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Heavy-duty aerodynamic testing for CO2 certification: A methodology comparison

Intl. Council on Clean Transportation-J. Felipe Rodriguez, Oscar Delgado
University of Technology Graz-Martin Rexeis, Martin Röck
  • Technical Paper
  • 2019-01-0649
To be published on 2019-04-02 by SAE International in United States
Air drag testing is a key component of the CO2 certification schemes for heavy-duty vehicles around the world. This paper presents and compares the regulatory approaches for measuring the air drag coefficient of heavy-duty vehicles in Europe, which uses a constant-speed test, and in the United States and Canada, which use a coastdown test. Two European trucks and one North American truck were tested using the constant-speed and coastdown methods. When corrected to zero yaw angle, a difference of over 10% was observed in the measured drag coefficients from the US coastdown procedure and the EU constant-speed test. The differences in the measured air drag coefficient can be attributed to the data post-processing required by each methodology, the assumptions in the speed-dependence of the tire rolling resistance, unaccounted frictional losses in the differential axle and transmission, as well as the behavior of the automated manual transmission during the coastdown run.
 

Research on Key Factors for Range and Energy Consumption of Electric Vehicles

Chongqing Changan New Energy Auto Co.Ltd.-Chen Zhao, Guan Gong, Cheng Yu, Ying Liu, Shu Zhong, Yanxing Song, Chenghao Deng, Anjian Zhou, Honglu Ye
  • Technical Paper
  • 2019-01-0723
To be published on 2019-04-02 by SAE International in United States
Investigations have been carried out to examine the potential to optimize the energy consumption and drive range of the Electric Vehicles (EV). Theoretically, the energy consumption is strongly influenced by system efficiency, coasting resistance and energy recovery technology. In this paper, these three aspects have been studied in detail through both simulation tool and experimental test. Research has been conducted on a Changan sedan EV to explore the influence of each factor on the energy consumption and drive range. The most paramount factor is the vehicle coasting resistance, followed by the power-train system efficiency. To reduce the coasting resistance, interests can be drawn to the application of tire with low resistance coefficient, low friction brake clamp and the modification of vehicle styling. The drive-train efficiency includes the motor efficiency, inverter efficiency and the gearbox efficiency. Interestingly, the effect of energy recovery technology is sensitive to the driving conditions. The I-pedal technology which can supply deceleration up to 0.2g has little influence over NEDC but can extend the range over real-world driving by up to 10%…
 

Development of Plastic Region Tightening 1.6-GPa Ultra-High Strength Bolt with High Delayed Fracture Resistance

Daido Steel Co., Ltd.-Tomohiro Ando
Ikeuchi Seiko Co., Ltd.-Hitoshi Kodama
  • Technical Paper
  • 2019-01-1116
To be published on 2019-04-02 by SAE International in United States
In our new Variable compression Turbo (VC-Turbo) engine, which has multi-link system to control the compression ratio (from 8:1 to 14:1 with this system), the high axial force is required for fastening of multi-link system which has the high input and down-sizing requirement. Therefore, it was necessary to develop the fastening bolts of the 1600MPa tensile length. The biggest issue of high strength bolt is delayed fracture with hydrogen embrittlement. In this study, the quenched and tempered alloy steels were chosen for 1600MPa tensile strength bolt by taking into account mass production and low cost. To improve the delayed fracture resistance, we proceeded the optimization of chemical composition and heat treatment condition as follows, 1) high-C and high-Si steel as a base to obtain sufficient strength even at high tempering temperature (around 600 degree) to make the fine and spherical carbide microstructure, 2) combined addition of Si, Cr and Mo as alloying elements for increasing temper softening resistance, 1.5% or more of precipitation hardening type element Mo was required to achieve high temperature tempering. We…
 

Numerical Analysis using Fast RANS simulations and Comparison with Experimental Measurements for Closed and Open Grille Realistic Car Models

