SI Engine Research Articles

Variable intake manifold geometry influence on volumetric efficiency enhancement at gaseous engine starting speeds

This paper studied the effect of variable intake length manifold on filling and volumetric efficiency at starting engine speeds using numerical and experimental process. The investigation is based on acoustic supercharging phenomenon. For this purpose, 1-D engine gas-flow model was developed and optimum intake lengths for several low engine speeds were determined using acoustic theory based-resolution. Using the method of characteristics, pressure waves were predicted at the end of intake line length (intake valve level) in order to test the dynamic inertial supercharging phenomena. The quarter-wave resonator technique was taken into consideration to explore the inlet pressure pulsations. Simulations of pressure wave propagation were achieved during intake stroke and intake valve closed phase. Simulation predictions confirmed the analytically calculated optimum intake length. Numerical investigations were carried out on five in-cylinder flow moving through intake system; air, air-gasoline, air-LPG, air-H2 and air-LPG-H2 blend. The percentages of supplied hydrogen with LPG were 0%, 5%, 10%, 15% and 20% in volume. To experimentally validate the analytical founded lengths, an instrumented cold-flow four cylinder Ford SI engine test bench was prepared. Flow through variable intake length manifold was analyzed. Geometry variation was performed on the plenum length. Three engine low speeds are tested; 500 rpm, 750 rpm and 1000 rpm. The experiment results showed an in-cylinder velocity increase by about 60%, 58% and 48% using the optimal intake length at 500 rpm, 750 rpm and 1000 rpm respectively. Furthermore, the collected data proves that varying intake pipe length continuously with the engine speed leads to an average of 39.7% improvement in volumetric efficiency from the original engine configuration at 1000 rpm.

Modelling of combustion and knock onset risk in a high-performance turbulent jet ignition engine

The reduction of CO2 emissions, and hence of fuel consumption, is currently a key driver for the development of innovative SI engines for passenger car applications. In recent years, motorsport technical regulations in the highest categories have seen the introduction of limits concerning the fuel flow rate and the total amount of fuel per race, thus driving engine development toward further reduction of specific fuel consumption. Among the different techniques that can be shared between conventional and high-performance SI engines, turbocharging, compression ratio increase and Turbulent Jet Ignition (TJI) have shown a significant potential for fuel consumption reduction. The combination of turbocharging and compression ratio increase, however, can promote the onset of knocking combustion, with detrimental effects on engine's efficiency and durability. Additionally, engines equipped with TJI systems show unusual combustion development and knock onset.In this study a methodology for the 3D-CFD modelling of combustion and knock onset risk was developed for a high-performance turbocharged engine featuring a passive TJI system. First, a comprehensive numerical study was carried out in a commercially available software, CONVERGE 2.4, in order to develop a 3D-CFD model able to reproduce the available experimental data. The resulting 3D-CFD model was then validated on different working conditions featuring different spark advances. Lastly, a methodology for the assessment of knock onset risk was developed, which led to the definition of two novel knock-risk indexes based on the progress of chemical reactions within the combustion chamber. The proposed knock-risk indexes showed good agreement with the experimental data.

Performance and Emission Characterization of Adjustable Cylinder Head Type Variable Compression Ratio in Two-Stroke SI Engine

A lot of technologies have been introduced to retain the petrol engines which exhibit a lot of drawbacks based on emissions and knocking. Variable compression ratio (VCR) technology is applied in the line of SI engines for a long period to give back the standards. This paper is going to analyze and experiment on a commercially available type of VCR technologies. The investigation can provide a great method of varying the compression ratio that is put forth, practically analyzed, and previewed with a change from the previous paper and taken to an account to restrict the compression ratio of +/-1.5. In this analysis, we use the same technology as commercially used two-stroke engines but the clearance volume is changed and introduces a metallic bung on the burning chamber. We have performed the test by varying the compression ratios to more or less than two from the original compression ratio. At lesser weight conditions, a low compression ratio is maintained throughout the experiment to boost up the turbocharger to get a better amount of volumetric efficiency without any trouble. The engine is tested at various compression ratios for the performance study and emissions from the power source at various load conditions. While adopting this method in commercial, we can achieve a potentially higher fuel economy, more power, lower emission compared to other available technologies in ongoing research.

