A Statistical Approach to Spark Advance Mapping

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Enrico Corti ◽  
Claudio Forte
Keyword(s):  
Steady State ◽  
Combustion Process ◽  
Maximum Amplitude ◽  
Operating Conditions ◽  
Effective Control ◽  
Angular Coefficient ◽  
Effective Pressure ◽  
Mean Values ◽  
Cycle Variation ◽  
Brake Mean Effective Pressure

Engine performance and efficiency are largely influenced by combustion phasing. Operating conditions and control settings influence the combustion development over the crankshaft angle; the most effective control parameter used by electronic control units to optimize the combustion process for spark ignition engines is spark advance (SA). SA mapping is a time-consuming process, usually carried out with the engine running in steady state on the test bench, changing SA values while monitoring brake mean effective pressure, indicated mean effective pressure (IMEP), and brake specific fuel consumption (BSFC). Mean values of IMEP and BSFC for a test carried out with a given SA setting are considered as the parameters to optimize. However, the effect of SA on IMEP and BSFC is not deterministic, due to the cycle-to-cycle variation; the analysis of mean values requires many engine cycles to be significant of the performance obtained with the given control setting. Finally, other elements such as engine or components aging, and disturbances like air-to-fuel ratio or air, water, and oil temperature variations could affect the tests results; this facet can be very significant for racing engine testing. This paper presents a novel approach to SA mapping with the objective of improving the performance analysis robustness while reducing the test time. The methodology is based on the observation that, for a given running condition, IMEP can be considered a function of the combustion phasing, represented by the 50% mass fraction burned (MFB50) parameter. Due to cycle-to-cycle variation, many different MFB50 and IMEP values are obtained during a steady state test carried out with constant SA. While MFB50 and IMEP absolute values are influenced by disturbance factors, the relationship between them holds, and it can be synthesized by means of the angular coefficient of the tangent line to the MFB50-IMEP distribution. The angular coefficient variations as a function of SA can be used to feed a SA controller, able to maintain the optimal combustion phasing. Similarly, knock detection is approached by evaluating two indexes; the distribution of a typical knock-sensitive parameter (maximum amplitude of pressure oscillations) is related to that of CHRNET (net cumulative heat release), determining a robust knock index. A knock limiter controller can then be added in order to restrict the SA range to safe values. The methodology can be implemented in real time combustion controllers; the algorithms have been applied offline to sampled data, showing the feasibility of fast and robust automatic mapping procedures.

A Statistical Approach to Spark Advance Mapping

2009 ◽  
Author(s):  
Enrico Corti ◽  
Claudio Forte
Keyword(s):  
Steady State ◽  
Combustion Process ◽  
Maximum Amplitude ◽  
Operating Conditions ◽  
Effective Control ◽  
Test Time ◽  
Angular Coefficient ◽  
Sampled Data ◽  
Mean Values ◽  
Cycle Variation

