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SAE International Journal of Passenger Cars Mechanical Systems
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SAE International Journal of Passenger Cars - Mechanical Systems

Dzmitry Savitski, Klaus Bernhard Augsburg
Technische Universitat Ilmenau-Vincenzo Ricciardi, Valentin Ivanov
  • Journal Article
  • 2017-01-2520.1
Published 2017-09-17 by SAE International in United States
This is a errata for 2017-01-2520.
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Reduced-Order Modeling of Vehicle Aerodynamics via Proper Orthogonal Decomposition

SAE International Journal of Passenger Cars - Mechanical Systems

Technische Universität Braunschweig, Germany-Rolf Radespiel
Volkswagen AG, Germany-Markus Mrosek, Carsten Othmer
  • Journal Article
  • 06-12-03-0016
Published 2019-10-21 by SAE International in United States
Aerodynamic optimization of the exterior vehicle shape is a highly multidisciplinary task involving, among others, styling and aerodynamics. The often differing priorities of these two disciplines give rise to iterative loops between stylists and aerodynamicists. Reduced-order modeling (ROM) has the potential to shortcut these loops by enabling aerodynamic evaluations in real time. In this study, we aim to assess the performance of ROM via proper orthogonal decomposition (POD) for a real-life industrial test case, with focus on the achievable accuracy for the prediction of fields and aerodynamic coefficients. To that end, we create a training data set based on a six-dimensional parameterization of a Volkswagen passenger production car by computing 100 variants with Detached-Eddy simulations (DES). Based on this training data, we reduce the dimension of the solution space via POD and interpolate the base coefficients with Kriging (aka Gaussian Process Regression) for predictions of the flow field at unseen parameter combinations. The error analysis of the fields and drag coefficient predictions reveal that 100 training samples are sufficient for this six-dimensional test case in…
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Overset Mesh-Based Computational Investigations on the Aerodynamics of a Generic Car Model in Proximity to a Side-Wall

SAE International Journal of Passenger Cars - Mechanical Systems

University of North Carolina at Charlotte, USA-Charles Patrick Bounds, Srivatsa Mallapragada, Mesbah Uddin
  • Journal Article
  • 06-12-03-0015
Published 2019-10-21 by SAE International in United States
This article discusses an approach to simulating a generic idealized car model (Ahmed body) moving in close proximity to a side-wall, using a transient Computational Fluid Dynamics (CFD) method. This phenomenon is very important in motorsports, where racing close to the safety barrier is common. Driving in close proximity to a side-wall alters the aerodynamic characteristics of the vehicle significantly; however, only a handful of published works exist in this area. Additionally, the experimental studies conducted in the past suffer from certain inadequacies, especially in terms of simulating the side-wall. This casts some uncertainty as to the relevance of these studies to the real-world problem. The present study attempts to imitate the real-world flow phenomenon by taking a nontraditional CFD approach of translating the body relative to the stationary surrounding fluid and side-wall instead of the classical method of flowing air over a stationary vehicle model. This was achieved by using a relatively new and computationally efficient meshing technique for overlapping grids called the “Overset” or “Chimera” mesh. The initial task was to accurately predict…
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A Predictive Tool to Evaluate Braking System Performance Using Thermo-Structural Finite Element Model

SAE International Journal of Passenger Cars - Mechanical Systems

Universiti Teknologi Malaysia, Malaysia-Wan Zaidi Wan Omar
University of Sciences and Technology of Oran, Algeria-Ali Belhocine
  • Journal Article
  • 06-12-03-0014
Published 2019-10-14 by SAE International in United States
The braking phenomenon is an aspect of vehicle stopping performance where with kinetic energy due to the speed of the vehicle is transformed into thermal energy produced by the brake disc and its pads. The heat must then be dissipated into the surrounding structure and into the airflow around the brake system. The thermal friction field during the braking phase between the disc and the brake pads can lead to excessive temperatures. In our work, we presented numerical modeling using ANSYS software adapted in the finite element method (FEM), to follow the evolution of the global temperatures for the two types of brake discs, full and ventilated disc during braking scenario. Also, numerical simulation of the transient thermal analysis and the static structural analysis were performed here sequentially, with coupled thermo-structural method. Numerical procedure of calculation relies on important steps such that Computational Fluid Dynamics (CFD) and thermal analysis have been well illustrated in three-dimensional form (3D), showing the effects of heat distribution over the brake disc. This CFD analysis helped us in the calculation…
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Study of a Mono-Tube Hydraulic Energy Harvesting Shock Absorber

SAE International Journal of Passenger Cars - Mechanical Systems

Zagazig University, Egypt-Anas A. Samn, A.M.M. Abdelhaleem, A.M. Kabeel, Emil H. Gad
  • Journal Article
  • 06-12-03-0013
Published 2019-09-23 by SAE International in United States
In this article, a mono-tube hydraulic energy harvesting shock absorber is proposed. The shock absorber is featured with the autogeneration where it permits harvesting waste energy with a proper asymmetric ratio of compression/extension damping force can be obtained. Using the continuity equation and including the compressibility of the oil, equations that describe the variation of the oil pressure in model chambers are derived. Then, relations that relate chambers’ pressure with the damping force, the harvested power, and the system efficiency are derived. Results illustrate the effects of frequency, amplitude, external resistance, and chambers’ size on the damping force and the harvested power. The proposed model can harvest an average power of 500 W with maximum peak of 1800 W using an external resistance of 10 Ω at an input amplitude of 50 mm and frequency of 1.67 Hz. In addition, the absorber can control the equivalent damping by proper tuning of external resistance to cover the damping force requirements of most passenger vehicles. Simulations are extended to include different sizes of the same absorber to…
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Torque and Pressure CFD Correlation of a Torque Converter

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Motor Company, USA-Steve Frait, Ram Devendran
Michigan Technological University, USA-Edward De Jesus Rivera, Mark Woodland, Darrell Robinette, Jason Blough, Carl Anderson
  • Journal Article
  • 06-12-03-0012
Published 2019-08-22 by SAE International in United States
A torque converter was instrumented with 29 pressure transducers inside five cavities under study (impeller, turbine, stator, clutch cavity between the pressure plate and the turbine shell). A computer model was created to establish correlation with measured torque and pressure. Torque errors between test and simulation were within 5% and K-Factor and torque ratio errors within 2%. Turbulence intensity on the computer model was used to simulate test conditions representing transmission low and high line pressure settings. When turbulence intensity was set to 5%, pressure simulation root mean square errors were within 11%-15% for the high line pressure setting and up to 34% for low line pressure setting. When turbulence intensity was increased to 50% for the low line pressure settings, a 6% reduced root mean square error in the pressure simulations was seen. For all pressure settings, cavities closer to the converter inlet required a 5% turbulence intensity while the cavities inside or near the torus were better suited with 50% turbulence intensity levels.
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