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A Priori Analysis of Acoustic Source Terms from Large-Eddy Simulation in Turbulent Pipe Flow

Graz University of Technology-Johannes Tieber, Helfried Steiner
  • Technical Paper
  • 2020-01-1518
To be published on 2020-06-03 by SAE International in United States
The absence of combustion engine noise pushes increasingly attention to the sound generation from other, even much weaker, sources in the acoustic design of electric vehicles. The present work focusses on the numerical computation of flow induced noise, typically emerging in components of flow guiding devices in electro-mobile applications. The method of Large-Eddy Simulation (LES) represents a powerful technique for capturing most part of the turbulent fluctuating motion, which qualifies this approach as a highly reliable candidate for providing a sufficiently accurate level of description of the flow induced generation of sound. Considering the generic test configuration of turbulent pipe flow, the present study investigates in particular the scope and the limits of incompressible Large-Eddy Simulation in predicting the evolution of turbulent sound sources to be supplied as source terms into acoustic analogies, which have been proposed for the computation of the acoustic pressure field. To this end, a comprehensive a priori analysis of fully resolved flow fields obtained from Direct Numerical Simulations (DNS) was carried out for different Reynolds numbers. The analysis of the…
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Iterative study to improve Air flow distribution on ventilation unit duct using CFD analysis

Subros Limited-ANIT SEN
Subros Ltd-SOMNATH SEN, Arunkumar Goel
  • Technical Paper
  • 2020-28-0030
To be published on 2020-04-30 by SAE International in United States
The aim of this paper is to optimize ventilation unit to meet desirable flow distribution on various ports of the ventilation unit. The adapter is modified and simulation is done on the various design changes. CFD analysis is carried out on the ventilation unit with iterative design and achieved the target airflow and distribution. The analysis been carried out on star CCM+ software. The same been validated on the final proto part developed and tested.
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Thermal management of electrified vehicle by means of system simulation

Gamma Technologies, LLC-Sanket Shah, Dig Vijay, Marek Lehocky
  • Technical Paper
  • 2020-28-0033
To be published on 2020-04-30 by SAE International in United States
With an objective of improving the range as well as other safety and comfort aspects, thermal management becomes increasingly important in the development of electrified vehicles both at the component as well as system level. The considerable increase in complexity of the thermal management system and its tighter interactions with the complete vehicle is driving an increasing trend towards system simulation compared to expensive testing. At the system level, different sub-systems interact with each other at varying extents. An example of one such strong interaction is between the coolant and AC circuits using battery chillers. Thermal management system simulation models must be capable of running such interactive systems. At the component level, ensuring the efficacy of the several components used in these intricately linked systems becomes increasingly important. An accurate prediction of temperature distribution inside the battery pack is essential to avoid damaging situations such as thermal runaway. An integrated approach of 1D-flow inside the cooling plates combined with 3D-thermal analysis of battery cells and cooling plates in GT-SUITE is described in this study. Also,…
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Automated Driving System Safety: Miles for 95% Confidence in “Vision Zero”

Driving Safety Consulting LLC-Richard Allen Young
  • Technical Paper
  • 2020-01-1205
To be published on 2020-04-14 by SAE International in United States
Engineering reliability models from RAND, MobilEye, and Volvo concluded that billions of miles of on-road data were required to validate that the real-world fatality rate of an “Automated Driving System-equipped vehicle” (AV) fleet for an improvement over human-driven conventional vehicles (CV). RAND said 5 billion miles for 20%, MobileEye 30 billion for 99.9%, and Volvo 5 billion for 50% improvement. All these models used the Gaussian distribution, which is inaccurate for low crash numbers. The current study proposes a new epidemiologic method and criterion to validate real-world AV data with 95% confidence for zero to ten fatal crashes. The upper confidence limit (UL) of the AV fatal crash rate has to be lower than the CV fatal crash rate with 95% confidence. That criterion is met if the UL of the AV fatal crash incidence rate ratio estimate is below one. That UL was estimated using the mid-P exact method for calculating confidence limits for a dual Poisson process, using a one-tailed 95% confidence level. The required AV mileage was adjusted by trial and error…
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Improvement of Tightening Reliability of Bolted Joints Using Elliptical Confidence Limit in Calibrated Wrench Method

Tokyo Metropolitan University-Soichi Hareyama, Ken-ichi Manabe, Satoshi Kobayashi
  • Technical Paper
  • 2020-01-0218
To be published on 2020-04-14 by SAE International in United States
The calibrated wrench method is used in the tightening of bolts in manufacturing industries in the case of a large amount of tightening work. It is important to apply a large initial clamping force to ensure tightening reliability and prevent self-loosening, fatigue breakage, and so forth. In this method, the clamping force of bolted joints is controlled using a torque wrench. However, since the clamping force is indirectly applied by a wrench, it varies greatly in the case of a large amount of tightening in a factory. Therefore, the calibrated wrench method is not so accurate from the viewpoint of clamping force control. It is conventionally thought that the distribution of the clamping force has the shape of a rhombus. When tightening torque and clamping force are considered to be two independent random variables, the clamping force is distributed within an elliptical confidence limit. Here, we show that the distribution of equivalent stress also has an elliptical confidence limit. Considering the permitted limit for working load stress on a bolted joint, the elliptical distribution has…
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Development of Cooling Fan Model and Heat Exchange Model of Condenser to Predict the Cooling and the Heat Resistance Performance of Vehicle

