Evaluation of the Effects of a Twin Spark Ignition System on Combustion Stability of a High Performance PFI Engine

Large bore natural gas engines have the perennial challenge to achieve ever higher efficiency with ever lower NOx emissions, while maintaining stable combustion, avoiding misfire and engine knock. A primary strategτy to achieve these goals is to run leaner and leaner. However, leaner mixtures lead to reduced combustion stability and the operating space between misfire and engine knock shrinks. Leaner operation requires a high performance ignition system. This report will highlight the fundamental challenges related to lean operation and the progress Woodward has made to create a novel high performance prechamber spark plug to achieve good combustion stability in a passive prechamber spark plug under lean conditions. The spark plug in combination with the appropriate ignition system enables faster and more stable combustion under increasingly lean conditions, improving fuel efficiency and emissions. Engine simulation modeling is used to demonstrate the benefits of lean gas mixtures and reduced combustion duration to enhance the NOx versus fuel consumption trade-off for a range of air fuel ratios. With this database available, a design requirements flow-down is performed such that combustion performance requirements can be specified a priori, which if met would ensure the high level engine emissions and performance targets would be met. With combustion requirements in hand, CFD simulations are used to identify the mechanisms by which flame propagation is improved with prechamber spark plugs in general, and by the Lean Quality Plug (WW-LQP) prechamber spark plug under development at Woodward. Experimental validation was carried out to confirm the benefits of lean operation and improvement of combustion stability (COV) on the NOx-efficiency trade-off. Operation with Woodward’s WW-LQP spark plug and IC1100 AC ignition system showed improved fuel efficiency at constant NOx on a high BMEP engine. Additionally, the enhanced stability and low COV of the WW-LQP enables extension of the natural gas lean limit closer to λ = 2.00 for an open chamber engine.

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Fundamental insights on ignition and combustion of natural gas in an active fueled pre-chamber spark-ignition system

Combustion and Flame ◽

10.1016/j.combustflame.2021.111561 ◽

2021 ◽

Vol 232 ◽

pp. 111561

Author(s):

Rajavasanth Rajasegar ◽

Yoichi Niki ◽

Jose Maria García-Oliver ◽

Zheming Li ◽

Mark P.B. Musculus

Keyword(s):

Natural Gas ◽

Spark Ignition ◽

Ignition System ◽

Ignition And Combustion

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Tumble Flow Measurements Using Three Different Methods and Its Effects on Fuel Economy and Emissions

ASME 2006 Internal Combustion Engine Division Spring Technical Conference (ICES2006) ◽

10.1115/ices2006-1335 ◽

2006 ◽

Cited By ~ 3

Author(s):

Myoungjin Kim ◽

Sihun Lee ◽

Wootae Kim

Keyword(s):

Fuel Economy ◽

High Performance ◽

Gasoline Engine ◽

Exhaust Emissions ◽

Combustion Stability ◽

Lean Burn ◽

Flow Measurements ◽

Part Load ◽

Gasoline Engines ◽

Dynamometer Test

In-cylinder flows such as tumble and swirl have an important role on the engine combustion efficiencies and emission formations. In particular, the tumble flow, which is dominant in-cylinder flow in current high performance gasoline engines, has an important effect on the fuel consumptions and exhaust emissions under part load conditions. Therefore, it is important to know the effect of the tumble ratio on the part load performance and optimize the tumble ratio of a gasoline engine for better fuel economy and exhaust emissions. First step in optimizing a tumble flow is to measure a tumble ratio accurately. In this research the tumble flow was measured, compared and correlated using three different measurement methods: steady flow rig, 2-Dimensional PIV, and 3-Dimensional PTV. Engine dynamometer test was performed to find out the effect of the tumble ratio on the part load performance. Dynamometer test results of high tumble ratio engine showed faster combustion speed, retarded MBT timing, higher exhaust emissions, and a better lean burn combustion stability. Lean limit of the baseline engine was expanded from A/F=18:1 to A/F=21:1 by increasing a tumble ratio using MTV.

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MODELING NANOSECOND-PULSED SPARK DISCHARGE AND FLAME KERNEL EVOLUTION

Journal of Energy Resources Technology ◽

10.1115/1.4051144 ◽

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.

