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The Virtual Engine Development for Enhancing the Compression Ratio of DISI-Engines by Means of Water Injection and Variable Valve Timing

FKFS-Antonino Vacca, Francesco Cupo, Marco Chiodi, Michael Bargende
Ford Werke GmbH-Oliver Berkemeier, Maziar Khosravi
  • Technical Paper
  • 2020-37-0010
To be published on 2020-06-23 by SAE International in United States
With the aim of significantly reducing emissions, while keeping CO2 production under control, gasoline engines are faced with a new challenge to survive the constraints imposed by the RDE cycles. Current downsized engines are developed with the most recent techniques for increasing efficiency, such as high direct injection pressure, selective valve actuation, variable turbine geometry, and innovative thermal management system. The factor limiting their further step towards enhanced efficiency is the onset of abnormal combustion process. Therefore the challenge for the further boost of modern engine efficiency is the improvement of the combustion process. Different combustion technics such as HCCI and the employment of pre-chamber have been investigated, but the possibility of effectively use them in a wide range of the engine map, by fulfilling at the same time the needing of fast load control are still limiting their dissemination. For these reasons the technologies for improving the characteristics of a standard combustion process are still deeply investigated. Among these water injection in combination with either early or late intake valve closing offers the possibility…
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A CFD Model of Supercritical Water Injection for ICEs as Energy Recovery System

University of Basilicata-Antonio Cantiani, Annarita Viggiano, Vinicio Magi
  • Technical Paper
  • 2020-37-0001
To be published on 2020-06-23 by SAE International in United States
Supercritical water injection for ICEs may be a valid option to recover engine wall heat transfer and energy from exhaust gases, with benefits in terms of efficiency and performances. Water is recovered from exhaust gases and is brought up to supercritical conditions by employing the waste heat during engine operations. A preliminary study of this energy recovery approach has already been performed in an authors’ previous work, by employing a port fuel injection (PFI) internal combustion engine quasi-dimensional model, which has been validated against experimental data, returning satisfactory results in terms of overall efficiency gain. In this work, in order to obtain a more reliable and accurate evaluation of the achievable energy recovery with supercritical water injection, a multidimensional CFD model of the engine has been set and validated. As regards the engine geometry, a simplified axial symmetric engine has been used, in order to reduce the computational time and storage. The combustion has been modelled with an ECFM model using an 88-species and 349-reactions chemical kinetics mechanism, in order to evaluate the pollutant emissions…
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Experimental Study of Additive-Manufacturing-Enabled Innovative Diesel Combustion Bowl Features for Achieving Ultra-low Emissions and High Efficiency

GM Global Propulsion Systems-Giacomo Belgiorno, Andrea Boscolo, Gennaro Dileo, Fabio Numidi, Francesco Concetto Pesce, Alberto Vassallo
Istituto Motori CNR-Roberto Ianniello, Carlo Beatrice, Gabriele Di Blasio
  • Technical Paper
  • 2020-37-0003
To be published on 2020-06-23 by SAE International in United States
In recent years the research on Diesel thermodynamics has been increasingly shifting from performance and refinement to ultra-low emissions and efficiency. In fact, the last two attributes are key for the powertrain competitiveness in the automotive electrified future, especially in European market where 95gCO2/km fleet average and Euro6d RDE Step2 are phasing in at the same time. The present paper describes some of the most innovative research that GM and Istituto Motori Napoli are performing in the field, exploring how the steel additive manufacturing can be used to create innovative combustion bowl features that optimize the combustion process to a level that was not compatible with standard manufacturing technologies. In particular, an innovative highly-reentrant sharp-stepped profile featuring radial-lips has been studied on a 0.5l single-cylinder engine, coupled to a state of art 2500bar fast-acting fuel injection system, with the objective to demonstrate the full potential of optimized fuel stratification and spray separation enabled by the radial mixing zone concept. The results confirm that excellent reduction of engine-out emissions vs a Euro6-b design could be achieved…
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Advanced Methods to handle LSPI in TGDI engines