Engines performance and efficiency are largely influenced by the combustion phasing. Operating conditions and control settings influence the combustion development over the crankshaft angle: the most effective control parameter used by Electronic Control Units (ECU) to optimize the combustion process for Spark Ignition (SI) engines is Spark Advance (SA). SA mapping is a time-consuming process, usually carried out with the engine running in steady state on the test bench, changing SA values while monitoring Brake and Indicated Mean Effective Pressure (BMEP, IMEP) and Brake Specific Fuel Consumption (BSFC). Mean values of IMEP and BSFC for a test carried out with a given SA setting are considered as the parameters to optimize. However, the effect of SA on IMEP and BSFC is not deterministic, due to the cycle-to-cycle variation: the analysis of mean values requires many engine cycles to be significant of the performance obtained with the given control setting. Finally other elements, such as engine or components ageing, and disturbances like Air-to-Fuel Ratio (AFR) or air, water and oil temperature variations, could affect the tests results: this facet can be very significant for racing engines testing. This paper presents a novel approach to SA mapping, with the objective of improving the performance analysis robustness, while reducing the test time. The methodology is based on the observation that, for a given running condition, IMEP can be considered a function of the combustion phasing, represented by the 50% Mass Fraction Burned (MFB50) parameter. Due to cycle-to-cycle variation, many different MFB50 and IMEP values are obtained during a steady state test carried out with constant SA. While MFB50 and IMEP absolute values are influenced by disturbance factors, the relationship between them holds, and it can be synthesized by means of the angular coefficient of the tangent line to the MFB50-IMEP distribution. The angular coefficient variations as a function of SA can be used to feed a SA controller, able to maintain the optimal combustion phasing. Similarly, knock detection is approached by evaluating two indexes: the distribution of a typical knock-sensitive parameter (MAPO, Maximum Amplitude of Pressure Oscillations) is related to that of CHRNET (net Cumulative Heat Release), determining a robust knock index. A knock limiter controller can then be added, in order to restrict the SA range to safe values. The methodology can be implemented in real-time combustion controllers: the algorithms have been applied offline to sampled data, showing the feasibility of fast and robust automatic mapping procedures.

scholarly journals Predicting Cycle-to-Cycle Variation With Concurrent Cycles in a Gasoline Direct Injected Engine With Large Eddy Simulations

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Daniel M. Probst ◽  
Sameera Wijeyakulasuriya ◽  
Eric Pomraning ◽  
Janardhan Kodavasal ◽  
Riccardo Scarcelli ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Engine Performance ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Effective Pressure ◽  
Cycle Variation ◽  
Brake Mean Effective Pressure ◽  
Large Eddy ◽  
Operating Points

Abstract High cycle-to-cycle variation (CCV) is detrimental to engine performance, as it leads to poor combustion and high noise and vibration. In this work, CCV in a gasoline engine is studied using large eddy simulation (LES). The engine chosen as the basis of this work is a single-cylinder gasoline direct injection (GDI) research engine. Two stoichiometric part-load engine operating points (6 brake mean effective pressure (BMEP) and 2000 revolutions per minute) were evaluated: a nondilute (0% exhaust gas recirculation (EGR)) case and a dilute (18% EGR) case. The experimental data for both operating conditions had 500 cycles. The measured CCV in indicated mean effective pressure (IMEP) was 1.40% for the nondilute case and 7.78% for the dilute case. To estimate CCV from simulation, perturbed concurrent cycles of engine simulations were compared with consecutively obtained engine cycles. The motivation behind this is that running consecutive cycles to estimate CCV is quite time consuming. For example, running 100 consecutive cycles requires 2–3 months (on a typical cluster); however, by running concurrently, one can potentially run all 100 cycles at the same time and reduce the overall turnaround time for 100 cycles to the time taken for a single cycle (2 days). The goal of this paper is to statistically determine if concurrent cycles, with a perturbation applied to each individual cycle at the start, can be representative of consecutively obtained cycles and accurately estimate CCV. 100 cycles were run for each case to obtain statistically valid results. The concurrent cycles began at different timings before the combustion event, with the motivation to identify the closest time before spark to minimize the run time. Only a single combustion cycle was run for each concurrent case. The calculated standard deviation of peak pressure and coefficient of variance (COV) of IMEP were compared between the consecutive and concurrent methods to quantify CCV. It was found that the concurrent method could be used to predict CCV with either a velocity or numerical perturbation. Both a large and small velocity perturbations were compared, and both produced correct predictions, implying that the type of perturbation is not important to yield a valid realization. Starting the simulation too close to the combustion event, at intake valve close (IVC) or at spark timing, underpredicted the CCV. When concurrent simulations were initiated during or before the intake even, at start of injection (SOI) or earlier, distinct and valid realizations were obtained to accurately predict CCV for both operating points. By simulating CCV with concurrent cycles, the required wall clock time can be reduced from 2–3 months to 1–2 days. In addition, the required core-hours can be reduced up to 41%, since only a portion of each cycle needs to be simulated.

