Design, construction and calibration of a portable boundary layer wind tunnel for field use
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Wind erosion is a natural process that has formed landscapes but threatens sustainable agriculture in many locations. Wind tunnels have been used for several decades to study wind erosion processes. Portable wind tunnels offer the advantage of testing natural surfaces in the field, but they must be carefully designed to ensure that a logarithmic boundary layer is formed and that wind erosion processes may develop without interference from the tunnel structures. Although large portable tunnels often meet the aerodynamic criteria, their size and transportation requirements often limit the locations where they may be employed. We designed and built a self-contained portable wind tunnel that is easily transported on a tandem-axle trailer and pulled with a pickup truck. The wind tunnel uses a centrifugal blower, a flow-conditioning section with optional abrader material feed, and a 1 m tall and 0.5 m wide working section that can vary in length from 2 m to 6 m. The maximum wind velocity attainable is 18.7 m s-1 although a mid-height centerline velocity of 12.6 m s-1 is normally used for field testing of natural surfaces. Based on measured wind velocity profiles in the tunnel working section, a conservative estimate of boundary layer depth within the working section is 0.5 m. Even though no wind tunnel can truly duplicate the scale and variability of the forces that drive wind erosion, tunnels such as this one with deeply developed boundary layers offer reasonable estimates of dust emissions and erodibilities of natural surfaces. This wind tunnel has been used to test rangeland and cropped surfaces in several locations and has provided reliable and useable soil erodibility and dust emission data.
American Society of Agricultural and Biological Engineers. Transactions
Copyright 2010 American Society of Agricultural and Biological Engineers (ASABE). The attached file is reproduced here in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Atmospheric Sciences not elsewhere classified
Land Capability and Soil Degradation