Velocity of Simulated Raindrops in a Wind Tunnel Measured by Different Technologies

摘要

The wind tunnel rainfall simulator at the International Center for Eremology (ICE) in Ghent, Belgium, has been intensively used for erosion studies. Described by Gabriels et al. (1997), the tunnel is 12 meters long and 1.2 meters wide. The rain is generated by 8 spray nozzles (Teejet TG SS 14) spaced one meter from each other, attached to its ceiling at 1.85 meters height. The wind is generated by an axial fan propelled by a 200 HP electric motor.This research is part of a large group of tests carried out to evaluate the velocity of raindrops. Results presented are restricted to the position located at 1.25 meters below the nozzles. Two different types of equipment were used to measure raindrop velocity: the UFLA DRGS (Dynamic Rain Gage System) and the PARSIVEL II laser disdrometer that was set either perpendicular (PP) or longitudinal to wind direction (PL). The water pressure at the nozzles was set to 1.5 bars to generate the simulated rainfall described in this research. The tests were carried out with a 6.4 m/s wind speed and also with no wind conditions. The measurement instruments were both installed under the fourth nozzle and also in-between the fourth and fifth nozzles. Treatments werereplicated three times, and statistical evaluations included analysis of variance (ANOVA) with a 5% significance level.