scholarly journals Knock Intensity Distribution and a Stochastic Control Framework for Knock Control

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Mateos Kassa ◽  
Carrie Hall ◽  
Michael Pamminger ◽  
Thomas Wallner
Keyword(s):  
Lognormal Distribution ◽  
Control Strategies ◽  
Fuel Efficiency ◽  
Probabilistic Approach ◽  
Engine Performance ◽  
Operating Conditions ◽  
Control Approach ◽  
Spark Timing ◽  
Almost All ◽  
Knock Control

Abstract One of the main factors limiting the efficiency of spark-ignited (SI) engines is the occurrence of engine knock. In high temperature and high pressure in-cylinder conditions, the fuel–air mixture auto-ignites creating pressure shock waves in the cylinder. Knock can significantly damage the engine and hinder its performance; as such, conservative knock control strategies are generally implemented which avoid such operating conditions at the cost of lower thermal efficiencies. Significant improvements in the performance of conventional knock controllers are possible if the properties of the knock process are better characterized and exploited in knock controller designs. One of the methods undertaken to better characterize knocking instances is to employ a probabilistic approach, in which the likelihood of knock is derived from the statistical distribution of knock intensity (KI). In this paper, it is shown that KI values at a fixed operating point for single fuel and dual fuel engines are accurately described using a mixed lognormal distribution. The fitting accuracy is compared against those for a randomly generated mixed-lognormally distributed dataset, and shown to exceed a 95% accuracy threshold for almost all of the operating points tested. Additionally, this paper discusses a stochastic knock control approach that leverages the mixed lognormal distribution to adjust spark timing based on KI measurements. This more informed knock control strategy would allow for improvements in engine performance and fuel efficiency by minimizing knock occurrences.

Analysis of Throttle Opening Variation Impact on a Diesel Engine Performance Using Second Law of Thermodynamics

2009 ◽  
Author(s):  
B. B. Sahoo ◽  
U. K. Saha ◽  
N. Sahoo ◽  
P. Prusty
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Second Law Of Thermodynamics ◽  
Operating Conditions ◽  
Second Law ◽  
Engine Fuel ◽  
Availability Analysis ◽  
Second Law Analysis

The fuel efficiency of a modern diesel engine has decreased due to the recent revisions to emission standards. For an engine fuel economy, the engine speed is to be optimum for an exact throttle opening (TO) position. This work presents an analysis of throttle opening variation impact on a multi-cylinder, direct injection diesel engine with the aid of Second Law of thermodynamics. For this purpose, the engine is run for different throttle openings with several load and speed variations. At a steady engine loading condition, variation in the throttle openings has resulted in different engine speeds. The Second Law analysis, also called ‘Exergy’ analysis, is performed for these different engine speeds at their throttle positions. The Second Law analysis includes brake work, coolant heat transfer, exhaust losses, exergy efficiency, and airfuel ratio. The availability analysis is performed for 70%, 80%, and 90% loads of engine maximum power condition with 50%, 75%, and 100% TO variations. The data are recorded using a computerized engine test unit. Results indicate that the optimum engine operating conditions for 70%, 80% and 90% engine loads are 2000 rpm at 50% TO, 2300 rpm at 75% TO and 3250 rpm at 100% TO respectively.

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

2018 ◽  
Author(s):  
Daniel Probst ◽  
Sameera Wijeyakulasuriya ◽  
Eric Pomraning ◽  
Janardhan Kodavasal ◽  
Riccardo Scarcelli ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Engine Performance ◽  
Turnaround Time ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Cycle Variation ◽  
Spark Timing ◽  
Large Eddy ◽  
Operating Points

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 BMEP, 2000 RPM) were evaluated: a non-dilute (0% EGR) case and a dilute (18% EGR) case. The experimental data for both operating conditions had 500 cycles. The measured CCV in IMEP was 1.40% for the non-dilute case and 7.78% for the dilute case. To estimate CCV from simulation, perturbed concurrent cycles of engine simulations were compared to 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 indicated mean effective pressure (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. A large and small velocity perturbation 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, under-predicted 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. Additionally, the required core-hours can be reduced up to 41%, since only a portion of each cycle needs to be simulated.

scholarly journals A Numerical Model to Study the Role of Surface Textures at Top Dead Center Reversal in the Piston Ring to Cylinder Liner Contact