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A New Approach for Ignition Timing Correction in Spark Ignition Engines Based on Cylinder Tendency to Surface Ignition

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.819.272 ◽

2016 ◽

Vol 819 ◽

pp. 272-276 ◽

Cited By ~ 2

Author(s):

Ali Ghanaati ◽

Mohd Farid Muhamad Said ◽

Intan Zaurah Mat Darus ◽

Amin Mahmoudzadeh Andwari

Keyword(s):

Spark Ignition ◽

Combustion Stability ◽

Spark Ignition Engines ◽

Gas Temperature ◽

New Approach ◽

Surface Ignition ◽

Spark Plug ◽

Engine Combustion ◽

Si Engines ◽

Exhaust Gas Temperature

The performance of Spark Ignition (SI) engines in terms of thermal efficiency can be restricted by knock. Although it is common for all SI engines to exhibit knock from compressed end-gas, knocks from surface ignition remains a more serious problem due to its effect on combustion stability and its obscurity to detect. This paper focuses on predicting the occurrence of knocks from surface ignition by monitoring exhaust gas temperature (EGT). EGT measured during an engine cycle without the spark plug firing. Therefore, EGT rises illustrated any combustion made by surface ignition. Modelling and simulation of a one-dimensional engine combustion done by using GT-Power. The new approach reduces the complexity as EGT monitoring does not require high computational demands, and the EGT signals are robust to noise. The method is validated against a variety of fuel properties and across engine conditions. A new approach is proposed as a measure to predict and detect the knock events.

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

Volume 1: Large Bore Engines; Fuels; Advanced Combustion; Emissions Control Systems ◽

10.1115/icef2014-5607 ◽

2014 ◽

Cited By ~ 7

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.

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Improvement on Energy Efficiency of the Spark Ignition System

10.4271/2017-01-0678 ◽

2017 ◽

Cited By ~ 7

Author(s):

Xiao Yu ◽

Shui Yu ◽

Zhenyi Yang ◽

Qingyuan Tan ◽

Mark Ives ◽

...

Keyword(s):

Energy Efficiency ◽

Spark Ignition ◽

Ignition System

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Effects of passive pre-chamber jet ignition on combustion and emission at gasoline engine

Advances in Mechanical Engineering ◽

10.1177/16878140211067148 ◽

2021 ◽

Vol 13 (12) ◽

pp. 168781402110671

Author(s):

Wei Duan ◽

Zhaoming Huang ◽

Hong Chen ◽

Ping Tang ◽

Li Wang ◽

...

Keyword(s):

Fuel Consumption ◽

Gasoline Engine ◽

Combustion Process ◽

Pressure Rise ◽

Spark Ignition ◽

Combustion Stability ◽

Intake Valve ◽

Part Load ◽

Significant Difference ◽

Valve Opening

Pre-chamber jet ignition is a promising way to improve fuel consumption of gasoline engine. A small volume passive pre-chamber was tested at a 1.5L turbocharged GDI engine. Combustion and emission characteristics of passive pre-chamber at low-speed WOT and part load were studied. Besides, the combustion stability of the passive pre-chamber at idle operation has also been studied. The results show that at 1500 r/min WOT, compared with the traditional spark ignition, the combustion phase of pre-chamber is advanced by 7.1°CA, the effective fuel consumption is reduced by 24 g/kW h, and the maximum pressure rise rate is increased by 0.09 MPa/°CA. The knock tendency can be relieved by pre-chamber ignition. At part load of 2000 r/min, pre-chamber ignition can enhance the combustion process and improve the combustion stability. The fuel consumption of pre-chamber ignition increases slightly at low load, but decreases significantly at high load. Compared with the traditional spark ignition, the NOx emissions of pre-chamber increase significantly, with a maximum increase of about 15%; the HC emissions decrease, and the highest decrease is about 36%. But there is no significant difference in CO emissions between pre-chamber ignition and spark plug ignition. The intake valve opening timing has a significant influence on the pre-chamber combustion stability at idle operation. With the delay of the pre-chamber intake valve opening timing, the CoV is reduced and can be kept within the CoV limit.

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Effect of injection and ignition timing on a hydrogen-lean stratified charge combustion engine

International Journal of Engine Research ◽

10.1177/14680874211034682 ◽

2021 ◽

pp. 146808742110346

Author(s):

Sanguk Lee ◽

Gyeonggon Kim ◽

Choongsik Bae

Keyword(s):

Internal Combustion Engines ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Combustion Stability ◽

Transport Sector ◽

Injection Timing ◽

Ignition Timing ◽

Particulate Emission ◽

Stratified Charge ◽

Lean Limit

Hydrogen can be used as a fuel for internal combustion engines to realize a carbon-neutral transport society. By extending the lean limit of spark ignition engines, their efficiency, and emission characteristics can be improved. In this study, stratified charge combustion (SCC) using monofueled hydrogen direct injection was used to extend the lean limit of a spark ignition engine. The injection and ignition timing were varied to examine their effect on the SCC characteristics. An engine experiment was performed in a spray-guided single-cylinder research engine, and the nitrogen oxide and particulate emissions were measured. Depending on the injection timing, two different types of combustion were characterized: mild and hard combustion. The advancement and retardation of the ignition timing resulted in a high and low combustion stability, respectively. The lubricant-based particulate emission was attributed to the in-cylinder temperature and area of the flame surface. Therefore, the results of the study suggest that the optimization of the hydrogen SCC based on the injection and ignition timing could contribute to a clean and efficient transport sector.

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