scholarly journals Comparison of Physics-Based, Semi-empirical and Neural Network-based Models for Model-based Combustion Control in a 3.0 L Diesel Engine

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3423 ◽  
Author(s):  
Hu ◽  
d’Ambrosio ◽  
Finesso ◽  
Manelli ◽  
Marzano ◽  
...  
Keyword(s):  
Neural Network ◽  
Steady State ◽  
Diesel Engine ◽  
Effective Pressure ◽  
Combustion Control ◽  
Ann Model ◽  
Control Applications ◽  
Model Based ◽  
Brake Mean Effective Pressure ◽  
Semi Empirical

A comparison of four different control-oriented models has been carried out in this paper for the simulation of the main combustion metrics in diesel engines, i.e., combustion phasing, peak firing pressure, and brake mean effective pressure. The aim of the investigation has been to understand the potential of each approach in view of their implementation in the engine control unit (ECU) for onboard combustion control applications. The four developed control-oriented models, namely the baseline physics-based model, the artificial neural network (ANN) physics-based model, the semi-empirical model, and direct ANN model, have been assessed and compared under steady-state conditions and over the Worldwide Harmonized Heavy-duty Transient Cycle (WHTC) for a Euro VI FPT F1C 3.0 L diesel engine. Moreover, a new procedure has been introduced for the selection of the input parameters. The direct ANN model has shown the best accuracy in the estimation of the combustion metrics under both steady-state/transient operating conditions, since the root mean square errors are of the order of 0.25/1.1 deg, 0.85/9.6 bar, and 0.071/0.7 bar for combustion phasing, peak firing pressure, and brake mean effective pressure, respectively. Moreover, it requires the least computational time, that is, less than 50 s when the model is run on a rapid prototyping device. Therefore, it can be considered the best candidate for model-based combustion control applications.

Influence of Diesel Fuel Injection Characteristics on Dual-Fuel Combustion Modes in a Large-Bore, Medium-Speed Engine

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Adam Klingbeil ◽  
Seunghyuck Hong ◽  
Roy J. Primus
Keyword(s):  
Diesel Fuel ◽  
Combustion Process ◽  
Operating Conditions ◽  
Critical Parameters ◽  
Dual Fuel ◽  
Injection Timing ◽  
Analytical Methodology ◽  
Cycle Variation ◽  
Medium Speed ◽  
Substitution Ratio

Abstract Experiments were conducted on a large bore, medium speed, single cylinder, diesel engine to investigate operation with substitution ratio of natural gas (NG) varying from 0% to 93% by energy. In a previous study by the same group, these data were used to validate an analytical methodology for predicting performance and emissions under a broad spectrum of energy substitution ratios. For this paper, these experimental data are further analyzed to better understand the performance and combustion behavior under NG substitution ratios of 0%, 60%, and 93%. These results show that by transitioning from diesel-only to 60% dual-fuel (DF) (60% NG substitution ratio), an improvement in the NOx-efficiency trade-off was observed that represented a ∼3% improvement in indicated efficiency at constant NOx. Further, the transition from 60% DF to 93% DF (93% NG substitution ratio) resulted in additional efficiency improvement with a simultaneous reduction in NOx emissions. The data suggest that this improvement can be attributed to the premixed nature of the high substitution ratio case. Furthermore, the results show that high cycle-to-cycle variation was observed for some 93% DF combustion tests. Further analysis, along with diesel injection rate measurements, shows that the observed extreme sensitivity of the combustion event can be attributed to critical parameters such as diesel fuel quantity and injection timing. These results suggest a better understanding of the relative importance of combustion system components and operating conditions in controlling cycle-to-cycle variation of combustion process.

