1998-02-23

Unique Correlation Technique For Real-World Flow Simulation in the Wind Tunnel 980033

An unique approach has been developed to simulate the real world flow condition in an indoor laboratory environment. An attempt has been made in this investigation to generate a velocity profile in front of the vehicle in a wind tunnel environment similar to the one existing in the outdoor driving condition. In order to establish this correlation several test vehicles from Ford car and truck vehicle lines were tested on the track to obtain representative real world road data. The same vehicles were tested in the Ford Motor's full scale wind tunnels. In each case, the frontal velocity profiles were determined using the same instrumentation as in the case of outdoor environment. This reference road data was then used to correlate with the frontal profile obtained in the wind tunnels. Based on the correlation analysis, a mathematical relationship was developed to represent the blockage correction in each wind tunnel as a function of the car frontal area and the distance from the base of the windshield to the nozzle exit plane. These blockage factor relationships were then implemented in the wind tunnel test system control software to establish a wind speed that corresponds to the track speeds. Implementation of this technique allowed us to achieve in Ford Motor's wind tunnels an identical velocity profile to the real world flow condition. Finally, tests were conducted to verify the accuracy of the correlation procedure by comparing the velocity profiles for different vehicles at different locations in the test sections of the wind tunnel with that obtained on the track.

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