The Effect of Using LPG in a SI engine instead of using Gasoline fuel

The fossil fuels used in internal combustion engines are among the largest contributors to environmental degradation, and this fuel has a high economic cost, so the need to use alternative fuels with less environmental impact and less cost-effective cost. Therefore, researchers resorted to using different kinds of alternative fuels, including liquefied petroleum gas. This study provides a practical study comparing the use of LPG and gasoline in terms of performance and emissions from the four-stroke spark ignition, single cylinder, air cooled with a constant pressure ratio and variable-speed 1500–2500 rpm. A difference in volume efficiency, the brake thermal efficiency, fuel consumption and emissions of gases (HC, NOx, CO2, CO) has been measured that results have shown improved fuel consumption and thermal efficiency when using LPG fuel compared to pure gasoline. In contrast, the volume efficiency showed negative results when using LPG. the results also showed an improvement in LPG emissions in HC, NOx, CO2, CO with the use of LPG.

Simplified algorithm for determining injection duration to achieve fast response in SI engines

For modern SI engines, the injection duration and its timing are one of the most important parameters which influence the mixture homogeneity, emissions, combustion efficiency, and engine response. In the present work, a simplified port fuel injection system with its driver algorithms was designed to control the injection duration and its timing. The Calibrated Dose method is used in this system instead of the stream mixing method. Therefore, the injected fuel mass is accurately computed according to the engine load, engine speed, engine operating condition, and the amount of air drawn into the engine. The system consists of a conventional port fuel injection system equipped with a micro-controller, a Throttle Position Sensor (TPS), a couple of Hall Effect Sensors (HES), load cell with its driver module, injector controller circuit, and a custom-made inlet port. The micro-controller is used to calculate the injection duration each engine cycle according to engine speed, amount of air drawn per cycle and engine load. The two HES are used to detect the injection timing and measure the engine speed. The TPS is used to monitor the throttle position angle so it can calculate the amount of air drawn into the engine at that time with respect to engine speed. The load cell and its driver module are used to measure the engine torque and consequently the brake power. The injector controller circuit is used to initiate the injection process at the perfect timing for the accurate duration.

Experimental investigation on a two stroke SI engine to optimize fuel consumption through electronic ignition

Two stroke spark ignition engines are characterized by simplicity in construction, a higher power and lower maintenance cost. However, the main, disadvantages are high specific fuel consumption, excessive exhaust emission of hydrocarbon monoxide. Great deal of research work is going all over the world to find an effective solution to the growing problem of environmental pollution and fuel conservation of gasoline powered 2-stroke S.I. Engine. Fuel conservation and environmental pollution are directly influenced by the characteristics of the combustion process. For an S.I. Engine spark is the source of ignition and combustion of the air fuel mixture inside the cylinder. Hence, the spark timings of an S.I. Engines have a significant effect on the fuel consumption and exhaust pollution. In the present work, the electronic spark timing unit was employed to vary the spark ignition timing and the engine performance was investigated.