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
N. Morris ◽  
R. Rahmani ◽  
H. Rahnejat ◽  
P. D. King ◽  
S. Howell-Smith
Keyword(s):  
Gas Flow ◽  
Fuel Efficiency ◽  
Surface Texturing ◽  
Engine Performance ◽  
Cylinder Liner ◽  
Operating Conditions ◽  
Ic Engine ◽  
Numerical Predictions ◽  
Combined Solution ◽  
Effect Of Surface

Minimization of parasitic losses in the internal combustion (IC) engine is essential for improved fuel efficiency and reduced emissions. Surface texturing has emerged as a method palliating these losses in instances where thin lubricant films lead to mixed or boundary regimes of lubrication. Such thin films are prevalent in contact of compression ring to cylinder liner at piston motion reversals because of momentary cessation of entraining motion. The paper provides combined solution of Reynolds equation, boundary interactions, and a gas flow model to predict the tribological conditions, particularly at piston reversals. This model is then validated against measurements using a floating liner for determination of in situ friction of an engine under motored condition. Very good agreement is obtained. The validated model is then used to ascertain the effect of surface texturing of the liner surface during reversals. Therefore, the paper is a combined study of numerical predictions and the effect of surface texturing. The predictions show that some marginal gains in engine performance can be expected with laser textured chevron features of shallow depth under certain operating conditions.

Novel design of an optimized synergetic control for dual stator induction motor

2019 ◽  
Vol 38 (6) ◽  
pp. 1828-1845
Author(s):  
Hossine Guermit ◽  
Katia Kouzi ◽  
Sid Ahmed Bessedik
Keyword(s):  
Induction Motor ◽  
Sliding Mode ◽  
Optimal Parameter ◽  
Control Strategies ◽  
Pso Algorithm ◽  
Operating Conditions ◽  
Content Type ◽  
Control Approach ◽  
Simulation Results ◽  
Synergetic Control

Purpose This paper aims to present a contribution to improve the performance of vector control scheme of double star induction motor drive (DSIM) by using an optimized synergetic control approach. The main advantage of synergetic control is that it supports all parametric and nonparametric uncertainties, which is not the case in several control strategies. Design/methodology/approach The suggested controller is developed based on the synergistic control theory and the particle swarm optimization (PSO) algorithm which allow to obtain the optimal parameter of suggested controller to improve the performance of control system. Findings To show the benefits of proposed controller, a comparative simulation results between conventional PI controller, sliding mode controller and suggested controller were carried out. Originality/value The obtained simulation results illustrate clearly that synergetic controller ensures a rapid response, asymptotic stability of the closed-loop system in the all range operating condition and system robustness in presence of parameter variation in all range of operating conditions.

An Approach for Investigating Adaptive Control Strategies to Improve Combustion Stability Under Dilute Operating Conditions

2005 ◽  
Author(s):  
K. Dean Edwards ◽  
Robert M. Wagner ◽  
Timothy J. Theiss ◽  
C. Stuart Daw
Keyword(s):  
Adaptive Control ◽  
Emission Reduction ◽  
Internal Combustion Engines ◽  
Control Strategies ◽  
Fuel Efficiency ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Combustion Model ◽  
Combustion Instabilities ◽  
The Impact

Dilute operation of internal combustion engines through lean fueling and/or high levels of exhaust gas recirculation (EGR) is frequently employed to increase fuel efficiency, reduce NOx emissions, and promote enhanced combustion modes such as HCCI. The maximum level of dilution is limited by the development of combustion instabilities that produce unacceptable levels of cycle-to-cycle combustion variability. These combustion instabilities are frequently stimulated by the nonlinear feedback associated with the residual and recirculated exhaust gases exchanged between successive cycles. However, with the application of adaptive control, it is possible to limit the severity of the combustion variability and regain efficiency and emission reduction benefits that would otherwise be lost. In order to better characterize the benefits of adaptive control, we have employed a two-zone phenomenological combustion model to simulate the onset of combustion instabilities under dilute operating conditions and illustrate the impact of these instabilities on emissions and fuel efficiency. The two-zone in-cylinder combustion model is coupled to a WAVE engine-simulation code, allowing rapid simulation of several hundred successive engine cycles with many external engine parametric effects included. By applying adaptive feedback control to the WAVE model, we demonstrate how mitigation of the extreme combustion events can result in improved efficiency and reduced emissions levels. We expect that this approach can be used to estimate the potential benefits of implementing adaptive control strategies on specific engine platforms to achieve further efficiency and emission-reduction gains.