Effects of EGR and Boost Pressure on Reactivity Controlled Compression Ignition (RCCI) Engine at High Load Operating Conditions

2014 ◽  
Author(s):  
Yifeng Wu ◽  
Rolf D. Reitz
Keyword(s):  
Peak Pressure ◽  
Pressure Rise ◽  
High Load ◽  
Operating Conditions ◽  
Boost Pressure ◽  
Compression Ignition ◽  
Effective Pressure ◽  
Reactivity Controlled Compression Ignition ◽  
Brake Mean Effective Pressure ◽  
Diesel Injection

Reactivity Controlled Compression Ignition (RCCI) at engine high load operating conditions is investigated in this study. The effects of EGR and boost pressure on RCCI combustion were studied by using a multi-dimensional computational fluid dynamics (CFD) code. The model was first compared with a previous CFD model, which has been validated against steady-state experimental data of gasoline-diesel RCCI in a multi-cylinder light duty engine. An RCCI piston with a compression ratio of 15:1 was then proposed to improve the combustion and emissions at high load. The simulation results showed that 18 bar indicated mean effective pressure (IMEP) could be achieved with gasoline-diesel RCCI at an EGR rate of 35 % and equivalence ratio of 0.96, while the peak pressure rise rate (PPRR) and engine combustion efficiency could both be controlled at reasonable levels. Simulations using both early and late direct-injection (DI) of diesel fuel showed that RCCI combustion at high load is very sensitive to variations of the exhaust gas recirculation (EGR) amount. Higher IMEP is obtained by using early diesel injection, and it is less sensitive to EGR variation compared to late diesel injection. Reduced unburned hydrocarbon (HC), carbon monoxide (CO), soot and slightly more nitrogen oxides (NOx) emissions were seen for early diesel injection. HC, CO and soot emissions were found to be more sensitive to EGR variation at late diesel injection timings. However, there was little difference in terms of peak pressure, efficiencies, PPRR and phasing under varying EGR rates. The effect of boost pressure on RCCI at high load operating conditions was also studied at different EGR rates. It was found that combustion and emissions were improved, and the sensitivity of the combustion and emission to EGR was reduced with higher boost pressures. In addition, cases with similar combustion phasing and reasonable PPRR were analyzed by using an experimentally validated GT-Power model. The results indicated that although higher IMEP was generated at higher boost pressures, the brake mean effective pressure (BMEP) was similar compared to that obtained with lower boost pressures due to higher pumping losses.

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

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5548
Author(s):  
Luca Marchitto ◽  
Cinzia Tornatore ◽  
Luigi Teodosio
Keyword(s):  
Fuel Consumption ◽  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Exhaust Emission ◽  
Cycle Variation ◽  
Spark Timing ◽  
Experimental Findings

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.

scholarly journals An experimental study of the combusition and emission performances of 2,5-dimethylfuran diesel blends on a diesel engine

2017 ◽  
Vol 21 (1 Part B) ◽  
pp. 543-553 ◽  
Author(s):  
Helin Xiao ◽  
Pengfei Zeng ◽  
Liangrui Zhao ◽  
Zhongzhao Li ◽  
Xiaowei Fu
Keyword(s):  
Diesel Engine ◽  
Diesel Fuel ◽  
Direct Injection ◽  
Operating Conditions ◽  
Effective Pressure ◽  
Compression Ignition Engine ◽  
Brake Mean Effective Pressure ◽  
Combustion Duration ◽  
Significant Difference ◽  
Hc Emissions

