Investigation of Multi-Pole Spark Ignition on Flame Kernel Development and in Engine Operation

2016 ◽  
Author(s):  
Kelvin Xie ◽  
Shui Yu ◽  
Tongyang Gao ◽  
Xiao Yu ◽  
Ming Zheng ◽  
...  
Keyword(s):  
Combustion Stability ◽  
Stable Operation ◽  
Ignition Process ◽  
Charge Motion ◽  
Kernel Development ◽  
Engine Operation ◽  
Flame Kernel ◽  
Excess Air ◽  
Spatially Distributed ◽  
Engine Stability

In order to meet the future carbon dioxide legislation, advanced clean combustion engines are tending to employ low temperature diluted combustion strategies along with intensified cylinder charge motion. The diluted mixtures are made by means of excess air admission or exhaust gas recirculation. A slower combustion speed during the early flame kernel development because of the suppressed mixture reactivity will reduce the reliability of the ignition process and the overall combustion stability. In an effort to address this issue, an ignition strategy using a multi-pole spark igniter is tested in this work. The igniter uses three electrically independent spark gaps to allow three spatially distributed spark discharge. The multi-pole spark strategy, when observed in an optical combustion vessel with lean methane-air mixtures, visually showed increased early flame kernel growth rate. The strategy was tested on an engine using gasoline fuel and low load, lean operation at 1.35 excess air ratio. The results indicated that the combustion phasing parameters were consistently advanced under the multi-pole spark strategy. In conditions where a conventional single spark exhibited stable operation, relatively little additional benefits were seen with the multi-pole strategy. At later spark timings when cycle-to-cycle variations had a greater impact on the engine stability, the multi-pole spark reduced the combustion variability.

Chemical effects of plasma gases on flame kernel development

1988 ◽  
Vol 418 (1855) ◽  
pp. 313-329 ◽  
Keyword(s):  
Combustion Chamber ◽  
Active Regions ◽  
Ignition Process ◽  
Flammability Limit ◽  
Kernel Development ◽  
Flame Kernel ◽  
Chemical Effects ◽  
Initial Plasma ◽  
Dimensional Distribution ◽  
Approach To Steady State

A study of the plasma jet ignition of lean methane-air mixtures was conducted to determine the effect of different plasma gases on flame kernel development. A plasma igniter, incorporating a shutter that separated the gases in the igniter from the reactant gases in a combustion chamber before discharge, allowed any combination of gases to be used without mixing. Measurements of the two-dimensional distribution of OH concentration by laser-induced fluorescence in a diametral plane above the igniter yielded information on the ignition process and the subsequent flame kernel development. The methane-air mixtures chosen for study had equivalence ratios, ϕ , near the lean flammability limit of ϕ ═ 0.53. To differentiate OH formation in the initial plasma from that generated during mixing and reaction with gas in the combustion chamber, experiments were conducted using the following combinations of plasma media and reactant gases: H 2 and 2H 2 + O 2 plasmas into air; Ar, N 2 , H 2 and 2H 2 + O 2 plasmas into ϕ ═ 0.50 CH 4 -air; and 2H 2 + O 2 plasma into ϕ ═ 0.65 CH 4 -air. In addition to OH measurements, the pressure in the combustion chamber was measured, and Schlieren photographs were taken. Results indicated relatively small, chemically active regions, generally off-axis and often associated with vortices. Measurements in lean mixtures that are known to discriminate strongly between plasma of different effectiveness confirm the higher incendivity, for the same total energy, of chemically active plasmas and demonstrate the higher concentration and longer persistence of OH during the approach to steady state flame conditions. Such chemically active plasmas promote combustion for hundreds of milliseconds in normally non-flammable sub-limit mixtures.

The Effects of Charge Motion on Early Flame Kernel Development

1993 ◽  
Author(s):  
David L. Lord ◽  
Richard W. Anderson ◽  
Diana D. Brehob ◽  
Youngil Kim
Keyword(s):  
Charge Motion ◽  
Kernel Development ◽  
Flame Kernel

Effect of Spark Discharge Duration and Timing on the Combustion Initiation in a Lean Burn SI Engine

2021 ◽  
Keyword(s):  
High Efficiency ◽  
Combustion Process ◽  
Marginal Effect ◽  
Ignition Process ◽  
Discharge Process ◽  
Charge Motion ◽  
Si Engine ◽  
Engine Operation ◽  
Discharge Duration ◽  
Si Engines

