Browse Topic: Air deflectors

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Experimental Investigations on Appendages of a Racing Motorcycle2026-01-50112/20/2026
In this experimental work, a detailed analysis of the wind tunnel measurements on scaled motorbike models equipped with different front wings was performed considering four wing configurations operating at different Reynolds numbers and roll angles. Global forces acting on the models were measured by a high-resolution dynamometric balance, while velocity fields in the wake were measured by means of the Particle Image Velocimetry technique. Throughout the paper, overall models’ performances are investigated, demonstrating similar behavior for drag coefficients and various trends for lift coefficients. The without- and single-wing configurations were shown to have positive sign, and conversely, the double- and closed-wing cases—with negative sign—generated downforce due to the presence of significant upward velocities, which in turn modified the wake shape. Furthermore, the improvements in closed-wing configuration compared to without- and single-wing ones were noticeable, while slight enhancements were observed for the double-wing case. It is evidenced how PIV technique can be used to advance the wing design by capturing the wake velocity and circulation. The proposed simple geometrical configurations are feasible at low costs and with easy manufacturing.
Moscato, Giorgio, Romano, Giovanni Paolo
Aerodynamic Analysis of Heavy-Duty Vehicles Using Computational Fluid Dynamics Approach2022-28-049212/23/2022
Fuel consumption of heavy-duty vehicles (HDV) is one of the major challenges in the automotive industry. In recent days, gasoline prices have been raised high, so the HDVs need to be designed to be more fuel-efficient. Many studies reported that aerodynamic optimization is one of the most important advancements in terms of fuel-efficient HDVs. The computational fluid dynamics (CFD) tool or approach is widely accepted for aerodynamic analysis. This study identifies the flow zones with the large pressure drag and design parameters, incorporating appropriate geometric changes into the design. The computational results show that the drag reduction of individual devices in cab and trailer is 15.9%. The cab deflector and boat tails are the most effective individual geometry and successfully reduce the drag up to 20%.
Sajjala, Sai Mukesh Reddy, Shaik, Mahaboob Subhani
Numerical Characterization of Brake System Cooling, Aerodynamic, and Particle Soiling Performances under Driving Conditions2020-01-162210/5/2020
Effective cooling of a heated brake system is critical for vehicle safety and reliability. While some flow devices can redirect airflow more favorably for convective cooling, such a change typically accompanies side effects, such as increased aerodynamic drag and inferior control of brake dust particles. The former is critical for fuel efficiency while the latter for vehicle’s soiling and corrosion as well as non-exhaust emissions. These competing objectives are assessed in this study based on the numerical simulations of an installed brake system under driving conditions. The thermal behavior of the brake system as well as aerodynamic impact and brake dust particle deposition on areas of interest are solved using a coupled 3D transient flow solver, PowerFLOW. Typical design considerations related to enhanced brake cooling, such as cooling duct, wheel deflector, and brake air deflector, are characterized to evaluate the thermal, aerodynamic and soiling performance targets. The leading mechanisms relating the changes in cooling airflow and their impact on performance are discussed. In addition, parametric sensitivity and interactions are analyzed in the design scenario. The proposed approach can be leveraged to evaluate the complex design trade-offs for a brake system in any development stage without the need for a physical model or testing.
Cho, Young-Chang, Jilesen, Jonathan, Kandasamy, Satheesh
Innovative Rear Air Blower Design Application for Improving Cabin Thermal Comfort with Improved Air Distribution and Air Quality2020-28-00348/18/2020
In recent times, overall thermal comfort and air quality requirement have increased for vehicle cabin by multifold. To achieve increased thermal comfort requirements, multiple design innovation has happened to improve HVAC performance. Most of the advance features like multizone HVAC, dedicated rear HVAC, Automatic climate control, advance air filters, and ionizers etc. lead to increase in cost, power consumption, weight, and integration issues. Besides this in the vehicle with only front HVAC, airflow is not enough to meet rear side comfort for many cars in the B/C/SUV segment. This study aims to analyze the various parameters responsible for human thermal comfort inside a car. The focus of study is to use light weight, low power consumption, compact Rear Blower to provide passengers comfort by providing optimum airflow inline of mean radiant temperatures and cabin air temperature. The rear blower incorporates external surfaces with a set of air modifier in the direction of flow outlet and an air deflator portion just upstream of outlet portion. The set of air modifier surfaces along with the air deflector portion results in improved entrainment of cabin air towards the primary air flow generated by the blower. The impact of rear airflow on thermal comfort was analyzed by conducting a jury test with and without rear blower during a cool-down test in climatic wind tunnel lab to establish the impact of the rear blower on enhanced thermal comfort.
