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Viewing 1 to 30 of 2625
2017-04-04
Event
Paper offers on the following topics are welcome: test facilities, unsteady aerodynamics, fuel economy, cooling airflow, fundamental aerodynamics and aerodynamics development.
2017-04-04
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.
2016-09-27
Technical Paper
2016-01-2095
Agata Suwala, Lucy Agyepong, Andrew Silcox
Reduction of overall drag to improve aircraft performance has always been one of the goals for aircraft manufacturers. One of the key contributors to decreasing drag is achieving laminar flow on a large proportion of the wing. Laminar flow requires parts to be manufactured and assembled within tighter tolerance bands than current build processes allow. Drilling of aircraft wings to the tolerances demanded by laminar flow requires machines with the stiffness and accuracy of a CNC machine while having the flexibility and envelope of an articulated arm. This paper describes the development and evaluation of high accuracy automated processes to enable the assembly of a one-off innovative laminar flow wing concept. This project is a continuation of a previously published SAE paper related to the development of advanced thermally stable and lightweight assembly fixture required to maintain laminar flow tolerances.
2016-09-27
Technical Paper
2016-01-8144
John Lacey
The trucking industry is being encouraged by environmental and cost factors to improve fuel efficiency. One factor that affects fuel efficiency is the aerodynamic design of the vehicles; that is, the vehicles with lower aerodynamic drag will get better fuel mileage, reducing both costs and carbon emissions. The automobile industry has made great improvements in fuel efficiency in part by using wind tunnels to achieve lower aerodynamic drag. Those wind tunnels are not optimum for testing the larger, longer heavy truck designs. Most of these wind tunnels are too small and/or too short for full scale tests, and subscale tests are problematic at best due to the high operating costs and availability of those wind tunnels. In addition, the wind tunnel design factors for the testing of long trucks are not well established.
2016-09-27
Journal Article
2016-01-8147
Justin J. Novacek, Bhargav Sowmianarayanan
Trailer positioning plays a significant role in the overall aerodynamics of a tractor-trailer combination and varies widely depending on configuration and intended use. In order to minimize aerodynamic drag over a range of trailer positions, adjustable aerodynamic devices may be utilized. For maximum benefit, it is necessary to determine the optimal position of the aerodynamic device for each trailer position. This may be achieved by characterizing a two-dimensional design space consisting of trailer height and tractor-trailer gap length, with aerodynamic drag as the response. CFD simulations carried out using a Lattice-Boltzmann based method were coupled with modeFRONTIER for the creation of multiple Kriging Response Surfaces. Simulations were carried out in multiple phases, allowing for the generation of intermediate response surfaces to estimate predictive error and track response surface convergence.
2016-09-27
Journal Article
2016-01-8133
Sam Waltzer, Dennis Johnson, Kuang Wei, Jonathan Wilson
Commercial, class-8 tractor-trailers were tested to develop a relationship between vehicle speed and fuel savings associated with trailer aerodynamic technologies representative of typical long-haul freight applications. This research seeks to address a concern that many long-distance U.S. freight companies hold that, as vehicle speed is reduced, the fuel savings benefits of aerodynamic technologies are not realized. In this paper, the reductions in fuel consumption were measured using the SAE J1231 test method and thru-engine fueling rates recorded from the vehicle’s electronic data stream. Constant speed testing was conducted on road at different speeds and corresponding testing was conducted on track to confirm results. Data was collected at four (4) vehicle speeds: 35, 45, 55, and 62 miles per hour. Two different trailer aerodynamic configurations were evaluated relative to a baseline tractor trailer.
