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CAE Simulation of Automotive Door Upper Frame Deflection Using Aerodynamic Loads

FCA US LLC-Sudhakar Doppalapudi, Khaled Sbeih, Kumar Srinivasan, Ramchandra Bhandarkar
Published 2018-04-03 by SAE International in United States
Upper frame deflection of automobile doors is a key design attribute that influences structural integrity and door seal performance as related to NVH. This is a critical customer quality perception attribute and is a key enabler to ensure wind noise performance is acceptable. This paper provides an overview of two simulation methodologies to predict door upper frame deflection. A simplified simulation approach using point loads is presented along with its limitations and is compared to a new method that uses CFD tools to estimate aerodynamic loads on body panels at various vehicle speeds and wind directions. The approach consisted of performing external aerodynamic CFD simulation and using the aerodynamic loads as inputs to a CAE simulation. The details of the methodology are presented along with results and correlation to experimental data from the wind tunnel.
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Detailed Aerodynamic Characterization and Optimization of a Pickup Truck Using Adaptive Sampling based DOE

FCA US LLC-Sam Jeyasingham, Kumar Srinivasan
Published 2018-04-03 by SAE International in United States
A detailed Design of Experiments (DOE) study is presented to understand the aerodynamic effects of exterior design features and shape parameters of a pick-up truck using Computational Fluid Dynamics (CFD). The goal of the study is to characterize several key design parameters and the interactions between them as related to overall drag of the vehicle. Using this data, the exterior shape is optimized to minimize drag within specified design constraints. An adaptive sampling methodology is also presented that progressively reduces errors in the design response surfaces generated. This combined with a Latin Hypercube based initial design space characterization yields computational efficiency. A trend-predictive meta-model is presented that can be used for early design development. Results from the meta-model are also correlated with experimental data from the wind tunnel.
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Further Analyses on Prediction of Automotive Spinning Wheel Flowfield with Full Width Moving Belt Wind Tunnel Results

SAE International Journal of Passenger Cars - Mechanical Systems

Exa Corporation-Young-Chang Cho
FCA US LLC-Arturo Guzman, John Tripp, Kumar Srinivasan
  • Journal Article
  • 2017-01-1519
Published 2017-03-28 by SAE International in United States
Pickup trucks are designed with a taller ride height and a larger tire envelope compared to other vehicle types given the duty cycle and environment they operate in. These differences play an important role in the flow field around spinning wheels and tires and their interactions with the vehicle body. From an aerodynamics perspective, understanding and managing this flow field are critical for drag reduction, wheel design, and brake cooling. Furthermore, the validation of numerical simulation methodology is essential for a systematic approach to aerodynamically efficient wheel design as a standard practice of vehicle design.This paper presents a correlation the near-wheel flow field for both front and rear spinning wheels with two different wheel designs for a Ram Quad Cab pick-up truck with moving ground.Twelve-hole probe experimental data obtained in a wind tunnel with a full width belt system are compared to the predictions of numerical simulations. In addition to the previous study on a minivan, this paper provides more detailed correlations for a set of new data with two different rim configurations and multiple…
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Automotive Vehicle Body Temperature Prediction in a Paint Oven

Chrysler Group LLC-Yu Hsien Wu, Sreekanth Surapaneni, Kumar Srinivasan, Paul Stibich
Published 2014-04-01 by SAE International in United States
Automotive vehicle body electrophoretic (e-coat) and paint application has a high degree of complexity and expense in vehicle assembly. These steps involve coating and painting the vehicle body. Each step has multiple coatings and a curing process of the body in an oven. Two types of heating methods, radiation and convection, are used in the ovens to cure coatings and paints during the process. During heating stage in the oven, the vehicle body has large thermal stresses due to thermal expansion. These stresses may cause permanent deformation and weld/joint failure. Body panel deformation and joint failure can be predicted by using structural analysis with component surface temperature distribution. The prediction will avoid late and costly changes to the vehicle design. The temperature profiles on the vehicle components are the key boundary conditions used to perform structure analysis. This paper presents an efficient method to predict vehicle body temperature profiles as the vehicle pass through the radiant section of an e-coat and/or paint oven. Transient analysis coupled with geometry movement is used to predict the vehicle…
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A Technique to Predict Thermal Buckling in Automotive Body Panels by Coupling Heat Transfer and Structural Analysis

Chrysler Group LLC-Paul R. Stibich, Yu Hsien Wu, Weidong Zhang, Michao Guo, Kumar Srinivasan, Sreekanth Surapaneni
Published 2014-04-01 by SAE International in United States
This paper describes a comprehensive methodology for the simulation of vehicle body panel buckling in an electrophoretic coat (electro-coat or e-coat) and/or paint oven environment. The simulation couples computational heat transfer analysis and structural analysis. Heat transfer analysis is used to predict temperature distribution throughout a vehicle body in curing ovens. The vehicle body temperature profile from the heat transfer analysis is applied as an input for a structural analysis to predict buckling. This study is focused on the radiant section of the curing ovens. The radiant section of the oven has the largest temperature gradients within the body structure. This methodology couples a fully transient thermal analysis to simulate the structure through the electro-coat and paint curing environments with a structural, buckling analysis. The ability to predict the buckling phenomenon using a virtual simulation will reduce the risk of late production changes to the vehicle class “A” surfaces.
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The Impact of Vehicle Front End Design on AC Performance