scholarly journals CFD Performance Analysis of a Spark Ignition Engine Fueled by Landfill Gas

2014 ◽  
Vol 7 (1) ◽  
pp. 26-33
Author(s):  
Daniel Swain ◽  
S.O. Bade Shrestha
Keyword(s):  
Greenhouse Gas Emission ◽  
Combustion Engine ◽  
Fluid Dynamic ◽  
Fuel Efficiency ◽  
Landfill Gas ◽  
Flame Temperature ◽  
Engine Performance ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Pure Methane

Landfill gas (LFG) that is generated in an anaerobic environment in landfills and consists primarily of methane and carbondioxide with small amount of nitrogen and other non-methane gases, could be collected and used to produce energy either by extracting methane or using the landfill gas directly in an internal combustion engine or a gas turbine. It amounts to be a net-negative greenhouse gas emission process. Carbondioxide component of LFG dilutes the fuel and absorbs some of the heat of combustion, causing reduced flame temperature that decreases NOx emissions and also suppresses knock. A model was developed and validated with the experimental data available in literature, using the computation fluid dynamic (CFD) code, KIVA-4. Various engine performance parameters at various operating conditions were evaluated and the benefits of methane purification and or direct use of LFG as a fuel in the engine scenarios were compared. It was found that landfill gas used directly at higher compression ratios can be used for pure methane fuel with higher fuel efficiency than can be achieved using pure methane fuel only.

Performance Analysis of an Electric Turbocompounding System for a Hybrid Vehicle Diesel Engine

2015 ◽  
Author(s):  
Zhanming Ding ◽  
Weilin Zhuge ◽  
Yangjun Zhang ◽  
Yong Yin ◽  
Shuyong Zhang
Keyword(s):  
Diesel Engine ◽  
Waste Heat ◽  
Combustion Engine ◽  
Control Strategies ◽  
Full Range ◽  
Engine Performance ◽  
Driving Cycle ◽  
Operating Conditions ◽  
Full Load ◽  
Power Turbine

Waste heat recovery (WHR) is one of the main approaches to improve the internal combustion engine (ICE) overall efficiency and reduce emissions. The electric turbocompounding (ETC) technology is considered as a promising WHR technology for vehicle engines due to its compactness and light weight. In order to improve the overall fuel efficiency of the engine at practical operating conditions, the impacts of the implementation of the ETC system should be investigated not only at engine full load conditions, but also under practical driving cycles. In this paper, an ETC system was designed for a 4.75 L diesel engine, in which a power turbine was installed down-stream to the turbocharger turbine. A performance simulation model of the ETC engine was developed on the basis of the diesel engine model, which was validated against engine performance experimental data. The control strategies of the wastegate of turbocharger turbine, the wastegate of power turbine and the operating torque of generator were determined. The relative variation in BSFC was studied under full range of operating conditions, and results show that the maximum improvement of fuel economy is 6.7% at an engine speed of 1000 rpm and 70% of full load, in comparison with the baseline diesel engine. Main factors lead to the performance differences between the ETC engine and the baseline engine were analyzed. Furthermore, the performance of the ETC engine under the C-WTVC driving cycle was investigated. Results show that the implementation of the ETC system resulted in a 1.2% fuel consumption reduction under the C-WTVC driving cycle.

The Effects of Oxygen Enrichment of Combustion Air for Spark-Ignition Engines Using a Thermodynamic Cycle Simulation

2005 ◽  
Author(s):  
Jerald A. Caton
Keyword(s):  
Fuel Consumption ◽  
Oxygen Concentration ◽  
Power Output ◽  
Combustion Process ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Heat Losses ◽  
Operating Conditions ◽  
Cycle Simulation ◽  
Spark Timing

