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Viewing 1 to 30 of 2611
2016-09-27
Technical Paper
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
Technical Paper
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 like a trim tab 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. These response surfaces were employed to generate an optimal positioning map for the given aerodynamic device. This methodology was further refined by obtaining performance maps for multiple tractor configurations.
2016-09-27
Technical Paper
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, Environment and Climate Change Canada, the US Environmental Protection Agency, and the National Research Council Canada to verify aerodynamic evaluation methodologies proposed by the US EPA. Coast-down and Constant-Speed tests were conducted with a modern aerodynamic tractor matched to a conventional 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 four track-side sonic anemometers that, when used in combination, provided reliable measurements of the wind conditions experienced by the vehicle during the tests.
2016-09-27
Technical Paper
2016-01-8022
Petter Ekman, Roland Gardhagen, Torbjörn Virdung PhD, 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
Technical Paper
2016-01-8139
Santosh Nalanagula, Varadharajan G T
Aerodynamic Drag Reduction for Commercial Trucks 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.
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.
2016-09-20
Technical Paper
2016-01-2026
Dhwanil Shukla, Nandeesh Hiremath, Narayanan Komerath
Rigid or semi-rigid airships are gaining appeal for several applications requiring steady cargo transport, long endurance, low downwash and noise over populated areas, and rescue missions. Modern rigid-hulled airships use auxiliary lift and propulsion for the load-carrying segments of their operations. Tilting ducted fans and quad-rotors have been typically considered for the purpose. We are developing a concept where cycloidal rotors are used. These can operate both as lifting devices and as propulsive devices. The size of an airship allows the cylcoidal rotor to have a much larger diameter than on a helicopter, so that the rotation speed is low, and while minimizing downwash and noise. These features make the cycloidal rotor/airship combination ideas for the hypercommuting-on-demand application over congested urban and suburban areas. In this paper, the literature on hypercommuting, airships and cycloidal rotors will be surveyed.
2016-09-20
Technical Paper
2016-01-2056
Nikolaus Thorell, Vaibhav Kumar, Narayanan Komerath
A combat aircraft in landing approach is likely to encounter wind turbulence, causing the flow over its swept wings to be 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 issue in this paper is the effect of yaw on these fluctuations, as well as on the aerodynamic loads on a wing. A 42 degree delta wing with rounded leading edges, roughly equivalent to a 1/25 scale of existing combat aircraft, is used in a 2.74 m low speed wind tunnel in the angle of attack range 18 to 35 degrees and at significant yaw settings.
2016-09-20
Technical Paper
2016-01-2010
Nandeesh Hiremath, Dhwanil Shukla, Narayanan Komerath
The design of advanced rotorcraft hinges on 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 above and below the rotor, and their evolution has a sharp influence on the aerodynamics loads experienced by the rotor, particularly the loads experienced at pitch links. To capture the load distribution, the surface pressure distribution must be captured. This has posed a severe problem in wind tunnel experiments. A 2-bladed teetering rotor with collective and cyclic pitch controls is used in a 2.74m wind tunnel, under conditions of dynamic stall and then in reverse flow. Stereoscopic particle image velocimetry us used. Recently we have shown that the accuracy of stereoscopic particle image velocimetry has reached the point where velocity measurements can be converted to pressure both at and away from the blade surface.
2016-09-20
Technical Paper
2016-01-2008
Alexander Grima, Colin Theodore, Oliver Garrow, Ben Lawrence, Linnea Persson
The Elytron 2S (Elytron Aircraft Inc. 2016) is a prototype for an advanced VTOL concept aircraft consisting of a box wing and a small centrally mounted tiltwing with tilting rotors. The concept aircraft is proposed in two sizes, 4 and 10 seater, and is envisaged for use as an air taxi or perhaps for transportation of crews of oil and gas rigs. This aircraft design, attained after 10 years of research, should allow helicopter VTOL capabilities as well as fixed wing like speeds with greatly reduced cost in comparison to any existing solutions. This paper will describe the modeling and analysis of the aerodynamic characteristics of a 2-seat experimental version of the aircraft using computational analysis in AVL (Drela and Youngren 2016) and RotCFD (Sukra Helitek Inc. 2016). The aim of the research is to model the vehicle and enable predictions of aerodynamic performance for comparison with experimental results obtained through flight testing.
2016-09-20
Technical Paper
2016-01-2033
Rudolf Neydorf, Ivan Chernogorov, Victor Polyakh, Orkhan Yarakhmedov, Julia Goncharova, Anna Neydorf
Experimental and computer modelling of statics and dynamics of vehicles may cause difficulties related with significant non-linearity of dependencies included in a model. This is due to the mechanical effects of friction, backlash etc., aerodynamic effects and other physical phenomena. Mathematical modeling of such objects is most frequently connected with mathematical processing of experimental data. Obtained pointlike dependencies of output variables on input ones are strongly nonlinear, piecewise, sometimes discontinuous. Approximation of these dependencies using polynomial resolution or spline-functions is problematic and may cause low accuracy. A radically new solution of this problem was suggested in the article [Neydorf, R., "Bivariate “Cut-Glue” Approximation of Strongly Nonlinear Mathematical Models Based on Experimental Data," SAE Int. J. Aerosp. 8(1):2015, doi:10.4271/2015-01-2394].
