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SAE International Journal of Passenger Cars Mechanical Systems
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Application of a New Method for Comparing the Overall Energy Consumption of Different Automotive Thermal Management Systems

SAE International Journal of Passenger Cars - Mechanical Systems

Jan Christoph Menken, Thomas Weustenfeld, Jürgen Köhler
  • Journal Article
  • 06-11-04-0024
Published 2018-10-03 by SAE International in United States
This article applies a new method for the evaluation and estimation of real-life energy consumption of two different thermal management systems based on driving behavior in the course of the day. Recent attempts to find energy-efficient thermal management systems for electric and plug-in hybrid electric vehicles have led to using secondary loop systems as an alternative approach for meeting dynamic heating and cooling demands and reducing refrigerant charge. However, the additional layer of thermal resistance, which influences the system’s transient behavior as well as passenger compartment comfort during cool-down or heat-up, makes it difficult to estimate the annual energy consumption. In this article, the overall energy consumption of a conventional and a secondary loop system is compared using a new method for describing actual customers’ driving behavior in the course of the day. Therefore, a reduced, representative set of 24-hour driving and stopping cycles from an actual data set of travel and transportation patterns in the United States is used. Additionally, respective weather data is considered. This method helps reduce simulation and testing effort significantly…
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Performance Margin for Geometric Road Design

SAE International Journal of Passenger Cars - Mechanical Systems

Virginia Polytechnic Institute and State University-Yong-suk Kang, John B. Ferris
  • Journal Article
  • 06-11-04-0022
Published 2018-08-08 by SAE International in United States
Although several methods exist for measuring the performance capability of a vehicle, many require detailed knowledge of the forces acting at each tire contact patch or do not account for both the vehicle dynamics and the road geometry. A simple vehicle model is proposed to estimate the upper limit of performance capability for a given operating condition (the Performance Envelope) based on the Effective Friction and the road geometry (slope and cross-slope). The Effective Friction accounts for both the vehicle dynamics and road surface properties and is estimated, through simulation or experimentation, using two standard vehicle dynamics tests: constant radius cornering and straight-line braking. The Performance Margin is defined as the additional performance capability available before the vehicle reaches the Performance Envelope, both represented in the intuitive units of gravity. The Performance Margin is applicable to both geometric road design and vehicle control; both of which are crucial as transportation agencies and vehicle manufacturers prepare for the introduction of autonomous vehicles.
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Steady Aeroelastic Response Prediction and Validation for Automobile Hoods

SAE International Journal of Passenger Cars - Mechanical Systems

Honda R&D Americas, Inc.-Austin Kimbrell, Peter Kang
Ohio State University-Justin Pesich, Jack McNamara
  • Journal Article
  • 06-11-04-0021
Published 2018-07-10 by SAE International in United States
The pursuit of improved fuel economy through weight reduction, reduced manufacturing costs, and improved crash safety can result in increased compliance in automobile structures. However, with compliance comes an increased susceptibility to aerodynamic and vibratory loads. The hood in particular withstands considerable aerodynamic force at highway speeds, creating the potential for significant aeroelastic response that may adversely impact customer satisfaction and perception of vehicle quality. This work seeks an improved understanding in computational and experimental study of fluid-structure interactions between automobile hoods and the surrounding internal and external flow. Computational analysis was carried out using coupled CFD-FEM solvers with detailed models of the automobile topology and structural components. The experimental work consisted of wind tunnel tests using a full-scale production vehicle. Comparisons between numerical and experimental results yielded important insights into required modeling fidelity, coupling, and challenges in validation for the aeroelastic response of automobile hoods.
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Force Transmission Characteristics for a Loaded Structural-Acoustic Tire Model

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Motor Company, USA-Matthew Black
Purdue University, USA-Rui Cao, J. Stuart Bolton
  • Journal Article
  • 06-11-04-0025
Published 2018-10-23 by SAE International in United States
Concerns about tire noise radiation arise partly from city traffic planning, environmental protection, and pedestrian safety standpoints, while from the vehicle passengers’ perspective, noise transmitted to the vehicle interior is more important. It is the latter concern that is addressed in this article. Sound-absorbing materials generally offer good absorption at higher frequencies, but the reduction of relatively low frequency, structure-borne tire noise is a continuing focus of many auto manufacturers. A tire’s internal, acoustic cavity resonance is a very strong contributing factor to tire-related structure-borne noise, and it can easily be perceived by passengers. Some reduction of vehicle cabin noise can be achieved through the insertion of sound-absorbing material in the tires. However, apart from the additional cost for such tires, there is also an increased complexity when repairing them because of the need to avoid damaging the sound-absorptive lining. In that light, modifying the design of the tire-rim and suspension system to decrease the cavity noise influence without the addition of sound-absorbing material has a clear benefit. To that end, a fully coupled, structural-acoustic…
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Passive Flow Control on a Ground-Effect Diffuser Using an Inverted Wing

SAE International Journal of Passenger Cars - Mechanical Systems

Cranfield University-Obinna Ehirim, Kevin Knowles, Alistair Saddington,, Mark Finnis
  • Journal Article
  • 06-11-04-0023
Published 2018-08-13 by SAE International in United States
In this experimental and computational study a novel application of aerodynamic principles in altering the pressure recovery behavior of an automotive-type ground-effect diffuser was investigated as a means of enhancing downforce. The proposed way of augmenting diffuser downforce production is to induce in its pressure recovery action a second pressure drop and an accompanying pressure rise region close to the diffuser exit. To investigate this concept with a diffuser-equipped bluff body, an inverted wing was situated within the diffuser flow channel, close to the diffuser exit. The wing’s suction surface acts as a passive flow control device by increasing streamwise flow velocity and reducing static pressure near the diffuser exit. Therefore, a second-stage pressure recovery develops along the diffuser’s overall pressure recovery curve as the flow travels from the diffuser’s low pressure, high velocity inlet to its high pressure, low velocity exit. Consequently, downforce production is increased with the use of the wing. Across the range of ride heights investigated, computational fluid dynamics simulations, validated against wind tunnel measurements, show an increase in downforce, with…
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