2016-09-27
Technical Paper
2016-01-8139
Santosh Nalanagula, G T Varadharajan
Aerodynamic drag contributes to 50-60% of fuel consumption in trucks on highways. The limits of conventional wind tunnel testing have forced researchers to study about the drag and ways of reducing it computationally. Due to the stricter norms and eco-friendly approaches, truck manufacturers have begun to invest more for developing truck aerodynamics. This paper evaluates a European vehicle on European conditions. Drag reduction are mostly made by geometric changes. Pressure drag, a major drag for trucks as they run at lower speeds is produced by the shape of the object. Making streamlined bodies as trucks are tougher since it can affect its purpose. Therefore, addition of some components can suffice the needs. The changes in geometry have been implied and analysis for these geometrical changes are done to analyze the better geometry which can provide drag reduction features. The geometrical changes considered are providing side skirts, boattails and roof deflector angle.
2016-09-27
Journal Article
2016-01-8148
Louis Carbonne, Niklas Winkler, Gunilla Efraimsson
The prediction in the design phase of the stability of ground vehicles subject to transient crosswinds become of increased concern with drag reduced shapes, platooning as well as lighter vehicles. The objective of this work is to assess the order of model complexity needed in numerical simulations to capture the behavior of a ground vehicle going through a transient crosswind. The performance of a full-dynamic coupling between aerodynamic and vehicle dynamic simulations, including a driver model, is evaluated. In the simulations a feedback from the vehicle dynamics into the aerodynamic simulation are performed in every time step. In the work, both the vehicle dynamics response and the aerodynamics forces and moments are studied. The results are compared to a static coupling approach on a set of different vehicle geometries.. One simplified bus geometry and five car-type geometries are evaluated.
2016-09-27
Journal Article
2016-01-8149
Thomas Gheyssens, Gandert Van Raemdonck
Due to the increasing awareness around harmful gasses and depleting oil sources, more sustainable transport systems are needed. The efficiency of long-haul, heavy-duty vehicles can be increased by driving in platoon formation in order to decrease drag and to increase fuel mileage. The drag behaviour of drafting vehicles is already studied but differences in aerodynamic drag reductions occur on the trailing vehicle. Some studies indicate a drag increase while other predict a drag decrease. This paper investigates the effect of the frontal edge radius of the Generalised European Transport System (GETS) model on the aerodynamic behaviour of three different vehicles in a platoon. A numerical investigation was performed solving Reynolds Averaged Navier-Stokes equations with the aid of a commercial package. Four different inter-vehicle distances were tested for the vehicles with several different frontal edge radii.
2016-09-27
Technical Paper
2016-01-8153
Prashanth Gururaja
To investigate the feasibility of various aerodynamic test procedures for the Phase 2 Greenhouse Gas Regulations for Heavy-Duty Vehicles in the United States, the US Environmental Protection Agency commissioned, through Southwest Research Institute, constant-speed torque tests of several heavy-duty tractors matched to a conventional 53 ft dry-van trailer. Torque was measured at the transmission output shaft and, for most tests, also on each of the drive wheels. Air speed was measured onboard the vehicle, and wind conditions were measured using a weather station placed along the road side. Tests were performed on a rural road in Texas. Measuring wind-averaged drag from on-road tests has historically been a challenge. By collecting data in various wind conditions at multiple speeds over multiple days, a regression-based method was developed to estimate wind-averaged drag with a high level of confidence for multiple tractor-trailer combinations.
2016-09-27
Technical Paper
2016-01-8154
Abhijith Balakrishna, Gang Wang
The aerodynamic performance between the gap of a tractor-trailer mounted with a refrigeration unit is studied while another trailer passes by on a freeway using transient computational fluid dynamics. Dynamic Meshing methodology available in Ansys Fluent was used to understand the dynamic pressure and flow regimes in and around the tractor trailer gap in general and refrigeration unit in particular, at various vehicle speeds. The influences of distance between the crossing trailers, speed and gap between the tractor trailers on the pressure distribution on the refrigeration unit have been studied.