P.857Cognitive reserve in child and adolescent offspring of patients diagnosed with schizophrenia or bipolar disorder

This study was conducted to investigate PM emissions and performance of SI engines fueled with butanol-methanol-gasoline during air dilution operation. Iso-butanol and methanol were blended with gasoline at volume concentrations of up to 40% (10, 20 vol% iso-butanol and methanol, respectively). The effects of lean mixture on engine performance and PM emissions with blends were investigated to find that the power performance of blended fuels is comparable to that of gasoline. High-proportion blends also showed higher brake thermal efficiency (BTE) than gasoline. The brake specific fuel consumption (BSFC) of blends was also about 10% higher than that of gasoline under stoichiometric conditions; with a lean mixture, a reduction of about 9% in the BSFC of blends was observed. The combustion stability of the blends was reduced relative to that of gasoline. CO emissions from the blends decreased rapidly as the mixture became leaner. The NOx emissions of blended fuels were about 30–50% lower than that of gasoline (lambda >1.15) and decreased rapidly as the mixture grew leaner – a reduction of up to 80% was observed. However, when the excess air ratio was less than 1.15, the NOx emissions were about 30% higher than that of gasoline. The increasing BTE trend of blended fuels was similar to that of gasoline as the load increased. A significant reduction in PM concentration was observed during lean mixture operation, which was further reduced with blended fuels. Reduction of accumulation mode particle was more pronounced for blended fuels relative to nucleation mode particles. The total surface area concentration markedly decreased due to a reduction in particle diameter and total concentration. These results altogether suggest that lean mixture reduces PM emissions of blends and improves BTE; n-butanol/methanol addition also contributed to higher BTE and lower gaseous and PM emissions.

Optimization of combustion and performance parameters by intake-charge conditions in a small-scale air-cooled hydrogen fuelled SI engine suitable for use in piston-prop aircraft

Purpose Spark ignition (SI) engines are used in a wide area in the transportation industry, from road vehicles to piston-prop aircraft. On the other hand, the decrease in reserves of fossil fuels used in SI engines and the increase in greenhouse gas emissions makes the use of alternative fuels inevitable. In this paper, optimization of in-cylinder combustion and engine performance parameters by intake-charge conditions [i.e. intake-air temperature, injection timing and exhaust gas recirculation (EGR)] in a hydrogen (H2)-fueled small SI engine is performed. Design/methodology/approach Experimental studies were performed at a 1,600 rpm engine speed of a single-cylinder, air-cooled engine having a stroke volume of 476.5 cm3, maximum output power of 13 HP and torque of 25 Nm. The hydrogen-fueled SI engine was operated by a lean air-fuel mixture (ϕ = 0.6) under wide-open throttle (WOT) conditions. Findings The findings of the paper show that improvements can be achieved in in-cylinder combustion, indicated engine performance, exhaust NOx emissions with optimum intake-air temperature, the start of H2 injection and the ERG rate. Practical Implications It has been determined that a 32°C intake-air temperature, 395°C (bTDC) start of H2 injection, and 5%–10% EGR rates are the most suitable values for the examined hydrogen fueled SI engine. Originality Value Hydrogen is a usable alternative fuel for SI engines used in a wide area from road vehicles to piston-prop aircraft engines. However, a number of problems remain that limit hydrogen fueled SI engines to some extent, such as backfire, a decrease of engine power, and high NOx emissions. Therefore, it is appropriate to examine the effects of intake-charge conditions on in-cylinder combustion, engine performance, and NOx emissions parameters in a hydrogen fuelled SI engine.

Individual Cylinder Combustion Optimization to Improve Performance and Fuel Consumption of a Small Turbocharged SI Engine

Stringent exhaust emission and fuel consumption regulations impose the need for new solutions for further development of internal combustion engines. With this in mind, a refined control of the combustion process in each cylinder can represent a useful and affordable way to limit cycle-to-cycle and cylinder-to-cylinder variation reducing CO2 emission. In this paper, a twin-cylinder turbocharged Port Fuel Injection–Spark Ignition engine is experimentally and numerically characterized under different operating conditions in order to investigate the influence of cycle-to-cycle variation and cylinder-to-cylinder variability on the combustion and performance. Significant differences in the combustion behavior between cylinders were found, mainly due to a non-uniform effective in-cylinder air/fuel (A/F) ratio. For each cylinder, the coefficients of variation (CoVs) of selected combustion parameters are used to quantify the cyclic dispersion. Experimental-derived CoV correlations representative of the engine behavior are developed, validated against the measurements in various speed/load points and then coupled to an advanced 1D model of the whole engine. The latter is employed to reproduce the experimental findings, taking into account the effects of cycle-to-cycle variation. Once validated, the whole model is applied to optimize single cylinder operation, mainly acting on the spark timing and fuel injection, with the aim to reduce the specific fuel consumption and cyclic dispersion.

