Data Acquisition of a Tractor-Trailer Combination to Register Aerodynamic Performances

Abstract

The design, production and verification of a data acquisition system to measure aerodynamic and mechanical characteristics of a tractor-trailer combination, operating in a real life environment, are presented. The main goal of this work is to derive a reference level of a truck with respect to its aerodynamic and mechanical performances. This way, if the truck is equipped with different aerodynamic aids, a correct comparison can be made between the aerodynamic drag reductions obtained by these devices. Also, a relation can be defined which links the aerodynamic drag reduction with fuel consumption savings. The acquisition system consists of an anemometer, which measures the wind speed and direction, and a two-axis inclination indicator, which is coupled to the FMS of the tractor via the CAN communication system and to the wipers to indicate if it is raining or not. The FMS of the tractor is measuring, for instance, the vehicle speed, the engine torque, the rpm, acceleration pedal position, cruise control, fuel rate, cargo weight and the like. All the measured data are registered on a hard disk and can be accessed through a simple USB connection. The processed data gives insight in the performance of the driver and in the aerodynamic behavior (CD value of 0.430) as well as the mechanical characteristics (power required breakdown; 47% rolling resistance, 39% aerodynamic drag and 15% mechanical losses; average speed of 75 km/h; fuel consumptio of 30 liters per 100 km) of the truck.