The PI-SWERL, which stands for Portable In-Situ Wind ERosion Lab, has been in development at DRI since 2000. The PI-SWERL concept was motivated by the need for a portable device to test and measure the potential for wind erosion and dust emissions from real-world surfaces. Traditional wind tunnels used for this purpose required long setup times and in some cases a crew of several people to operate. The goal in developing the PI-SWERL was to provide a turn-key device that was easy to move, required minimal setup, and could be operated by one person. A prototype developed in 2000 and tested alongside the University of Guelph large, field wind tunnel provided early indication of the feasibility of the PI-SWERL concept. Since then several models have been used in numerous field investigations. The latest miniature version (MPS-2a) has been a workhorse instrument for DRI since 2005 and its design has remained essentially constant. In 2007, DRI licensed the PI-SWERL technology to Dust-Quant LLC to make it commercially available to users worldwide.
The PI-SWERL is contained in an open-bottomed, cylindrical chamber operated by a direct-current motor that spins a metal, annular ring about 2.5 in. above and parallel to the soil surface. Principles of fluid mechanics allow simulation of high winds that produce dust storms. The spinning ring creates known wind shear, lofting soil and dust particles and passing them through particulate monitors. The PI-SWERL electronically measures the number and size of entrained particles over the duration of a test cycle, typically under 10 minutes. By controlling the speed of the ring to simulate varying wind speeds, the potential for a soil surface to produce PM10 dust emissions can be determined under a range of simulated wind conditions.