Study On Design And Aerodynamic Performance Of Movable Wind Erosion Tunnel

Based on the review and analysis of wind erosion and wind erosion tunnel researches over the world, the paper expounded the necessity for developing the movable wind erosion tunnels, and put forward some aerodynamic criteria and design conditions for designing the wind erosion tunnels through analyzing the requirements of the similarities for the atmospheric boundary simulation and the function requirements of experiments for the functions of the wind tunnels. According to the criteria and the conditions posed by the study, a portable wind erosion tunnel was designed and a complete set of its accessory measurement system was formed, and lastly the study took the performance validation and evaluations for the integer wind erosion tunnel and the functional components. The total length of the portable wind erosion tunnel developed is about 11.8m, and the length of the working section composed of three subsections is about 7.2m; the cross section the of the working section is 1.0m wide and 1.2m high; the contraction section is 1.2m long and the contraction ratio is 1.70; the settling chamber is 0.41m long and the cross section is 1.16m wide and 1.76m high, a stainless steel hexagon honeycomb and a 18 mesh stainless steel screen embedded inside the settling chamber; The wind is produced by a BK-57 model axial fan which is driven by the 40KW generator unit modeled with 40GF. The measurement apparatus collocated includes pressure and velocity measuring systems composed of Pitot tubes, deferential pressure transducers ,AD modulus and a computer , wind profiler and cyclone type sand collector. The auxiliary functional equipment includes a sand feeder and a artificial equipment for simulating the near surface atmospheric boundary layer and for adjusting the wind profile. The wind speed can be adjusted smoothly by a frequency actiyator within the speed range of 0～20m/s. The assembly and disassembly of the tunnel components are easy to perform. It realized the functions of moving and transporting while using in the fields. By the test run and the maneuverability test, the collectivity mechanical properties meet with the design requirements and each functional component realizes the scheduled functions. By the performance testing, each aerodynamic guideline accords with the design requirements; the artificial adjusting equipment of atmospheric boundary layer can realize the functions of thickening the boundary layer and adjusting the tunnel wind profile. The sand feeder developed can make the movable wind erosion tunnel simulate the wind with different extent of entrapped blown sand. The collecting efficiency of the sand sampler composed of multiple cyclone deduster for those particles with diameters being lager than 0.076mm can reach above 97%. The study provides a research tool, which has the functions of simulating the near surface atmospheric boundary layer and adjusting the wind profile, and can be used for wind erosion studies both in fields and in laboratory. The study established a theoretical base for the design of movable wind erosion tunnels.