Experiments were carried out in a direct injection compression ignition engine fueled with diesel-dimethylfuran blends. The combustion and emission performances of diesel-dimethylfuran blends were investigated under various loads ranging from 0.13 to 1.13 MPa brake mean effective pressure, and a constant speed of 1800 rpm. Results indicate that diesel-dimethylfuran blends have different combustion performance and produce longer ignition delay and shorter combustion duration compared with pure diesel. Moreover, a slight increase of brake specific fuel consumption and brake thermal efficiency occurs when a Diesel engine operates with blended fuels, rather than diesel fuel. Diesel-dimethylfuran blends could lead to higher NOx emissions at medium and high engine loads. However, there is a significant reduction in soot emission when engines are fueled with diesel-dimethylfuran blends. Soot emissions under each operating conditions are similar and close to zero except for D40 at 0.13 MPa brake mean effective pressure. The total number and mean geometric diameter of emitted particles from diesel-dimethylfuran blends are lower than pure diesel. The tested fuels exhibit no significant difference in either CO or HC emissions at medium and high engine loads. Nevertheless, diesel fuel produces the lowest CO emission and higher HC emission at low loads of 0.13 to 0.38 MPa brake mean effective pressure.

Deep learning procedure for knock, performance and emission prediction at steady-state condition of a gasoline engine

2020 ◽  
Vol 234 (14) ◽  
pp. 3347-3361
Author(s):  
Seunghyup Shin ◽  
Sangyul Lee ◽  
Minjae Kim ◽  
Jihwan Park ◽  
Kyoungdoug Min
Keyword(s):  
Deep Learning ◽  
Steady State ◽  
Gasoline Engine ◽  
Pressure Rise ◽  
Learning Model ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Steady State Condition ◽  
Brake Mean Effective Pressure ◽  
Deep Learning Model

Recently, deep learning has played an important role in the rise of artificial intelligence, and its accuracy has gained recognition in various research fields. Although engine phenomena are very complicated, they can be predicted with high accuracy using deep learning because they are based on the fundamentals of physics and chemistry. In this research, models were built with deep neural networks for gasoline engine prediction. The model consists of two sub-models. The first predicts the knock occurrence, and the second predicts performance, combustion, and emissions. This includes maximum cylinder pressure, crank angle at maximum cylinder pressure, maximum pressure rise rate, and brake mean effective pressure, brake-specific fuel consumption, brake-specific nitrogen oxides, and brake-specific carbon oxide, which are representative results of the engine (for normal combustion cases without knock). Model input parameters were selected considering engine operating conditions, and physically measurable sensor values. For test cases, the accuracy of the first model for knock classification is 99.0%, and the coefficient of determination (R2) values for the second model are all above 0.99. Test times of both models were approximately 2 ms. The robustness of all the models was verified using K-fold cross-validation. A sensitivity study of accuracy, according to the amount of training utilized, was also conducted to determine how many data points are required to effectively train the deep learning model. Accordingly, a deep learning approach was applied to predict the steady-state conditions of a gasoline engine. Achieved model accuracies and robustness proved deep learning to be an effective modeling approach, and test time was recognized to be able to apply for the real-time prediction. The sensitivity analysis can be applied for the preliminary study to define the number of experimental points for the deep learning model.

Combustion Characteristics of Stratified Mixture in Lean-Burn LPG Direct-Injection Engine With Spray-Guided Combustion System

2014 ◽  
Author(s):  
Cheolwoong Park ◽  
Seungmook Oh ◽  
Taeyoung Kim ◽  
Heechang Oh ◽  
Choongsik Bae
Keyword(s):  
Fuel Consumption ◽  
Compression Ratio ◽  
Fuel Economy ◽  
Direct Injection ◽  
Combustion Process ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Direct Injection Engine ◽  
Brake Mean Effective Pressure

