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NVH Comfort of Range Extenders for Electric Vehicles

FEV Europe GmbH-Christoph Steffens, Georg Eisele, Frank Wolter
  • Technical Paper
  • 2020-01-1551
To be published on 2020-06-03 by SAE International in United States
The most appreciated driving characteristics of electric vehicles are the quietness and spontaneous torque rise of the powertrain. The application of range extenders (REX) with internal combustion engines (ICEs) to increase the driving range is a favourable solution regarding costs and weight, especially in comparison with larger battery capacities. However, the NVH integration of a REX is challenging, if the generally silent driving characteristics of electric vehicles shall remain preserved. This paper analyses key NVH aspects for a REX design and integration to fulfil the high expectations regarding noise and vibration comfort in an electric vehicle environment. The ICE for a REX is typically dimensioned for lower power outputs, incorporating a low number of cylinder units, which is even more challenging concerning the NVH integration. The basic REX concept is evaluated by considering power and fuel efficiency demands in combination with an interior noise forecast. It will be explained that sophisticated, innovative technologies are required on component and vehicle side to ensure best possible NVH comfort. On component side, essential excitations must be addressed. In…
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Dynamic behavior of in-cylinder pressure causing fatigue failure of reed valves

Subros Ltd.-Ankit Shukla, Paulson Parayil, Arun Kumar Goel, Kamal Sharma
  • Technical Paper
  • 2020-28-0031
To be published on 2020-04-30 by SAE International in United States
For years, researchers have presented numerous studies that consider interaction between working fluid and reed valve motion in displacement compressors. The computing capacities and available CFD and FEA simulation tools have allowed modeling of fully coupled interaction of fluids and moving structures. The present paper describes our experience and results from developing a simplified model of a multi-cylinder reciprocating piston compressor and estimation of pressure surge during sudden acceleration of such compressors. The results show that sudden speed change causes surge in pressures due to formation of pressure waves that reflect back and forth within cylinder. For the chosen geometry and operating conditions, the duration of such waves is much shorter (~ 0.2ms) as compared to longer response time of reed valves (1 ms) that are stiff and highly inelastic. These high pressure waves eventually exceed the fatigue limit of reed valves and cause failures. These pressure waves also influence the performance of reciprocating by causing noise and vibrations which eventually dissipate in to heat thereby lowering the COP of compressor. Simulation results compare well…
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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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On Maximizing Argon Engines' Performance via Subzero Intake Temperatures in HCCI Mode at High Compression Ratios

King Abdullah University of Science & Technology-Ali Elkhazraji, Abdulrahman Mohammed, Sufyan Jan, Jean-Baptiste Masurier, Robert Dibble, Bengt Johansson
  • Technical Paper
  • 2020-01-1133
To be published on 2020-04-14 by SAE International in United States
Maximizing the indicated thermal efficiency with minimal amount of emissions is one of the main challenges to overcome in the field of internal combustion engines. The main obstacle that hinders achieving this goal is the typically low thermodynamic efficiency which is the ratio of the positive produced work on the piston to the amount of heat released inside the cylinder. Many concepts and technologies were innovated to maximize the thermodynamic efficiency. One of the main guidelines that have been followed to achieve so, is the ideal Otto’s cycle that predicts that increasing the compression ratio and/or the specific heat ratio of the combustion reactants, will maximize the thermodynamic efficiency. This study combines both high compression ratios and a high specific heat ratio via two of the main approaches used to maximize the thermodynamic efficiency. First, is the HCCI combustion mode. HCCI is typically operated at fuel-lean conditions, allowing to operate at higher compression ratios without having intense knock (pressure waves, generated by undesired autoignition, that can damage the engine). Second, air was replaced by an…
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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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High-pressure laminar burning velocity measurements of ethanol- a Co-Optima fuel candidate

Public Authority for Applied Education & Training-Bader Almansour
University of Central Florida-Gihun Kim, Anthony Terracciano, Subith Vasu
  • Technical Paper
  • 2020-01-0332
To be published on 2020-04-14 by SAE International in United States
Co-Optimization of Fuels and Engines initiative (Co-Optima) of the U.S Department of Energy initiated investigations on several candidates of biofuels and blends for internal combustion engines. Several biofuels were selected by screening criteria, which were boiling point, toxicity, research octane number, octane sensitivity, laminar flame speed, and economical distribution system, etc. In this study, we focused our investigation on ethanol – a key fuel candidate. Measurements of properties such as ignition delay time and laminar burning velocity (LBV) are necessary for these fuels in order to understand their performance and applicability in engines. One key combustion metric is the fuel’s LBV in air over a range of equivalence ratios. LBV is dependent on reactive mixture composition, temperature, and pressure, but it is independent of hydrodynamic conditions, such as stretch rate, turbulent intensity, and Reynolds number. LBV is useful as it: (i) gives a measure of combustion efficiency and heat release rate; (ii) enables validation of chemical kinetic mechanisms; (iii) and gives engine design engineers a metric for the expected time required to burn the fuel…
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Stability of Flowing Combustion in Adaptive Cycle Engines