Garg, Ravi, maske, Suraj, Kushwah, Yogendra Singh
Aeroelastic Response and Structural Improvement for Heavy-Duty Truck Cab Deflectors2019-01-50041/14/2019
Numerical simulations on the fluid-structure interaction were conducted using commercial software STAR-CCM+ and ABAQUS. The aeroelastic responses of a deflector under several different working conditions were simulated utilizing finite volume and finite element methods to investigate the aeroelastic problem of automotive deflectors. Results showed that the structural response of a top deflector is minimal under the influence of aerodynamics given its large structural stiffness. The size of the top deflector was optimised by using thickness as a variable. The volume and quality of the top deflector were significantly reduced, and its lightweight performance was improved to satisfy the stiffness performance requirement. The vibration of a side deflector structure was mainly induced by the turbulence on the structure surface. The amplitude of vibration was small and the vibration gradually converged in a few seconds without obvious regularity. Six structures were constructed to reduce the deformation of the side deflector structure and improve the noise, vibration and harshness performance of the heavy-duty truck. Five of these structures significantly reduced the elastic response of the side deflector.
Wang, Jing-yu, Yan, Wei, Sang, Tao, Guo, Peng, Wu, Bin, Zhang, Jing-long, Hu, Xingjun, Dong, Chun-bo
Method for Preventing Contamination on Trucks Cabin Side Using CFD2017-36-008011/7/2017
Although ignored by most people not directly involved with highway and off-road commercial trucks operation the accumulation of dust and mud on cabin side can become a rather annoying issue. Besides adhering to the passengers clothes dirt contamination may also compromise driver visibility constituting a safety concern. For a truck manufacturer it can revert into quality complaints and negatively influence customers’ future buying decisions. In this context, fascia air deflectors are common devices used in truck industry to control the airflow over the cabin panels and ultimately prevent contamination deposition. This paper presents a methodology to avoid dust and mud accumulation on commercial trucks cabin doors based on the predicted airflow field by computational fluid dynamics (CFD) and a reference flow metric defined through a simple bench test. Comparing the results of the CFD analysis with an experimental study it is demonstrated that without resorting to costly wind tunnel tests or complex and computationally demanding Eulerian or Lagrangian multiphase simulations the proposed methodology ensures consistent results for tuning a deflector design to effectively prevent dirt accumulation. Soling simulations have also been performed as an add-on for further assessing the design directions provided by the method.
Costa, Edinilson Alves, Nalin, Rogério
Glowing aerodynamic add-ons could boost big-rig fuel economy by 7-10%17TOFHP02_072/1/2017
“Headlight white” and “stoplight red,” the characteristic colors of the highway at night, could soon get a companion: “plasma purple”-that is, if a new fuel-saving, aerodynamic technology catches on big with big-rig trucks. The electric plasmas emitted by the devices, which glow purple-violet in the dark, can smooth the turbulent wakes that sweep off the rear edges of truck trailers travelling at highway speeds. Simulations and wind tunnel tests indicate that these novel active-flow control systems could reduce the aerodynamic drag generated by semi-trailers by almost one-fifth, thus lowering fuel consumption by up to 10%. Plasmas, the lesser-known “fourth state of matter,” are clouds of charged atomic ions created in the air by high-voltage electric fields. The glowing electric-flame phenomena are commonly seen in household air purifiers and more rarely in natural phenomena such as St. Elmo's Fire, the ghostly purple haze sometimes seen hanging off airplane wings. For application to trucks, strong electric fields emitted by surface electrodes push the plasmas around, producing breezes that can redirect critical airflows at the trailing edges of “bluff-bodied” vehicles such as Class 8 cargo trucks, helping to smooth out the turbulent, high-drag wakes.
