An Experimental Methodology for Measuring of Aerodynamic Resistances of Heavy Duty Vehicles in the Framework of European CO2 Emissions Monitoring Scheme

Due to the diversity of Heavy Duty Vehicles (HDV), the European CO2 and fuel consumption monitoring methodology for HDVs will be based on a combination of component testing and vehicle simulation. In this context, one of the key input parameters that need to be accurately defined for achieving a representative and accurate fuel consumption simulation is the vehicle's aerodynamic drag. A highly repeatable, accurate and sensitive measurement methodology was needed, in order to capture small differences in the aerodynamic characteristics of different vehicle bodies. A measurement methodology is proposed which is based on constant speed measurements on a test track, the use of torque measurement systems and wind speed measurement. In order to support the development and evaluation of the proposed approach, a series of experiments were conducted on 2 different trucks, a Daimler 40 ton truck with a semi-trailer and a DAF 18 ton rigid truck. Two different torque measurement systems (wheel rim torque sensors and half shaft torque sensors) were used for the measurements and two different vehicle tracking approaches were investigated (high precision GPS and opto-electronic barriers). Results were pooled and compared against results from similar measurements performed by the OEMs at their own proving grounds. The method was proven to be accurate. The analysis showed good repeatability and reproducibility characteristics and a good sensitivity of the method. Based on the findings it was decided that this measurement methodology is suitable and can be included in the European legislation.