Cylinder-Specific Combustion Phasing Modeling for a Multiple-Cylinder Diesel Engine

2018 ◽  
Author(s):  
Wenbo Sui ◽  
Carrie M. Hall
Keyword(s):  
Prediction Model ◽  
Diesel Engines ◽  
Measurement Errors ◽  
Equivalence Ratio ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Integral Model ◽  
Low Carbon ◽  
Crank Angle ◽  
The Impact

An optimal combustion phasing leads to a high combustion efficiency and low carbon emissions in diesel engines. With the increasing complexity of diesel engines, model-based control of combustion phasing is becoming indispensable, but precise prediction of combustion phasing is required for such strategies. Since cylinder-to-cylinder variations in combustion can be more significant with advanced combustion techniques, this work focuses on developing a control-oriented combustion phasing model that can be leveraged to provide cylinder-specific estimates. The pressure and temperature of the intake gas reaching each cylinder are predicted by a semi-empirical model and the coefficients of this intake pressure and temperature model are varied from cylinder-to-cylinder. A knock integral model is leveraged to estimate the SOC (start of combustion) and the burn duration is predicted as a function of EGR fraction, equivalence ratio of fuel and residual gas fraction in a burn duration model. After that, a Wiebe function is utilized to estimate CA50 (crank angle at 50% mass of fuel has burned). This cylinder-specific combustion phasing prediction model is calibrated and validated across a variety of operating conditions. A large range of EGR fraction and fuel equivalence ratio were tested in these simulations including EGR levels from 0 to 50%, and equivalence ratios from 0.5 to 0.9. The results show that the combustion phasing prediction model can estimate CA50 with an uncertainty of ±0.5 crank angle degree in all six cylinders. The impact of measurement errors on the accuracy of the prediction model is also discussed in this paper.

scholarly journals Cylinder-specific model-based control of combustion phasing for multiple-cylinder diesel engines operating with high dilution and boost levels

2018 ◽  
Vol 21 (7) ◽  
pp. 1231-1250
Author(s):  
Wenbo Sui ◽  
Carrie M Hall ◽  
Gina Kapadia
Keyword(s):  
Steady State ◽  
Diesel Engines ◽  
Specific Model ◽  
Integral Model ◽  
Loop Control ◽  
Model Based Control ◽  
Model Based ◽  
Crank Angle Degree ◽  
Crank Angle ◽  
The Impact

Accurate control of combustion phasing is indispensable for diesel engines due to the strong impact of combustion timing on efficiency. In this work, a non-linear combustion phasing model is developed and integrated with a cylinder-specific model of intake gas. The combustion phasing model uses a knock integral model, a burn duration model, and a Wiebe function to predict CA50 (the crank angle at which 50% of the mass of fuel has burned). Meanwhile, the intake gas property model predicts the exhaust gas recirculation fraction and the in-cylinder pressure and temperature at intake valve closing for different cylinders. As such, cylinder-to-cylinder variation of the pressure and temperature at intake valves closing is also considered in this model. This combined model is simplified for controller design and validated. Based on these models, two combustion phasing control strategies are explored. The first is an adaptive controller that is designed for closed-loop control and the second is a feedforward model–based control strategy for open-loop control. These two control approaches were tested in simulations for all six cylinders, and the results demonstrate that the CA50 can reach steady-state conditions within 10 cycles. In addition, the steady-state errors are less than ±0.1 crank angle degree with the adaptive control approach and less than ±1.3 crank angle degree with feedforward model–based control. The impact of errors on the control algorithms is also discussed in the article.

