Artificial simulation of complex unsteady wind in an ABL wind tunnel with dual axial fans

The wind tunnel test plays an important role in studying the mechanism of aeolian sand transport. An atmospheric boundary layer (ABL) wind tunnel with dual axial flow fans to simulate unsteady wind is described in this paper. Air flow is generated using two fans arranged at each end of the wind tunnel. During the experiment, the rotation rates of the fans are changed by varying the frequency of the converters, which can be controlled by PLC. The speed of each fan varies according to a sinusoidal function. As a result of changing the parameters of the sinusoidal function, the two fans produce different forms of sinusoidal wind, and finally compose the controllable unsteady wind, which manifests as typical unsteady wind characteristics in the test section of the wind tunnel. The experimental results show that the wind speed profile of unsteady wind generated in the wind tunnel conforms to the logarithmic profile of the ABL. The proposed method is very useful for experimental research on the unsteady sand transport mechanism.