2016-09-27
Technical Paper
2016-01-8151
Prashanth Gururaja
To investigate the feasibility of various aerodynamic test procedures for the Phase 2 Greenhouse Gas Regulations for Heavy-Duty Vehicles in the United States, the US Environmental Protection Agency commissioned, through Southwest Research Institute, coastdown testing of several heavy-duty tractors matched to a conventional 53 ft dry-van trailer. Three vehicle configurations were tested, two of which included common trailer drag-reduction technologies. Air speed was measured onboard the vehicle, and wind conditions were measured using a weather station placed along the road side. Tests were performed on a rural road in Texas. One vehicle configuration was tested over several days to evaluate day-to-day repeatability and the influence of changing wind conditions.
2016-09-27
Journal Article
2016-01-8152
Brian R. McAuliffe, David Chuang
In an effort to support Phase 2 of Greenhouse Gas Regulations for Heavy-Duty Vehicles in the United States, a track-based test program was jointly supported by Transport Canada (TC), Environment and Climate Change Canada (ECCC), the U.S. Environmental Protection Agency (EPA), and the National Research Council Canada (NRC) to assess aerodynamic evaluation methodologies proposed by the EPA and to provide a site-verification exercise against a previous test campaign with the same vehicle. Coast-down tests were conducted with a modern aerodynamic tractor matched to a conventional 16.2 m (53 ft) dry-van trailer, and outfitted with two drag reduction technologies. Enhanced wind-measurement instrumentation was introduced, consisting of a vehicle-mounted fast-response pressure probe and track-side sonic anemometers that, when used in combination, provided improved reliability for the measurements of wind conditions experienced by the vehicle.
2016-09-27
Journal Article
2016-01-8016
Devaraj Dasarathan, Matthew Ellis, Surya Chinnamani, Ray Ayala, James Haws
In 2015, the United States Environmental Protection Agency and Department of Transportation’s National Highway Traffic Safety Administration released their proposal for the second phase of regulations to reduce greenhouse gas (GHG) emissions from on-road heavy duty vehicles. This second phase of proposed regulations is similar to the first phase of regulations, that went in to effect on model year 2014 heavy duty vehicle, in that the proposals continue to push for further reductions in GHG emissions. One difference is that this new proposal takes a more systematic approach to reducing emissions by considering the impact that trailers have on the fuel efficiency, and therefore the emissions. The new proposed regulations will continue to allow manufacturers to evaluate aerodynamic performance of designs using alternative methods such as computational fluid dynamics (CFD) simulations and wind tunnel tests. It is important for the industry to have confidence in these alternative methods.
2016-09-27
Journal Article
2016-01-8022
Petter Ekman, Roland Gardhagen, Torbjörn Virdung, Matts Karlsson
Reducing energy consumption and emissions are ongoing challenges for the transport sector. The increased number of goods transports emphasize these challenges even more, as greenhouse gas emissions from these vehicles has increased by 20 % since 1990 in Sweden. One special case of goods transports is that of timber. Today in Sweden, around 2000 timber trucks transport around six billion ton kilometers every year. For every ton kilometer these vehicles use around 0.25 liter diesel, and there should exist large possibilities to reduce the fuel consumption and the emissions. These timber trucks spend most of their operation time travelling in speeds of around 80 km/h. At this speed aerodynamic drag contributes to around 30% of the total vehicle resistance, which makes the aerodynamic drag a significant part of the energy consumption. One of the big challenges with timber trucks is that they travel empty half of the time.
2016-09-27
Journal Article
2016-01-8023
Bernard Tanguay
The quality of the aerodynamic data obtained from track tests hinges on the ability to determine the free-stream speed and yaw angle that the test vehicle experiences. Due to the turbulent nature of the terrestrial wind, the use of on-board anemometry for quantifying free-stream velocity is of paramount importance. However, the aerodynamic perturbation induced by the vehicle’s presence causes a significant bias in the velocity sensed by a conventional boom-mounted anemometer, relative to the sought free-stream value. It was shown that an anemometer located 2.5 metres forward of the nose of a HDV and at mid-height can report a wind speed 10% lower than the free-stream value and a yaw angle almost twice as large, resulting in a 20% overestimate of CD. A method was developed to predict the free-stream (unperturbed) velocity based on track-side anemometric measurements, resulting in a calibration function to correct the onboard anemometer readings through post-processing.