Ashley, Steven
2017 Nissan Titan gets new platform, powertrain, cab and bed features16AUTP10_1210/1/2016
The second-generation Nissan Titan launches with the model's first-ever single cab and adds a direct-injection V8 and 7-speed transmission plus significantly improved vehicle aerodynamics and NVH attenuation. And while the 2017 model does not achieve a net mass reduction versus the previous Titan, fuel efficiency has been improved 28%, engineers claim. The new Titan also brings a cool new approach to cargo bed illumination and claims an industry first: the first full-size pickup with a 5-year/100,000 mile bumper-to-bumper warranty. There's also a V6 engine in the development pipeline.
Buchholz, Kami
Analysis of Aerodynamic Performance of a High Energy Efficiency Prototype2012-36-031810/2/2012
This paper presents a study developed in order to improve the aerodynamic performance of an automotive prototype by means of simulations carried out by a software that makes of the finite volume method. The prototype will be built at the Laboratory of Automotive Engineering of the Lutheran University of Brazil - ULBRA. Taking into account the original design of the automotive prototype, three virtual models were generated and analyzed. There were three steps to simulate the aerodynamic behavior on a 3D model: generation of the geometry with the employment of CAD software, generation of the mesh for the faces and volume that involve the car, using specific software, and solving the flow, with a CFD software. The results of the analysis allowed identifying the model with the lowest aerodynamic drag. That model had some modifications on its design, when compared to the original one, like wheels and their housings. Also, an air deflector was included on the back of the virtual prototype, in order to reduce the drag. The results obtained were reasonable, because of the deflector, which gave a drag reduction around of 6%.
Rodrigues, Antonio Flavio Aires, Gertz, Luiz Carlos, Cervieri, Andre, Da Silveira, Marilia Amaral, Da Silva, Tiago Portolon
Aerodynamics soarAUTOSEP09_049/1/2009
Automakers toil to minimize drag and maximize fuel economy. Decades ago, it was conventional wisdom that by now we would all be driving slippery, low-slung, low-drag transportation modules optimized for efficient consumption of limited resources. All the futuristic movies said it was so. Triumph-apparently unaware that the future would not include that marque-touted the wedgy TR7 as “The Shape of Things to Come.” And so it seemed it would be, with the popularization of the sleek Ford Taurus family sedan in the mid-′80s. But then came a couple decades of cheap gasoline, the SUV boom, and the defiantly blunt Chrysler 300 sedan, and the notion of designing for drag reduction seemed to have been swept away in an eddy current of a Hummer's wake.
Carney, Dan
Development of a Cost Effective Power Train Cooling System for a Passenger Car with Rear Engine2009-01-01694/20/2009
The present automobile era in India is driven by development of small size and low cost ‘value for money’ cars. Proper utilization of space and low cost engineering of the vehicle aggregates plays a key role for attaining the goal of low cost-small cars. This paper illustrates the development of power train cooling system of such cost sensitive passenger car with rear engine and rear mounted heat exchangers. The major obstacle for the power train cooling system of rear engine-rear mounted heat exchanger (radiator) is absence of ram air effect at higher vehicle speeds and air temperatures higher then ambient, as observed for front mounted heat exchanger. The subject vehicle encountered power train cooling system failure at max speed operating condition and the project timeline required a quick solution without any major modifications and cost escalation. In case of subject vehicle because of its packaging, the air flow rate for heat exchanger was fully dependent of fan capacity. However, at higher vehicle speeds there was an opportunity to boost the air flow rate by proper air management within vehicle boundaries. After DOE and CFD analysis, an air deflector was introduced at the bottom of heat exchanger which improved the heat transfer rate by utilizing the high velocity air underneath the vehicle.
T, Rajesh A, Pol, Sharad
CFD Application in Automotive Front-End Design2006-01-03374/3/2006
The front-end design process in the automotive industry today is time consuming and expensive. Although CFD (Computational Fluid Dynamics) modeling is helpful, many vehicle development tests in different wind tunnels are still required to balance the competing requirements of power train cooling, vehicle aerodynamics, climate control, styling, body structure, and product cost. For example, engine cooling and climate control heat exchangers require adequate airflow to achieve their performance. But, this airflow increases cooling drag and can compromise vehicle handling. Internal air deflectors (ducting) are often used to make the frontal opening more efficient and help prevent heat recirculation from the hot engine compartment to the A/C condenser at idle. But this increases product cost and can compromise underhood temperature. A more efficient and faster process is needed to support these trade-off discussions. The objective of this report is to examine the suitability of using one CFD model to address this need. One front-end CFD model is used for all three attributes: power train cooling, thermal re-circulation at idle and cooling drag. The focus is on SUV and Pickup Trucks with mechanical fans. The following parameters are investigated: fan speed, engine heat rejection, and air deflector (air ducting) impact on recirculation. Overall, the CFD quantitative results look very reasonable and offer the promise of improving the product development process. The qualitative flow field and temperature contour maps were very helpful to the understanding of the results.
