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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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Research on Factors to Influence Coasting Resistance for Electric Vehicles

Changan Mazda Auto Company-Yong Ren
Chongqing Changan New Energy Auto Co Ltd-Guan Gong, Chen Zhao, Xiaohang Zhou, Chenghao Deng, Cheng Yu, Fuyong Yu, Anjian Zhou
  • Technical Paper
  • 2020-01-1068
To be published on 2020-04-14 by SAE International in United States
The research on coasting resistance is vital to electric vehicles, since the smaller the coasting resistance, the longer the coast-down distance. Vehicle resistance consists of rolling resistance, vehicle inner resistance and the aerodynamic drag. The vehicle inner resistance is mainly caused by driveline’s friction loss and oil splash loss. The rolling resistance is decided by tire resistance coefficient, which is influenced by tires and road conditions. And the aerodynamic drag is affected by vehicle’s shape and air. In this paper, four factors that are tire pressure, road surface condition, air circulating mode, and atmosphere temperature are examined. Experimental tests have been conducted on three different vehicles: one subcompact sedan, one compact sedan and one compact SUV. The outcome shows that, when the tire pressure is 20% less, the average coasting resistance is increased by 1% to 3% depending on vehicle types, which indicates an increase in energy consumption by 0.9% to 2.4%. On wet road surface, the average coasting resistance is increased by 10% - 20%, which could decrease the NEDC range by 6% to…
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Comparison of Different Methods for Panel Dent Resistance using Numerical Assessment and Influence of Materials used in Automotive Industry

Tata Technologies Ltd-Ashish Sathaye, Deepak Srivastava, Manivasagam Shanmugam
  • Technical Paper
  • 2020-01-0483
To be published on 2020-04-14 by SAE International in United States
Traditionally, the automotive outer panels, giving vehicle its shape, have been manufactured from steel sheets. The outer panels are subjected to loads due to wind loading, palm-prints, person leaning on the vehicle, cart hits, and hail stones for example. Consumer awareness about these two panel characteristics: Oilcanning and Dent resistance, has been increased through recent marketing studies. Apart from perceptive quality, another factor depending on the dent performance is insurance and respective cost implications. Dents can occur due to several reasons such as object hits, parking misjudgment, hail stones etc. Phenomenon can be divided in two types, static and dynamic denting. Static dent case covers scenario wherein interaction with outer panel is mostly quasi-static. Hail stones presents dynamic case where object hits a panel with certain kinetic energy. Automotive companies usually perform static dent assessment to cover all the cases. In this paper, scope is to discuss the comparison between two methods and its results using Finite Element Analysis. Influence of panel stiffness on dent resistance is also studied. Panel dent resistance depends on different…
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Material development for low viscosity oil

NOK Corporation-Keita Otani, Kenichi Kunieda, Yuki Sato
  • Technical Paper
  • 2020-01-0232
To be published on 2020-04-14 by SAE International in United States
In recent years, it is a big trend to decrease oil viscosity as regards in the drive-train system in order to progress the fuel efficiency by reducing frictional loss of each mechanical unit. However, we found that the oil-seal performance get worse in cold environment with applying the low viscosity oil, and it leads to oil leakage. The presumed mechanism is that the rubber material used in the oil-seal loses its flexibility at a low temperature to deteriorate the shaft runout followability, while the low viscosity oil can flow even such environment. Concerning rubber material, acrylic rubber (ACM) is widely used as a seal component for automobiles including drive-train system because it has a good balance of heat resistance, cold resistance, and oil resistance. As results of investigation low viscosity oil under development using our lineup ACM which has excellent low temperature property (TR-10:-37℃), we confirmed that the shaft runout limit deteriorates with decrease oil viscosity, and this result shows the need of further enhanced rubber material. In this study, we describe the improvement in…
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A Method for Simultaneous State of Charge, Maximum Capacity and Resistance Estimation of a Li-Ion Cell Based on Equivalent Circuit Model

Auburn Univ-Yang Hu
Auburn University-Saurabh Gairola
  • Technical Paper
  • 2020-01-1182
To be published on 2020-04-14 by SAE International in United States
Accurate estimation of the State of Charge (SOC), maximum capacity (Qmax) and internal resistance are critical for battery monitoring, i.e., determining the status, health, and performance figures of a battery. SOC is a key indicator of the instant status for battery systems, while Qmax and internal resistance are related to the capacity fade (SOHQ) and power fade (SOHP) respectively, which represent the abilities of a battery to store energy, retain charge over extended periods and provide the required power for acceleration, etc. Traditional methods using complex models and look-up tables have high computation requirements which makes them unsuitable for online applications. In this paper, we propose a simple method for simultaneous SOC, Qmax and internal resistance estimation based on a second-order equivalent circuit model (ECM). A Variable Model framework based Adaptive Extended Kalman filter (VM-AEKF) is implemented for joint SOC and model parameter estimation where the VM framework is designed specifically to improve the stability and accuracy of parameter estimation under conditions when the system is not sufficiently excited by the input signal. Simultaneously, a…
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Potential Analysis and Virtual Development of SI Engines Operated with Synthetic Fuel DMC+

