Examination of Initialization and Geometric Details on the Results of CFD Simulations of Diesel Engines

2010 ◽  
Vol 133 (4) ◽  
Author(s):  
Michael J. Bergin ◽  
Ettore Musu ◽  
Sage Kokjohn ◽  
Rolf D. Reitz
Keyword(s):  
Diesel Engines ◽  
Cylinder Head ◽  
Fluid Dynamic ◽  
Direct Injection ◽  
Valve Lift ◽  
Low Temperature Combustion ◽  
Swirl Ratio ◽  
Dynamic Simulations ◽  
Temperature Combustion ◽  
Honeycomb Cell

Computational fluid dynamic simulations using the AVL FIRE and KIVA 3V codes were performed to examine commonly accepted techniques and assumptions used when simulating direct injection diesel engines. Simulations of a steady-state impulse swirl meter validated the commonly used practice of evaluating the swirl ratio of diesel engines by integrating the valve flow and torque history over discrete valve lift values. The results indicate the simulations capture the complex interactions occurring in the ports, cylinder, and honeycomb cell impulse swirl meter. Geometric details of engines due to valve recesses in the cylinder head and piston cannot be reproduced axisymmetrically. The commonly adopted axisymmetric assumption for an engine with a centrally located injector was tested by comparing the swirl and emissions history for a noncombusting and a double injection low temperature combustion case with varying geometric fidelity. Consideration of the detailed engine geometry including valve recesses in the piston altered the swirl history such that the peak swirl ratio at TDC decreased by approximately 10% compared with the simplified no-recess geometry. An analog to the detailed geometry of the full 3D geometry was included in the axisymmetric geometry by including a groove in the cylinder head of the mesh. The corresponding emissions predictions of the combusting cases showed greater sensitivity to the altered swirl history as the air-fuel ratio was decreased.

Examination of Initialization and Geometric Details on the Results of CFD Simulations of Diesel Engines

2009 ◽  
Author(s):  
Mike Bergin ◽  
Ettore Musu ◽  
Sage Kokjohn ◽  
Rolf D. Reitz
Keyword(s):  
Diesel Engines ◽  
Fluid Dynamic ◽  
Direct Injection ◽  
Valve Lift ◽  
Low Temperature Combustion ◽  
Swirl Ratio ◽  
Cfd Simulations ◽  
Complex Interactions ◽  
Temperature Combustion ◽  
Honeycomb Cell

Computational Fluid Dynamic (CFD) simulations using the AVL Fire and Kiva 3v codes were performed to examine commonly accepted techniques and assumptions used when simulating direct injection diesel engines. Simulations of a steady state impulse swirl meter validated the commonly used practice of evaluating the swirl ratio of diesel engines by integrating the valve flow and torque history over discrete valve lift values [1]. The results indicate the simulations capture the complex interactions occurring in the ports, cylinder and honeycomb cell impulse swirl meter. The commonly adopted axisymmetric assumption for an engine with a centrally located injector was tested by comparing the swirl and emissions history for a motored case and a double injection low temperature combustion case. Consideration of the detailed engine geometry including valve recesses in the piston and the head lowered the peak swirl ratio at TDC by approximately 10% compared to the simplified no-recess case. The corresponding combusting cases also had different heat release and emissions predictions but could be partially compensated for by lowering the initial swirl ratio for the axisymmetric case.

Study of Cylinder Charge Control for Enabling Low Temperature Combustion in Diesel Engines

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Prasad Divekar ◽  
Usman Asad ◽  
Xiaoye Han ◽  
Xiang Chen ◽  
Ming Zheng
Keyword(s):  
Low Temperature ◽  
Diesel Engines ◽  
Direct Injection ◽  
Flame Temperature ◽  
Stable Operation ◽  
Low Temperature Combustion ◽  
Multiple Control ◽  
Engine Load ◽  
Combustion Modes ◽  
Temperature Combustion

Suitable cylinder charge preparation is deemed critical for the attainment of a highly homogeneous, diluted, and lean cylinder charge, which is shown to lower the flame temperature. The resultant low temperature combustion (LTC) can simultaneously reduce the NOx and soot emissions from diesel engines. This requires sophisticated coordination of multiple control systems for controlling the intake boost, exhaust gas recirculation (EGR), and fueling events. Additionally, the cylinder charge modulation becomes more complicated in the novel combustion concepts that apply port injection of low reactivity alcohol fuels to replace the diesel fuel partially or entirely. In this work, experiments have been conducted on a single cylinder research engine with diesel and ethanol fuels. The test platform is capable of independently controlling the intake boost, EGR rates, and fueling events. Effects of these control variables are evaluated with diesel direct injection and a combination of diesel direct injection and ethanol port injection. Data analyses are performed to establish the control requirements for stable operation at different engine load levels with the use of one or two fuels. The sensitivity of the combustion modes is thereby analyzed with regard to the boost, EGR, fuel types, and fueling strategies. Zero-dimensional cycle simulations have been conducted in parallel with the experiments to evaluate the operating requirements and operation zones of the LTC combustion modes. Correlations are generated between air–fuel ratio (λ), EGR rate, boost level, in-cylinder oxygen concentration, and load level using the experimental data and simulation results. Development of a real-time boost-EGR set-point determination to sustain the LTC mode at the varying engine load levels and fueling strategies is proposed.