Ding, Wei, Williams, Jack, Karanth, Dinakara, Sovani, Sandeep
Shape Study for a Low-Air Resistance Air Deflector - The Second Report9506332/1/1995
We reported, in our first report1), the study of shapes of air deflectors that have strong yawing angle characteristics for the air resistance encountered when vehicles are running at high speed, taking into account the ambient wind. However, it is rarely the case that the optimum shape of air deflector, which was obtained and reported in our first report, is directly adopted for practical use. This paper reports the results of measurement tests on how the air resistance increases (worsens) when an air deflector is mounted on the cab of a vehicle: in the case when the air deflector was slightly changed on the same vehicle; or when the parameters of the vehicle (the height of the rear body) were changed for the same air deflector. We obtained the following results: Considerations and adjustments are required not to allow flows passing over upper and side surfaces of the air deflector to hit the front surface of the rear body. Further, the fuel consumption under the above conditions was also estimated by simulation.
Fujimoto, Tsutomu, Niinuma, Atsushi, Sakai, Katsuharu
Shape Study for a Low Air Resistance Air Deflector9303013/1/1993
The van-type truck is frequently equipped with an air deflector to reduce fuel consumption. When studying the shape of the air deflector, it is necessary to choose a shape that is less sensitive to yaw characteristics. Side wind induced yaw conditions are more typical of on-road usage. In this study, the basic characteristics for a shape with strong yaw sensitivity were first examined. Subsequently, an angle change test was carried out by replacing the space over the cab with a rectangular parallelopiped and letting the upper and side edges, just in front of the rear body be the reference lines. The yaw angle was varied between 0°, 5°, and 10°. From this result, the existence of the optimum upper and side incident angles was confirmed. Furthermore, the reduction in fuel consumption using the optimum shape as compared with the conventional shape was estimated by simulation.
Fujimoto, Tsutomu
Comparison of On-Road and Wind-Tunnel Tests for Tractor-Trailer Aerodynamic Devices, and Fuel Savings Predictions8502862/1/1985
Wind tunnels which are large enough for full-scale trucks are rare, and the cost of satisfactorily-detailed models for smaller tunnels is high. The work presented shows the results from the application of a method which provides an over-the-road evaluation of the incremental changes in fuel consumption and drag coefficient produced following the addition of a variety of aerodynamic drag reducing devices to a tractor-trailer truck combination. The devices tested were an aerodynamic sunvisor, a roof-mounted air deflector, cab extenders, cab skirts, a trailer nose fairing, a set of trailer quads (quarter-rounds), and trailer skirts which were mounted on a low-forward-entry tractor and high box-van trailer. The significant differences between the wind tunnel and on-road drag reductions suggest that the effects of on-road wind turbulence can substantially reduce the wind tunnel results even though a 1.5% turbulence intensity level was used in the tunnel experiments. These experiments have highlighted that the wind tunnel results were optimistic and suggest a need for on-road testing to more accurately evaluate the benefit of aerodynamic devices for trucks. The on-road results finally are used to predict the resultant fuel economies for various loads and speed conditions.
Saunders, Jeffrey W., Watkins, Simon, Hoffmann, Peter H., Buckley, Frank T.
TOWABILITY DESIGN CRITERIA—PASSENGER CARS AND LIGHT DUTY TRUCKSJ1142A_197806 (Historical)6/1/1978
Towability Committee
TOWABILITY DESIGN CRITERIA—PASSENGER CARSJ1142_197607 (Historical)7/1/1976
Towability Committee
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.
