Abstract 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.
Abstract A high performance rigid airfoil profile sunroof wind deflector has been developed for high speed freeway driving with the sunroof open. This deflector is clearly superior to the conventional bar type deflector and less expensive compared to tall flexible fabric mesh deflectors applied on high end vehicles today. It provides superior speech intelligibility under high speed driving with sunroof open. The criterion for designing this deflector was to get the highest airspeed possible to span the sunroof opening under all conditions. The customized shape also utilizes flow unsteadiness, including those at the onset of buffeting, in order to condition the shear layer. The airfoil profiled deflector yielded superior mid and high frequency acoustic performance with acceptable low frequency performance. A shorter airfoil deflector was sufficient to keep the external airflow from entering the forward tilted sunroof opening on a mid-size SUV under test.
Abstract The performance of several aerodynamic technologies and approaches, such as trailer skirts, trailer boat tails, gap reduction, was evaluated using track testing, model wind tunnel testing, and CFD simulation, in order to assess the influence of the design, position and combination of various aerodynamic devices. The track test procedure followed the SAE J1321 SAE Fuel Consumption Test Procedure - Type II. Scale model wind tunnel tests were conducted to have direct performance comparisons among several possible configurations. The wind tunnel tests were conducted on a 1/8 scale model of a tractor in combination with a 53-foot semi-trailer. Among others, the wind tunnel tests and CFD simulations confirmed the influences of trailer skirts' length observed during the track tests and that the wider skirt closer to the ground offer better results.
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.
Abstract 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.
Development of the First Sheet Molding Compound (SMC) Body Component: The Chrysler Station Wagon Air Deflector
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.