scholarly journals Turbulent Flame Velocity Model for SI Engine

2011 ◽  
pp. 127-135
Author(s):  
Rashid Ali ◽  
Nafis Ahmad
Keyword(s):  
Compression Ratio ◽  
Equivalence Ratio ◽  
Engine Speed ◽  
Present Model ◽  
Turbulent Flame ◽  
Spark Ignition Engine ◽  
Operating Parameters ◽  
Flame Velocity ◽  
Wide Range ◽  
Good Agreement

A new model for turbulent flame velocity of premixed flame in spark ignition engine for Iso-octane air mixture has been developed and validated for a wide range of engine operating parameters. The model developed is a zero dimensional thermodynamic model. The effects of engine speed (600-1160 rpm), equivalence ratio (0.7-1.1), unburnt mixture temperature (532- 650 Rankine), compression ratio (5-8) and ignition timing (5-30 degree before top dead center) have been studied in detail. The comparison between theoretical and experimental burning velocity has been made for a wide range of engine operating parameters such as compression ratio, angle of spark, equivalence ratio, flame radius, engine speed and unburnt mixture temperature. The flame velocity obtained from the present model is in good agreement with the experimental and theoretical flame velocity of Cakir. The flame velocity computed by the present model is also in good agreement with the flame velocity calculated by Malik model.

Pressure Sensitivity of HCCI Auto-Ignition Temperature for Oxygenated Reference Fuels

2012 ◽  
Author(s):  
Ida Truedsson ◽  
Martin Tuner ◽  
Bengt Johansson ◽  
William Cannella
Keyword(s):  
Compression Ratio ◽  
Ignition Temperature ◽  
Equivalence Ratio ◽  
Engine Speed ◽  
Pressure Sensitivity ◽  
Hcci Combustion ◽  
Air Temperatures ◽  
Auto Ignition ◽  
Temperature Heat ◽  
Pressure Trace

The current research focuses on creating an HCCI fuel index suitable for comparing different fuels for HCCI operation. One way to characterize a fuel is to use the Auto-Ignition Temperature (AIT). The AIT can be extracted from the pressure trace. Another potentially interesting parameter is the amount of Low Temperature Heat Release (LTHR) that is closely connected to the ignition properties of the fuel. The purpose of this study was to map the AIT and amount of LTHR of different oxygenated reference fuels in HCCI combustion at different cylinder pressures. Blends of n-heptane, iso-octane and ethanol were tested in a CFR engine with variable compression ratio. Five different inlet air temperatures ranging from 50°C to 150°C were used to achieve different cylinder pressures and the compression ratio was changed accordingly to keep a constant combustion phasing, CA50, of 3±1° after TDC. The experiments were carried out in lean operation with a constant equivalence ratio of 0.33 and with a constant engine speed of 600 rpm. The amount of ethanol needed to suppress LTHR from different PRFs was evaluated. The AIT and the amount of LTHR for different combinations of n-heptane, iso-octane and ethanol were charted.

The Development of Combustion Strategy in Improving the Performances of SI-PFI Engine Using E50 of Gasoline-Bioethanol Fuel Blend

2021 ◽  
pp. 115-135
Author(s):  
M. Paloboran ◽  
H. Syam ◽  
M. Yahya ◽  
Darmawang
Keyword(s):  
Linear Programming ◽  
Compression Ratio ◽  
Engine Speed ◽  
Standard Condition ◽  
Spark Ignition Engine ◽  
Ignition Timing ◽  
Fuel Blend ◽  
Non Linear Programming ◽  
Non Linear ◽  
Bioethanol Fuel

This research aims to improve the combustion performance of gasoline-bioethanol fuel blended in the ratio of 50:50 (E50) on the spark-ignition engine by employing a new combustion strategy. The Box Behnken Design of Response Surface Methodology and Non-Linear Programming was employed to optimize the performance of the engine and create some engine parameters. The performance of the engine consists of power, torque, thermal efficiency, fuel consumption, and the emission of CO and HC, while the engine and combustion parameters are compression ratio, ignition timing, and engine speed. A new combustion strategy will be applied in this study with a tiered mapping process for each engine parameter based on the MBT. The brake torque increased by 13.5 % while HC and CO emissions decreased by 15 % and 71 % respectively when the combustion strategy applied if compared o the pure gasoline in engine standard condition. Furthermore, the BSFC increased by 33 % while BTE decreased by 15 % towards the gasoline fuel. The non-linear programming applied in this study intended to figure out the best combination of the engine parameters in obtaining optimum engine performances. In the RSM analysis, the codes --1, 0, 1 represented 12, 12.5, and 13 of compression ratio, 16, 20, and 24 BTDC of ignition timing and 2000, 5000, and 8000 rpm of engine speed. Therefore, 20 BTDC of ignition timing and 13:1 of compression ratio is the optimum engine parameters used in gaining the optimal performance of the engine when E50 runs in SI-PFI engine of 150 cm3

Diagnosis of hydrous ethanol combustion in a spark-ignition engine

2020 ◽  
Vol 235 (1) ◽  
pp. 245-259
Author(s):  
Caio H Rufino ◽  
Waldyr LR Gallo ◽  
Janito V Ferreira
Keyword(s):  
Engine Speed ◽  
Combustion Characteristics ◽  
Spark Ignition Engine ◽  
Ignition Timing ◽  
Operational Parameters ◽  
Fuel Ratio ◽  
Combustion Duration ◽  
Wide Range ◽  
Hydrous Ethanol ◽  
The Relationship

