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Effect of Fender Coverage Angle on the Aerodynamic Drag of a Bicycle

Delhi Technological University-Vishesh Kashyap, B.B. Arora, Sourajit Bhattacharjee
Published 2019-10-11 by SAE International in United States
While riding cycles, cyclists usually experience an aerodynamic drag force. Over the years, there has been a global effort to reduce the aerodynamic drag of a cycle. Fenders affect the aerodynamic drag of a cycle to a large extent, and fender coverage has a pronounced effect on the same. In this article, various fender coverage angles, varying from 60° to 270°, were studied to predict the aerodynamic drag with the help of a validated CFD model in SolidWorks Flow Simulation. The model was based on the Favre-Averaged Navier-Stokes (FANS) equations solved using the k-ɛ model. It was predicted that aerodynamic drag coefficient reduced fender coverage angle up to 135°, and thereafter started increasing. Analyses were carried out at velocities of 6 m/s, 8 m/s and 10 m/s and the results were found to be similar, with a minimum aerodynamic drag coefficient at 135° occurring in all the cases under study. There was an observed optimum decrease in drag coefficient to the extent of 4.6%, 4.5% and 4.6% as compared to the bicycle without fenders for…
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Smart 24 V Battery Switch for a Reliable Redundant Power Supply in Commercial, Construction, and Agriculture Vehicles (CAV)

Infineon Technologies AG-Vincent Usseglio, Andre Mourrier
Published 2019-10-11 by SAE International in United States
For highly automated driving, commercial vehicles require an Electric/Electronic (E/E) architecture, which - in addition to sensor fusion - ensures safety-critical processes such as steering and braking at all times. Among other things, a redundant 24 V supply with corresponding disconnection is required. The battery switch is a key component. Commercial, construction, and agricultural vehicles (CAV) need to operate at the highest possible availability and the lowest possible cost of ownership. This is why automated and autonomous driving has the potential to revolutionize the CAV sector. Driverless machines can be operated around the clock and almost non-stop. Platooning allows automated, interconnected trucks to drive in a convoy and very close to each other. Platooning saves fuel. The North American Council for Freight Efficiency has calculated the following:In a scenario with two virtually connected trucks, the fuel consumption of the front vehicle is reduced by 4.5%, and by 10% in the rear vehicle, due to reduced aerodynamic drag on all of the vehicles.In a scenario with three connected trucks, platooning even leads to an average savings…
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Fuel Rate Curve-Based Reverse Engineering Approach for Common Rail Diesel Injectors

Norwegian University of Science and Technology-Vladimir Krivopolianskii, Nicolas Lefebvre, Sergey Ushakov, Eilif Pedersen
Published 2019-09-20 by SAE International in United States
When focusing on optimization of the combustion process in a direct injection engine, it is essential to understand its dynamic performance with respect to engine loading settings. One of the most important factors influencing the energy conversions efficiency is fuel delivery characteristics. The understanding of the injector performance is usually associated with availability of a high-fidelity model based on the geometric and hydraulic features of the injector. In this paper, a so-called reverse engineering method was applied to characterize the internal arrangement of a solenoid-driven common rail injector using fuel rate curves and solenoid valve excitation current profiles. Operational modes corresponding to a highly transient injector state were considered during spray momentum flux experiments to examine the injector flow characteristics. The experimental results were eventually used as a reference for the parameter search algorithm to tune a hypothetical model of the studied injector. In this work, the multi-start trust region optimization method was chosen as a relatively computationally cheap algorithm that allows realistic constrained parametrization of injector components. Based on the obtained results, it could…
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Effect of Inventory Storage on Automotive Flooded Lead-Acid Batteries

