Spray characteristics of artificial aerosol clouds in a low-speed icing wind tunnel

This article investigates liquid water content (LWC) and its uniformity in supercooled aerosol clouds produced in a low-speed horizontal icing wind tunnel used for simulating atmospheric icing. The dependence of LWC obtained at mid-height of the tunnel test section on thermodynamic parameters of the air stream and on dynamic parameters applied to the nozzle system is determined empirically for two types of nozzles. The investigation reveals that LWC increases with air velocity, reaches a maximum at a low airspeed (below 30 m/s), and decreases as was observed at high airspeeds used for modeling aircraft icing (up to 160 m/s) only after passing this maximum. This complex behavior is explained by the concurrence of two processes: the vertical separation of droplets of different size due to the effect of gravity, and the vertical and transverse shrinkage of the aerosol cloud co-occurring with its streamwise expansion.