Study of Cylinder Charge Control for Enabling Low Temperature Combustion in Diesel Engines

2013 ◽  
Author(s):  
Prasad Divekar ◽  
Usman Asad ◽  
Xiaoye Han ◽  
Xiang Chen ◽  
Ming Zheng
Keyword(s):  
Low Temperature ◽  
Diesel Engines ◽  
Direct Injection ◽  
Flame Temperature ◽  
Stable Operation ◽  
Low Temperature Combustion ◽  
Multiple Control ◽  
Engine Load ◽  
Combustion Modes ◽  
Temperature Combustion

Suitable cylinder charge preparation is deemed critical for the attainment of a highly homogeneous, diluted, and lean cylinder charge which is shown to lower the flame temperature. The resultant low temperature combustion (LTC) can simultaneously reduce the NOx and soot emissions from diesel engines. This requires sophisticated coordination of multiple control systems for controlling the intake boost, exhaust gas recirculation (EGR), and fueling events. Additionally, the cylinder charge modulation becomes more complicated in the novel combustion concepts that apply port injection of low reactivity alcohol fuels to replace the diesel fuel partially or entirely. In this work, experiments have been conducted on a single cylinder research engine with diesel and ethanol fuels. The test platform is capable of independently controlling the intake boost, EGR rates, and fuelling events. Effects of these control variables are evaluated with diesel direct injection and a combination of diesel direct injection and ethanol port injection. Data analyses are performed to establish the control requirements for stable operation at different engine load levels with the use of one or two fuels. The sensitivity of the combustion modes is thereby analyzed with regard to the boost, EGR, fuel types and fueling strategies. Zero-dimensional cycle simulations have been conducted in parallel with the experiments to evaluate the operating requirements and operation zones of the LTC combustion modes. Correlations are generated between air-fuel ratio (λ), EGR rate, boost level, in-cylinder oxygen concentration and load level using the experimental data and simulation results. Development of a real-time boost-EGR set-point determination to sustain the LTC mode at the varying engine load levels and fueling strategies is proposed.

A Comprehensive Review on Low-Temperature Combustion Technologies for Emission Reduction in Diesel Engines

2021 ◽  
Vol 18 (4) ◽  
Author(s):  
Amit Jhalani ◽  
Dilip Sharma ◽  
Pushpendra Kumar Sharma ◽  
Digambar Singh ◽  
Sumit Jhalani ◽  
...  
Keyword(s):  
Low Temperature ◽  
Diesel Engines ◽  
Alternative Fuels ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Lean Burn ◽  
Performance And Emissions ◽  
Temperature Combustion ◽  
Hc Emissions ◽  
Ci Engines

Diesel engines are lean burn engines; hence CO and HC emissions in the exhaust are less likely to occur in substantial amounts. The emissions of serious concern in compression ignition engines are particulate matter and nitrogen oxides because of elevated temperature conditions of combustion. Hence the researchers have strived continuously to lower down the temperature of combustion in order to bring down the emissions from CI engines. This has been tried through premixed charge compression ignition, homogeneous charge compression ignition (HCCI), gasoline compression ignition and reactivity controlled compression ignition (RCCI). In this study, an attempt has been made to critically review the literature on low-temperature combustion conditions using various conventional and alternative fuels. The problems and challenges augmented with the strategies have also been described. Water-in-diesel emulsion technology has been discussed in detail. Most of the authors agree over the positive outcomes of water-diesel emulsion for both performance and emissions simultaneously.

Comparison of Filter Smoke Number and Elemental Carbon Mass From Partially Premixed Low Temperature Combustion in a Direct-Injection Diesel Engine

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
William F. Northrop ◽  
Stanislav V. Bohac ◽  
Jo-Yu Chin ◽  
Dennis N. Assanis
Keyword(s):  
Diesel Engine ◽  
Low Temperature ◽  
Elemental Carbon ◽  
Direct Injection ◽  
Low Temperature Combustion ◽  
Soot Mass ◽  
Temperature Combustion ◽  
Carbon Mass ◽  
Partially Premixed ◽  
Premixed Low Temperature Combustion