HIGH OPERATING-TEMPERATURE AND ENGINE AND CAR OPERATION2600161/1/1926
This subject is treated in a paper in two parts. Part I, by Alex Taub, deals with laboratory tests to prove by comparative data that the higher average operating-temperatures maintained in the engine by the constant-temperature, or evaporation, system of cooling have negligible detrimental effects. Part II, by L. P. Saunders, gives the results of road-tests of cars operated under the same conditions when fitted with a standard water-cooling radiator-core and with a constant-temperature cross-flow condenser-core. Although contamination of the crankcase oil by heavy ends of the fuel is not prevented by the higher temperature of constant-temperature operation, it is asserted that this higher temperature is effective in striking an acceptable balance in such contamination and results of the tests show that the cylinder-walls are maintained at temperatures sufficiently above the vaporization point of water to reduce the condensation of water vapor to the minimum. Water in the crankcase is the objectionable element. Oil dilution by fuel up to a certain amount is not detrimental; in fact, experience shows that about 16 per cent of such dilution is necessary to facilitate starting a cold engine. Even when an anti-freeze solution containing 50 per cent of alcohol is used and the boiling temperature reduced to 184 deg. fahr., the cylinder-wall temperatures are maintained at 212 deg. or more. Since a boiling liquid does not change its temperature, it affords the simplest means of maintaining a constant operating-temperature and also the simplest, least expensive and lightest means of providing for quick warming-up of the engine and slow cooling-down, because there is no circulation of water except when steam is passing from the engine-block to the radiator or condenser. Test runs were made in the laboratory with an engine fitted with a Muir constant-temperature system which could be converted to water-cooling by blocking-off the circulation through the cylinder-head with a special gasket to provide for concentrated circulation around the exhaust-valves. Outlet-water temperatures were controlled by admitting more or less cold water. Results of the tests indicate that fuel consumption is approximately the same for constant-temperature cooling at 212-deg. outlet temperature and water-cooling at 170-deg. outlet temperature; that with both systems the spark-lever advance for maximum torque is safely below the degrees of advance at which detonation, or spark knock, begins; that the falling-off in torque with reduction in richness of the fuel mixture is virtually parallel for the two systems; that the difference in volumetric efficiency of the engine when operated on the two systems amounts to only 2 per cent, which is within the allowable error of the air-meter used; that the brake engine-pull is nearly identical; that the temperature of the lubricating oil is not affected by the system of cooling but by the temperature of the cooling medium, and that the temperature of the walls and inlet and exhaust-valve seats of the No. 1 and No. 6 cylinders of a six-cylinder engine is much more uniform with constant-temperature cooling than with water-cooling. Cylinder-head formation and spark-plug location are important factors as regards detonation. A compact head with spark-plug carefully located to allow the maximum spark-advance before detonation starts provides sufficient leeway for the use of higher operating-temperatures. With constant-temperature cooling it is advisable that the normal water-level be such that, in operation, the water flowing from the radiator to the engine-block will fill the pipe only about half full and allow air to escape above it, thereby eliminating the possibility of an air-trap in the water-pump. A steam-dome capacity equal to 21 per cent of the normal quantity of water in the engine-block gives the proper proportion of water and steam passing to the radiator. The smallest possible quantity of water is the proper quantity to use, as the quantity of water in the block controls the warming-up period. The normal water-level is raised between 12 and 15 per cent by expansion and volcanic action of the water when the engine is running, and the capacity of the steam dome is thereby reduced 6 or 9 per cent. If the steam dome is too small, excess water will pass to the radiator. That the high operating-temperatures that develop with constant-temperature cooling are safe is indicated by the much higher operating-temperatures in air-cooled engines. In Part II, after pointing out the general recognition of over-cooling by the water cooling-system in winter, as made evident by the use of air shields on the radiators, and describing the operation of the Muir cross-flow condenser-core, L. P. Saunders gives the results of many road-tests of cars with water-cooling and constant-temperature cooling. It is shown that the cross-flow core, when used as a water-cooler, maintains a lower temperature of the outlet water from the radiator than the conventional core and still lower temperatures when used as a constant-temperature system. Miles per gallon of fuel consumed are increased by constant-temperature cooling with the cross-flow core as compared with water-cooling with the standard core. Acceleration tests showed a slight advantage for the former system, while deceleration times were slightly longer than with water-cooling. The constant-temperature system showed higher speeds in hill-climbing. Better ventilation of the engine hood may be necessary with the constant-temperature system to avoid uncomfortable heat in the driving portion of the car body. Size of the radiator-core cannot be decreased, as many cars are now inadequately cooled under certain extreme conditions of driving and air temperature and density. The fan size should remain as large, at least, as at present. The paper is concluded with a chart showing the effects of temperatures in the water-jacket and in the lower part of the radiator caused by starting and stopping of the car in cold weather.
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