Browse Topic: Air deflectors

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The Aerodynamic Development of the New Audi Q52017-01-15223/28/2017
The aerodynamic development of the new Audi Q5 (released in 2017) is described. In the course of the optimization process a number of different tools has been applied depending on the chronological progress in the project. During the early design phase, wind tunnel experiments at 1:4 scale were performed accompanied by transient DES and stationary adjoint simulations. At this stage the model contained a detailed underbody but no detailed engine bay for underhood flow. Later, a full scale Q5 model was built up for the aerodynamic optimization in the 1:1 wind tunnel at Audi AG. The model featured a detailed underbody and engine bay including original parts for radiators, engine, axles and brakes from similar vehicles. Also the 1:1 experiments were accompanied by transient DES and stationary adjoint simulations in order to predict optimization potential and to better understand the governing flow. The strong coupling of experimental and numerical tools enabled a best-in-class drag coefficient to be achieved not only for a single optimized vehicle setup but for the majority of four cylinder diesel and gasoline engines in base configuration even in SUV ground clearance (as required for LDT). This is not only true if the vehicle is equipped with the aerodynamically optimized “aero wheel” but also a number of optional rim designs allow comparably low drag values. In order to reach such low aerodynamic drag values, a variety of design and technical measures were necessary. A description of their definition and function is subject of the present paper.
Blacha, Thomas, Islam, Moni
Investigation of a Trailer Underbody Fairing for Heavy Vehicle Aerodynamic Drag Reduction2008-01-260110/7/2008
The drag reduction capability of a trailer underbody fairing is investigated using steady Reynolds-averaged Navier-Stokes simulations of a full-scale heavy vehicle traveling at highway speed within a crosswind. The flow field about the vehicle is modeled for two different fairing designs of varying length that yield reductions in the drag coefficient ranging from 0.013 to 0.042. Analysis of the trailer underbody flow field indicates that the fairings decrease the size of a recirculation zone that exists immediately downstream of the tractor drive wheels by providing a surface to which the separated underbody flow can reattach. A comparison of the pressure coefficients across the surface of the fairings demonstrates that the longer fairings produce greater pressure coefficients, hence resulting in a larger reduction in drag than the shorter fairings. One of the fairings is shown to outperform traditional trailer side skirts, which yield a reduction in the drag coefficient of 0.035. The results of this investigation indicate that the fairing may be a viable add-on device for mitigating trailer underbody drag, while providing ground clearances greater than that of trailer side skirts.
Ortega, J. M., Salari, K.
Vehicle Wind Buffeting Noise Reduction via Window Openings Optimization2008-01-06784/14/2008
Vehicle wind buffeting noise occurs when one window of a vehicle is opened in a certain way during driving. By optimizing window openings, the buffeting noise can be significantly reduced or may be even eliminated. In addition, the optimized window openings will also provide sufficient fresh air circulation while allows the driver still be able to enjoy listening to radio. This paper provides such an optimization and describes the principle with the results from both laser imaging and road tests.
Chen, F., Qian, P.
Simple and Low-Cost Aerodynamic Drag Reduction Devices for Tractor-Trailer Trucks2003-01-337711/10/2003
Three simple, low cost aerodynamic drag reduction devices have been developed for application to the trailer of a tractor-trailer truck. The three devices have undergone extensive operational testing where they have amassed over 85,000 miles of use. These technologies have shown a combined fuel savings of 10% at an average speed of 47.5 mph. This improvement in fuel economy correlates to an equivalent drag reduction of approximately 30% with a corresponding drag coefficient of 0.45. Observations and anecdotal evidence from the test activity have shown that the addition of these devices to the trailers has not had a negative impact on either the operational utility of the trailers or the maintenance procedures and requirements.
Wood, Richard M., Bauer, Steven X. S.