FKFS-Cornelius Wagner, Michael Grill, Mahir-Tim Keskin
FKFS / University of Stuttgart-Michael Bargende
  • Technical Paper
  • 2020-01-0342
To be published on 2020-04-14 by SAE International in United States
On the way to emission-free mobility, future fuels must be CO2 neutral. To achieve this, synthetic fuels are being developed. In order to better assess the effects of the new fuels on the engine process, simulation models are being developed that reproduce the chemical and physical properties of these fuels. In this paper, the fuel DMC+ is examined. DMC+ (a mixture of DMC and MeFo mainly, characterized by the lack of C-C Bonds and high oxygen content) offers advantages with regard to evaporation heat, demand of oxygen and knock resistance. Furthermore, its combustion is almost particle free. With the aid of modern 0D/1D-Simulation methods, an assessment of the potential of DMC+ can be made. It is shown that the simulative conversion of a state-of-the-art gasoline engine to DMC+ (a mixture of DMC and MeFo mainly, characterized by the lack of C-C Bonds and high oxygen content) fuel offers advantages in terms of efficiency in many operating points even if the engine design is not altered. This is mainly due to the higher knock resistance and…
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Combustion Enhancement in a Gas Engine Using Low Temperature Plasma

Chiba Univ-Tatsuya Kuboyama
Chiba Univ.-Yasuo Moriyoshi
  • Technical Paper
  • 2020-01-0823
To be published on 2020-04-14 by SAE International in United States
Low temperature plasma ignition has been proposed as a new ignition technique as it has features of good wear resistance, low energy release and combustion enhancement. In the authors’ previous study, lean burn limit could be extended by low temperature plasma ignition while a voltage drop during discharge, leading to the transition to arc discharge, was found. In this study, the structure of plug and power supply’s performance with steep voltage rising with time, dV/dt, are examined to investigate the effects on combustion performance. As a result, the following conclusions were deduced. (1) The lean combustion limit was extended when a four-pole plug with IES power source was used due to volumetric ignition. (2) A modified one-pole plug to improve the electric insulation, leading to prevent the voltage drop, could not extend the lean limit due to less volumetric ignitability. The specifications of plug must be improved to expand the ignition volume. (3) Using a variable dV/dt power source, the effect of dV/dt was tested. The combustion characteristics were not affected by dV/dt in this…
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Sensitivity Analysis of Aerodynamic Drag Coefficient to EPA Coastdown Ambient Condition Variation

FCA US LLC-Todd Lounsberry, John Tripp, Gregory Fadler
  • Technical Paper
  • 2020-01-0666
To be published on 2020-04-14 by SAE International in United States
The test cycle average drag coefficient is examined for the variation of allowable EPA coastdown ambient conditions. Coastdown tests are ideally performed with zero wind and at SAE standard conditions. However, often there is some variability in actual ambient weather conditions during testing, and the range of acceptable conditions is further examined in detail as it pertains to the effect on aerodynamic drag derived from the coastdown data. In order to “box” the conditions acceptable during a coastdown test, a sensitivity analysis was performed for wind averaged drag ((CDW ) ̅) as well as test cycle averaged drag coefficients (CDWC) for the fuel economy test cycles. Test cycle average drag for average wind speeds up to 16 km/h and temperatures ranging from 5C to 35C, along with variation of barometric pressure and relative humidity are calculated. The significant effect of ambient cross winds on coastdown determined drag coefficient is demonstrated.
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An Experimental Methodology for Measuring Resistance Forces of Light-Duty Vehicles under Real-World Conditions and the Impact on Fuel Consumption

Aristotle University of Thessaloniki-Dimitrios Komnos, Leonidas Ntziachristos
European Commission Joint Research-Georgios Fontaras, Jelica Pavlovic, Biagio Ciuffo
  • Technical Paper
  • 2020-01-0383
To be published on 2020-04-14 by SAE International in United States
A key element of any vehicle-certification test is the use of representative values for the vehicle resistance forces. In most certification procedures, including the WLTP recently adopted by the EU, the latter is achieved mainly through coast down tests. Subsequently, the resistance values measured are used for setting up the chassis-dyno resistances applied during the laboratory measurements. These reference values are obtained under controlled conditions, while a series of corrections are applied to make the test procedure more repeatable and reproducible. In real driving, the reference road loads are influenced by a series of factors leading to a divergence between the certified fuel consumption values, and the real-world ones. An approach of calculating representative road loads during on-road tests can help to obtain a clearer view of vehicle efficiency and quickly validate the officially declared road loads. This approach is crucial also for validating simulations and achieving better estimates of the actual fuel consumption, a requirement introduced by the new policy adopted in the EU. In this direction, a series of on-road experiments were conducted,…
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Optimization of the Aerodynamic Lift and Drag of LYNK&CO 03+ with Simulation and Wind Tunnel Test

Dassault Systemes(Shanghai) Info Tech Co-Weiliang Xie, Bo Li, Xiaowei Zhao
Geely Automobile Research Institute-Qian Feng, Biaoneng Luo, Huixiang Zhang, Hong Peng, Zhenying Zhu, ZHI DING, Ling Zhu
  • Technical Paper
  • 2020-01-0672
To be published on 2020-04-14 by SAE International in United States
Based on the first sedan of the LYNK&CO brand from Geely, a high performance configuration with the additional aerodynamic package was developed. The aerodynamic package including the front wheel deflector, the front lip, the side skirt, the rear spoiler and the rear diffuser, were upgraded to generate enough aerodynamic downforce for better handing stability, without too much compromising of the aerodynamic drag of the vehicle to keep a low fuel consumption. Simulation approach with PowerFLOW, combined with the design space exploration method were used to optimize both of the aerodynamic lift and drag. Wind tunnel test was also used to firstly calibrate the simulation results and finally to validate the optimized design. The results turn out to be appropriate trade-off between the lift and the drag to meet the aerodynamics requirement, and a consistently good matching between the simulation and test.