2016-09-20
Technical Paper
2016-01-2008
Alexander Grima, Colin Theodore, Oliver Garrow, Ben Lawrence, Linnea Persson
Abstract The Elytron 2S is a prototype aircraft concept to allow VTOL capabilities together with fixed wing aircraft performance. It has a box wing design with a centrally mounted tilt-wing supporting two rotors. This paper explores the aerodynamic characteristics of the aircraft using computational fluid dynamics in hover and low speed forward flight, as well as analyzing the unique control system in place for hover. The results are then used to build an input set for NASA Design and Analysis if Rotorcraft software allowing trim and flight stability and control estimations to be made with SIMPLI-FLYD.
2016-09-20
Technical Paper
2016-01-2019
Richard P. Johnston
Abstract An advanced composite Blended Wing Body (BWB) air frame previously used as a study aircraft to transport a 75-ton military cargo halfway around the world and back unrefueled has been modified and evaluated as a 150-ton heavy lifter. The modifications include enlarging the forward trim canard, reducing fuel load by 151,850 lbs, increasing the high-mach NASA-type counter-rotating propellers from 12 feet to 13 feet diameter, extending the propeller support pylons' height by 6 inches and modifying cruise flight and prop control strategies. Due to structural and propulsion system changes, the air frame Operational Empty Weight (OEW) was increased by 1,850 lbs. but the maximum Take Off Gross Weight (TOGW) was held to 800,000 lbs. Brief descriptions of the major propulsion system components are provided. In addition, a comparison of three different counter-rotating propeller systems is presented. The first is a Standard configuration.
2016-09-20
Technical Paper
2016-01-2010
Nandeesh Hiremath, Dhwanil Shukla, Narayanan Komerath
Abstract The design of advanced rotorcraft requires knowledge of the flowfield and loads on the rotor blade at extreme advance ratios (ratios of the forward flight speed to rotor tip speed). In this domain, strong vortices form below the rotor, and their evolution has a sharp influence on the aero-dynamics loads experienced by the rotor, particularly the loads experienced at pitch links. To understand the load distribution, the surface pressure distribution must be captured. This has posed a severe problem in wind tunnel experiments. In our experiments, a 2-bladed teetering rotor with collective and cyclic pitch controls is used in a low speed subsonic wind tunnel in reverse flow. Stereoscopic particle image velocimetry is used to measure the three component spatial velocity field. Measurement accuracy is now adequate for velocity data, and can be converted to pressure both at and away from the blade surface.
2016-09-20
Technical Paper
2016-01-2026
Dhwanil Shukla, Nandeesh Hiremath, Narayanan Komerath
Abstract An architecture is proposed for on-demand rapid commuting across congested-traffic areas. A lighter-than-air (LTA) vehicle provides the efficient loitering and part of the lift, while a set of cycloidal rotors provides the lift for payload as well as propulsion. This combination offers low noise and low downwash. A standardized automobile carriage is slung below the LTA, permitting driveway to driveway boarding and off-loading for a luxury automobile. The concept exploration is described, converging to the above system. The 6-DOF aerodynamic load map of the carriage is acquired using the Continuous-Rotation method in a wind tunnel. An initial design with rear ramp access is modified to have ramps at both ends. The initial design shows a divergence sped in access of 100 mph. An effort to improve the ride quality using yaw stabilizers, failed as the dynamic behavior becomes unstable. The requirements for control surfaces and instrumentation are discussed.
2016-09-20
Technical Paper
2016-01-2033
Rudolf Neydorf, Ivan Chernogorov, Victor Polyakh, Orkhan Yarakhmedov, Julia Goncharova, Anna Neydorf
Abstract Mathematical modeling of technical objects is most frequently connected with mathematical processing of experimental data. The obtained pointlike dependencies of output variables on input ones are often strongly nonlinear, piecewise, and sometimes discontinuous. Approximation of these dependencies using polynomial resolution and spline-functions is problematic and may cause low accuracy. A radically new solution to this problem was suggested in a number of previous works. The method is based on partitioning of experimental dependencies into patches, approximation of each patch by analytic functions, multiplicative cutting of fragments from each function along the patch border and additive gluing of the fragments into a single function -- namely the model of approximated dependence. The analytic properties of this approximating glued function appear to be the major distinguishing feature and advantage of the method.