Truck Aerodynamics Reborn - Lessons from the Past2003-01-337611/10/2003
During the late 1970's and early 1980's considerable effort was expended in the improvement of truck aerodynamics to reduce fuel consumption. This first-generation effort focused on aerodynamic drag reduction obtained from add-on aerodynamic aids to the cab or the trailer, from improved cab shaping and from body/trailer front-end edge rounding. Rising fuel prices have renewed interest in further aerodynamic improvements. This paper will review past developments and show that several unused concepts offer potential as second-generation, add-on, fuel-saving technology. It will raise the issue of finding successful means for bringing them profitably into service, which will require concerted action by the trucking industry, manufacturers and government.
Cooper, Kevin R.
Numerical Study on the Wake Flow and Rear-Spoiler Effect of a Commercial Bus Body2003-01-12533/3/2003
CFD for automobile industry has matured since the 1980's. One sign of the maturity is the use of CFD for product development, instead of validation only. The author of the present paper provides an impressive case of using CFD for product development. The paper shows that the aerodynamic drag for a commercial bus can be reduced by 16% with the use of a rear-spoiler. If such a reduction can be materialized for real vehicles, huge saving in energy consumption can be yielded.
Kim, Min-Ho
Compression Molded Sheet Molding Compound (SMC) for Automotive Exterior Body Panels: A Cost and Market Assessment9702462/24/1997
Automotive exterior body panels are a critical component of today's vehicle. They provide a surface for painting, offer the first line of defense against damage from accidents and the elements, and in most cases add to the overall stiffness of the vehicle. Despite small inroads from aluminum and polymer systems, steel remains the predominant body panel material. Of the alternatives, sheet molding compound (SMC) has been the most successful challenger. This paper examines the cost and market conditions affecting SMC today and in the near future. The impact on cost of SMC compression molding process improvements is assessed over a ten year period for a full body panel set. These results are compared to stamped steel as a function of annual production volume and other key factors. The result is a cost “crossover” point below which SMC has the lower cost. On the market side, the idea of decreasing annual model builds is quantified to understand the overall number of panels that are candidates for SMC adoption. These are compared to current examples of SMC use in order to put a realistic upper bound on SMC substitution.
Dieffenbach, Jeff R.
A New 5MPH Bumper System94227711/1/1994
A new bumper system which provides 8 kph (5 mph) vehicle protection with superior quality, outstanding durability and high value is in production. The system includes five new technologies: Hot stamped, ultra high strength front beam, 970 N/mm2 (160 KSI) which also is the #1 body structure crossmember. Ultra high strength roll formed rear beam 1150 N/mm2 (190 KSI). polypropylene foam isolators designed for controlled energy management Thermoplastic olefin (TPO), injection molded fascias Two component urethane paint for long term color, gloss and scratch resistance. This bumper system, installed on over 100,000 vehicles so far, meets both MPV and passenger car 8 kph standards. Consumer and insurance industry trends indicate increasing demand for Multi Purpose Vehicle (MPV) bumper systems which meet 8 kph criteria. The major competitors in the MPV market (Aerostar, Grand Caravan, Toyota Previa, GM APV's, and Mazda MPV) have either 0 kph or at best 4 kph systems. All Ford cars and most passenger cars have 8 kph bumper systems. Consistent, high quality vehicle to vehicle exterior appearance is a must in the marketplace. Today's sophisticated consumer expects good fits and long life from the vehicle. Many current bumper systems are unable to be assembled, manufactured and delivered to meet these requirements due these typical approaches: Operator dependant installation of fascias (do not locate directly to surrounding sheetmetal). PGM's which locate independently to structure and do not locate the beam well. Materials and paints which cannot achieve the most recent demands for high milage. Developing a mini-van bumper system which met the performance and quality needs along with the other cost, weight, investment, timing, testing, styling, manufacturing and assembly criteria required the team to investigate new technologies. Five technologies allowed all needs and criteria to be met or exceeded. The purpose of this paper is to provide an understanding of these technologies and encourage additional applications.
Dellock, P. K., Sweder, T. A.