Meeting the increasingly stringent emission and fuel efficiency standards is the primary objective of the automotive research. Lean/diluted combustion is a promising avenue to realize high-efficiency combustion and reduce emissions in SI engines. Under the diluted conditions, the flame propagation speed is reduced because of the reduced charge reactivity. Enhancing the in-cylinder charge motion and turbulence, and thereby increasing the flame speed, is a possible way to harness the combustion process in SI engines. However, the charge motion can have a significant effect on the spark ignition process because of the reduced discharge duration and frequent restrikes. A longer discharge duration can aid in the formation of the self-sustained flame kernel and subsequent stable ignition. Therefore, an empirical study is undertaken to investigate the effect of the discharge duration and ignition timing on the ignition and early combustion in a port fueled SI engine, operated under lean conditions. The discharge duration is modulated from 1 ms to 8 ms through a continuous discharge strategy. The discharge current and voltage measurements are recorded during the engine operation to characterize the discharge process. The in-cylinder charge is diluted using fresh air to achieve lean combustion. The in-cylinder pressure measurement and heat release analysis are used to investigate the ignition and combustion characteristics of the engine. Preliminary results indicate that while the discharge duration has a marginal effect on the ignition delay, cyclic variations are notably impacted.

scholarly journals A Numerical Study on Early Stage of Flame Kernel Development in Spark Ignition Process for Methane/Air Combustible Mixtures

2007 ◽  
Vol 73 (732) ◽  
pp. 1745-1752 ◽  
Author(s):  
Shinji NAKAYA ◽  
Kazuo HATORI ◽  
Mitsuhiro TSUE ◽  
Michikata KONO ◽  
Daisuke SEGAWA ◽  
...  
Keyword(s):  
Numerical Study ◽  
Early Stage ◽  
Spark Ignition ◽  
Ignition Process ◽  
Kernel Development ◽  
Flame Kernel ◽  
Combustible Mixtures

4735 Numerical Analysis on flame kernel development in spark ignition process for methane/air combustible mixtures

2006 ◽  
Vol 2006.3 (0) ◽  
pp. 297-298
Author(s):  
Shinji NAKAYA ◽  
Kazuo HATORI ◽  
Mitsuhiro TSUE ◽  
Michikata KONO ◽  
Daisuke SEGAWA ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Spark Ignition ◽  
Ignition Process ◽  
Kernel Development ◽  
Flame Kernel ◽  
Combustible Mixtures

Stabilizing Excessive EGR With an Oxidation Catalyst on a Modern Diesel Engine

2002 ◽  
Author(s):  
Ming Zheng ◽  
David K. Irick ◽  
Jeffrey Hodgson
Keyword(s):  
Diesel Engine ◽  
Oxidation Catalyst ◽  
Stable Operation ◽  
Exhaust Gas ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Turbocharged Diesel Engine ◽  
New Approach ◽  
Cyclic Variations ◽  
Gas Recirculation

For diesel engines (CIDI) the excessive use of exhaust gas recirculation (EGR) can reduce in-cylinder oxides of nitrogen (NOx) generation dramatically, but engine operation can also approach zones with high instabilities, usually accompanied with high cycle-to-cycle variations and deteriorated emissions of total hydrocarbon (THC), carbon monoxide (CO), and soot. A new approach has been proposed and tested to eliminate the influences of recycled combustibles on such instabilities, by applying an oxidation catalyst in the high-pressure EGR loop of a turbocharged diesel engine. The testing was directed to identifying the thresholds of stable operation at high rates of EGR without causing cycle-to-cycle variations associated with untreated recycled combustibles. The elimination of recycled combustibles using the oxidation catalyst showed significant influences on stabilizing the cyclic variations, so that the EGR applicable limits are effectively extended. The attainability of low NOx emissions with the catalytically oxidized EGR is also evaluated.

Siemens SGT-800 Industrial Gas Turbine Enhanced to 50MW: Combustor Design Modifications, Validation and Operation Experience

2013 ◽  
Author(s):  
Daniel Lörstad ◽  
Annika Lindholm ◽  
Jan Pettersson ◽  
Mats Björkman ◽  
Ingvar Hultmark
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Cooling System ◽  
Good Condition ◽  
Combined Cycle ◽  
Combustion Stability ◽  
Combustion System ◽  
Design Work ◽  
Engine Operation ◽  
Cooling Air

Siemens Oil & Gas introduced an enhanced SGT-800 gas turbine during 2010. The new power rating is 50.5MW at a 38.3% electrical efficiency in simple cycle (ISO) and best in class combined-cycle performance of more than 55%, for improved fuel flexibility at low emissions. The updated components in the gas turbine are interchangeable from the existing 47MW rating. The increased power and improved efficiency are mainly obtained by improved compressor airfoil profiles and improved turbine aerodynamics and cooling air layout. The current paper is focused on the design modifications of the combustor parts and the combustion validation and operation experience. The serial cooling system of the annular combustion chamber is improved using aerodynamically shaped liner cooling air inlet and reduced liner rib height to minimize the pressure drop and optimize the cooling layout to improve the life due to engine operation hours. The cold parts of the combustion chamber were redesigned using cast cooling struts where the variable thickness was optimized to maximize the cycle life. Due to fewer thicker vanes of the turbine stage #1, the combustor-turbine interface is accordingly updated to maintain the life requirements due to the upstream effect of the stronger pressure gradient. Minor burner tuning is used which in combination with the previously introduced combustor passive damping results in low emissions for >50% load, which is insensitive to ambient conditions. The combustion system has shown excellent combustion stability properties, such as to rapid load changes and large flame temperature range at high loads, which leads to the possibility of single digit Dry Low Emission (DLE) NOx. The combustion system has also shown insensitivity to fuels of large content of hydrogen, different hydrocarbons, inerts and CO. Also DLE liquid operation shows low emissions for 50–100% load. The first SGT-800 with 50.5MW rating was successfully tested during the Spring 2010 and the expected performance figures were confirmed. The fleet leader has, up to January 2013, accumulated >16000 Equivalent Operation Hours (EOH) and a planned follow up inspection made after 10000 EOH by boroscope of the hot section showed that the combustor was in good condition. This paper presents some details of the design work carried out during the development of the combustor design enhancement and the combustion operation experience from the first units.