MAHLE Engine Components India, Chennai-Hariprasath ARIVUKKARASU, Rajkumar Mani
Vellore Inst. of Technology, Vellore-Sekarapandian N, Ashok KANNAIYAN, Selvaraji Muthu
  • Technical Paper
  • 2020-28-0008
To be published on 2020-04-30 by SAE International in United States
In order to meet the stringent emission norms like EU6 and EU7 together with CAFÉ/CAFC norms, down-sizing of the engine is one of the thrust areas of focus among the OEMs. To this end, keeping the engine size small but to achieve the required power output, advanced Turbo charged Gasoline Direct Injection engine technology (TGDI) has emerged. However, TGDI technology is susceptible to an abnormal combustion phenomenon termed as Low Speed Pre-Ignition (LSPI) event. This event happens prior to the intended combustion, which causes the catastrophic engine damage. Several studies in terms of simulation and experiments to understand this phenomenon are reported in the literature. The main factors influencing this occurrence are found to be engine design and calibration, fuel types and engine oil formulation (in terms of calcium content). In this paper, advanced methods to handle the LSPI occurrence severity and component level advances in design robustness to avoid the engine damage are reported. The developed techniques include robust piston design, advanced pin coating, Piston ring design and coating technologies. In overall, the techniques…
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Downsized-Boosted Gasoline Engine with Exhaust Compound and Dilute Advanced Combustion

General Motors LLC-Jeremie Dernotte, Paul M. Najt, Russell P. Durrett
  • Technical Paper
  • 2020-01-0795
To be published on 2020-04-14 by SAE International in United States
This article presents experimental results obtained with a disruptive engine platform, designed to maximize the engine efficiency through a synergetic implementation of downsizing, high compression-ratio, and importantly exhaust-heat energy recovery in conjunction with advanced lean/dilute low-temperature type combustion. The engine architecture is a supercharged high-power output, 1.1-liter engine with two-firing cylinders and a high compression ratio of 13.5: 1. The integrated exhaust heat recovery system is an additional, larger displacement, non-fueled cylinder into which the exhaust gas from the two firing cylinders is alternately transferred to be further expanded.The main goal of this work is to implement in this engine, advanced lean/dilute low-temperature combustion for low-NOx and high efficiency operation, and to address the transition between the different operating modes. Those include well-mixed charge compression-ignition at low-load, and a mixed-mode combustion at higher loads, before transitioning to boosted homogenous and stochiometric spark-ignited combustion. Here, the mixed-mode combustion strategy is composed of a deflagration of a stratified mixture created by a late direct injection, then triggering a controlled autoignition of the surrounding gas, improving the robustness…
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Numerical Modeling of Spray Formation under Flash-boiling Conditions

ANSYS Inc-Mingyuan Tao, Long Liang, Yue Wang, Ellen Meeks
  • Technical Paper
  • 2020-01-0328
To be published on 2020-04-14 by SAE International in United States
Flash boiling occurs in sprays when the ambient gas pressure is lower than the saturation pressure of the injected fuel. In the present work, a numerical study was conducted to investigate solid-cone spray behaviors under various flash-boiling conditions. A new spray cone angle correlation that is a function of injection parameters was developed and used for spray initialization at the nozzle exit to capture plume interactions and the global spray shape. The spray-breakup regime control was adjusted to enable catastrophic droplet breakup, characterized by Rayleigh-Taylor (RT) breakup, near the nozzle exit. The model was validated against experimental spray data from five different injectors, including both multi-hole and single-hole injectors, with injection pressure varying from 100 to 200 bar. Different fuels, including iso-octane, n-heptane, n-pentane, ethanol, and n-butanol, were investigated under a wide range of flash-boiling conditions, in which flash boiling was induced by high injected fuel temperature, ranging from 323 to 493 K, and/or low ambient gas pressure, ranging from 0.1 bar to atmospheric. It is found that flash boiling can significantly increase the spray…
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Effects of Direct Injection Timing and Air Dilution on the Combustion and Emissions Characteristics of Stratified Flame Ignited (SFI) Hybrid Combustion in a 4-Stroke PFI/DI Gasoline Engine

Brunel University London-Hua Zhao
CATARC-Jian-Jun Yang, Shuang-Xi Liu, Haiyang Gao
  • Technical Paper
  • 2020-01-1139
To be published on 2020-04-14 by SAE International in United States
Controlled Auto-Ignition (CAI) combustion can effectively improve the thermal efficiency of conventional spark ignition (SI) gasoline engines, due to shortened combustion processes caused by multi-point auto-ignition. However, its commercial application is limited by the difficulties in controlling ignition timing and violent heat release process at high loads. Stratified flame ignited (SFI) hybrid combustion, a concept in which rich mixture around spark plug is consumed by flame propagation after spark ignition and the unburned lean mixture closing to cylinder wall auto-ignites in the increasing in-cylinder temperature during flame propagation, was proposed to overcome these challenges. The combustion and emissions characteristics in the SFI hybrid combustion were experimentally investigated in a single-cylinder 4-stroke gasoline engine operating at medium to high loads when direct injection timing was retarded from -100 °CA to -40 °CA after top dead center (ATDC) and excess air coefficient was increased from 1.0 to 1.2 at the direct injection ratio of 30%. The experimental results show that direct injection timing and excess air coefficient control the ignition timing and combustion duration. Ignition timing advances…
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Investigation of Diesel/Natural Gas RCCI Combustion Using Multiple Reaction Mechanisms at Various Engine Operating Conditions

