort. The Representative Interactive Flamelet (RIF) model has gained widespread attention owing to its ability of correctly describing ignition, combustion and pollutant formation phenomena. This is achieved by incorporating very detailed chemistry for the gas phase as well as the soot particle growth and oxidation, without imposing any significant computational penalty. The model, which is based on the laminar flamelet concept, treats a turbulent flame as an ensemble of thin, locally one-dimensional flame structures, whose chemistry is fast. A potential explanation for the significant underprediction of part load soot observed in previous studies applying the model is the neglect of wall heat losses in the flamelet chemistry model. By introducing an additional source term in the flamelet temperature equation, directly coupled to the wall heat transfer predicted by the CFD-code, flamelets exposed to walls are assigned heat losses of various magnitudes. Results using the model in three-dimensional simulations of the combustion process in a small-bore direct injection diesel engine indicate that the experimentally observed emissions of soot may have their origin in flame quenching at the relatively cold combustion chamber walls.

Effects of EGR on combustion process of DI diesel engine during cold start

2008 ◽  
Vol 2 (2) ◽  
pp. 202-210 ◽  
Author(s):  
Haiyong Peng ◽  
Yi Cui ◽  
Lei Shi ◽  
Kangyao Deng
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Cold Start ◽  
Di Diesel Engine

scholarly journals Development of an optical swirl sensor for DI-diesel engines

2009 ◽  
Vol 137 (2) ◽  
pp. 37-49
Author(s):  
Robin VANHAELST ◽  
Werner HENTSCHEL ◽  
Christian MÜLLER ◽  
Jakub CZAJKA
Keyword(s):  
Diesel Engine ◽  
Optical Sensor ◽  
High Speed ◽  
Swirling Flow ◽  
Combustion Process ◽  
Optical Probe ◽  
Swirl Ratio ◽  
Acceptance Angle ◽  
Di Diesel Engine ◽  
Dimensional Simulation

In this paper the systematic development of an optical swirl sensor to measure the swirl ratio in an operating serial turbocharged DI-diesel engine is described. The optical sensor detects the visible light of the combustion, in particular the emission of the sooting flame in a wavelength range from 600 nm up to 1000 nm. The acceptance angle is so small that the soot clouds from every spray can be detected as they are being turned under the optical sensor by the swirling flow. In a first part the new optical probe method was validated on a transparent engine by comparison with high speed video recordings. In the second part several hardware variations were made on a serial DI-diesel engine which was equipped with a variable swirl valve. The influence of the opened- and closed swirl valve constellation and the piston geometry on the swirl ratio was measured with the optical probe technique. The results were compared with a zero dimensional simulation model. There was a good agreement between the swirl measurements and the 0D-model. The optical swirl sensor has proven to be a powerful tool to optimise the combustion process. Without any modifications on the cylinder head, the effect of application parameters and hardware parts on the swirl strength can be quantified for all engine loads and speeds.

Effects of the Re-Entrant Bowl Geometry on a DI Turbocharged Diesel Engine Performance and Emissions—A CFD Approach

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
S. Pasupathy Venkateswaran ◽  
G. Nagarajan
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Engine Performance ◽  
Maximum Diameter ◽  
Diffusion Combustion ◽  
Turbocharged Diesel Engine ◽  
Performance And Emissions ◽  
Di Diesel Engine ◽  
Fuel Mixing

The purpose of this study is to investigate the influence of re-entrant bowl geometry on both engine performance and combustion efficiency in a direct injection (DI), turbocharged diesel engine for heavy-duty applications. The piston bowl design is one of the most important factors that affect the air–fuel mixing and the subsequent combustion and pollutant formation processes in a DI diesel engine. The bowl geometry and dimensions, such as the pip region, bowl lip area, and toroidal radius, are all known to have an effect on the in-cylinder mixing and combustion processes. Based on the idea of enhancing diffusion combustion at the later stage of the combustion period, three different bowl geometries, namely, bowl 1 (baseline), bowl 2, and bowl 3 were selected and investigated. All the other relevant parameters, namely, compression ratio, maximum diameter of the bowl, squish clearance and injection rate were kept constant. A commercial CFD code STAR-CD was used to model the in-cylinder flows and combustion process, and experimental results of the baseline bowl were used to validate the numerical model. The simulation results show that, bowl 3 enhance the turbulence and hence results in better air-fuel mixing among all three bowls in a DI diesel engine. As a result, the indicated specific fuel consumption and soot emission reduced although the NOx emission is increased owing to better mixing and a faster combustion process. Globally, since the reduction in soot is larger (−46% as regards baseline) than the increase in NOx (+15% as regards baseline), it can be concluded that bowl 3 is the best trade-off between performance and emissions.

Visualization of the Effects of Post Injection and Swirl on the Combustion Process of a Passenger Car Common Rail DI Diesel Engine

2003 ◽  
Author(s):  
Arjan Helmantel ◽  
Joop Somhorst ◽  
Ingemar Denbratt
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Flame Temperature ◽  
Combustion Process ◽  
Small Diameter ◽  
Ccd Camera ◽  
Common Rail ◽  
Post Injection ◽  
Passenger Car ◽  
Di Diesel Engine

The effects of variations in injection strategy and swirl on a DI Diesel engine performance and emissions were tested. The cylinder head was fitted with a small diameter endoscope, coupled with a triggered CCD camera, in order to study the effect of these variations on the combustion process. The images that were taken of the combustion process were used to calculate the spatial and temporal distribution of flame temperature and soot kks factor by using the 2-color method. The engine used in the experiments is a single cylinder version of a modern, passenger car type, common rail Diesel engine with a displacement of 480 cc. The fitted endoscope caused very little interference with the combustion chamber due to its small dimensions. The 65 degree angle view of the endoscope allowed coverage of a large portion of the entire combustion chamber. The combustion images and derived temperatures and soot concentrations were used to study the influence of post injection and high swirl. Adding a third (post) injection to the pilot and main injection increases the mixing and the flame temperature during the second half of the combustion process, thereby improving soot oxidation. The fuel efficiency was not negatively affected by the later phasing of part of the heat release. Increased swirl of the intake air was also studied. An 80% increase in swirl-ratio was achieved by closing off one of the two intake ports with a butterfly valve. The improved mixing gave significant reductions in soot emissions, with a small increase in NOx formation.

Simulation Research on Post-Injection of Electronically Controlled Heavy-Duty Diesel Engine

2011 ◽  
Vol 121-126 ◽  
pp. 2238-2242
Author(s):  
Ming Hai Li ◽  
Feng Jiang ◽  
Biao Liu ◽  
Ming Gao Ouyang
Keyword(s):  
Diesel Engine ◽  
Fuel Injection ◽  
Direct Injection ◽  
Combustion Process ◽  
Pressure Rise ◽  
Injection System ◽  
Post Injection ◽  
Simulation Research ◽  
Di Diesel Engine ◽  
Heavy Duty Diesel

GT-Suite software is used to establish the simulation model of electronic fuel injection system for 16V280ZJ diesel engine. Combustion process simulation calculation is conducted to the direct injection (DI) diesel engine based on a main-post double injection scheme. Simulation parameters are modified based on the comparison with given experimental results. The calculation results effectively reflect the influence of fuel ratio and the interval angle between main and post injection over emission and fuel economy. Finally, in order to improve the engine emissions and reduce the pressure rise rate, we get the optimal injection solution for the main-post injection mode.

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