Simerics Inc.-Sujan Dhar, Yu Jiang
  • Technical Paper
  • 2019-01-0655
To be published on 2019-04-02 by SAE International in United States
Over the past few years, the DrivAer car geometry has driven development of simulation methodology for vehicle aerodynamics. Due to the realistic geometry of the DrivAer car model the results obtained from simulations can be easily extended to the aerodynamic design process of production vehicles. This paper details a comprehensive CFD study of all three variants of the DrivAer car geometries: Fastback, Notchback and Estate configurations. The most realistic geometry was chosen for each of the variants; with detailed underbody, wheels and mirrors. In addition to the closed-grille standard DrivAer models, the open–grille variant has also been simulated. Simulations are performed both with and without ground simulation. Mesh generation was performed without surface alterations (e.g. wrapping) using a novel Binary-Tree automatic unstructured mesher. All simulations were performed using RANS turbulence model. A consistent modeling methodology was developed that was rigorously applied to all variants of the DrivAer model and the simulations are shown to have consistently good agreement with experimental measurements. This demonstrates the potential of using such a methodology for several different types of…
 

An Investigation of Aerodynamic Characteristics of Three Bluff Bodies in Close Longitudinal Proximity

Coventry University-Geoffrey Le Good, Peter Boardman, Max Resnick, Brian Clough
  • Technical Paper
  • 2019-01-0659
To be published on 2019-04-02 by SAE International in United States
The benefit in fuel-saving for road vehicles travelling in close longitudinal proximity stems from the potential reduction in total aerodynamic drag compared to the sum of that for the same number of vehicles when travelling alone. Research in the 1980s considered travelling in close proximity, termed “platooning”, as a means for reducing congestion, but the aerodynamic drag reduction and fuel-savings found in wind tunnel tests and road-trials became the primary focus of further investigations. Practical application was limited by the lack of systems to control vehicle spacing which was critical to the aerodynamic efficiency of the platoon and for safety. However, vehicle communication and control systems associated with the recent development of connected and autonomous vehicles has provided greater opportunity for platooning to be considered again within future traffic management systems. Early research involving passenger cars, and also more recent studies using heavy goods vehicles, has been based on ‘vehicle spacing’ as the test variable. Platoons were of homogeneous constituents and the aerodynamic characteristics of most vehicles in these studies comprised large separated wakes –…
 

Research into Running Resistance Correction Technology Focused on Tire Temperature and a Tire Heat Balance Model

Honda R&D Co., Ltd.-Takeshi Hotaka, Tomonori Sakai, Hideki Miura
  • Technical Paper
  • 2019-01-0623
To be published on 2019-04-02 by SAE International in United States
Basic practice is currently to measure running resistance outdoors, so the weather environment at the time of the testing has a great impact on the data. Laws enacted by individual countries about the influences of the natural environment stipulate the testing environment at the time of measurement, and correction methods have been set. Running resistance is divided between rolling resistance and aerodynamic drag, and both are corrected to standard temperature (20°C), using the air temperature at the time of measurement, under the current regulation correction. This kind of correction by air temperature alone may be unable to correctly reflect current rolling resistance. We recognize the following two issues: One is that, compared to conventional tires, the rolling resistance of low fuel consumption tires of recent years is more highly dependent on temperature. The other is the factor of tire temperature variation relative to air temperature at the time of measurement. This paper focuses on factors such as tire temperature properties, and has established correction technology by using a special rolling tester. Specifically, we used a…
 

Added masses and volumes of stationary bodies in non-uniform streams

Miroslav Mokry
  • Technical Paper
  • 2019-01-0661
To be published on 2019-04-02 by SAE International in United States
The added mass is an abstract concept that found its usefulness in the determination of the forces and moments on bodies accelerating in an otherwise still fluid. It is based on the observation that a body accelerating relative to the surrounding fluid changes the kinetic energy of the fluid. In manner analogous to Newton’s second law of motion, the force that the body must exert to accelerate the surrounding fluid is identified as the product of the acceleration and the mass of the fluid, “added” to that of the body. Equivalent results can be obtained for a stationary body in unsteady flow, with the exception of fluid rotations. The connection between the added masses and the forces on stationary bodies in steady, non-uniform streams can be established using the long wave analogy. Similarly to the “volume times pressure gradient” formula in hydrostatics, of interest is rather the added volume than the mass of the fluid added to that of the body. Since the added volume is a tensor, the direction of the pressure gradient may…
 