Today, we are faced with the problems of global warming and fossil fuel depletion, and they have led to the enforcement of new emissions regulations. Direct-injection spark-ignition engines are a very promising technology that can comply with the new regulations. These engines offer the advantages of better fuel economy and lower emissions than conventional port-injection engines. The use of LPG as the fuel reduces carbon emissions because of its vaporization characteristics and the fact that it has lower carbon content than gasoline. An experimental study was carried out to investigate the combustion process and emission characteristics of a 2-liter spray-guided LPG direct-injection engine under lean operating conditions. The engine was operated at a constant speed of 2000 rpm under 0.2-MPa brake mean effective pressure, which corresponds to a common operation point of a passenger vehicle. Combustion stability, which is the most important component of engine performance, is closely related to the operation strategy and it significantly influences the degree of fuel consumption reduction. In order to achieve stable combustion with a stratified LPG mixture, an inter-injection spark ignition (ISI) strategy, which is an alternative control strategy to two-stage injection, was employed. The effects of the compression ratio on fuel economy were also assessed; due to the characteristics of the stratified LPG mixture, the fuel consumption did not reduce when the compression ratio was increased.

Transient “Single-Fuel” RCCI Operation With Customized Pistons in a Light-Duty Multicylinder Engine

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Christopher W. Gross ◽  
Rolf D. Reitz
Keyword(s):  
Steady State ◽  
Compression Ratio ◽  
Fuel Injection ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Maximum Pressure ◽  
Engine Operation ◽  
Volume Percentage ◽  
Light Duty ◽  
Brake Mean Effective Pressure

Reactivity controlled compression ignition (RCCI) combustion in a light-duty multicylinder engine (MCE) over transient operating conditions using fast response exhaust unburned hydrocarbon (UHC1), nitric oxide (NO), and particulate matter (PM) measurement instruments was investigated. RCCI has demonstrated improvements in efficiency along with low NOx and PM emissions by utilizing in-cylinder fuel blending, generally using two fuels with different reactivity in order to optimize stratification. In the present work, a “single-fuel” approach for RCCI combustion using port-injected gasoline and direct-injected gasoline mixed with a small amount of the cetane improver 2-ethylhexyl nitrate (EHN) was studied with custom designed, compression ratio (CR) of 13.75:1, pistons under transient conditions. The EHN volume percentage in the mixture for the direct-injected fuel was set at 3%. In an experimental investigation, comparisons were made to transient RCCI combustion operation with gasoline/diesel. The experiments were performed over a step load change from 1 to 4 bar brake mean effective pressure (BMEP) at constant 1500 rev/min on a General Motors (GM) Z19DTH 1.9-L diesel engine. The transients were conducted by changing the accelerator pedal command to provide a desired torque output with a DRIVVEN engine control unit (ECU) that replaced the original Bosch ECU. All relevant engine parameters are adjusted accordingly, based on 2D-tables. Previous to the transient engine operation, four steady-state points were used to obtain performance and emission values. Engine calibration at these four points, as well as the interpolation of the intermediate points, allowed for smooth operation during the instantaneous step changes. Differences between the steady-state and transient results indicate the complexity of transient operation and show the need for additional controls to minimize undesirable effects. The steady-state points were calibrated by modifying the fuel injection strategy (actual start of injection (aSOI) timing, port-fuel injection (PFI) fraction, etc.), exhaust gas recirculation (EGR), and rail pressure in order to obtain predefined values for the crank-angle at 50% of total heat release (CA50). Furthermore, emission targets (HC1 < 1500 ppmC3, NO < 10 ppm, filter smoke number (FSN)<0.1 with a maximum pressure rise rate (MPRR) < 10 bar/deg) and noise level targets (<95 dB) for RCCI combustion were maintained during the calibration and mapping. The tests were performed with a closed-loop (CL) calibration by using a next-cycle (NC) controller to adjust the PFI ratio of each cycle in order to reach the steady-state CA50 values in the table. The results show that single-fuel RCCI operation can be achieved, but requires significant alteration of the operating conditions, and NOx emissions were significantly elevated for gasoline/gasoline–EHN operation. While combustion phasing could not be matched, UHC1 emissions were at a similar level as for gasoline/diesel combustion. It is expected that the implementation of different injection strategies and boosted operation, combined with use of higher compression ratio pistons in order to compensate for the lower reactivity direct injection (DI) fuel, could raise the potential for improved performance.

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