• Journal of the Korean Society of Visualization
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• v.21 no.2
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• pp.8-13
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• 2023

The primary challenge in improving fuel efficiency and reducing air pollution for commercial vehicles is reducing their aerodynamic drag. Various flow control devices, such as cab-roof fairing, gap fairing, cab extender, and side skirt have been introduced to reduce drag, however, the drag reduction effect and applicability are different depending on each commercial vehicle model. To evaluate the fuel consumption of heavy vehicles, a comprehensive research approach, including drag force measurement, flow field analysis is required. This study investigated the effect of a cab extender, which installed rear region of cab, on a drag coefficient of commercial vehicle through wind tunnel experiments and CFD. The results showed that the cab extender significantly modified the flow structure around the vehicle, leading to 8.2% reduction in drag coefficient compared to the original vehicle model. These results would provide practical application for enhancing the aerodynamic performance and fuel efficiency of heavy vehicle.

• Wind and Structures
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• v.26 no.1
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• pp.35-43
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• 2018

This paper describes the effect of different testing parameters (configuration of infrastructure and truck position on road) on truck aerodynamic coefficients under cross wind conditions, by means of a numerical approach known as Large Eddy Simulation (LES). In order to estimate the air flow behaviour around both the infrastructure and the truck, the filtered continuity and momentum equations along with the Smagorinsky-Lilly model were solved. A solution for these non-linear equations was approached through the finite volume method (FVM) and using temporal and spatial discretization schemes. As for the results, the aerodynamic coefficients acting on the truck model exhibited nearly constant values regardless of the Reynolds number. The flat ground is the infrastructure where the rollover coefficient acting on the truck model showed lowest values under cross wind conditions (yaw angle of $90^{\circ}$), while the worst infrastructure studied for vehicle stability was an embankment with downward-slope on the leeward side. The position of the truck on the road and the value of embankment slope angle that minimizes the rollover coefficient were determined by successfully applying the Response Surface Methodology.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.207-218
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• 2017

Improving fuel consumption, particularly that of commercial vehicles, has become a global concern. The reduction in logistics cost has been a key issue in efforts to improve fuel economy and efficiency of transportation equipment. Typical technologies for reducing reduce fuel usage include air resistance reduction technologies, tire rolling resistance technologies, and idle technologies among others. Air resistance technology is a highly effective method that can be easily applied in a short period. As with air resistance technology, several devices involving side skirt, boat tail and gap fairing have been developed based on an analytical 3-D modeling technique for reducing air resistance attributed to the vehicle configuration. The devices were on a 45 feet tractor-trailer and the emission test was done using PEMS equipment. Fuel economy was evaluated by introducing several devices to reduce outer air resistance. The test was conducted by changing the experimental method of SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test. As a result, air resistance decreased by at least 15 % and fuel economy improved by at least 13 %. This study sought to reduce greenhouse gas and improve fuel economy by applying several devices to a test vehicle to lower air resistance.