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Rainfall Simulation

Team Members Heading link

  • Aleksander Kowalkowski
  • Phil Mcdonough
  • Jesus Resendiz
  • Hoa Tran

Advisor: Dr. Michael Brown

Sponsor: Spraying Systems Co.

Project Description Heading link

Many devices are expected to operate under rainfall conditions for extended periods of time without suffering significant loss in functionality. Waiting for such conditions to arise naturally is impractical for the purpose of product testing, which imposes the need for a system that can artificially replicate these environmental effects. This paper provides a fresh examination of the issue, with a particular focus on the production of large droplets. Guided by a review of documented literature on the subject of rain simulation, as well as conversations with engineers from Spraying Systems Co., a selection of current and novel solutions were chosen for further testing. By making use of high-speed cameras and imaging software, the resulting droplet size from each concept was measured and compared based on various industry standard metrics. With an aim of generating droplets on the order of 4000 μm or above, it is clear that common solutions involving full-cone nozzles (such as those manufactured by Spraying Systems, and used in many rain simulators) are not ideal for the task. These methods involve a stream of fluid which atomizes as it passes through the nozzle; however, it is the determination of this report that larger droplet size is achievable if fluid leaves the nozzle in a solid stream and becomes atomized at some point afterward. This can be accomplished by means of a deflection surface oriented normal to the nozzle, against which the fluid stream can break up. Droplet size also is affected by the position, diameter, and texture of this deflection surface, and the specific effects of changing these parameters are explored. While a standard full-cone nozzle was capable of producing droplets with a diameter of 2285 μm (Dv0.9), this diameter increases to 4387 μm when using a stationary deflection surface method with the optimal parameters.

See supporting documentation in the team’s Box drive.