Methodology for Icing Tanker Spray Rig Design and Evaluation

A methodology for developing spray rigs for icing cloud simulation is presented. This methodology includes Computational Fluid Dynamics (CFD) analysis and icing tunnel experiments and was applied to design a spray rig system for a small airborne icing tanker. An in-house spray system was developed and tested in a laboratory to assess two commercially available nozzles - a single-jet type and a multi-jet type - which were capable of producing both FAR Part 25 Appendix C and SLD icing clouds. Spray rig characteristics evaluated during the laboratory tests included air and water flow rates as well as droplet size and distributions. The effects of airspeed and nozzle spacing on spray plume size and uniformity were investigated in a small icing tunnel facility with a two-nozzle spray rig. The experimental data were compared with three-dimensional numerical simulation results obtained with the FLUENT software. Good qualitative agreement between experimental and computational plume sizes was demonstrated. The CFD model was next applied to support the design of a six- and a seven-nozzle spray rig. Computed plume sizes for the two spray rig configurations are presented.