American Automobile Association Inc.-Matthew Garrett Lum
University of Central Florida-Matthew W. Logan, Arturo D. Annese, Fernando J. Uribe-Romo
Published 2019-09-20 by SAE International in United States
The battery is a central part of the vehicle’s electrical system and has to undergo cycling in a wide variety of conditions while providing an acceptable service life. Within a typical distribution chain, automotive lead-acid batteries can sit in storage for months before delivery to the consumer. During storage, batteries are subjected to a wide variety of temperature profiles depending on facility-specific characteristics. Additionally, batteries typically do not receive any type of maintenance charge before delivery. Effects of storage time, temperature, and maintenance charging are explored. Flooded lead-acid batteries were examined immediately after storage and after installation in vehicles subjected to normal drive patterns. While phase composition is a major consideration, additional differences in positive active material (PAM) were observed with respect to storage parameters. Batteries stored in a hot environment and kept at constant float voltage for a significant duration exhibited favorable PAM characteristics relative to other storage environments. In all cases, batteries kept on float charge throughout storage exhibited favorable PAM characteristics relative to batteries stored under equivalent conditions on open-circuit charge.
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3D Numerical Study of Sloshing Attenuation Using Vertical Slotted Barriers

Helwan University Faculty of Engineering-Mohamed Fahmy Younes
Published 2019-07-25 by SAE International in United States
The present study deals with the reduction of fluid vibrations by dissipating the kinetic energy in a closed vibrating container partly filled using vertical slotted obstacles. The effect of the barriers on the liquid vibration inside a closed container exposed to a harmonic excitation is numerically studied. A single vertical slotted barrier (SVSB) and multivertical slotted barrier (MVSB) systems are considered for different liquid levels. The 3D liquid domain with the tank and the barrier as boundaries is modelled and solved numerically using ANSYS-CFX software. The reduction in pressures on the walls and the ceiling of the tank due to the influences of the slot size and numbers were evaluated to optimize the size and the numbers of the slots. The numerical approach shows an ability to simulate the nonlinear behavior of the liquid vibration when using vertical slotted barriers (VSB). The obtained results show that the SVSB is more efficient than the MVSB to decrease the dangers of dynamic impacts of the liquid vibrations inside the container. The system-damping factor depends mainly on the…
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Minimizing Power Consumption of Fully Active Vehicle Suspension System Using Combined Multi-Objective Particle Swarm Optimization

Helwan University-Ahmed Elsawaf, H. Metered, A. Abdelhamid
Published 2019-07-16 by SAE International in United States
This paper introduces an optimum design for a feedback controller of a fully active vehicle suspension system using the combined multi-objective particle swarm optimization (CMOPSO) in order to minimize the actuator power consumption while enhancing the ride comfort. The proposed CMOPSO algorithm aims to minimize both the vertical body acceleration and the actuator power consumption by searching about the optimum feedback controller gains. A mathematical model and the equations of motion of the quarter-car active suspension system are considered and simulated using Matlab/Simulink software. The proposed active suspension is compared with both active suspension system controlled using the linear quadratic regulator (LQR) and the passive suspension systems. Suspension performance is evaluated in time and frequency domains to verify the success of the proposed control technique. The simulated results reveal that the proposed controller using CMOPSO grants a significant enhancement of ride comfort and road holding, and reduction of actuator power consumption.
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Developing a Real-World, Second-by-Second Driving Cycle Database through Public Vehicle Trip Surveys

Ford Motor Company-Joseph Supina, Fazal Syed
Wayne State University College of Engineering-Nizar Khemri, Hao Ying
Published 2019-07-08 by SAE International in United States
Real-world second-by-second vehicle driving cycle data is very important for vehicle research and development. A project solely dedicated to generating such information would be tremendously costly and time consuming. Alternatively, we developed such a database by utilizing two publicly available passenger vehicle travel surveys: 2004-2006 Puget Sound Regional Council (PSRC) Travel Survey and 2011 Atlanta Regional Commission (ARC) Travel Survey. The surveys complement each other - the former is in low time resolution but covers driver operation for over one year whereas the latter is in high time resolution but represents only one-week-long driving operation. After analyzing the PSRC survey, we chose 382 vehicles, each of which continuously operated for one year, and matched their trips to all the ARC trips. The matching is carried out based on trip distance first, then on average speed, and finally on duration. Of the total 509,158 trips made by the 382 PSRC vehicles, 496,276 trips (97.47%) were successfully matched to single original ARC trips. The remaining trips were matched to either ARC sub-trips or combined ARC trips. The…
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Optimization Approach to Passive Engine Mounting System for Reducing Automotive Vibrations