A thermodynamic cycle simulation was used to examine the effects of oxygen enriched combustion air on engine performance for a range of operating conditions and for different sized engines. The use of oxygen enriched combustion air will have a direct effect on the combustion process and on the overall engine thermodynamics. For example, for cases with higher inlet oxygen concentration (and hence less nitrogen dilution), for the same operating conditions, the combustion gas temperatures and engine cylinder heat losses will be higher. In addition, the engine using oxygen enriched combustion air will be smaller than an engine using normal air for the same power output. The major objective of this study was to quantify these expectations for a range of operating conditions. One special feature of a portion of the current study is the constant engine power output by decreasing engine size as the oxygen concentration increased in the combustion air. Results include detail thermodynamic results of temperatures, pressures and properties as functions of the oxygen concentration of the combustion air. Results also include engine performance parameters such as power, torque, fuel consumption, thermal efficiency, and exhaust temperatures. For one comparison, engine performance and fuel consumption were obtained for an equivalence ratio of 1.0, MBT spark timing, and 2500 rpm. For oxygen enriched combustion air with 32% oxygen, equal power output was obtained with 73% of the displaced volume (all else the same). For the higher oxygen case, the brake fuel consumption increased about 11% primarily due to higher heat losses and higher exhaust gas energy which were a consequence of the higher gas temperatures. For the MBT spark timing case, the nitric oxide emissions increased by about 11% as the oxygen concentration increases from 21% to 25%.

scholarly journals Innovative Control Strategies for the Diagnosis of Injector Performance in an Internal Combustion Engine via Turbocharger Speed

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1420 ◽  
Author(s):  
Michele Becciani ◽  
Luca Romani ◽  
Giovanni Vichi ◽  
Alessandro Bianchini ◽  
Go Asai ◽  
...  
Keyword(s):  
Combustion Engine ◽  
Control Strategies ◽  
Integrated Control ◽  
Combustion Process ◽  
Engine Performance ◽  
Operating Conditions ◽  
Correct Operation ◽  
Control Units ◽  
The Right ◽  
High Level

In order to ensure a high level of performance and to comply with the increasingly severe limitations in terms of fuel consumption and pollution emissions, modern diesel engines need continuous monitoring of their operating conditions by their control units. With particular focus on turbocharged engines, which are presently the standard in a large number of applications, the use of the average and the instantaneous turbocharger speeds is thought to represent a valuable feedback of the engine behavior, especially for the identification of the cylinder-to-cylinder injection variations. The correct operation of the injectors and control of the injected fuel quantity allow the controller to ensure the right combustion process and maintain engine performance. In the present study, two different techniques are presented to fit this scope. The techniques are discussed and experimentally validated, leading to the definition of an integrated control strategy, which features the main benefits of the two, and is able to correctly detect the cylinder-to-cylinder injection variation and, consequently, properly correct the injection in each cylinder in order to balance the engine behavior. In addition, the possibility of detecting misfiring events was assessed.

Probabilistic Engine Performance Scatter and Deterioration Modeling

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Stefan Spieler ◽  
Stephan Staudacher ◽  
Roland Fiola ◽  
Peter Sahm ◽  
Matthias Weißschuh
Keyword(s):  
Test Data ◽  
Probabilistic Approach ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Performance Data ◽  
Maintenance Cost ◽  
Performance Parameters ◽  
Engine Operation ◽  
The Impact

The change of performance parameters over time due to engine deterioration and production scatter plays an important role to ensure safe and economical engine operation. A tool has been developed which is able to model production scatter and engine deterioration on the basis of elementary changes of numerous construction features. In order to consider the characteristics of an engine fleet as well as random environmental influences, a probabilistic approach using Monte Carlo simulation (MCS) was chosen. To quantify the impact of feature deviations on performance relevant metrics, nonlinear sensitivity functions are used to obtain scalars and offsets on turbomachinery maps, which reflect module behavior during operation. Probability density functions (PDFs) of user-defined performance parameters of an engine fleet are then calculated by performing a MCS in a performance synthesis program. For the validation of the developed methodology pass-off test data, endurance engine test data, as well as data from engine maintenance, incoming tests have been used. For this purpose, measured engine fleet performance data have been corrected by statistically eliminating the influence of measuring errors. The validation process showed the model’s ability to predict more than 90% of the measured performance variance. Furthermore, predicted performance trends correspond well to performance data from engines in operation. Two model enhancements are presented, the first of which is intended for maintenance cost prediction. It is able to generate PDFs of failure times for different features. The second enhancement correlates feature change and operating conditions and thus connects airline operation and maintenance costs. Subsequently, it is shown that the model developed is a powerful tool to assist in aircraft engine design and production processes, thanks to its ability to identify and quantitatively assess main drivers for performance variance and trends.

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