Combustion In Spark Ignition Engine Research Articles

The effect of swirl on spark-ignition engine combustion.

In order to investigate the effect of swirl on combustion in a spark-ignition engine, a new experimental apparatus, namely, the single-event engine was prepared. The swirl flow in the cylinder was visualized by a smoke-wire method, and a laser Doppler anemometer and a hot-wire anemometer were adopted for the velocity measurement. The turbulence intensity was determined on the basis of the hot-wire data. A stoichiometric propane-air mixture was ignited at the center of the combustion chamber ; thus, the flame was propagated almost axisymmetrically in the flow field at various swirl intensities with no squish flow. The burning velocity, ST, and the thickness of burning zone, δT, were determined in the spark-ignition engine cylinder. The result show that ST and δT increase with increasing the turbulence intensity, and that δT is correlated linearly with ST except under the condition of weak turbulence.

Recent advances in spark-ignition engine combustion research.

This paper presents an overview of the current trend of combustion research in spark-ignition engines. The subject of greatest and continuing interest is the elucidation of the mechanism of turbulent flame propagation and/or the flame structure. Although there remain some problems as yet, the goal may not necessarily be so far away, considering the remarkable progress in diagnostic techniques during the last decade. Advances in numerical aerodynamics have made it possible to simulate the flow phenomena in an engine. The field of numerical aero-thermo-chemistry, however, is still immature. Also, the investigation into knock has recently become a subject of growing interest. This review covers the above subjects, in some depth.

The effect of swirl on spark-ignition engine combustion.

The effect of swirl on spark-ignition engine combustion.

Heat loss and heat release on premixture combustion in a stratified charge spark ignition engine with an auxiliary combustion chamber.

高効率・低公害化機関を目的とした層状給気機関の一つである副室付き火花点火機関において,燃焼機構と熱損失を実験的に調査した.特にこの形式の機関の特徴である連絡孔からの火炎噴流と熱損失および熱発生との因果関係を熱流束と燃焼圧力とから求め,この燃焼方式の機関における熱伝達率を推定する実験式を得た.さらに熱発生率の形が連絡孔径だけではなく熱損失によっても変化することを明らかにした.

Turbulent flame propagation and combustion in spark ignition engines

Pressure measurements synchronized with high-speed motion picture records of flame propagation have been made in a transparent piston engine. The data show that the initial expansion speed of the flame front is close to that of a laminar flame. As the flame expands, its speed rapidly accelerates to a quasi-steady value comparable with that of the turbulent velocity fluctuations in the unburned gas. During the quasi-steady propagation phase, a significant fraction of the gas behind the visible front is unburned. Final burnout of the charge may be approximated by an exponential decay in time. The data have been analyzed in a model independent way to obtain a set of empirical equations for calculating mass burning rates in spark ignition engines. The burning equations contain three parameters: the laminar burning speed s l , a characteristic speed u T, and a characteristic length l T. The laminar burning speed is known from laboratory measurements. Tentative correlations relating u T and l T to engine geometry and operating variables have been derived from the engine data.

Cycle-to-Cycle Fluctuation of Lean Mixture Combustion in Spark-Ignition Engineers

The cycle-to-cycle fluctuation of combustion in spark-ignition engines operated with a homogeneous lean-mixture of propane and air was investigated. The main results are as follows : (l) The configuration and size of flames in the early stage of combustion fluctuate remarkably from cycle to cycle, even if the mixture composition is kept constant. (2) A reduction of combustion period suppresses the cycle-to-cycle fluctuation of combustion. (3) The influence of the combustion fluctuation in the early stage on the whole combustion fluctuation varies with the length of the main combustion period.

Cycle-to-Cycle Fluctuation of Lean Mixture Combustion in Spark-Ignition Engines

Cycle-to-Cycle Fluctuation of Lean Mixture Combustion in Spark-Ignition Engines

Performance and NOxEmissions of Spark Ignited Combustion Engines Using Alternative Fuels—Quasi One-Dimensional Modeling I. Hydrogen Fueled Engines

Abstract Hydrogen and methanol have been suggested as potential non-petroleum derived substitutes for current reciprocating engine fuels. The present paper reports the results of a computer simulation of the performance and NOx emissions of hydrogen fueled spark ignition engines. The engine combustion process is modeled by employing a semi-empirical turbulent flame speed expression. The NOx emissions are determined by integrating the chemical rate equations resulting from the extended Zeldovich mechanism over the boundary conditions determined by the cycle analysis. Hydrogen exhibits very rapid burning rates and the resulting high pressures and temperatures lead to fast NO formation and destruction rates. Maximum NO emissions are predicted for lean mixtures near φ = 0.8 in agreement with experimental observations. For richer mixtures rapid decomposition of NO during the expansion stroke lowers exhaust emissions. NOx control by exhaust gas recirculation is much more effective in lean mixtures than in stoic...

