Minimum Backpressure Wastegate Control for a Boosted Gasoline Engine With Low Pressure External EGR

2016 ◽  
Author(s):  
Shima Nazari ◽  
Anna Stefanopoulou ◽  
Jason Martz
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Low Pressure ◽  
Gasoline Direct Injection ◽  
Efficiency Gain ◽  
Engine Simulation ◽  
Trade Offs ◽  
Torque Response

Turbocharging and downsizing (TRBDS) a gasoline direct injection (GDI) engine can reduce fuel consumption but with increased drivability challenges compared to larger displacement engines. This tradeoff between efficiency and drivability is influenced by the throttle-wastegate control strategy. A more severe tradeoff between efficiency and drivability is shown with the introduction of Low-Pressure Exhaust Gas Recirculation (LP-EGR). This paper investigates and quantifies these trade-offs by designing and implementing in a one-dimensional (1D) engine simulation two prototypical throttle-wastegate strategies that bound the achievable engine performance with respect to efficiency and torque response. Specifically, a closed-wastegate (WGC) strategy for the fastest achievable response and a throttle-wastegate strategy that minimizes engine backp-pressure (MBWG) for the best fuel efficiency, are evaluated and compared based on closed loop response. The simulation of an aggressive tip-in (the driver’s request for torque increase) shows that the wastegate strategy can negotiate a 0.8% efficiency gain at the expense of 160 ms slower torque response both with and without LP-EGR. The LP-EGR strategy, however offers a substantial 5% efficiency improvement followed by an undesirable 1 second increase in torque time response, clarifying the opportunities and challenges associated with LP-EGR.

Economy and emission characteristics of the optimal dilution strategy in lean combustion based on GDI gasoline engine equipped with prechamber

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110381
Author(s):  
Li Wang ◽  
Zhaoming Huang ◽  
Wang Tao ◽  
Kai Shen ◽  
Weiguo Chen
Keyword(s):  
Fuel Economy ◽  
Gasoline Engine ◽  
Direct Injection ◽  
Engine Performance ◽  
Gasoline Direct Injection ◽  
Dilution Ratio ◽  
Lean Combustion ◽  
Excess Air ◽  
Combustion Phase ◽  
Hc Emissions

EGR and excess-air dilution have been investigated in a 1.5 L four cylinders gasoline direct injection (GDI) turbocharged engine equipped with prechamber. The influences of the two different dilution technologies on the engine performance are explored. The results show that at 2400 rpm and 12 bar, EGR dilution can adopt more aggressive ignition advanced angle to achieve optimal combustion phasing. However, excess-air dilution has greater fuel economy than that of EGR dilution owing to larger in-cylinder polytropic exponent. As for prechamber, when dilution ratio is greater than 37.1%, the combustion phase is advanced, resulting in fuel economy improving. Meanwhile, only when the dilution ratio is under 36.2%, the HC emissions of excess-air dilution are lower than the original engine. With the increase of dilution ratio, the CO emissions decrease continuously. The NOX emissions of both dilution technologies are 11% of those of the original engine. Excess-air dilution has better fuel economy and very low CO emissions. EGR dilution can effectively reduce NOX emissions, but increase HC emissions. Compared with spark plug ignition, the pre chamber ignition has lower HC, CO emissions, and higher NO emissions. At part load, the pre-chamber ignition reduces NOX emissions to 49 ppm.

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.

Effect of Spark Timing on Performance of a Hydrogen Gasoline Engine

2015 ◽  
Vol 713-715 ◽  
pp. 239-242 ◽  
Author(s):  
Wei Bo Shi ◽  
Xiu Min Yu ◽  
Ping Sun
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Engine Performance ◽  
Spark Ignition Engine ◽  
Gasoline Direct Injection ◽  
Hydrogen Energy ◽  
Energy Fraction ◽  
Direct Injection Engine ◽  
Excess Air ◽  
Spark Timing

Hydrogen-gasoline blends is an effective way to improving the performance of spark ignition engine at stoichiometric and lean conditions. Spark timing is one of the important parameters affect the engine performance. This paper investigated the effect of spark timing on performance of a hydrogen-gasoline engine. A four cylinder, gasoline direct injection engine was modified to be a gasoline port injection, hydrogen direct injection engine. The hydrogen energy fraction was set as 0% and 30%. For a specified hydrogen addition, the engine was operated at four excess air ratios of 0.8, 1.0, 1.2 and 1.5. Under the specified excess air ratio condition, the spark timing was varied from 4 to 19°CA before top dead center (BTDC) with an interval of 3°CA. The test result showed that the indicated mean effective pressure (IMEP) climb up and then decline with the increase of spark advance. For hydrogen-gasoline engine, the optimum spark timing for the max IMEP was retarded at a specified excess air ratio. The max thermal efficiency appeared at the optimum spark timing.

