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Viewing 1 to 30 of 2527
2015-06-22
Event
This session is to present numerical and experimental work pertaining to noise due to flow around the vehicle body, such as flow-induced interior noise, flow over protrusions, sunroofs, windows, noise from ventilation systems, or flow noise in exhaust system. Papers on aerodynamics alone without sound are excluded. Numerical studies may include new models or models based on existing theory as long as they are adequately supported by experimental or theoretical verifications.
2015-06-22
Event
This session is devoted to NVH issues arising within the aeronautical and aerospace industries, such as community noise, aircraft interior noise, aerospace vibro-acoustics, noise prediction, modeling and modal analysis.
2015-04-23
Event
Vehicle aerodynamic development, drag reduction and fuel economy, handling and stability, cooling flows, surface soiling and water management, vehicle internal environment, tyre aerodynamics and modelling, aeroacoustics, structural response to aerodynamic loading, simulating the on-road environment, onset flow turbulence, unsteady aerodynamics, fundamental flow structures, new test methods and facilities, new applications of computational fluid dynamics simulation, competition vehicle aerodynamics.
2015-04-23
Event
Vehicle aerodynamic development, drag reduction and fuel economy, handling and stability, cooling flows, surface soiling and water management, vehicle internal environment, tyre aerodynamics and modelling, aeroacoustics, structural response to aerodynamic loading, simulating the on-road environment, onset flow turbulence, unsteady aerodynamics, fundamental flow structures, new test methods and facilities, new applications of computational fluid dynamics simulation, competition vehicle aerodynamics.
2015-04-22
Event
Vehicle aerodynamic development, drag reduction and fuel economy, handling and stability, cooling flows, surface soiling and water management, vehicle internal environment, tyre aerodynamics and modelling, aeroacoustics, structural response to aerodynamic loading, simulating the on-road environment, onset flow turbulence, unsteady aerodynamics, fundamental flow structures, new test methods and facilities, new applications of computational fluid dynamics simulation, competition vehicle aerodynamics.
2015-04-22
Event
Vehicle aerodynamic development, drag reduction and fuel economy, handling and stability, cooling flows, surface soiling and water management, vehicle internal environment, tyre aerodynamics and modelling, aeroacoustics, structural response to aerodynamic loading, simulating the on-road environment, onset flow turbulence, unsteady aerodynamics, fundamental flow structures, new test methods and facilities, new applications of computational fluid dynamics simulation, competition vehicle aerodynamics.
2015-04-21
Event
The purpose of this session is to bring awareness among the automotive aerodynamics, thermal and hydraulic systems development community to address the need of reliability analysis and robust design to improve the overall product quality. This session also introduces CAE based optimization of aero-thermal and fluid systems to improve automotive fuel economy. This session presents papers covering both testing and simulation.
2015-04-21
Event
Vehicle aerodynamic development, drag reduction and fuel economy, handling and stability, cooling flows, surface soiling and water management, vehicle internal environment, tyre aerodynamics and modelling, aeroacoustics, structural response to aerodynamic loading, simulating the on-road environment, onset flow turbulence, unsteady aerodynamics, fundamental flow structures, new test methods and facilities, new applications of computational fluid dynamics simulation, competition vehicle aerodynamics.
2015-04-21
Event
Vehicle aerodynamic development, drag reduction and fuel economy, handling and stability, cooling flows, surface soiling and water management, vehicle internal environment, tyre aerodynamics and modelling, aeroacoustics, structural response to aerodynamic loading, simulating the on-road environment, onset flow turbulence, unsteady aerodynamics, fundamental flow structures, new test methods and facilities, new applications of computational fluid dynamics simulation, competition vehicle aerodynamics.
2015-04-21
Event
Vehicle aerodynamic development, drag reduction and fuel economy, handling and stability, cooling flows, surface soiling and water management, vehicle internal environment, tyre aerodynamics and modelling, aeroacoustics, structural response to aerodynamic loading, simulating the on-road environment, onset flow turbulence, unsteady aerodynamics, fundamental flow structures, new test methods and facilities, new applications of computational fluid dynamics simulation, competition vehicle aerodynamics.
2015-04-14
Technical Paper
2015-01-0441
Takashi Takiguchi, Yasuhiro Takii, Yusuke Yano, Nobuyuki Ohta
We require fast and accurate prediction to know the thermal performance for each car package. We established a highly accurate full-vehicle thermal prediction method applying the identification coefficients that we get from vehicle test results. The primary method of predicting this is Computational Fluid Dynamics (CFD) of conjugate heat transfer. CFD predicts external and exhaust gas flow, including their temperatures. Conditions taken into consideration are vehicle speed and temperature, heat rejection rate of the condenser, radiator, fan rotation speed, and exhaust gas flow. There are three identification coefficients required by each process. 1) Water temperature prediction process: Calculate ENG cooling loss and solar load by the 1D model, and input it into CFD as a heat rejection rate of the radiator and condenser.