By evaluating combustion duration and flame development, it is possible to evaluate the effects of utilizing a new type of fuel. This allows for optimization of the operational parameters such as the ignition timing, air–fuel ratio, and throttle opening with respect to efficiency, knock, emissions, and performance. In this work, the combustion of a Brazilian hydrous ethanol fuel was evaluated in a commercial flexfuel engine. Investigations were conducted by performing a heat release analysis of the experimental data and providing combustion characteristics. The experimental design comprised of variations in engine speed, load, ignition timing, and air–fuel ratio under lean condition. The results indicated the relationship between the engine parameters and combustion characteristics under a wide range of operational conditions, and identified the relationship between the physical characteristics of the fuels and their combustion in the commercial engine. For high engine speed, lean combustion presented a similar duration to the stoichiometric combustion duration. When comparing the combustion characteristics obtained for the hydrous ethanol with gasoline combustion, the main differences noted were reduced sensitivity to detonation and a shorter duration of combustion, although the temperature at the start of combustion was lower for ethanol. In addition to shorter combustion duration, ethanol presented a lower value for the Wiebe exponent. The results obtained from the combustion duration values and Wiebe function parameters enable the composition of a set of data required for a simplified combustion simulation.

Hydrogen Fuelled Spark-Ignition Engines: Predictive and Experimental Performance

2003 ◽  
Author(s):  
Hailin Li ◽  
Ghazi A. Karim
Keyword(s):  
Compression Ratio ◽  
Power Efficiency ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Zone Model ◽  
Engine Fuel ◽  
Oxidation Reactions ◽  
Chemical Kinetic Model ◽  
Wide Range

Hydrogen is well recognized as a suitable fuel for spark-ignition engine applications that has many unique attractive features and limitations. It is a fuel that can continue potentially to meet the ever increasingly stringent regulations for exhaust and greenhouse gas emissions. The application of hydrogen as an engine fuel has been tried over many decades by numerous investigators with varying degrees of success. The performance data reported often tend not to display consistent agreement between the various investigators mainly because of the wide differences in engine type, size, operating conditions used and the differing criteria employed to judge whether knock is taking place or not. With the ever-increasing interest in hydrogen as an engine fuel, there is a need to be able to model extensively various features of the performance of spark ignition (S.I.) hydrogen engines so as to investigate and compare reliably the performance of widely different engines under a wide variety of operating conditions. The paper employs a quasi-dimensional two-zone model for the operation of S.I. engines when fuelled with hydrogen. In this approach, the engine combustion chamber at any instant of time during combustion is considered to be divided into two temporally varying zones: a burned zone and an unburned zone. The model incorporates a detailed chemical kinetic model scheme of 30 reaction steps and 12 species, to simulate the oxidation reactions of hydrogen in air. A knock prediction model, developed previously for S.I. methane-hydrogen fuelled engine applications (Shrestha and Karim 1999(a) and 1999(b)) was extended to consider operation on hydrogen. The effects of changes in operating conditions, including a very wide range of variations in equivalence ratio on the onset of knock and its intensity, combustion duration, power, efficiency and operational limits were investigated. The results of this predictive approach were shown to validate well against corresponding experimental results of our own and those of others, obtained mostly in a variable compression ratio CFR engine. On this basis, the effects of changes in some of the key operational engine variables, such as compression ratio, intake temperature and spark timing are presented and discussed. Some guidelines for superior knock free-operation of engines on hydrogen are made also.

Experimental Investigation into the Influence of Compression Ratio on Operating Characteristics of Single Cylinder CNG Engine with Port Injection

2019 ◽  
Vol 889 ◽  
pp. 396-402
Author(s):  
Tran Dang Quoc ◽  
Tran Thanh Tam ◽  
Le Anh Tuan
Keyword(s):  
Compression Ratio ◽  
Engine Speed ◽  
Vibration Signal ◽  
Experimental Results ◽  
Operating Parameters ◽  
Operating Characteristics ◽  
Single Cylinder ◽  
Compression Stroke ◽  
Abnormal Sound ◽  
Cng Engine

This paper indicates the early experimental results of a Ricardo model CNG engine R&D activity in Vietnam, the experiments were mainly focused on the effects of compression ratio on operating parameters of the tested single cylinder CNG engine particularly designed and fabricated for varying compression ratio purpose. The compression ratio was set in the range of ε = 10 to 15 with the change step of Δε = 1. For each compression ratio, the engine speed were varried from 1000rpm to 2200rpm with the change step of Δn = 200. The early spark angle was also changed to find out the maximum break torque. The limitation of compression ratio and engine speed at each operating point was determined by vibration signal and abnormal sound. The experimental results indicated the early spark angle must be adjusted premature in case of compression ratio and/or engine speed enhenced. Especially, the portion of indispensable power to perform the compression stroke is smaller in comparison with the portion to execute the both strokes of intake and exhaust. In addition, the shape of combustion chamber affected strongly the operating characteristics also found in this study.

A Thermo-Viscoplastic Constitutive Equation Based on Hyperbolic-Shape Thermo-Activated Barriers

1984 ◽  
Vol 106 (4) ◽  
pp. 331-336 ◽  
Author(s):  
Li-Lih Wang
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Present Model ◽  
Strain Rate Effects ◽  
Bcc Metals ◽  
Special Cases ◽  
Wide Range ◽  
Rate Effects ◽  
Simple Parameter ◽  
Good Agreement

A thermo-viscoplastic constitutive equation is proposed on the basis of thermoactivated mechanism with a spectrum of hyperbolic-shape barriers, suitable for a wide range of strain rate and temperature. Relations with other existing models or rate theories, which may be regarded a special cases of present model, are examined. Good agreement with experimental data for both fcc and bcc metals is shown. The activation volume is found dependent on temperature according to an exponential law. A simple parameter, which describes the equivalence between strain rate effects and temperature effects on flow stress, is suggested similar to Zener-Hollomon parameters

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