An Application of Wing Aerodynamic Principles to the Reduction of Road Vehicle Air Drag Loads9018669/1/1990
A wind tunnel program examined front end modifications for Cab-Over-Engine tractors. A Design based on a wing airfoil was used to produce a wind weighted drag reduction of ten percent. The truck was considered to be a small aspect ratio “Wing” with a plane of symmetry on the road surface. The shape was able to achieve smooth flow at the vehicle side when the incoming flow was yawed from the truck's longitudinal axis. Drag measurements were made and tufts on the body and smoke off the body were observed. The wind tunnel results were supported by data obtained from a road test. Comments by operators currently driving equipped trucks tend to support the work and point to handling qualities advantages related to the design.
Salmirs, Seymour, Reed, William H.
Thermoset Injection Molding of Horizontal Body Panels from ZMC to ZMC Plus8803542/1/1988
Monnet, Bernard
Aerodynamic Characteristics of the Fiat UNO Car8402972/1/1984
The purpose of this article is to describe the work conduced in aerodynamic field throughout the 4-year development and engineering time span required by the project of the UNO car. A description is given of all the parametric studies carried out. Through these studies two types of cars at present in production were defined and the characteristics of a possible future sports version laid down. A movable device, to be fitted in the back window, was also set up and patented. When actuated it reduces soiling of back window. A description is also provided of the measurements made in the car flow field and some considerations are outlined about the method applied. This method is still in development phase but it already permits some considerations and in-depth investigations to be made on the vehicle wake.
Costelli, A.F.
Polypropylene and Polyamide Developments in the European Automotive Industry8309926/6/1983
The priorities for the development of cars were never so quickly changed than in the last 10 years. Whereas safety was the main target in the 1970's, it is now energy saving. Therefore plastics consumption has increased tremendously. Main contenders are POLYPROPYLENE and POLYAMIDES. Recently developed items in POLYPROPYLENE for the bumper systems, for seats, for fascias and interior trim applications are discussed. POLYAMIDE developments are mainly based on under bonnet applications like header tanks and airfilter parts, but also get wider acceptance for exterior parts.
Döring, E.
A Summary of NASA Dryden's Truck Aerodynamic Reasarch8212842/1/1982
A combination of subscale wind tunnel model tests and full-scale coast-down and highway fuel consumption tests have been conducted on baseline and low-drag tractor-trailer configurations. Fuel savings calculated for the low-drag configuration, based on the model drag data or the full-scale drag data, correlate quite well with fuel savings obtained from over-the-road tests at highway speeds. Sub-scale drag tests for flow-vane and boattail devices provided drag reductions of about 48 percent and 15 percent, respectively, for bus- or motor-home-type vehicles. Full-scale boattail drag data are also presented.
Saltzman, Edwin J.
Experimental Shape Research of Ideal Aerodynamic Characteristics for Industrial Vehicles80140211/1/1980
This paper illustrates an experimental aerodynamic research study of industrial vehicles. Tractor-trailer, truck and bus shapes are considered; in each of them the research is pursued with the aid of a representative one-half-scale model in the wind tunnel in three phases: local shape modifications and add-on devices study; definition of alternative shapes; definition and optimization of ideal shapes. Reductions of ∼ 45% for tractor-trailers, 30% for trucks, and 27% for buses are obtained. This means fuel reductions of ∼ 9% (tractor-trailer) and 10.5% (truck).
Berta, C., Bonis, B.
Practical Economic Aspects of Tractor/Trailer Aerodynamics7601032/1/1976
The consumption of diesel fuel by intercity tractor/trailer combinations can be reduced significantly by improving the aerodynamics of the tractor/trailer combination. Theoretical data developed in the University of Maryland Wind Tunnel with 1/8th scale models is reconciled with actual vehicle tests conducted under closely controlled conditions. Reductions in fuel consumption offered by other features and devices are compared with the savings provided by aerodynamic features.
Holmes, Harleigh R.
Development of the First Sheet Molding Compound (SMC) Body Component: The Chrysler Station Wagon Air Deflector7204932/1/1972
The Chrysler Corporation made use of a thermosetting polyester sheet-molding-compound (SMC) to provide an efficient, neat-appearing, and economical station wagon air deflector for its 1969 full-size station wagons. This marked Chrysler's first usage of this material for a major automotive body component.
Currier, George J.
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