A Numeral Simulation Determining Optimal Ignition Timing Advance of SI Engines Using 2.5-Dimethylfuran-Gasoline Blends

Today, humans are dealing with two urgent issues: energy security and environmental pollution and finding sources to replace traditional fuels such as gasoline and diesel that are part of human interest. Lignocellulose biomass can be obtained through a variety of basic chemicals or intermediates that generate energy, such as ethanol, butanol, and dimethylfuran. 2.5-dimethylfuran (DMF) is considered a potential alternative fuel because it is a water-insoluble substance used as an additive mixed with gasoline fuel. Formerly, there have been many studies on combustion engines and emissions properties using the DMF-gasoline blend, especially SI engines. However, there has been no published research about the optimal ignition timing advance of SI engines when using these blends. This paper present how to determine the optimal ignition timing advance of SI engines using DMF-gasoline combinations with AVL-Boost simulation software. The simulation conditions were set up at 50% load, and speed at 2500 and 3000 rpm using blends are DMF20, DMF30, and DMF40 (corresponding with the DMF ratio in DMF-gasoline blends is 20%, 30%, and 40% in volume). The simulation result shows that the optimal ignition timing advance of SI engines using DMF-gasoline blends at a 2500 and 3500 rpm speed corresponding with 23 and 31 crank angle degrees (CAD) (reduce 2CAD compare to when using pure gasoline). At these optimal ignition timing advances, the power engine, torque, and thermal efficiency (BTE) reach its maximum value, while the fuel consumption rate is also lowest.

Large-eddy simulations of a stratified-charge direct-injection spark-ignition engine: Comparison with experiment and analysis of cycle-to-cycle variations

Multiple-cycle large-eddy simulations (LES) have been performed for an optically accessible, single-cylinder, four-stroke-cycle, spray-guided direct-injection spark-ignition (SG-DISI) engine operating in a stratified globally fuel-lean mode. The simulations combine a standard Smagorinsky turbulence model, a stochastic Lagrangian parcel method for liquid fuel injection and fuel spray modeling, a simple energy-deposition spark-ignition model, and a modified thickened flame model for turbulent flame propagation through highly stratified reactant mixtures. Comparisons between simulations and experiments include individual-cycle and ensemble-average pressure and apparent-heat-release-rate traces, individual-cycle and ensemble-average indicated mean effective pressures (IMEP), and instantaneous two-dimensional vapor-equivalence-ratio contours. Although the number of LES cycles is small (35), the results show that the simulations are able to capture the global combustion behavior that is observed in the experiments, including cycle-to-cycle variations. The simulation results are then analyzed further to provide insight into the conditions that lead to misfire versus robust combustion. As has been reported in earlier experimental and LES studies for homogeneous-charge SI engines, local conditions in the vicinity of the spark gap at the time of ignition largely determine the subsequent flame development. However, in contrast to homogeneous-charge engines, no single local or global quantity correlates as strongly with the eventual peak pressure or IMEP for each cycle. Rather, it is the interplay among the early flame kernel, the velocity field that it experiences, and the fuel distribution that it encounters that ultimately determines the fate of each combustion event. Deeper analysis and quantitative statistical comparisons between experiments and simulations will require the simulation of larger numbers of engine cycles.

