Preliminary Wind Tunnel Tests on the Influence of Ground Board Length on the Aerodynamic Drag of Simple Commercial Vehicle Models

摘要

Preliminary results are presented following a series of tests in a closed working section, open return wind tunnel on eight simple rectangular block models mounted above a full span ground board. Measurements of body axis drag, sideforce and yawing moment were made on each vehicle in the yaw angle range 6 to + 20 degrees. The ground board is fitted with removable sections such that its overall length, and consequently, the position of its trailing edge downstream of the model base, can be varied. Tests were carried out with ground board trailing edge positions in the range 3.2 to 0.2 w downstream, where w is the width of the body under test. Variations in drag coefficient are considered with respect to changes in model geometry, yaw angle, and ground board length. Explanations of the influence of ground board length on the flowfield and the mechanisms involved are limited by the data available from these simple tests. It is however, apparent that ground board length can have a considerable effect on measured aerodynamic drag and recommendations are made for further tests.