Characteristics of Flame Bases for V-Gutters Stabilized Premixed Flames

2013 ◽  
Author(s):  
Fan Gong ◽  
Yong Huang
Keyword(s):  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Equivalence Ratio ◽  
Premixed Flames ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Heat Conducting ◽  
Inlet Velocity ◽  
The Impact

The objective of this work is to investigate the flame stabilization mechanism and the impact of the operating conditions on the characteristics of the steady, lean premixed flames. It’s well known that the flame base is very important to the existence of a flame, such as the flame after a V-gutter, which is typically used in ramjet and turbojet or turbofan afterburners and laboratory experiments. We performed two-dimensional simulations of turbulent premixed flames anchored downstream of the heat-conducting V-gutters in a confined passage for kerosene-air combustion. The flame bases are symmetrically located in the shear layers of the recirculation zone immediately after the V-gutter’s trailing edge. The effects of equivalence ratio of inlet mixture, inlet temperature, V-gutter’s thermal conductivity and inlet velocity on the flame base movements are investigated. When the equivalence ratio is raised, the flame base moves upstream slightly and the temperature gradient dT/dx near the flame base increases, so the flame base is strengthened. When the inlet temperature is raised, the flame base moves upstream very slightly, and near the flame base dT/dx increases and dT/dy decreases, so the flame base is strengthened. As the V-gutter’s thermal conductivity increases, the flame base moves downstream, and the temperature gradient dT/dx near the flame base decreases, so the flame base is weakened. When the inlet velocity is raised, the flame base moves upstream, and the convection heat loss with inlet mixture increases, so the flame base is weakened.

Intake-Air Oxygen-Enrichment of Diesel Engines as a Power Enhancement Method and Implications on Pollutant Emissions

2009 ◽  
Author(s):  
Theodoros C. Zannis ◽  
Dimitrios T. Hountalas ◽  
Elias A. Yfantis ◽  
Roussos G. Papagiannakis ◽  
Yiannis A. Levendis
Keyword(s):  
Theoretical Investigation ◽  
Diesel Engines ◽  
Equivalence Ratio ◽  
Combustion Efficiency ◽  
Oxygen Enrichment ◽  
Pollutant Emissions ◽  
Particulate Emissions ◽  
Engine Simulation ◽  
Hc Emissions ◽  
Experimental Findings

Increasing the in-cylinder oxygen availability of diesel engines is an effective method to improve combustion efficiency and to reduce particulate emissions. Past work on oxygen-enrichment of the intake air, revealed a large decrease of ignition delay, a remarkable decrease of soot emissions as well as reduction of CO and unburned hydrocarbon (HC) emissions while, brake specific fuel consumption (bsfc) remained unaffected or even improved. Moreover, experiments conducted in the past by authors revealed that oxygen-enrichment of the intake air (from 21% to 25% oxygen mole fraction) under high fuelling rates resulted to an increase of brake power output by 10%. However, a considerable increase of NOx emissions was recorded. This manuscript, presents the results of a theoretical investigation that examines the effect of oxygen enrichment of intake air, up to 30%v/v, on the local combustion characteristics, soot and NO concentrations under the following two in-cylinder mixing conditions: (1) lean in-cylinder average fuel/oxygen equivalence ratio (constant fuelling rate) and (2) constant in-cylinder average fuel/oxygen equivalence ratio (increased fuelling rate). A phenomenological engine simulation model is used to shed light into the influence of the oxygen content of combustion air on the distribution of combustion parameters, soot and nitric oxide inside the fuel jet, in all cases considered. Simulations were made for a naturally aspirated single-cylinder DI diesel engine “Lister LV1” at 2500 rpm and at various engine loads. The outcome of this theoretical investigation was contrasted with published experimental findings.

Quantification of the Impact of Uncertainties in Operating Conditions on the Flame Transfer Function With Nonintrusive Polynomial Chaos Expansion

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Alexander Avdonin ◽  
Wolfgang Polifke
Keyword(s):  
Transfer Function ◽  
Equivalence Ratio ◽  
Polynomial Chaos ◽  
Finite Impulse Response ◽  
Laminar Flame ◽  
Operating Parameter ◽  
Polynomial Chaos Expansion ◽  
Operating Conditions ◽  
Chaos Expansion ◽  
The Impact