An evaluation based on energy and exergy analyses in SI engine fueled with waste bread bioethanol-gasoline blends

In this study, the operation of a single cylinder, four stroke, SI engine powered by fuels created by blending two different bioethanol with gasoline was evaluated on the basis of energy and exergy analyses. Within the scope of the study, test engine was tested by operating it with fuel blends, prepared by adding both bioethanol, one of them was produced from waste bread and the other, originating from sugar beet, was supplied, to gasoline at different rates by of 5, 10, 15, 85 and 100% under five different engine loads at maximum torque speed, 2500 rpm. The variation of energy and exergy parameters was examined by comparing the blends, prepared to have similar volumetric content, each other and by comparing all with gasoline. As a result of the study, it was determined that the addition of bioethanol had generally decreasing effect on energy loss rate, exergy loss rate and exergy destruction rate. For fuel blends containing low levels of bioethanol, variation of ethanol has created little differences on all energy and exergy parameters but bioethanol type clearly showed its effect when bioethanol rate increased to 85% and 100%. Although waste bread bioethanol could not catch sugar beet bioethanol in terms of thermal efficiency (14.4% for E100b and 16.4% for E100 as load average) and exergetic efficiency (12.9% for E100b and 14.7% for E100 as load average), both bioethanol have been found to improve both thermal efficiency (12.2% for E0) and exergetic efficiency (11.4% for E0) than that of gasoline.

Effects of hydrogen direct injection on combustion and emission characteristics of a hydrogen/Acetone-Butanol-Ethanol dual-fuel spark ignition engine under lean-burn conditions

Acetone-Butanol-Ethanol (ABE) is an essential product in the production process of butanol, which is considered as an effective way to replace butanol used in engines because of the lower production cost of ABE. Hydrogen is an ideal fuel for engines because of its low ignition energy and high flame propagation speed. In this study, the effects of hydrogen addition on the combustion and emission characteristics of a spark ignition ABE engine under lean-burn conditions are investigated. Specifically, five hydrogen blending ratios (0, 5%, 10%, 15%, 20%) and three λ values (1, 1.1, 1.2) are studied. The results show that adding hydrogen can increase the maximum cylinder temperature and pressure, decrease the flame development and propagation duration of the hydrogen/ABE dual-fuel SI engine. In addition, hydrogen addition can reduce the COVIMEP, BSFC, CO, HC emissions, and improve the IMEP, but increase NOx emissions; however, a lower NOx emissions for the hydrogen/ABE engine working under learn-burn conditions (λ equals 1.2) can be achieved with a suitable proportion of hydrogen adding (proportion = 5%) than that of engine working under stoichiometric air-fuel ratio condition. Thus, hydrogen addition can facilitate the combustion of ABE in engines, especially under lean-burn conditions.

Comparative study on effects of injection mode on combustion and emission characteristics of a combined injection n-butanol/gasoline SI engine with hydrogen direct injection

In this paper, on the basis of combined injection technique, three injection modes with five n-butanol/gasoline volume ratios (νN) were put forward, aiming to compare and evaluate the relationship between the injection mode and the combustion and emission characteristics of an n-butanol/gasoline SI engine equipped with an extra hydrogen direct injection system. The results indicated that under low load condition, compared with NGP (n-butanol/gasoline port injection) mode, the NGPD (n-butanol/gasoline combined injection) mode and NGPH (n-butanol/gasoline with hydrogen combined injection) mode can both improve the combustion performance. The peak cylinder pressure of NGPD and NGPH mode was 5.58% and 11.63% higher than that of NGP mode on average, respectively. Furthermore, the combined injection modes concentrated the process of heat release, shortened the combustion duration, increased the power performance and improved the combustion stability at all νN. As for emissions, the NGPD and NGPH combined modes significantly decreased the HC and CO emissions, but increased the NOX emissions. Among all the test conditions, the NGPH mode with 25% νN obtained the best combustion quality. Additionally, the effect rules of νN on combustion and emission characteristics under NGP mode were found to be consistent with those under NGPD and NGPH combined modes.