Illinois Institute of Technology-Prashanth Tamilselvam, Francisco Ruiz
  • Technical Paper
  • 2020-01-0296
To be published on 2020-04-14 by SAE International in United States
In an Adaptive Cycle Engine (ACE), thermodynamics favors combustion starting while the compressed, premixed air and fuel are still flowing into the cylinder through the transfer valve. Since the flow velocity is typically high and is predicted to reach sonic conditions by the time the transfer valve closes, the flame might be subjected to extensive stretch, thus leading to aerodynamic quenching. It is also unclear whether a single spark, or even a succession of sparks, will be sufficient to achieve complete combustion. Given that the first ACE prototype is still being built, this issue is addressed by numerical simulation using the G-equation model, which accounts for the effect of flame stretching, over a 3D domain representing a flat-piston ACE cylinder, both with inward- and outward-opening valves. A k-epsilon turbulence model was used for the highly turbulent flow field. It was found that the flame would suffer local blow-off under most operating conditions, but the blow-off is never complete so that the regions affected are later re-ignited by the remaining parts of the flame, and combustion…
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A Holistic Approach to Develop a Modern High Power Density Diesel Engine to Meet Best-in-class NVH levels.

Mahindra & Mahindra, Ltd.-Vikraman Vellandi, Prasad Namani, Rajkumar Bhagate, Madhu Chalumuru
  • Technical Paper
  • 2020-01-0406
To be published on 2020-04-14 by SAE International in United States
The ever-increasing customer expectations put a lot of pressure on car manufacturers to constantly reduce the noise, vibration and harshness (NVH) levels. This papers presents the holistic approach used to achieve best-in-class NVH levels in a modern high-power density 1.5 lit 4 cylinder diesel engine. The base engine architecture was designed with NVH reduction features such as crank-offset, cast iron crankcase, stiffened ladder frame, structural oil pan and front cover. Piston skirt profile was optimized to reduce the slapping noise by carefully studying the secondary motion and skirt contact pressure. The plastic parts such as cylinder head cover and intake manifold were designed with closely spaced ribs and high wall thickness. Natural frequency targets for different parts were set for the entire engine at component level and system level and confirmed through simulations. High frequency acoustic simulation was carried out to identify and improve the areas of high surface velocity. "Acoustic holography" technology was extensively used to identify the areas of high noise radiation in the running engine. Based on the measurements, it was identified…
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Numerical investigations on strong knocking combustion under compression ignition conditions

State Key Lab of Engines-Jiaying Pan
Tianjin University-Lin Chen, Jianfu Zhao
  • Technical Paper
  • 2020-01-1137
To be published on 2020-04-14 by SAE International in United States
Homogeneous charge compression ignition (HCCI) combined with high compression ratio is an effective way to improve engines’ thermal efficiency. However, the severe thermodynamic conditions at high load may induce knocking combustion thus damage engine body. In this study, compression ignition knocking characteristics were parametrically investigated through RCM experiments and simulation analysis. First, the knocking characteristics were optically investigated. The experimental results show that there even exists detonation when the knock occurs thus the combustion chamber is damaged. Considering both safety and costs, the effects of different initial conditions were numerically investigated and the results show that knocking characteristics is more related to initial pressure other than initial temperature. The initial pressure have a great influence on peak pressure and knock intensity while initial temperature on knock onset. Further analysis shows that knock intensity is mainly related to the energy density of the in-cylinder mixture and energy density is higher under higher pressure conditions. Then the effects of different cylinder wall temperature on the local auto-ignition thus knocking characteristics were further discussed. The results show that…
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Study on the Effect of Manifold Induction of Acetylene in a Dual-fuelled CI Engine

NIT Rourkela-Rakesh Kumar Sahoo, Akshat Jaiswal, Murugan Sivalingam
  • Technical Paper
  • 2020-01-0817
To be published on 2020-04-14 by SAE International in United States
The utilization of gaseous fuels in internal combustion (IC) engines is receiving more significant greater interest in recent years because of their better fuel mixing characteristics. Apart from potential gaseous fuels such as liquefied natural gas (LPG), compressed natural gas (CNG) and hydrogen, other gaseous fuels are being explored for their utilization in IC engines. The reason for this exploration is mainly because of the durability and robust nature of compression ignition (CI) engines, more research focuses on the utilization of a variety of gaseous fuels in CI engines. However, gaseous fuels need to be used in CI engines on dual fuel mode only. In this investigation, a single-cylinder, four-stroke, air-cooled diesel engine was converted into Acetylene run dual-fuel CI engine by changing the intake manifold of the test engine. Acetylene at three flow rates viz., 2lpm, 4lpm, and 6lpm were introduced into the intake port by manifold induction technique while Jatropha biodiesel was injected directly into the cylinder. In this paper, the effect of manifold induction of Acetylene on the performance and emission characteristics…