Passive Simulation Of The Atmospheric Boundary Layer In Wind Tunnel

The proper simulation is necessary to the reliability of structural wind tunnel test results. The Joint Laboratory wind tunnel and wave flume of HIT has been completed, simulation of atmospheric boundary layer in the wind tunnel is necessary.The methods of atmospheric boundary layer simulation contain active simulation and passive simulation. The active simulation mainly include multiple fans wind tunnel technology and vibratile spire technology. The equipments of the passive simulation main include spire, roughness element, apron and gridiron. The passive simulation technology is simple and economical, so it has been widely used.In this dissertation, the passive simulation method with spires and roughness elements is used for the boundary layer simulation, some general rules of arrangement are summarized, and the four terrains in Chinese Load Standard are finally reached. The main work are as follows:1. Some normal approaches of atmospheric boundary layer simulation were summarized. Advantages and shortcomings of active and passive simulation methods were concluded, which can guide the usage of each.2. The spires and rough elements were designed and fabricated, the usage in the wind tunnel was also described. Furthermore, the detailed measurement plan and data processing methods were introduced.3. The effect of several parameters on the results of boundary layer simulation was investigated, which include the shape and location of spires, size of the roughness elements, and the arrangement of the roughness elements.Some qualitative conclusions were reached and some important parameters for the adjust of wind speed and turbulence profile were determined. That is, the shape of spires plays a leading role for the simulation of speed profile, the spacing of spires would significantly affect the turbulence in whole height, sphere of influence of roughness element is 5 times the height. To set large roughness elements close to the spires similar to change the local shape of spire, which can increase turbulence at the bottom of wind tunnel.There has direct relation between the effect of change and number of rows of large roughness elements, which can be used for easy adjust. The more rows, the smaller of the relative wind speed at the bottom , the greater the turbulence. All these empirical results can provide reference for further simulation and adjustment.4. Finally, the database of boundary layer simulation results for small test section of The Jonit Laboratory of Wind Tunnel and Wave Flume in Harbin Institute of Technology was developed, which can be used for easy inquiring and modification.