Experimental Study on an Si Engine Fuelled by LPG/Acetylene Mixtures

In the current time, sustainability and development of internal combustion engines is subjected to two kinds of threats which are fossil fuel depletion and environmental pollution. So, considerable efforts in the world have been exerted to develop and introduce alternative gaseous fuels to replace conventional fuel by partial or total replacement. In this study, the effect of adding acetylene to LPG-fuelled SI engine has been examined. This addition was with flow rates of 500, 750 and 1000 g/h for 25 % load and 1000 g/h for 50 % load, respectively. An experimental investigation has been carried out on 4 stroke, 4- cylinder, water-cooled spark ignition (SI) engine at constant speed (1500 rpm). Also, performance and emissions parameters have been tested at different excess air coefficients (λ = 0.8, 1, 1.2 and 1.7). As a result, it has been found optimum conditions which are the addition of 750 g/h acetylene for 25 % load (almost 41 % of the LPG-acetylene mixture at λ = 1.2) and 1000 g/h for 50 % load (almost 36 % of the LPG-acetylene mixture at λ = 1.5). In addition, hydrocarbon (HC) and carbon monoxide (CO) emissions decreased, while NO emissions increased when compared to that of baseline LPG operation.

Specific Soft Computing Strategies for Evaluating the Performance and Emissions of an SI Engine Using Alcohol-Gasoline Blended Fuels—A Comprehensive Analysis

The huge fossil fuel consumption has created an unprecedented situation and, with the accompanying rise in car numbers, pollution levels have been well beyond human control. This is alarming enough to note that the level of pollution has surpassed all levels and the need for the hour is to find an alternative fuel that can really be of great help in reducing exhaust emissions and that efficiency. Experiments performed on S.I engine are considered to be time-consuming and the expenses met to perform these experiments are too costly, so the need of soft computing techniques involved in this area. Soft computing has shown a great deal of potential in providing researchers with the exact solution that could be used to validate or predict performance and emission parameters. The different software computing methods are widely used, includes the Adaptive Neuro Fuzzy Inference System (ANFIS), the Artificial Neural Network (ANN), the Fuzzy Expert System (FES), Response Surface Methodology (RSM) and Support Vector Machine (SVM). The one and only objective of this effort is to bring out the comprehensive review of various researchers who have carried out the work on soft computing techniques on S.I engines with a variety of alternative fuels.

Analysis of performance, emission, combustion and endoscopic visualization of micro-arc oxidation piston coated SI engine fuelled with low carbon biofuel blends

The low carbon biofuel (pine oil) derived from the pine tree is endowed with enhanced fuel properties with good octane rating and can be used for SI engine applications. In order to operate pine oil blends with improved fuel efficiency, engine design modification is required. This work investigates the change reflected on the engine characteristics of the port fuelled SI engine due to a thin thermal barrier coating layer formed on the piston crown using the Micro-arc oxidation technique. Furthermore, an endoscopic visualization technique was adopted to compare the combustion flames of uncoated and coated piston engines fuelled with pine oil blends. The coated piston engine fuelled by pine oil blends displayed improved peak in-cylinder pressure and heat release rate. Among the pine oil blends, P20 (20% pine oil + 80% gasoline) blend showed superior engine characteristics at all engine load conditions. The brake thermal efficiency of the coated piston engine fuelled with the P20 blend was improved by 1.8% compared to the uncoated piston fuelled with gasoline. With the P20 blend, the CO, HC emissions were decreased by 8% and 14% respectively and NO emission was increased by 19% for coated piston when compared to gasoline with an uncoated piston engine.