On-line Lithium-Ion Battery State-of-Power Prediction By Twice Recursive Method Based On Dynamic Model

Tongji University-Xiaoyue Wang, Xuezhe Wei, Haifeng Dai
  • Technical Paper
  • 2019-01-1311
To be published on 2019-04-02 by SAE International in United States
State-of-Power (SoP) prediction of Li-ion battery is necessary in battery management system for electric vehicles in order to deal with limited conditions, prevent overcharge and over discharge situations, increase the life of battery and provide effective battery operation. This article suggests a method to on-line predict the 10-s discharge and 10-s charge peak power of Li-ion battery cell by twice recursions. First based on dynamic battery model we use the first recursion based on least square method to get parameters which are influenced by the state of charge of Li-ion battery, temperature, etc. The dynamic model is derived according to equivalent circuit model of battery. Current and voltage are inputted online into the battery model. By recursion based on least square method the parameters are updated real time. Moreover, when we use recursive method to get real-time parameters, we add a extra proper parameter to abandon old data, which increase the real-time capability of state-of-power prediction. Next we derive the formula of 10-s resistance by the second recursion. By assuming constant current input and using…
 

Numerical Simulations of Performance of Plate Fin Tube Heat Exchanger using Rectangular Winglet type Vortex Generator with Punched holes

Guru Jambheshwar University of Science & Technology-Munish Gupta
Indian Institute of Technology- Delhi-Aditya Roy
  • Technical Paper
  • 2019-01-0145
To be published on 2019-04-02 by SAE International in United States
Heat transfer performance of fin-tube heat exchanger can be enhanced by using longitudinal vortex generators which produces longitudinal vortices. In the present work numerical simulations have been performed to investigate the heat transfer and flow resistance characteristics of rectangular winglet pair type vortex generators (VGs) with a punched hole of circular shape (RWPH). RWPH have been placed in Common Flow Down (CFD) and Common Flow Up (CFU) configuration in downstream as well as upstream direction. Heat transfer characteristics and flow behavior have been compared for both the configurations i.e. CFD and CFU, in downstream as well as upstream using Colburn’s factor(j), friction factor(f) and performance evaluation criterion, R = (j/j0)/(f/f0)1/3. Simultaneously, Reynolds number has been varied from 1400 to 9000. The punched hole considerably improves the thermohydraulic performance of RWP and decreases the flow resistance due to a reduction in the face area. The result shows the comparisons of using RWP with a punched hole in different configurations and locations for heat transfer augmentation.
 

Impedance Modeling and Aging Mechanisms of the Lithium-ion Batteries using the EIS Technique

Tongji University-Qian Gao, Haifeng Dai, Xuezhe Wei, Bo Jiang
  • Technical Paper
  • 2019-01-0596
To be published on 2019-04-02 by SAE International in United States
Along with the rapid progress of electric vehicles (EVs), the battery’s producing and managing technologies attach increasingly general attention. Among them, the methods of estimating the state of health (SoH) and predicting remaining useful life become the focus, which are essential to ensure their reliability and optimum performance over time. This paper mainly focuses on impedance modeling and aging studies (aging diagnosis and life prediction) of lithium-ion batteries. Electrochemical impedance spectroscopy (EIS) technique is used to obtain impedance characteristic of batteries. On the one hand, equivalent circuit modeling can be motivated by EIS, with the goal to fit measured impedance data using circuit elements. On the other hand, the aging research of batteries can be analyzed using the resistance information provided by EIS due to the correlation between battery resistance and lifetime. This paper provides the possible causes of battery aging based on changes in the impedance spectrum, which are obtained under different life conditions through an accelerated life test. According to the result and the corresponding electrode process, an improved Randels model is then…