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Title COMPARISON OF DRAG AREA ESTIMATION USING NATURAL COAST DOWN AND CONSTANT SPEED TEST METHODS
URL
Publication Date
Degree MS
Discipline/Department Mechanical and Aerospace Engineering
Degree Level thesis
University/Publisher West Virginia University
Abstract Currently in US, more than 26 percent of the total GHG emissions comes from transportation and mostly from heavy duty vehicles. Similarly, the European Council stated that 25 percent of the emissions comes from heavy duty transportation and they expect it to be further increased in the future. However, with the new coming regulations US EPA and European Council aiming to reduce the emissions by 80 percent in US and 60 percent in EU. In order to keep track and control the emissions, both authorities published new regulations and testing methods for certifying the new vehicles. Aerodynamic testing is one of the most important part of certification since, aerodynamic drag is a major contributor of total road load acting on a vehicle which is highly related with emissions of a vehicle. Besides, simulation tools for certification such as “Vehicle Energy Consumption Calculation Tool (VECTO)” and “Greenhouse Gas Emission Model (GEM)” needs drag area ( ) as an input. Moreover, it is essential to determine the drag area correctly, therefore, emission of a vehicle, to be able to estimate the amount of total emissions from heavy duty vehicles. Two different regulatory testing methods were published by US EPA and European Council to determine the drag area ( ) for certification of heavy duty vehicles. While US regulations requires “coast-down (CD)” test, EU regulations requires “constant speed (CST)” test. The objective of this study is to compare these two different regulatory approaches with their different assumptions. In order to be able to make a comparison of these two testing methods, CD and CST performed with same tractor and trailer combination, which is a Class 8 truck for US market, in same conditions. Results yielded up to 9 percent difference between two methods. Possible cause of this difference can be listed as, the different assumptions of each testing method such as speed dependency of losses, different approaches for tire rolling resistance and some neglected or unaccounted loses. These possible reasons were also investigated individually in this study.
Subjects/Keywords Coast-down; fuel consumption; constant speed test; chassis dynamometer; drag area; drag coefficient; tire rolling resistance; Navigation, Guidance, Control, and Dynamics; Other Mechanical Engineering
Contributors Arvind Thiruvengadam; Marc C. Besch; Marc C. Besch
Country of Publication us
Record ID oai:researchrepository.wvu.edu:etd-4976
Repository wvu
Date Retrieved
Date Indexed 2020-07-20
Created Date 2019-01-01 08:00:00

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…31 4.1. DRAG AREA RESULTS .................................................................................................... 31 4.2. FUEL CONSUMPTION RESULTS…

…32 TABLE 4-4: DRAG AREA COMPARISON OF CONSTANT SPEED AND COAST DOWN METHODS ............. 33 TABLE 4-5: BREAKDOWN OF ROAD LOAD CONTRIBUTIONS AFTER ELIMINATIONS DONE ................. 35 TABLE 4-6: DRAG AREA RESULTS WITHOUT TRR SPEED DEPENDENCY…

…x29; Where; 𝐹 is the drag force, 𝜌 is the density of the fluid, 𝑣 is the speed of the vehicle relative to the fluid, 𝐶 is the drag coefficient, a dimensionless number, 𝐴 is the cross-sectional area of the vehicle. As it can be seen at equation…

…2.2, aerodynamic drag is a function of the density of air, speed of air, drag coefficient and cross-sectional area of the vehicle. Drag coefficient is a dimensionless quantity which is used to model all the complex dependencies of shape and flow…

…attached to the powertrain of the dynamometer to simulate the down grade motoring effect of the vehicle’s mass. The road load applied to the vehicle is determined by the road load power equation which is function of vehicle speed (𝑉), drag area

…Road load applied to the vehicle is determined by the speed of the vehicle at that moment since rolling resistance coefficient, vehicle mass, air density and drag area in this function are constant. 15 3.4. Test Procedures 3.4.1. Constant Speed…

…VECTO – Air Drag) which was released by European Council. It is a regulatory software and it performs data validation, filtering and calibration. If the input test data passes the validity criteria, it calculates the drag area and rolling resistance…

…to find the drag area. 12 passes for each direction performed which results 24 measurements for each direction for each speeds. Results of the VECTO will be presented in the Chapter 4. 3.4.2. Coast Down Test Procedure U.S. EPA clearly describes the…

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