K. N. Toosi University of Technology-Reza Abedi, Amir H. Shamekhia
Shahid Beheshti University-Abbas Rahi
Published 2019-07-08 by SAE International in United States
Improvised noise, vibration, and harshness (NVH) performance of vehicle implies better comfort for passengers. Apart from road inputs, engine vibration is one of the major contributors to interior vibrations in automotive. The aim of this paper is to optimize specifications and locations of engine mounts to reduce vehicle vibration without affecting engine performance and to provide better ride comfort. This paper also includes the challenges involved in the analysis of engine vibration on critical conditions such as movement on the road surface or braking action. Therefore, a fully numerical simulation expands to a four-cylinder engine by considering piston side force. In this model, the mass distribution in the connecting rod and crankshaft, outside of the center pin, and friction between the cylinder and piston have been considered. Furthermore, simulation analysis is implemented for an engine in vehicle movement with constant speed on the road class B roughness and braking conditions. Engine location, the angle of placement, and dynamic characteristics of mounts are the important parameters to reduce vibrations transferred to the vehicle frame. The optimization…
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Determination of a Tyre’s Rolling Resistance Using Parallel Rheological Framework

University of Birmingham-Hamad Sarhan Aldhufairi, Oluremi Olatunbosun, Khamis Essa
Published 2019-06-20 by SAE International in United States
Nowadays, rolling resistance sits at the core of tyre development goals because of its considerable effect on the car’s fuel economy. In contrast to the experimental method, the finite element (FE) method offers an inexpensive and efficient estimation technique. However, the FE technique is yet to be a fully developed product particularly for rolling-resistance estimation. An assessment is conducted to study the role of material viscoelasticity representation in FE, in linear and non-linear forms, through the use of Prony series and parallel rheological framework (PRF) models, respectively, on the tyre’s rolling-resistance calculation and its accuracy. A unique approach was introduced to estimate the rolling resistance according to the tyre’s hysteresis energy coefficient. The non-linear PRF choice resulted in rolling-resistance calculations that reasonably match that of the experimental work and the literature for various vertical load and inflation cases, whereas the Prony series option was found irresponsive to the tyre’s deformation in which it gave unreliable and infinitesimal outputs.
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Experimental Investigation of the Droplet Field of a Rotating Vehicle Tyre

FKFS, Forschungsinstitut für Kraftfahrwesen und Fahrzeugmoto-Domenik Schramm, Timo Kuthada
Helmut-Schmidt-Universität Hamburg-Franz Joos
Published 2019-06-18 by SAE International in United States
The consideration of vehicle soiling in the development process becomes ever more important because of the increasing customer demands on current vehicles and the increased use of camera and sensor systems due to autonomous driving. In the process of self-soiling, a soil-water mixture is whirled up by the rotation of the car’s own wheels and deposits on the vehicle surface. The validation of the soiling characteristics in vehicle development usually takes place in an experimental manner, but is increasingly supported by numerical simulations.The droplet field at the tyre has been investigated several times in the past. However, there are no published information regarding the physical background of the droplet formation process and the absolute droplet sizes considering the position at the tyre and the behaviour at different velocities. In the numerical self-soiling simulations, this droplet whirl up process is modelled by a non-rotating wheel, where equally sized droplets are injected tangentially from homogenous emitter lines on the tyre surface into the airfield. The impact of the simplifications of this approach on the final result of…
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