Design & Construction of a Portable Wind Tunnel for Soil Erosion Research




A portable wind tunnel has been designed and constructed by senior geological engineering students enrolled in the capstone course 'Geological Engineering Design II' at South Dakota School of Mines and Technology, Rapid City, SD.  The project involved research, design, analysis and implementation phases under the constraints of a budget.  The experience offered students a first-hand view of an actual design process where critical design decisions were required at various stages of the project.  The result was a research quality field wind tunnel that will be used to research wind erosion of soil and sediment from numerous landuse categories across western South Dakota.  The tunnel has an overall length of 8.5 m with a working section 4.5 m long, 0.5 m high and 0.5 m wide.  Power was supplied using a 6.5 kW generator driving a 0.62 m axial fan.  An in-line power inverter allowed a variable current to be supplied to the fan thereby controlling wind speed.  A diffuser was used at the downstream edge of the working section to recover pressure losses.  Aerodynamic stability was achieved using a 2:1 expansion of the flow immediately downstream of the fan and passing it through a perforated plate and a plastic honeycomb at low velocity.  A subsequent 4:1 constriction increased velocity to the working section where it passed over the natural surface.  The tunnel was constructed of composite aluminum-honeycomb fiberglass panels that were cut to size and fiberglassed together yielding a total weight of less than 50 kg.  The tunnel consisted of 6 sections that were each 1.5 m long which were connected in the field using an external frame and latch system.  The tunnel was transported and moved in the field using a 1.5 x 3.0m trailer and a 1.0m crane.



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