2015-04-14
Technical Paper
2015-01-0440
Julio Carrera, ALFREDO NAVARRO, Concepcion Paz, Alvaro SANCHEZ, Jacobo Porteiro
Recent emissions standards have become more restrictive in terms of CO2 and NOx reduction. This has been translated into higher EGR rates at higher exhaust gas temperatures with lower coolant flow rates for much longer lifetimes. In consequence, Thermal Load for EGR components, specially EGR coolers, has been increased and thermal fatigue durability is now a critical issue during the development. Consequently a new Thermo-Mechanical Analysis (TMA) procedure has been developed in order to calculate durability. The TMA calculation is based on a Computational Fluid Dynamics simulation (CFD) in which a boiling model is implemented for obtaining realistic temperature predictions of the metal parts exposed to possible local boiling. The FEM model has also been adjusted to capture the correct stress values by submodeling the critical areas. Life calculation is based on a Multiaxial Fatigue Model that has also been implemented in FEM software for node by node life calculation.
2015-04-14
Technical Paper
2015-01-1551
Andrew D'Hooge, Luke Rebbeck, Joaquin Gargoloff, Bradley Duncan
Aerodynamic evaluation of vehicles using static yaw angle changes in wind tunnel testing and numerical simulation has been used as standard practice for evaluating vehicle performance under a range of wind conditions. However, this approach does not consider dynamic wind effects coming from changing wind conditions, passing other vehicles and roadside obstacles, and transient non-uniform wind conditions coming from environmental turbulence. In previous work by the authors, computational fluid dynamics (CFD) simulation methodology for considering dynamic wind conditions and on-road turbulence was demonstrated, showing the important effects of the wind conditions on the vehicle aerodynamics. The technique allows the vehicle to be tested under a range of transient gust conditions, also accounting for wind turbulence coming from upstream vehicles and natural environmental wind fluctuations.
2015-04-14
Technical Paper
2015-01-1546
Andrew Wood, Martin Passmore, David Forbes, Daniel Wood, Adrian Gaylard
The pressure on the base of a vehicle is a major contributor to the aerodynamic drag of all practical vehicle geometries, and for some vehicles, such as an SUV, it is particularly important because it can account for up to 50% of the overall drag. Understanding the mechanisms that influence the base pressure and developing our simulation tools to ensure that base pressure is accurately predicted are essential requirements for the vehicle design and engineering process. This paper reports an experimental study to investigate the base pressure on a specifically designed generic SUV model. The results from ¼ scale wind tunnel tests include force and moment data, surface pressures over the base region and particle image velocimetry (PIV) in the wake. Results are presented for the vehicle in different ride height, underfloor roughness and wheel configurations and the paper includes some description of the experimental errors. Some initial CFD simulations are also reported.
2015-04-14
Technical Paper
2015-01-1562
Matts Karlsson, Petter Ekman
There is a need for reducing fuel consumption and thereby also reducing CO2 and other emissions in all areas of transportation and the forest industry is no exception. In the particular case of timber trucks special care have to be taken when designing such vehicles; they have to be sturdy and operate in harsh conditions and they are being driven empty half the time. It is well known that the aerodynamic resistance constitutes a significant part of the vehicles driving resistance and four areas in particular, front of vehicle, gap, side/underbody and rear of the vehicle contributes about one quarter each. In order to address these issues a wind tunnel investigation was initiated where a 1:6 scale model of a timber truck was designed to operate in a 3.6 m (diameter) wind tunnel. The present model resembles a generic timber truck with a flexible design such that different configurations could be tested easily.
2015-04-14
Technical Paper
2015-01-1547
Ramiz Omur Icke, Halil Yilmaz, Cenk Dinc
With the increasing market share of long-distance tractors, aerodynamic drag is becoming one of the most important vehicle attributes of heavy-duty commercial vehicles. Especially for high vehicle speeds, aerodynamic drag has a significant contribution to fuel economy. Conventionally, the aerodynamic performance of vehicles is determined by computational fluid dynamics (CFD) simulations and wind tunnel tests. An alternative physical testing method, on-road testing, is frequently preferred for wind tunnel tests, considering the reduction of costly wind tunnel experiments in the overall product development cycle. This study focuses on the correlation of on-road tests with CFD simulations regarding the aerodynamic drag coefficient (CD) for open front end case. The whole cooling pack and underhood geometric details are taken into consideration for the accurate representation of cooling drag.