2016-09-20
Technical Paper
2016-01-2035
Rudolf Neydorf, Anna Neydorf
The main difficulties of the mathematical models vehicles creation are defined by strongly nonlinearity of dependences which connect various variable 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. Approximating creation of mathematical models (MM) of such dependences by modern mathematical methods (polynomial decomposition, a spline functions, etc.) is laborious and insufficiently exact. The author investigated possibility of a method creation of high-precision analytical approximation of nonlinear dependences by mathematical models. The received results are stated in two fundamental articles: [Neydorf R.A.
2016-09-20
Technical Paper
2016-01-2019
Richard P. Johnston
The author recently presented a technical paper describing an advanced BWB air frame capable of transporting a 75-ton military cargo half-way around the world and back without re-fueling. This paper will look at the flight and range characteristics of that air frame modified to transport a 150-ton military cargo. Limited NASA open literature prop data from the Hamilton-Standard CRP-X1 high Mach 1986 UTC testing will be applied to characterize the counter-rotating prop performance. Air frame propulsion will be provided by 4 sets of C/R propellers driven by 8 separate Advanced Variable Cycle Diesel (AVCD) engines turbo-compounded to 14,000 SHP for take-off. Some discussion of the possible interactive aerodynamics of the highly loaded propeller sets at low Mach using a simplified disk-actuator explanation will be made. Mission table results of air frame and engine, prop and fuel consumption characteristics will be presented as the flight proceeds.
2016-07-12
WIP Standard
AMS1428/2
The foundation specification (AMS1428) and the category specifications (AMS1428/1 and AMS1428/2) cover deicing/anti- icing materials in the form of a fluid. 1.1.1 Foundation and Category Specifications The foundation specification establishes the requirements for all Type I deicing/anti-icing fluids and defines the terms Glycol (Conventional and Non-Conventional) and Non-Glycol and contains technical and other requirements that apply to both Glycol (Conventional and Non-Conventional) and Non-Glycol based fluids. The category specification AMS1428/1 covers Glycol (Conventional and Non-Conventional) based fluids whereas the category specification AMS1428/2 covers Non-Glycol based fluids. 1.2 Other Scope Requirements Other Scope requirements are set in AMS1428.
2016-07-12
WIP Standard
AMS1428/1
1.1 Form The foundation specification (AMS1424M) and the category specifications (AMS1424/1 and AMS1424/2) cover deicing/anti-icing materials in the form of a fluid. 1.1.1 Foundation and Category Specifications The foundation specification establishes the requirements for all Type I deicing/anti-icing fluids and defines the terms Glycol (Conventional and Non-Conventional) and Non-Glycol and contains technical and other requirements that apply to both Glycol (Conventional and Non-Conventional) and Non-Glycol based fluids. The category specification AMS1424/1 covers Glycol (Conventional and Non-Conventional) based fluids whereas the category specification AMS1424/2 covers Non-Glycol based fluids. 1.2 Other Scope Requirements Other Scope requirements are set in AMS1424M.
2016-06-15
Technical Paper
2016-01-1803
Hannes Frank, Claus-Dieter Munz
Avoiding narrowband components in the acoustic spectrum is one of the most critical objectives in the automotive aeroacoustic optimization process. The underlying physical mechanisms are not completely understood. In a preceding numerical and experimental investigation, we performed large eddy simulations of an early-development stage realistic side-view mirror, where tonal noise was captured and the principle mechanisms were identified. In this contribution, we present simulations on a simplified two-dimensional geometry that is based on these findings. It is shown that the basic flow topology relevant for tonal noise generation on the original side-view mirror as well as the tonal noise source is reproduced in the 2D case. Furthermore, we present comparisons with measurements and the necessity and influence of a splitter plate downstream of the 2D body to avoid large scale vortex shedding.
2016-06-15
Technical Paper
2016-01-1807
Olga Roditcheva, Lennart Carl Lofdahl, Simone Sebben, Pär Harling cEng, Holger Bernhardsson
Abstract This paper presents an experimental study of aeroacoustical sound sources generated by the turbulent flow around the side mirror of a Volvo V70. Measurements were carried out at the Volvo Cars aerodynamical wind tunnel (PVT) and at the aeroacoustical wind tunnel of Stuttgart University (FKFS). Several different measurement techniques were applied in both tunnels and the results were compared to each other. The configurations considered here were: side mirror with a cord and without the cord. The results discussed in this paper include intensity probe measurements in the flow around the side mirror, sound source localization with beamforming technique using a three-dimensional spherical array as well as standard measurements inside the car with an artificial head. This experimental study focused on understanding the differences between testing at the PVT and FKFS.
