Wind Tunnel Experimental Simulation of Downburst Outflow Based on Wall Jet Model

In order to study the wind field characteristics of downburst wall jet section, the wind tunnel test of downburst wall jet section was carried out by modifying the traditional wind tunnel with fan and nozzle. By using characteristic length and characteristic velocity to deal with it dimensionless, the consistency and effectiveness of simulating the downburst section by using wall jet steady state wind tunnel test were verified according to the test results of different rough wall jet flows downstream. Consistency and validity; by increasing the roughness element to change the blocking ratio at the bottom of the wind tunnel and increase the disturbance of the incoming flow, the topography of various atmospheric boundary layers is simulated, and the effects of the surface roughness of the wall jet section on the horizontal and vertical profiles of the wall jet area, the maximum wind speed height and the wall flow field in downburst flow are studied. The experimental results show that the dimensionless treatment of wall jet with different roughness has certain self-similarity. With the increase of wall roughness, the turbulence near the wall increases significantly, the internal and external peaks of the turbulence profile increase significantly, and the velocity at the lower part of the wind profile decreases gradually, which has a significant impact on the characteristics of the near-wall wind field.