2015-04-14
Technical Paper
2015-01-1527
Andreas Kremheller
Temporal changes of the onset flow field during on-road driving events such as overtaking and passing causing a complex interaction between aerodynamics of two vehicles, vehicle dynamics as well as steering input from the driver which, in extreme situations, can cause a risk to driving comfort and safety. In order to optimize a vehicles shape and dynamics a fundamental understanding of the underlying pressure distribution during these scenarios is necessary. This paper describes the experimental method to measure the surface pressure and vehicle motion during overtaking a vehicle and passing a vehicle on a proving ground. Two vehicles, a C-Hatchback and a B-Crossover where equipped with surface pressure transducers and a medium sized van and a 3.5 t truck where used as support vehicles. The highly asymmetric pressure distribution acting on the tested vehicles during the driving events is characterized using a simplified illustration method.
2015-04-14
Technical Paper
2015-01-1538
Neil Ashton, Alistair Revell PhD
Computational Fluid Dynamics (CFD) has increasingly provided the methodology behind an important design tool for the automotive industry. With a desire to reduce noise levels and improve fuel efficiency, reliable CFD simulations of the complex separated turbulent flow around vehicles is becoming an ever more crucial goal. The Ahmed car body [1] has long been one of the most popular automotive test cases because of detailed experimental data and an extensive record of previous simulations. Unfortunately whilst the Ahmed car body represents some of the key aerodynamic features of a full car (such as the vortex shedding and 3D separation), it is still a much-simplified model. A recent development to bridge this gap between models such as the Ahmed car body and a realistic full car model is the DrivAer model [2]. Together with recent experimental and numerical simulations it represents an excellent open-source full-car test case to validate and develop turbulence models.
2015-04-14
Technical Paper
2015-01-1541
Kuo-huey Chen, Bahram Khalighi
Various drag reduction strategies have been applied to a full size production pickup truck to evaluate their effectiveness by using a Computational Fluid Dynamics (CFD). The drag reduction devices evaluated in this study were placed at the rear end of the truck bed and the tailgate. Two types of devices were evaluated: (1) boat tail-like extended plates attached to the tailgate and (2) flat plates partially covering the truck bed. The effect of drag reduction by various combination of the above are presented in this paper. Twenty-four configurations were evaluated in the study with the best achievable drag reduction of around 21 counts (ΔCd=0.021). A detailed breakdown of the pressure differentials at the base of the truck is provided in order to understand the flow mechanism for the drag reduction. It is concluded that the added surfaces near the tailgate lower the static pressure on the inner side of the tailgate in addition to the pressure increase at the base.
2015-04-14
Technical Paper
2015-01-1532
Nicholas Oettle, Mohammed Meskine, Sivapalan Senthooran, Andrew Bissell, Gana Balasubramanian, Robert Powell
Car manufacturers put large efforts into reducing wind noise to improve the comfort level of their cars. Each component of the vehicle is designed to meet its individual noise target to ensure the wind noise passenger comfort level inside the vehicle is met. Sunroof designs are tested to meet low-frequency buffeting targets as well as broadband noise targets for the sunroof in vent position and any noise generated by deflectors. Experimentally testing designs and making changes to meet these design targets typically involves high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the use of a reliable numerical prediction capability early in the vehicle design process.
2015-04-14
Technical Paper
2015-01-1554
Bastian Schnepf, Thomas Schütz, Thomas Indinger
Efforts in aerodynamic optimization of road vehicles have been steadily increasing in recent years, mainly focusing on the reduction of aerodynamic drag. This has been motivated by the need of reducing CO2 emissions as well as extending the range of electric vehicle concepts. Both targets can only be achieved when all driving resistances are minimized. At velocities higher than 70 kph aerodynamic drag, which increases with the square of velocity, even becomes the dominant force. Breaking a passenger car’s aerodynamic drag down into the contributions of certain areas, wheels and wheel houses account for approx. 25 percent [1], a large share compared to their geometric dimensions. Consequently, industry and academia have been investigating the flow around automotive wheels intensively at an increasing level of detail lately.
2015-04-14
Technical Paper
2015-01-1542
Masaaki Arai, Keitaro Tone, Keiichi Taniguchi, Mikako Murakami, Munehiko Oshima
This paper describes the development of the aerodynamics of the new Nissan Murano. This vehicle was developed using full-scale wind tunnel testing and Computational Fluid Dynamics simulations (CFD). Three key aerodynamic features -front spoiler, active grille shutter and rear upper body were developed in particular for reducing aerodynamic drag. A large front spoiler was designed to reduce floor drag, especially drag produced by a uneven floor. The front spoiler shape was optimized by designing the lip shape to augment the separation angle of flow, thereby inhibiting the penetration of strong flow to the floor. An active grille shutter was adopted behind the front lower grille opening to reduce engine room drag substantially when engine cooling air is unnecessary. Based on a parameter study, we found that a lower grille is beneficial for the inlet for cooling. Therefore, the upper grille opening area was minimized, and conversely the lower grille opening area was maximized.