MODELING NANOSECOND-PULSED SPARK DISCHARGE AND FLAME KERNEL EVOLUTION

2021 ◽  
pp. 1-22
Author(s):  
Joohan Kim ◽  
Vyaas Gururajan ◽  
Riccardo Scarcelli ◽  
Sayan Biswas ◽  
Isaac Ekoto
Keyword(s):  
Electrical Discharge ◽  
Internal Combustion Engines ◽  
Initial Conditions ◽  
Fuel Mixture ◽  
Spark Ignition ◽  
Combustion Stability ◽  
Flame Kernel ◽  
Wide Range ◽  
Challenging Environment ◽  
Kernel Growth

Abstract Dilute combustion, either using exhaust gas recirculation or with excess-air, is considered a promising strategy to improve the thermal efficiency of internal combustion engines. However, the dilute air-fuel mixture, especially under intensified turbulence and high-pressure conditions, poses significant challenges for ignitability and combustion stability, which may limit the attainable efficiency benefits. In-depth knowledge of the flame kernel evolution to stabilize ignition and combustion in a challenging environment is crucial for effective engine development and optimization. To date, comprehensive understanding of ignition processes that result in the development of fully predictive ignition models usable by the automotive industry does not yet exist. Spark-ignition consists of a wide range of physics that includes electrical discharge, plasma evolution, joule-heating of gas, and flame kernel initiation and growth into a self-sustainable flame. In this study, an advanced approach is proposed to model spark-ignition energy deposition and flame kernel growth. To decouple the flame kernel growth from the electrical discharge, a nanosecond pulsed high-voltage discharge is used to trigger spark-ignition in an optically accessible small ignition test vessel with a quiescent mixture of air and methane. Initial conditions for the flame kernel, including its thermodynamic state and species composition, are derived from a plasma-chemical equilibrium calculation. The geometric shape and dimension of the kernel are characterized using a multi-dimensional thermal plasma solver. The proposed modeling approach is evaluated using a high-fidelity computational fluid dynamics procedure to compare the simulated flame kernel evolution against flame boundaries from companion schlieren images.

Numerical and Experimental Analysis of Ignition and Combustion Stability in EGR Dilute GDI Operation

2014 ◽  
Author(s):  
Riccardo Scarcelli ◽  
Nicholas S. Matthias ◽  
Thomas Wallner
Keyword(s):  
Flame Propagation ◽  
Numerical Results ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Ignition Process ◽  
Ignition System ◽  
Cyclic Variability ◽  
Beneficial Effects ◽  
Engine Testing ◽  
Ignition And Combustion

This paper discusses the characteristics of EGR dilute GDI engines in terms of combustion stability. A combined approach consisting of RANS numerical simulations integrated with experimental engine testing is used to analyze the effect of the ignition source on flame propagation under dilute operating conditions. A programmable spark-based ignition system is compared to a production spark system in terms of cyclic variability and ultimately indicated efficiency. 3D-CFD simulations are carried out for multiple cycles with the goal of establishing correlations between the characteristics of the ignition system and flame propagation as well as cycle-to-cycle variations. Numerical results are compared to engine data in terms of in-cylinder pressure traces. The results show that an improved control over the energy released to the fluid surrounding the spark domain during the ignition process has beneficial effects on combustion stability. This allows extending the dilution tolerance for fuel/air mixtures. Although affected by cyclic variability, numerical results show good qualitative agreement with experimental data. The result is a simple but promising approach for relatively quick assessment of stability improvements from advanced and alternative ignition strategies.

The Effect of Sparkplug Design on Initial Flame Kernel Development and Sparkplug Performance

2006 ◽  
Author(s):  
Terry Alger ◽  
Barrett Mangold ◽  
Darius Mehta ◽  
Charles Roberts
Keyword(s):  
Kernel Development ◽  
Flame Kernel ◽  
Initial Flame
Sign in / Sign up

Export Citation Format

Share Document