An on-road investigation into the conditions experienced by a heavy goods vehicle operating within the United Kingdom

•On-road drag coefficient of a heavy goods vehicle was found to be 0.730.•The effective average effective yaw angle was found to be 6.0°.•The average on-road yaw angle was found to be −0.5° with magnitude of 4.7°.•Four Strouhal shedding frequencies were found at St=0.002, 0.004, 0.006 and 0.0010. Wind tunnels are designed to be low in turbulence to enable accurate, repeatable data measurement. This stable environment, however, does not reflect the nature of the on-road, turbulent flow. Full scale on-road testing was conducted over a period of two months within the United Kingdom using a heavy goods vehicle. Various delivery routes throughout the UK were recorded to determine the wind yaw angle and wind velocity the heavy goods vehicle was subject to. The average on-road yaw angle was recorded as −0.4° with an average magnitude |β| of 7.9°. The corresponding average wind speed (VW) was found to be 8.4ms−1. Within the wind data, four low frequencies were recorded which arose possibly due to vortex shedding from leading and overtaking vehicles, the Strouhal shedding frequencies were found to be St=0.002, 0.004, 0.006 and 0.0010. MATLAB® Simulink® was used to model the wind speed, vehicle velocity and wind direction in conjunction with wind tunnel data in order to estimate the on-road drag coefficient. The results from the simulation found an average drag coefficient of 0.770, this value was close to the expected wind averaged drag coefficient of 0.805. This value differed from prior estimates as the logged on-road vehicle speeds were close to the maximum permitted, this resulted in a reduced effect from the wind direction and hence a reduced effective yaw angle. The average drag coefficient calculated corresponded to an average effective yaw angle of 7.1°.