2016-06-15
Technical Paper
2016-01-1804
Stefan Becker, Katrin Nusser, Marco Oswald
Abstract Aim of the ongoing development of passenger cars is to predict the interior acoustics early in the development process. A significant noise component results from the flow phenomena in the area of the side window. Wind noise is a physical problem that involves the three complicated aspects each governed by different physics: The complex turbulent flow field in the wake of the a-pillar and the side mirror is characterized by velocity and pressure fluctuations. The flow field generates sound which is transmitted into the passenger cabin. In addition to that, it excites the structure, resulting in a radiation of structure-borne noise into the interior of the car. Therefore, the sound generation is governed by fluid dynamics of the air flow. The sound transmission through the structure due to vibrations is determined by structural mechanics of the body structure. The sound propagation inside the cabin is influenced by interior room acoustics.
2016-05-18
WIP Standard
AMS1424/3
This detail specification AMS1424/3 covers the use of In-Truck Manufacturing of a deicing SAE Type I deicing/anti-icing fluid. This detailed specification contains technical and other requirements that apply for the In-Truck Manufacturing of Type I deicing/anti-icing fluid.
2016-05-17
Magazine
Base-engine value engineering for higher fuel efficiency and enhanced performance Continuous improvement in existing engines can be efficiently achieved with a value engineering approach. The integration of product development with value engineering ensures the achievement of specified targets in a systematic manner and within a defined timeframe. Integrated system engineering for valvetrain design and development of a high-speed diesel engine The lead time for engine development has reduced significantly with the advent of advanced simulation techniques. Cars poised to become 'a thing' Making automobiles part of the Internet of Things brings both risks and rewards. Agility training for cars Chassis component suppliers refine vehicle dynamics at the high end and entry level with four-wheel steering and adaptive damping.
2016-05-09
WIP Standard
ARP4902C
This document provides information and guidance material to assist in assessing the need for and feasibility of developing deicing facilities, the planning (size and location) and design of deicing facilities, and assessing environmental considerations and operational considerations associated with de-icing facilities. The document presents relevant information necessary to define the need for a deicing facility and factors influencing its size, location and operation. The determination of the need for deicing facilities rests with Airports. Although this document intends to provide information to airport operator and deicing facility planner/designer, all stakeholders, including deicing service providers, should be involved in the development process.
2016-04-20
Standard
ARP6852A
This document describes methods that are known to have been used by aircraft manufacturers to evaluate aircraft aerodynamic performance and handling effects following application of aircraft ground deicing/anti-icing fluids (“fluids”), as well as methods under development. Guidance and insight based upon those experiences are provided, including: - Similarity Analyses - Icing Wind Tunnel Tests - Flight Tests - Computational Fluid Dynamics and other Numerical Analyses This document also describes: - The history of evaluation of the aerodynamic effects of fluids - The effects of fluids on aircraft aerodynamics - The testing for aerodynamic acceptability of fluids for SAE and regulatory qualification performed in accordance with AS5900 - Additionally, Appendices A to E present individual aircraft manufacturers’ histories and methodologies which substantially contributed to the improvement of knowledge and processes for the evaluation of fluid aerodynamic effects.
2016-04-14
Event
It's vital that we continue to explore fundamental aerodynamic effects and processes, to underpin future vehicle development. This two-part session underlines the importance of simplified models in building our understanding of wake structure, wheel rotation, cooling flows, onset flow turbulence and crosswinds. Beyond this, careful analysis of existing cars is used to provide further insights into multiple-vehicle platooning, and drag reduction technologies.
2016-04-14
Event
In this session the use of the Adjoint Method and its role in vehicle shape optimization will be explored. New simulation approaches will be presented, including Partially-Averaged Navier-Stokes (PANS) and a novel RANS and Implicit LES Hybrid Turbulence Model. The use of CFD for Cooling Drag sensitivity analysis is also discussed.
2016-04-14
Event
It's vital that we continue to explore fundamental aerodynamic effects and processes, to underpin future vehicle development. This two-part session underlines the importance of simplified models in building our understanding of wake structure, wheel rotation, cooling flows, onset flow turbulence and crosswinds. Beyond this, careful analysis of existing cars is used to provide further insights into multiple-vehicle platooning, and drag reduction technologies.
2016-04-13
Event
Experimental facilities and methods continue to develop. This session covers wind tunnel interferences and their correction, along with a new ground simulation system and methods for introducing atmospheric levels of turbulence into wind tunnel testing. Developments presented in measurement techniques include: Tomographic PIV, Quantitative Tuft Image Processing, Strip Tube pressure measurement and a new small-scale PIV system.
2016-04-13
Event
The emergence of unsteady simulation as a viable tool along with the continuing development of experimental methods has led to an increasing focus on the unsteady aerodynamic effects experienced by cars in use. This session investigates aerodynamics influences on vehicle dynamics: dynamic pitching, cross wind effects. Surface contamination is receiving increased attention as customer expectations rise. Hence, simulating soiling of rear vehicle surfaces and wetting of brake discs are explored.
Viewing 1 to 30 of 2611

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