Measurement of wall shear stress in wind-blown sand environment

As a key driving force of aeolian sand movement, wall shear stress is of importance in the study of aeolian sand movement. However, at present, the experimental measurement of the surface shear force in the wind-blown sand environment is extremely scarce, which has become a bottleneck for the further development of the wind-blown sand research. This paper introduces a method based on the hot-film technology for accurate measurement of the wall shear stress in the wind-blown sand environment. The wall shear stress was measured under conditions without sand using hot-film probes and two-dimensional hot-wire probes, respectively. The result shows that the hot-film probe has a good response to the wall shear stress, and the difference between the measurement results of the friction velocity of these two probes is less than 6.6%. The measurement results of the hot-film probe for the wall shear stress of flow around the square column are in good agreement with the OpenFOAM numerical simulation results, which further proves the effectiveness of the hot-film probe for the measurement of the wall shear stress. In addition, the particle impact test results of the hot film probes show that the influence of particle impact on the hot-film signal is negligible, so the hot-film probe can be used to effectively measure the wall shear stress in the wind-blown sand environment. Based on this technology, the spatial distribution characteristics of the wall shear stress along the flow direction in the wind-blown sand environment were tested. And for the first time, the spatial distribution of the wall shear stress in the wind-blown sand environment was obtained by means of actual measurement. In view of the high-frequency response capability of the hot-film probe, this technology will play an important role in the experimental research on the mechanism of aeolian sand movement in the turbulent boundary layer.