Honda R&D Co., Ltd.-Yuichi Fukuchi, Kunihiko Yoshitake, Kazutaka Yokota
  • Technical Paper
  • 2020-01-0157
To be published on 2020-04-14 by SAE International in United States
The cooling performance and the heat resistance performance of commercial vehicle are balanced with aerodynamic performance, output power of power train, styling, the location of sensors, cost and many other parameters. Therefore, it is desired to predict the cooling performance and the heat resistance performance with high accuracy at the early stage of development. Three forms of heat transfer consist of conduction, convection and radiation. Among of these components, it is sometimes difficult to solve the thermal conduction accurately, because to prepare accurate shape and properties needs lots of time and efforts at the early stage of development. Therefore, the cooling performance of heat exchangers and the air temperature distribution in the engine compartment are predicted to access the cooling and the heat resistance performance of vehicle at the preliminary design stage. The air temperature distribution is dominated by the distribution of heat radiation on heat exchangers, the flow distribution which is produced by fans and thermal convection at the surface of parts in the engine compartment. For the case of middle or high vehicle…
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Development of a New High Orientation Paint System to Achieve Outstanding Real Metallic Designs

Toyota Motor Corporation-Takao Tsukimori
  • Technical Paper
  • 2020-01-0899
To be published on 2020-04-14 by SAE International in United States
High metallic silver colors using thin, smooth aluminum flake pigments are typically adopted for the luxury grades by each car manufacturer. Regarding the paint formulation for these types of colors, low non-volatile(N.V.) content and high aluminum flake pigment content are generally known to be necessary to achieve high metallic appearance designs. However, poor distribution of the aluminum flake pigments can cause mottling. In addition, a high concentration of aluminum flake pigments can result in a weak coating. Therefore, current paint systems are limited in the degree of high metallic appearance design that is possible. As a countermeasure to those problems, we investigated whether cellulose nanofiber (CNF) dispersion liquid can function as both the coating binder and rheology control agent in a new type of waterborne paint system. CNF is an effective rheology control agent because it forms strong hydrogen bonds with other fiber surfaces when it is dispersed for waterborne paint. For example, viscosity versus shear rate testing of an aqueous solution of 0.4wt% CNF and less than N.V. 5wt% showed a response curve similar…
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A Robust Methodology for Predicting the Fatigue Life of an Automotive Closures System Subjected to Hinge and Check Link Load

Ford India Pvt., Ltd.-Nirmal Puthuvayil, Sivasankari S
RLE India Pvt., Ltd.-Thoheer Zaman
  • Technical Paper
  • 2020-01-0599
To be published on 2020-04-14 by SAE International in United States
Quality in the automotive industry symbolizes the development and the manufacturing of vehicles whose specifications meet customer requirements. Among the quality issues, opening and closing effort of any closures in a vehicle is a characteristic that strongly affects the customer first opinion about vehicle design. The closure opening and closing effort is affected by different uncertainties like opening angle, load to the check-link, hinge stoppage, materials and manufacturing process. A check stop & hinge stop load durability cycle occurs when a customer opens the closures beyond the closure detent position with a force applied on the check link or hinge check stops. Due to few uncertainties like abuse opening, manufacturing imperfections, weak mounting locations, the closures will be subjected to fatigue failure. The present study is aimed to introduce a probabilistic frame-work for fatigue life reliability analysis that addresses the uncertainties associated with door opening-closing effort due to check-hinge loads, door closure opening angles and hinge stop tolerance. A fatigue life probabilistic model of various closure systems was developed using Monte-Carlo simulation, where the stress…
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The Review of Vehicle Purchase Restriction in China

Tsinghua University-Feiqi Liu, Han Hao, Fuquan Zhao, Zongwei Liu
  • Technical Paper
  • 2020-01-0972
To be published on 2020-04-14 by SAE International in United States
In the past two decades, rapidly expanding economy in China led to burst in travel demand and pursuit of quality of life. It further promoted the rapid growth of China's passenger car market. China had already become the largest vehicle sales country, exceeding the U.S. in 2010. By the end of 2018, there had been over 240 million cars in China, with over 200 million passenger cars. The surge of car ownership has also brought a series of problems, like traffic congestion, long commuting time, insufficient parking space, etc. Therefore, some local governments in China introduced vehicle purchase restriction policies to control the growth and gross of vehicle stock. Different cities issued different rules. Lottery and auction mechanisms both exist. There are also differences in classification and licensing of electric vehicles. However, with the recent slowdown of economic development, China's car sales began to decline in 2018, and the trend of 2019 is also not optimistic. As a result, the central government issued document, indicating that it is strictly forbidden to introduce new restrictions on…
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Impact of plasma length on flame kernel development under flow condition

University of Windsor-Hua Zhu, Qingyuan Tan, Xiao Yu, Zhenyi Yang, Li Liang, Ming Zheng, Graham Reader
Zhuzhou Torch Spark Plug Co., Ltd.-Jin Qian
  • Technical Paper
  • 2020-01-1114
To be published on 2020-04-14 by SAE International in United States
Advanced ignition systems with enhanced discharge current level have been extensively investigated in research, since they are highly regarded to have potentials to overcome challenges arisen when spark-ignition engines are running under lean or EGR diluted conditions. Local flow field is also of particularly importance to improve the ignitability of the ignition system as spark plasma channel is stretched under flow conditions, leading to more thermal spark energy distribution to the air-fuel mixture in the vicinity of the spark plug. Research results have shown that a constantly high discharge current is considered to be effective to maintain stable discharge with less restrikes and longer plasma holding period. However, with the further increase of the discharge current, plasma channel becomes thicker, and the stretched plasma length becomes shorter under certain flow speed, which may suppress the advantages of the presence of air flow. In this work, the interaction between discharge current level and plasma length under flow conditions is investigated. Whether a thick but short plasma or a thin but stretched long plasma are more effective…