2015-04-14
Technical Paper
2015-01-1548
Anton Lundberg, Per Hamlin, Davangere shankar, Alexander Broniewicz, Tim Walker, Christoffer Landström PhD
1. Key Purpose The foremost aim of the work presented in this paper is to improve fuel economy and decrease CO2 emissions by reducing the aerodynamic drag of passenger vehicles. In vehicle R&D, CAE methods have become a development driver tool rather than a design assessment tool. Exploring and developing the capabilities of current CAE tools is therefore of great importance. The framework and chosen approach of an automated vehicle shape optimization tool, designed to be compatible with VCC's aerodynamics CFD environment, is presented in this paper. The tool implements recent advancements in neural networks and evolutionary optimization. The same has been developed to help the aerodynamicist find the optimal solution(s) within a defined design space, improve efficiency, maximize information output from CFD calculations, and be an aid in discussions with other attributes such as Design etc. 2.
2015-04-14
Technical Paper
2015-01-1533
Massimiliana Carello, Serra Andrea, Andrea Giancarlo Airale, Alessandro Ferraris
XAM is a prototype (developed at the Politecnico of Torino) of a two seat city vehicle, equipped with a hybrid propulsion system., to obtain low consumptions and reduced environmental impact. The designing process of this vehicle was carried out keeping attention to the requirements of the weight reduction and of the aerodynamic optimization of the shapes of the body, constitute the main specification considered designing XAM in order to consequently get a reduction of consumptions, while guarantying roominess and comfort. According to this, it has been designed a windscreen that makes a one-piece with the roof in order to avoid any discontinuity and consequently any loss due to whirling dissipations in the intersection area.
2015-04-14
Technical Paper
2015-01-1528
Kenichi Hirose, Rina Nakagawa, Yukitaka Ura, Hideyuki Kawamata, Hisashi Tanaka, Munehiko Oshima
The door mirrors of a vehicle are one of the significant components generating drag, due to projection from the vehicle body. The ratio of door mirror drag accounts for 2.5-5 percent of the overall aerodynamic drag of the vehicle. The drag ratio is larger than the frontal area ratio of door mirrors and vehicle body. Since it is considered that door mirror drag is composed of not only profile drag but also interference drag that is generated by the mixing of airflow streamlines between door mirrors and vehicle body. However, the generation mechanism of interference drag remained unexplained, so elucidating mechanisms for countermeasures have been needed. In this study, the prediction formulas for door mirror drag expressed by functions in relation to velocities around the vehicle body were derived and verified by wind tunnel test. Door mirror drag is defined as the difference between aerodynamic drag on a vehicle with and without mirrors.
2015-04-14
Technical Paper
2015-01-1559
Jeff Howell
The aerodynamic drag characteristics of a passenger car are typically defined by a single parameter, the drag coefficient at zero yaw angle. While this has been acceptable in the past, it may not allow a true comparison between vehicles with regard to the impact of drag on performance, especially fuel economy. An alternative measure of aerodynamic drag should take into account the effect of non-zero yaw angles and some proposals have been made in the past, including variations of a wind-averaged drag coefficient. For almost all cars the drag increases with yaw, but the increase can vary significantly between vehicles. In this paper the effect of various parameters on the drag rise with yaw are considered for a range of different vehicle types. The increase of drag with yaw is shown to be an essentially induced drag, which is strongly dependent on both side force and lift. Shape factors which influence the sensitivity of drag with yaw are discussed.
2015-04-14
Technical Paper
2015-01-1530
Todd Lounsberry, Joel Walter
There has been a lot of attention in recent years on open jet correction methods, in particular on the two-measurement method set forth by E. Mercker, K. Cooper, and co-workers. This method accounts for blockage and static pressure gradient effects in automotive wind tunnels and has been shown by both computations and experiments to appropriately adjust drag coefficients towards an on-road condition, thus allowing results from different wind tunnels to be better compared. However, most wind tunnels have yet to adopt the method as standard practice due to difficulties in practical application. In particular, it is necessary to measure the aerodynamic forces on every vehicle configuration in two different static pressure gradients to capture that portion of the correction. Building on earlier proof-of-concept work, this paper demonstrates a practical method for implementing the two-measurement procedure and demonstrates how it can be used for production testing.
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