2016-09-20
Technical Paper
2016-01-2035
Rudolf Neydorf, Anna Neydorf
Abstract The main difficulties of the mathematical models vehicles creation are defined by strongly nonlinearity of dependences which connect various variables their states and conditions of the movement environment. Most it belongs to aircrafts as aerodynamic interactions are characterized by essential nonlinearity up to discontinuity of variables and their derivatives. Creation process of these models is complicated by high-dimensionality, characteristic for the mechanical movement laws. Experimental creation of the mathematical models (MM) of such dependences is carried out by various mathematical methods of approximation of data. Universal remedies of the solution of the formulated task don't exist. Each of it possesses both benefits, and considerable shortcomings. In this regard the possibilities of a method creation of high-precision analytical approximations of the strongly nonlinear dependences using the analytical functions have been investigated.
2016-09-20
Technical Paper
2016-01-2056
Nikolaus Thorell, Vaibhav Kumar, Narayanan Komerath
Abstract Combat aircraft maneuvering at high angles of attack or in landing approach are likely to encounter conditions where the flow over the swept wings is yawed. This paper examines the effect of yaw on the spectra of turbulence above and aft of the wing, in the region where fins and control surfaces are located. Prior work has shown the occurrence of narrowband velocity fluctuations in this region for most combat aircraft models, including those with twin fins. Fin vibration and damage has been traced to excitation by such narrowband fluctuations. The narrowband fluctuations themselves have been traced to the wing surface. The issue in this paper is the effect of yaw on these fluctuations, as well as on the aerodynamic loads on a wing, without including the perturbations due to the airframe.
2016-09-01
Magazine
Solving the Greenhouse Gas puzzle While automakers and policymakers debate the TAR, engineers and product planners prepare for the steep climb to meet GHG and CAFE rules beyond 2022. Revving up thermal characterization in the component lab The latest generation of high-speed infrared cameras can capture airbag deployments and other fast-moving actions quickly and accurately. C3 consortium aims for soot solution A newly formed group of companies led by CFD specialists Convergent Science targets exhaust particulate reduction in the combustion chamber. Inside the autonomous vehicle With less focus on driver needs, comfort, safety, and occupant productivity will become key. Editorial: Bad gas?
2016-08-24
Video
Your vehicle's rearview mirrors are an endangered species. In this episode of SAE Eye on Engineering, Editor-In-Chief Lindsay Brooke looks at Valeo's plans to have a camera-based rearview mirror system ready for production by 2018. SAE Eye on Engineering also airs Monday mornings on WJR 760 AM Detroit's Paul W. Smith Show. Access archived episodes of SAE Eye on Engineering.
2016-08-10
WIP Standard
AIR6211A
This test method provides stakeholders (runway deicing chemical manufacturers, deicing/anti-icing chemical operators and airport authorities) with a relative ice penetration capacity of runway deicing/anti-icing chemicals, by measuring the ice penetration as a function of time. Such runway deicing/anti-icing chemicals are often also used on taxiways and other paved areas. This test method does not quantitatively measure the theoretical or extended time of ice penetration capability of ready-to-use runway deicing/anti-icing chemicals in liquid or solid form.
2016-08-10
WIP Standard
AIR6170A
This test method provides stakeholders (runway deicing chemical manufacturers, deicing/anti-icing chemical operators and airport authorities) with relative ice melting capacity of runway deicing chemicals, by measuring the amount of ice melted as a function of time. Such runway deicing chemicals are often also used on taxiways. This test method does not quantitatively measure the theoretical or extended time ice melting capability of ready-to-use runway deicing/anti-icing chemicals in liquid or solid form.
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