Turbulence and turbulent combustion in spark-ignition engines

Nowadays, the carbon-free policies and the crisis of crude oil make natural gas get increasing attention. However, spark-ignited natural gas engines continually suffer from problems of thermal efficiency and NOx emissions. Optimizing intake and combustion systems are effective ways to improve combustion and emission performance, but comprehensive work involving both intake and combustion systems is still lacking, especially for heavy-duty commercial engines. In this work, both intake and combustion systems of spark-ignited heavy-duty natural gas engines were investigated using muti-dimensional numerical simulations. Two intake ports and four combustion chambers were considered. An optimized chemical model was employed to accelerate the computation efficiency of combustion processes. The optimal combination of intake and combustion systems was obtained, with impressive thermal efficiency and acceptable emission performance. The results show that the mixed-flow intake port performs better than the swirl intake port for the natural gas engine with premixed combustion mode, manifesting increased in-cylinder tumble ratio and turbulent kinetic energy. Meanwhile, the eccentric hemispherical combustion chamber (EHCC) combined with mixed-flow intake ports presents the best optimal combustion performance, exhibiting an effective thermal efficiency beyond 41.53%. However, the EHCC scheme shows an increased NOx emission due to fast combustion speed and high combustion temperature while negligible CO and CH4 emissions. Despite this, natural gas engines equipped with three-way catalysis after-treatment can still meet emission regulations under stoichiometric operating conditions.

Computer simulation for combustion and exhaust emissions in spark ignition engine

In order to predict the exhaust emission concentration without any measured pressure data or empirical burned mass fraction, a new method of combustion simulation was developed. It consists of two major parts: A flame propagation model, and an emission formation model. The flame propagation model, which is based on the burning velocity of the gaseous mixture, gives the pressure and temperature history in the cylinder and in the burned mass fraction for various parameters. In this model, the flame was assumed to propagate across the combustion cylinder as a spherical front centered around a spark plug; a heterogenous temperature field and uniform pressure in the cylinder were assumed. The cylinder consists, of unburned gas and numerous elements of burned gas which burned during successive small increments, of the crank angle. Using various values obtained with the flame propagation model, emission concentration were calculated in individual elements of burned gas, assuming partial equilibrium. Eleven chemical species were taken into consideration. Nine species, other than N and NO, were assumed to be equal to the equilibrium concentration throughout the time of interest. The formation of NO was assumed to be a nonequilibrium process controlled by chemical kinetics and to take place only in the post flame. Computer simulation developed here gives results consistent with the experimental data and it may be utilized for the practical design of a spark ignition engine.

Kinetics of pollutant formation and destruction in combustion

Ethanol, as the most produced renewable biofuel, is considered a promising low-carbon alternative to petroleum-based fuels in the transport sector due to its high energy density and auto-ignition resistance. The lean-burn combustion in spark-ignition (SI) engines has the potential to further improve thermal efficiency in regard to knock mitigation and the reduction of combustion temperature. However, the characteristics of lean-burn combustion in an ethanol-fueled engine in relation to the combustion losses and the gas-exchange process remain unclear, especially for high-load operation. This study contributes with a deeper understanding of the high-load performance of an ethanol-fueled heavy-duty SI engine using lean-burn combustion. Based on the experimental results from a single-cylinder engine test, a 6-cylinder engine model is built by integrating a validated predictive combustion model to characterize the lean-burn combustion process. The engine’s thermal efficiency and combustion phasing are evaluated for knock limited operation and then compared to the theoretical optimum which is regardless of knock. The energy and exergy balances are applied to evaluate the effect of dilution with excess air ratios up to 1.8. Losses through heat transfer, exhaust flow, and incomplete combustion are quantified. In addition, entropy generated through combustion is discussed to identify the relationship between exergy destruction and different operating conditions. In the context of lean-burn combustion, the thermal efficiency at high-load operation incrementally increases from 40.4% at stoichiometric condition to 47.3% at an excess air ratio of 1.8. At the same time, the exergy destruction through combustion increases by 3.3 percentage points across the selected dilution range. Furthermore, the challenging requirements to realize lean-burn combustion with lower exhaust gas temperatures and higher intake boost pressures is assessed through an exergy analysis of the turbocharging system.

On the Rate of Combustion in the Gasoline-Injection Spark-Ignition Engine

In this paper, the rate of combustion in the cylinder of the gasoline-injection engine is calculated by analyzing the indicator cards, and the relations between the rate of combustion and thermal efficiency, and the effects of the combustion progress on the performance are investigated. In the fuel-injection engine, the combustion proceeds faster at the early stage after ignition than in the carburetor engine. The nature of the cycle, therefore, resembles to that in the constant volume combustion cycle and has good thermal efficiency. The highest indicated thermal efficiency is obtained when the spark is so timed that the highest rate of combustion appears right after TDC.

Combustion Pressures in Spark-Ignition Engines

IT has come to the notice of investigators interested in combustion and detonation in spark-ignition engines that the combustion pressures may attain values which, even when no heat losses are considered, appeared to surpass those found by calculation, making use of the normally accepted data for such processes. The inadequacy of pressure indicating apparatus, especially when measurements were made under conditions of incipient or even persistent detonation, has for long prevented adequate attention being paid to this phenomenon.