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 A Comparison of Ethanol, Methanol, and Butanol Blending with Gasoline and Its Effect on Engine Performance and Emissions Using Engine Simulation

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1322
Author(s):  
Simeon Iliev
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Exhaust Emissions ◽  
Engine Simulation ◽  
Engine Model ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Blended Fuels

Air pollution, especially in large cities around the world, is associated with serious problems both with people’s health and the environment. Over the past few years, there has been a particularly intensive demand for alternatives to fossil fuels, because when they are burned, substances that pollute the environment are released. In addition to the smoke from fuels burned for heating and harmful emissions that industrial installations release, the exhaust emissions of vehicles create a large share of the fossil fuel pollution. Alternative fuels, known as non-conventional and advanced fuels, are derived from resources other than fossil fuels. Because alcoholic fuels have several physical and propellant properties similar to those of gasoline, they can be considered as one of the alternative fuels. Alcoholic fuels or alcohol-blended fuels may be used in gasoline engines to reduce exhaust emissions. This study aimed to develop a gasoline engine model to predict the influence of different types of alcohol-blended fuels on performance and emissions. For the purpose of this study, the AVL Boost software was used to analyse characteristics of the gasoline engine when operating with different mixtures of ethanol, methanol, butanol, and gasoline (by volume). Results obtained from different fuel blends showed that when alcohol blends were used, brake power decreased and the brake specific fuel consumption increased compared to when using gasoline, and CO and HC concentrations decreased as the fuel blends percentage increased.

scholarly journals High Speed Shadowgraphy of Transparent Nozzles as an Evaluation Tool for In-Nozzle Cavitation Behavior of GDI Injectors

2017 ◽  
Author(s):  
Dmitrii Mamaikin ◽  
Tobias Knorsch ◽  
Philipp Rogler ◽  
Philippe Leick ◽  
Michael Wensing
Keyword(s):  
High Speed ◽  
Gasoline Engine ◽  
Transient Flow ◽  
Direct Injection ◽  
Ambient Air ◽  
Gasoline Direct Injection ◽  
Fuel Injector ◽  
Evaluation Tool ◽  
Long Distance ◽  
Cavitation Behavior

Gasoline Direct Injection (GDI) systems have become a rapidly developing technology taking up a considerableand rapidly growing share in the Gasoline Engine market due to the thermodynamic advantages of direct injection. The process of spray formation and propagation from a fuel injector is very crucial in optimizing the air-fuel mixture of DI engines. Previous studies have shown that the presence of some cavitation in high-pressure fuel nozzles can lead to better atomization of the fluid. However, under some very specific circumstances, high levels of cavitation can also delay the atomization process; spray stabilization due to hydraulic flip is the most well-known example. Therefore, a better understanding of cavitation behavior is of vital importance for further optimization of next generation fuel injectors.In contrast to the abundance of investigations conducted on the inner flow and cavitation patterns of diesel injectors, corresponding in-depth research on the inner flow of gasoline direct-injection nozzles is still relatively scarce. In this study, the results of an experiment performed on real-size GDI injector nozzles made of acrylic glass are presented. The inner flow of the nozzle is visualized using a high-power pulsed laser, a long-distance microscope and a high- speed camera. The ambiguity of dark areas on the images, which may represent cavitation regions as well as ambient air drawn into the nozzle holes, is resolved by injecting the fuel both into a fuel or gas filled environment. In addition, the influence of backpressure on the transient flow characteristics of the internal flow is investigated. In good agreement with observations made in previous studies, higher backpressure levels decrease the amount of cavitation inside the nozzles. Due to the high temporal and spatial resolution of the experiment, the transient cavitation behavior during the opening, quasi-steady and closing phases of the injector needle motion can be analyzed. For example, it is found that cavitation patterns oscillate with a characteristic frequency that depends on the backpressure. The link between cavitation and air drawn into the nozzle at the beginning of injection is alsorevealed.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4639

Development of a Low Pressure Direct Injection System for a Small 2S Engine. Part II - Experimental Analysis of the Engine Performance and Pollutant Emissions

2015 ◽  
Author(s):  
Luca Romani ◽  
Giovanni Vichi ◽  
Giovanni Ferrara ◽  
Francesco Balduzzi ◽  
Paolo Trassi ◽  
...  
Keyword(s):  
Experimental Analysis ◽  
Direct Injection ◽  
Engine Performance ◽  
Low Pressure ◽  
Pollutant Emissions ◽  
Injection System ◽  
Engine Part

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.

Experimental and numerical analyses of the combustion process in a direct injection gasoline engine

2000 ◽  
Vol 1 (2) ◽  
pp. 147-161 ◽  
Author(s):  
J Reissing ◽  
H Peters ◽  
J. M. Kech ◽  
U Spicher
Keyword(s):  
Numerical Investigation ◽  
Gasoline Engine ◽  
Numerical Models ◽  
Direct Injection ◽  
Combustion Process ◽  
Experimental Methods ◽  
Spark Ignition Engine ◽  
Gasoline Direct Injection ◽  
Direct Injection Gasoline Engine ◽  
Gdi Engines

Gasoline direct injection (GDI) spark ignition engine technology is advancing at a rapid rate. The development and optimization of GDI engines requires new experimental methods and numerical models to analyse the in-cylinder processes. Therefore the objective of this paper is to present numerical and experimental methods to analyse the combustion process in GDI engines. The numerical investigation of a four-stroke three-valve GDI engine was performed with the code KIVA-3V [1]. For the calculation of the turbulent combustion a model for partially premixed combustion, developed and implemented by Kech [4], was used. The results of the numerical investigation are compared to experimental results, obtained using an optical fibre technique in combination with spectroscopic temperature measurements under different engine conditions. This comparison shows good agreement in temporal progression of pressure. Both the numerical simulation and the experimental investigation predicted comparable combustion phenomena.

Investigations on Low Pressure Gasoline Direct Injection for a Standard GDI Combustion System

2010 ◽  
Author(s):  
Stephan Schmidt ◽  
Martin Joyce ◽  
Jonathan Wall ◽  
Alexander Trattner ◽  
Roland Kirchberger ◽  
...  
Keyword(s):  
Direct Injection ◽  
Low Pressure ◽  
Gasoline Direct Injection ◽  
Combustion System
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