Partially premixed low temperature combustion (LTC) is an established advanced engine strategy that enables the simultaneous reduction of soot and NOx emissions in diesel engines. Measuring extremely low levels of soot emissions achievable with LTC modes using a filter smoke meter requires large sample volumes and repeated measurements to achieve the desired data precision and accuracy. Even taking such measures, doubt exists as to whether filter smoke number (FSN) accurately represents the actual smoke emissions emitted from such low soot conditions. The use of alternative fuels such as biodiesel also compounds efforts to accurately report soot emissions since the reflectivity of high levels of organic matter found on the particulate matter collected may result in erroneous readings from the optical detector. Using FSN, it is desired to report mass emissions of soot using empirical correlations derived for use with petroleum diesel fuels and conventional modes of combustion. The work presented in this paper compares the experimental results of well known formulas for calculating the mass of soot using FSN and the elemental carbon mass using thermal optical analysis (TOA) over a range of operating conditions and fuels from a four-cylinder direct-injection passenger car diesel engine. The data show that the mass of soot emitted by the engine can be accurately predicted with the smoke meter method utilizing a 3000 ml sample volume over a range of FSN from 0.02 to 1.5. Soot mass exhaust concentration calculated from FSN using the best of the literature expressions and that from TOA taken over all conditions correlated linearly with a slope of 0.99 and R2 value of 0.94. A primary implication of the work is that the level of confidence in reporting the soot mass based on FSN for low soot formation regimes such as LTC is improved for both petroleum diesel and biodiesel fuels.

Early Direct-Injection, Low-Temperature Combustion of Diesel Fuel in an Optical Engine Utilizing a 15-Hole, Dual-Row, Narrow-Included-Angle Nozzle

2008 ◽  
Vol 1 (1) ◽  
pp. 1057-1082 ◽  
Author(s):  
Glen C. Martin ◽  
Charles J. Mueller ◽  
David M. Milam ◽  
Michael S. Radovanovic ◽  
Christopher R. Gehrke
Keyword(s):  
Low Temperature ◽  
Diesel Fuel ◽  
Direct Injection ◽  
Low Temperature Combustion ◽  
Included Angle ◽  
Optical Engine ◽  
Temperature Combustion

Study of the steady flow produced by direct injection diesel engine intake ports

2001 ◽  
Vol 215 (2) ◽  
pp. 285-298 ◽  
Author(s):  
J M Desantes ◽  
J V Pastor ◽  
A Doudou
Keyword(s):  
Spectral Analysis ◽  
Diesel Engine ◽  
Flow Field ◽  
Steady Flow ◽  
Cylinder Head ◽  
Laser Doppler Anemometry ◽  
Direct Injection ◽  
Valve Lift ◽  
Turbulent Structures ◽  
Direct Injection Diesel Engine

In this paper laser Doppler anemometry is used to characterize the steady flow field inside the cylinder generated by the two intake ports of a four-valve diesel head over the whole valve lift range and to compare the patterns at two different sections commonly used for global characterization in order to decide which is more appropriate for cylinder head evaluation. A more detailed investigation is performed for two valve lifts where the change in the flow patterns is more evident by applying a spectral analysis with the local normalized slotting technique to study the turbulent structures accompanying the in-cylinder swirl development.

scholarly journals The Strategies of NOx Emission Reduction for Diesel Engines

2018 ◽  
Vol 3 (11) ◽  
pp. 32-36 ◽  
Author(s):  
Cao Dao Nam ◽  
Van Vang Le
Keyword(s):  
Diesel Engines ◽  
Combustion Engine ◽  
Control Strategies ◽  
Direct Injection ◽  
Low Temperature Combustion ◽  
Technical Problems ◽  
Direct Injection Engines ◽  
The Road ◽  
Loading Mode ◽  
On The Road

Diesel engines are more efficient than forced ignition engines but due to diffused combustion and work with high air residue levels, burning products contain soot and NOx, pollutants that work Handling it on the road today still has many technical problems. The technology of organizing the combustion of diesel engines directly affects the level of pollution generated. Direct injection diesel engines have a lower fuel consumption than a combustion engine with a separation of about 10% and a lower level of soot emissions when the engine is operating in local loading mode. However, direct injection engines work noisier and generate more pollutants (NOx, HC). Today, this type of combustion chamber is only used for heavy-duty truck engines. Limiting the optimal emission level for diesel engines needs to balance the concentration of the two main pollutants, NOx and soot. Low temperature combustion (LTC) engines need different enabling technologies depending on the fuel and strategy used to achieve combustion of the premixed fuel–air mixture. Controlling the combustion rate is one of the major challenges in LTC engines, particularly in PPCI combustion engine to achieve higher thermal efficiency, the desired phasing of combustion timings is essential even at moderate combustion rates. Present chapter describes the combustion control variables and control strategies used for LTC engines. Various methods demonstrated to control the LTC engines can be categorized in to two main strategies: (i) altering pressure–temperature and (ii) altering fuel reactivity of the charge.

Sign in / Sign up

Export Citation Format

Share Document