Chrysler Group LLC-Ken T. Lan, Kumar Srinivasan, Sadek S. Rahman
MEDA Limited-Ling Xiao
Published 2013-04-08 by SAE International in United States
Vehicle front end air flow management affects many aspects of vehicle aero/thermal performances. The HVAC system capacity is greatly driven by the airflow and the air temperature received at the condenser. In this paper, front end design practices are investigated using computer simulation and full vehicle test to evaluate their effects on AC system performance.A full vehicle 3D CFD model is developed and used to predict the airflow and temperature in underhood and around the vehicle body, and specifically the conditions entering the condenser. The condenser inlet airflow and temperature profiles from 3D CFD model are then used as inputs for the 1D AC system model. The 1D AC system model, which includes condenser, compressor, evaporator and TXV (Thermal eXpansion Valve), is developed to observe the critical AC performance indicators such as panel out air temperature and compressor head pressure. Both 3D and 1D simulation models are validated and reasonable correlation with full vehicle tests are achieved.Four design changes to the front end are studied in this paper. They are placement of transmission oil cooler…
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Prediction of HVAC System Aero/Acoustic Noise Generation and Propagation using CFD

CD Adapco-Fred Mendonca, Nachiket Pai
Chrysler Group LLC-Mayur Sah, Kumar Srinivasan
Published 2013-04-08 by SAE International in United States
With the advent of quieter powertrain and improved cabin acoustic sealing, there is an increased focus on noise generated in the HVAC unit and climate control ducting system. With improved insulation from exterior noise sources such as wind & road noise, HVAC noise is more perceptible by the occupants and is a key quality indicator for new generation vehicles. This has increased the use of simulations tools to predict HVAC noise during the virtual development phase of new vehicle programs. With packaging space being premium under the instrument panel, changes to address noise issues are expensive and often impractical. The current methodology includes the best practices in simulation accumulated from prior aero acoustics validation studies on fans, ducts, flaps and plenum volume discharge. The paper details the acoustic noise generation and propagation in the near field downstream of an automotive HVAC unit in conjunction with ducting system. The simulation process is based on Detached Eddy Simulation (DES) with compressibility. The overall sound pressure level at a nearfield cabin location is compared with test data. Good…
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Influences of Free Stream Conditions on Vehicle Thermal Management – An Analytical Study

Belcan Corporation-Ken T. Lan
Chrysler LLC-Kumar Srinivasan
Published 2009-04-20 by SAE International in United States
During the development phase of a vehicle, several thermal tests have to be conducted in order to validate the design and ensure all vehicle level functional objectives are met. Physical tests are performed both in controlled climatic drive cells and on the road at specific test sites. These tests must be done under specified conditions, since the test data is influenced by various environmental conditions and data correction methods have to be used to interpret the test results. For road trip tests, the results are influenced by several uncontrollable factors, such as ambient temperature, tail and cross wind, free stream turbulence etc. In climatic drive cell tests, some conditions can be controlled but still some conditions such as boundary layer thickness, inlet turbulence level etc, are not consistent with those when driving a vehicle at various test locations. It is therefore important to understand the effects of these free stream conditions on vehicle thermal management. It can help us better interpret the test results and accurately evaluate vehicle thermal performance.Underhood/underbody (UH/UB) CFD analysis is now…
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An Efficient Procedure for Vehicle Thermal Protection Development

DaimlerChrysler Corporation-Kumar Srinivasan, George Woronowycz, Michael Zabat, John Tripp
Published 2005-04-11 by SAE International in United States
Vehicle thermal protection is an important aspect of the overall vehicle development process. It involves optimizing the exhaust system routing and designing heat shields to protect various components that are in near proximity to the exhaust system. Reduced time to market necessitates an efficient process for thermal protection development. A robust procedure that utilizes state of the art CFD simulation techniques proactively during the design phase is described. Simulation allows for early detection of thermal issues and development of countermeasures several months before prototype vehicles are built. Physical testing is only used to verify the thermal protection package rather than to develop heat shields. The new procedure reduces the number of physical tests and results in a robust, efficient methodology. In the past, complexity of the geometry involved in vehicle under-hood and underbody environments rendered traditional mesh generation approaches impractical and time consuming. The current work uses an interior-to-boundary method wherein the need for creating a ‘water-tight’ surface mesh is not a pre-requisite for volume mesh generation. This significantly reduces grid generation time allowing for…
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