Nonintrusive polynomial chaos expansion (NIPCE) is used to quantify the impact of uncertainties in operating conditions on the flame transfer function (FTF) of a premixed laminar flame. NIPCE requires only a small number of system evaluations, so it can be applied in cases where a Monte Carlo simulation is unfeasible. We consider three uncertain operating parameters: inlet velocity, burner plate temperature, and equivalence ratio. The FTF is identified in terms of the finite impulse response (FIR) from computational fluid dynamics (CFD) simulations with broadband velocity excitation. NIPCE yields uncertainties in the FTF due to the uncertain operating conditions. For the chosen uncertain operating bounds, a second-order expansion is found to be sufficient to represent the resulting uncertainties in the FTF with good accuracy. The effect of each operating parameter on the FTF is studied using Sobol indices, i.e., a variance-based measure of sensitivity, which are computed from the NIPCE. It is observed that in the present case, uncertainties in the FIR as well as in the phase of the FTF are dominated by the equivalence-ratio uncertainty. For frequencies below 150 Hz, the uncertainty in the gain of the FTF is also attributable to the uncertainty in equivalence-ratio, but for higher frequencies, the uncertainties in velocity and temperature dominate. At last, we adopt the polynomial approximation of the output quantity, provided by the NIPCE method, for further uncertainty quantification (UQ) studies with modified input uncertainties.

On the Effects of Injection Strategy, EGR, and Intake Boost on TSCI With Wet Ethanol

2019 ◽  
Author(s):  
Brian Gainey ◽  
Ziming Yan ◽  
Mozhgan Rahimi-Boldaji ◽  
Benjamin Lawler
Keyword(s):  
Heat Release ◽  
Thermal Stratification ◽  
Equivalence Ratio ◽  
Combustion Efficiency ◽  
Split Injection ◽  
Load Range ◽  
Release Process ◽  
Injection Strategy ◽  
Compression Stroke ◽  
The Impact

Abstract Using a split injection of wet ethanol, where a portion of the fuel is injected during the compression stroke, has been shown to be an effective way to enable thermally stratified compression ignition (TSCI), an advanced, low temperature combustion (LTC) mode that aims to control the heat release process by enhancing thermal stratification, thereby extending the load range of LTC. Wet ethanol is the ideal fuel candidate to enable TSCI because it has a high latent heat of vaporization and low equivalence ratio sensitivity. Previous work has shown “early” compression stroke injections (−150 to −100 deg aTDC) have the potential to control the start of combustion while “mid” compression stroke injections (−90 to −30 deg aTDC) have the potential to control in-cylinder thermal stratification, thereby controlling the heat release rate. In this work, a mixture of 80% ethanol and 20% water by mass is used to further study the injection strategy of TSCI combustion. Additionally, the impact of external, cooled exhaust gas recirculation (EGR) and intake boost level on the effectiveness of a split injection of wet ethanol to control the heat release process are investigated. It was found that neither external, cooled EGR, nor intake boost level has any impact on the effectiveness of the compression stroke injection(s) at controlling the burn rate of TSCI. It was also seen that external, cooled EGR has the potential to increase the overall tailpipe combustion efficiency, while intake boost has the potential to decrease NOx emissions at the expense of combustion efficiency by lowering the global equivalence ratio.

Development of main components of device for measuring residual stresses

2019 ◽  
pp. 65-69
Author(s):  
N. F. Wroblewski ◽  
P. N. Gerasimov ◽  
O. A. Korotky
Keyword(s):  
Stress State ◽  
Residual Stresses ◽  
Measurement Errors ◽  
Operating Conditions ◽  
Electromagnetic Properties ◽  
Machine Elements ◽  
Main Components ◽  
Object Material ◽  
Magnetic Resistance ◽  
The Impact

The paper presents the results of the study of the stress state of machine elements and structures in which there are residual stresses. Examines the use of overhead eddy current and magneto-elastic transducers, investigates the process of measurement of residual stresses. It is proved that the cause of measurement errors is the instability of the gap between the transducer and the surface of the object. It is proved that during calibration and measurements, the installation of the gap and its control should be carried out by the magnitude of the magnetic resistance. Undesirable effects of variable electromagnetic properties of the object material on the installation result can be eliminated by using the method of vortex currents. As a result, a device for measuring the stress state of objects made of ferromagnetic metals has been developed, which uses a magnetoelastic converter. Using the values of the frequency increment of the corresponding oscillator, it is possible to significantly reduce the impact of changes in operating conditions on the measurement result.