Closed Loop Control of the Combustion Phase in SI Engines Using Alternative Fuels

<div class="section abstract"><div class="htmlview paragraph">Combustion engines using alternative and/or renewable fuels are vital to reduce emission of greenhouse gases. The property of such fuels may vary significantly. The heat release rate of bio and natural gas varies of natural reasons, which is known to cause problems when used in internal combustion engines. Hydrogen is an attractive renewable fuel that has a high potential to reduce greenhouse gas emission. Bio and natural gas can be mixed with hydrogen and the content may vary depending on the availability, e.g., depending on the production from solar and wind power. Variations in the fuel property reduces the engine efficiency, unless the combustion phase is estimated and the ignition (combustion) timing is adapted to compensate for the varying fuel property. Hereby the drivability can be improved, and the fuel consumption decreased significantly, reducing the total cost of ownership and emission of greenhouse gases. However, there is not yet any widespread industrially available technique to estimate the combustion phase. In-cylinder pressure measurement is not a practical solution due to cost and life-time issues. Here, a strategy for ion current measurement signal processing is proposed as a viable alternative to in cylinder pressure sensors by estimating the peak pressure location (PPL) from the ion current. The PPL estimate meets the robustness requirements of industrial applications. The approach is described and evaluated on engine measurements. The results show that ion sense can be used for PPL estimation and the standard deviation from one estimate to another is in the order of 1-2 CAD, which can be further reduced by averaging. The PPL estimates can be used in a closed control loop to compensate the ignition timing when the fuel property varies - saving cost and reducing greenhouse gas emission.</div></div>

The Effects of EGR Composition on Combustion Performance and Efficiency

<div class="section abstract"><div class="htmlview paragraph">Because of the thermodynamic relationship of pressure, temperature and volume for processes which occur in an internal-combustion engine (ICE), and their relationship to ideal efficiency and efficiency-limiting phenomena e.g. knock in spark-ignition engines, changing the thermo-chemical properties of the in-cylinder charge should be considered as an increment in the development of the ICE engine for future efficiency improvements. Exhaust gas recirculation (EGR) in spark-ignited gasoline engines is one increment that has been made to alter the in-cylinder charge. EGR gives proven thermal efficiency benefits for SI engines which improve vehicle fuel economy, as demonstrated through literature and production applications. The thermal efficiency benefit of EGR is due to lower in-cylinder temperatures, reduced heat transfer and reduced pumping losses. The next major increment could be modifying the constituents of the EGR stream, potentially through the means of a membrane. By doing so, this can change both the chemical and thermodynamic properties of the in-cylinder gas mixture and therefore have an impact on combustion and efficiency. This study evaluated conventional EGR, CO<sub>2</sub>-only and N<sub>2</sub>-only EGR on a single-cylinder engine under non-knocking and knock limited conditions. Overall, this study demonstrated the impacts of CO<sub>2</sub>-only and CO<sub>2</sub>-reduced EGR on efficiency, combustion stability, burn rate, knock abatement and compression ratio on a single-cylinder engine. Through analysis with Chemkin and GT-Power, it also sought to explain the behaviors observed.</div></div>

Advanced Intra-Cycle Detection of Pre-Ignition Events through Phase-Space Transforms of Cylinder Pressure Data

<div class="section abstract"><div class="htmlview paragraph">The widespread adoption of boosted, downsized SI engines has brought pre-ignition phenomena into greater focus, as the knock events resulting from pre-ignitions can cause significant hardware damage. Much attention has been given to understanding the causes of pre-ignition and identify lubricant or fuel properties and engine design and calibration considerations that impact its frequency. This helps to shift the pre-ignition limit to higher specific loads and allow further downsizing but does not fundamentally eliminate the problem. Real-time detection and mitigation of pre-ignition would thus be desirable to allow safe engine operation in pre-ignition-prone conditions. This study focuses on advancing the time of detection of pre-ignition in an engine cycle where it occurs. Phase space transforms through time-delay embedding of cylinder pressure and principal component analysis were applied to same-cycle detection of pre-ignition and shown to enable detection on the order of a crank degree earlier than deviation in cylinder pressure can be identified through direct statistical observation of the pressure data. Additionally, it appears that the deviation of the trajectory in phase space may offer the opportunity to extend this method to further extend the detection window and allow more time for mitigation actions to occur.</div></div>