Spray Rig Design for Airborne Icing Tankers

An experimental and numerical study was performed to design a spray system for existing icing tankers to produce both Appendix C and SLD icing clouds. The study assessed the characteristics of the spray clouds generated by air-atomizing nozzles in terms of the plume size, air and water flow rates, cloud intensity and droplet size distributions. Two commercially available nozzles, single-jet and multi-jet nozzles, which can produce both Appendix C and SLD icing conditions, were evaluated using an in-house developed spray control system. The system monitors the performance of the spray nozzle and documents the volume air and water flow rates of the nozzles for a range of air and water pressures. Droplet sizes were measured using a two-component Phase Doppler Particle Analyzer (PDPA). The effect of the air speed on the spray cloud were investigated in the 7-ft x 10-ft wind tunnel at Wichita State University. The spray cloud intensity and plume sizes at several axial locations from the nozzle in the wind tunnel were measured using a laser sheet illumination technique. The experimental measurements were used to validate a 3-D numerical spray model in the FLUENT software, which was used to simulate the Appendix C and SLD clouds generated by a multi-nozzle spray rig. The simulated results from a preliminary 6-nozzle spray rig design produced an Appendix C plume diameter of approximately 31 inches, and the diameter of the SLD plume was approximately 54 inches. The validated spray model is being used to optimize the nozzle spacing in a new spray rig design in order to increase plume diameter and to improve cloud intensity distribution.