FEV North America Inc.-Mufaddel Dahodwala, Satyum Joshi, Erik Koehler, Michael Franke, Dean Tomazic
Michigan Technological University-Jeffrey Naber
  • Technical Paper
  • 2020-01-0801
To be published on 2020-04-14 by SAE International in United States
Past experimental studies conducted by the current authors on a 13 liter 16.7:1 compression ratio heavy-duty diesel engine have shown that diesel /natural gas Reactivity Controlled Compression Ignition (RCCI) combustion targeting low NOx emissions becomes progressively difficult to control as the engine load is increased due to difficulty in controlling reactivity levels at higher loads. For the current study, CFD investigations were conducted using the SAGE combustion solver in Converge with the application of Rahimi mechanism. Studies were conducted at a load of 5 bar BMEP to validate the simulation results against RCCI test data. In the low load study, it was found that the Rahimi mechanism was not able to predict the RCCI combustion behavior for diesel injection timings advanced beyond 30bTDC. This behavior was found at multiple engine speed and load points. To resolve this, multiple reaction mechanisms were evaluated and a new reaction mechanism that combines the GRI Mech 3.0 mechanism with the Chalmers mechanism was proposed. This mechanism was found to accurately predict the ignition delay and combustion behavior with early…
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Design and Simulation of a Multi Fuel Gas Mixture System of a Rotary Engine

University of Applied Sciences Zwickau-Tobias Dost, Joern Getzlaff
  • Technical Paper
  • 2020-01-0548
To be published on 2020-04-14 by SAE International in United States
The paper first includes the main objective and boundary conditions for design and simulation of a multi fuel gas mixture system of a rotary engine. New regenerative fuels are more and more important for use in automotive propulsion and stationary applications of combustion engines. Due the special design and operation of rotary engines there are opportunities for running these engines in future electric and hybrid applications with new designed liquids and gaseous fuels based on regenerative energy sources. The focus is on basic research and analyses of main physical and thermodynamic properties of separate lean burn gases (lower calorific value, mixed calorific value, AFR) and their effects on fuel mixing and combustion behavior. The work is focused on the development of simulation models capable to simulate the entire engine process and to map all factors influencing mixture formation and combustion of unconventional gaseous fuels. Moreover, analytical methods and modellation of the power estimation and fuel mixing are compared with 1d simulations of the fuel mixing and rotary engine thermodynamic performance. Analytical modells and calculations estimate…
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Numerical Investigation of the Combustion Kinetics of Partially Premixed Combustion (PPC) Fueled with Primary Reference Fuel

King Abdullah University of Science & Technology-Xinlei Liu
Tianjin University-Yuanyuan Zhao, Hu Wang, Daojian Liu, Wang Chen, Hongyan Zhu, Mingfa Yao
  • Technical Paper
  • 2020-01-0554
To be published on 2020-04-14 by SAE International in United States
This work numerically investigates the detailed combustion kinetics in a gasoline compression ignition (GCI) engine using three fuel injection strategies, including single-injection, double-injection, port fuel injection and direct injection (PFI+DI). A reduced Primary Reference Fuel (PRF) chemical kinetics mechanism was coupled with CONVERGE-SAGE CFD model to predict GCI combustion under various operating conditions. To provide insight into key reaction pathways, a post-process tool was used. The validated Converge CFD code with the PRF chemistry and the post-process tool was applied to investigate how the ignition occurs during the low-to high-temperature reaction transition and how it varies due to single- and double-injection and PFI+DI injection strategies. Three characteristic GCI combustion features were selected: (1) initial low temperature heat release (LTHR); (2) intense LTHR, where both iso-octane and n-heptane were converted to intermediates through oxygen-related reactions; (3) early stage high temperature heat release (HTHR) with CH2O as the core source species. It is found that the heat release was primarily dominated by the reaction H+O2 (+M)=HO2 (+M) and AC8H¬17+O2=AC8H17O2 during LTHR. For single- and double-injection, the high…