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As a simulation of road driving, wind tunnel testing of full-size vehicles produces certain errors in the aerodynamic forces, aerodynamic moments, and surface pressures. The magnitude of these errors, in general, depends on the following: a Flow quality b Determination of the reference dynamic pressure c Wind tunnel floor boundary layer d Test section geometry and position of the car within that geometry e Shape of the vehicle f Blockage ratio: The ratio of the cross-sectional area of the vehicle to the cross-sectional area of the wind tunnel nozzle g Wheel rotation h Internal flow in the model The SAE Standards Committee, Open Throat Wind Tunnel Adjustments had as a goal to document the knowledge of the influence of model interference on wind tunnel test results for automotive open jet wind tunnels.

As a simulation of road driving, wind tunnel testing of full-size vehicles produces certain errors in the aerodynamic forces, aerodynamic moments, and surface pressures. The magnitude of these errors, in general, depends on the following: a Flow quality b Determination of the reference dynamic pressure c Wind tunnel floor boundary layer d Test section geometry and position of the car within that geometry e Shape of the vehicle f Blockage ratio: The ratio of the cross-sectional area of the vehicle to the cross-sectional area of the wind tunnel nozzle g Wheel rotation h Internal flow in the model The SAE Standards Committee, Open Throat Wind Tunnel Adjustments had as a goal to document the knowledge of the influence of model interference on wind tunnel test results for automotive open jet wind tunnels.

The scope of this SAE Information Report is confined to wind-tunnel testing, although it is recognized that many aspects of the aerodynamic characteristics of road vehicles can be investigated in other test facilities (such as water-tanks) or, especially, on the road. For example, coastdown testing is often used to determine aerodynamic drag (either in isolation or as part of the total resistance), and artificial gust generators are used to investigate the sensitivity of vehicles to cross-wind gusts. Also excluded from the present Report are climatic wind-tunnel tests of road vehicles, which are defined in more detail in Section 3. The Report covers the aerodynamic requirements of a wind-tunnel for automotive testing, together with the facility equipment needed and the requirements affecting the test vehicle or model.

The scope of this SAE Information Report is confined to wind-tunnel testing, although it is recognized that many aspects of the aerodynamic characteristics of road vehicles can be investigated in other test facilities (such as water-tanks) or, especially, on the road. For example, coastdown testing is often used to determine aerodynamic drag (either in isolation or as part of the total resistance), and artificial gust generators are used to investigate the sensitivity of vehicles to cross-wind gusts. Also excluded from the present Report are climatic wind-tunnel tests of road vehicles, which are defined in more detail in Section 3. The Report covers the aerodynamic requirements of a wind-tunnel for automotive testing, together with the facility equipment needed and the requirements affecting the test vehicle or model.