Predicting the Distribution of Combustion Timing Ensemble in an HCCI Engine

2009 ◽  
Author(s):  
Mahdi Shahbakhti ◽  
Ahmad Ghazimirsaied ◽  
Charles Robert Koch
Keyword(s):  
Empirical Model ◽  
Probability Distributions ◽  
Exchange Process ◽  
Operating Conditions ◽  
Integral Model ◽  
Average Error ◽  
Statistical Control ◽  
Hcci Combustion ◽  
Crank Angle ◽  
Primary Reference

Control of Homogeneous Charge Compression Ignition (HCCI) engines to obtain the desirable operation requires understanding of how different charge variables influence the cyclic variations in HCCI combustion. Combustion timing for consecutive cycles at each operating point makes an ensemble of combustion timing which can exhibit different shapes of probability distributions depending on the random and physical patterns existing in the data. In this paper, a combined physical-statistical control-oriented model is developed to predict the distribution of HCCI combustion timing (CA50, crank angle of 50% fuel mass fraction burnt) for a range of operating conditions. The statistical model is based on the Generalized Extreme Value (GEV) distribution and the physical model embodies a modified knock integral model, a fuel burn rate model, a semi-empirical model for the gas exchange process and an empirical model to estimate the combustion timing dispersion. The resulting model is parameterized for the combustion of Primary Reference Fuel (PRF) blends using over 5000 simulations from a detailed thermo-kinetic model. Empirical correlations in the model are parameterized using the experimental data obtained from a single-cylinder engine. Once the model is parameterized it only needs five inputs: intake pressure, intake temperature, Exhaust Gas Recirculation (EGR) rate, equivalence ratio and engine speed. The main outputs of the model are CA50 and the Probability Density Function (PDF) metrics of CA50 distribution. Experimental CA50 is compared with predicted CA50 from the model and the results show a total average error of less than 1.5 degrees of crank angle for 213 steady-state operating points with four different PRF fuels at diversified operating conditions. Predicted PDF of the CA50 ensemble is compared with that of the experiments for PRF fuels at different running conditions. The results indicate a good agreement between simulation and the experiment.

Modeling and Analysis of Tier 4 Locomotives Operating in a High-Altitude Tunnel

2017 ◽  
Author(s):  
Kevin S. McElhaney ◽  
Robert Mischler
Keyword(s):  
High Altitude ◽  
Diesel Engines ◽  
Ambient Air ◽  
Operating Conditions ◽  
Tier 2 ◽  
Electric Locomotive ◽  
Design Changes ◽  
Engine Design ◽  
The Impact ◽  
Cooling And Lubrication

Tunnels represent one of the most severe operating conditions for diesel engines in diesel-electric locomotive applications, specifically for non-ventilated tunnels located at high elevation. High ambient air temperatures are observed in these tunnels due to heat rejected from the locomotive engines through the exhaust and engine cooling and lubrication systems. Engine protection algorithms cause the maximum allowable engine horsepower to be reduced due to these conditions leading to a reduction in train speed and occasionally train stall. A first law based model was developed to simulate the performance of a train pulled by GE diesel-electric locomotives equipped with medium speed diesel engines in a high altitude and non-ventilated tunnel. The model was compared against and calibrated to actual tunnel operation data of EPA Tier 2 compliant locomotives. The model was then used to study the impact of engine design changes required for EPA Tier 4 compliant locomotives, specifically the introduction of exhaust gas recirculation (EGR), on engine, locomotive, and train performance in the tunnel. Simulations were completed to evaluate engine control strategies targeting same or better train performance than the EPA Tier 2 compliant locomotive baseline case. Simulation results show that the introduction of EGR reduces train performance in the tunnel by increasing the required reduction in engine horsepower, but is slightly offset by improved performance from other engine design changes. The targeted engine and train performance could be obtained by disabling EGR during tunnel operation.

scholarly journals Improving the Uncertainty of Exhaust Gas Temperature Measurements in Internal Combustion Engines

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Nick Papaioannou ◽  
Felix Leach ◽  
Martin Davy
Keyword(s):  
Measurement Errors ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Combustion Engines ◽  
Gas Temperature ◽  
Crank Angle ◽  
Reconstructed Temperature ◽  
Exhaust Gas Temperature

Abstract Accurate measurement of exhaust gas temperature (EGT) in internal combustion engines (ICEs) is a challenging task. The most common, and also the most practical, method of measurement is to insert a physical probe, for example, a thermocouple or platinum resistance thermometer, directly into the exhaust flow. Historically, consideration of the measurement errors induced by this arrangement has focused on the effects of radiation and the loss of temporal resolution naturally associated with a probe of finite thermal inertia operating within a pulsating flow with a time-varying heat input. However, a recent numerical and experimental study has shown that conduction errors may also have a significant effect on the measured EGT, with errors approaching ∼80 K depending on engine operating conditions. In this work, the authors introduce a new temperature compensation method that can correct for the combined radiation, conduction, and dynamic response errors introduced during the measurement and thereby reconstruct the “true” crank-angle resolved EGT to an estimated accuracy of ±1.5%. The significance of this result is demonstrated by consideration of a first law energy balance on an engine. It is shown that the exhaust gas enthalpy term is underestimated by 15–18% when calculated using conventional time-averaged data as opposed to using the mass-average exhaust enthalpy that is obtained by combining the reconstructed temperature data with crank angle-resolved exhaust flow rates predicted by a well-validated one-dimensional (1D) simulation.

Quantification of the Impact of Uncertainties in Operating Conditions on the Flame Transfer Function With Non-Intrusive Polynomial Chaos Expansion

2018 ◽  
Author(s):  
Alexander Avdonin ◽  
Wolfgang Polifke
Keyword(s):  
Transfer Function ◽  
Impulse Response ◽  
Equivalence Ratio ◽  
Polynomial Chaos ◽  
Finite Impulse Response ◽  
Operating Parameter ◽  
Polynomial Chaos Expansion ◽  
Operating Conditions ◽  
Chaos Expansion ◽  
The Impact

Non-intrusive polynomial chaos expansion (NIPCE) is used to quantify the impact of uncertainties in operating conditions on the flame transfer function of a premixed laminar flame. NIPCE requires only a small number of system evaluations, so it can be applied in cases where a Monte Carlo simulation is unfeasible. We consider three uncertain operating parameters: inlet velocity, burner plate temperature, and equivalence ratio. The flame transfer function (FTF) is identified in terms of the finite impulse response from CFD simulations with broadband velocity excitation. NIPCE yields uncertainties in the FTF due to the uncertain operating conditions. For the chosen uncertain operating bounds, a second-order expansion is found to be sufficient to represent the resulting uncertainties in the FTF with good accuracy. The effect of each operating parameter on the FTF is studied using Sobol indices, i.e. a variance-based measure of sensitivity, which are computed from the NIPCE. It is observed that in the present case uncertainties in the finite impulse response as well as in the phase of the FTF are dominated by the equivalence-ratio uncertainty. For frequencies below 150 Hz, the uncertainty in the gain of the FTF is also attributable to the uncertainty in equivalence-ratio, but for higher frequencies the uncertainties in velocity and temperature dominate. At last, we adopt the polynomial approximation of the output quantity, provided by the NIPCE method, for further UQ studies with modified input uncertainties.

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