"Humidity Optimisation Tool:Outside humidity treatment is a main contributor to aircraft ECS (environmental control system) power requirements. To reduce this power it is needed to know exactly the not to exceed outlet humidity at the pack outlet. Liquid water at Low Pressure ducting participates to cabin cooling but, if this quantity is too high, a fog can be seen.The purpose of the “Humidity Optimization Tool” project is to develop a tool able to predict generation and growth of water fogs in the ECS, in order to avoid them. The project can be separated into three sub-topics:1) Determination by tests of a visibility fog criteria based on physical properties (air speed, liquid water content, blowing temperature, droplet size, etc.)2) Development of a 0D tool to predict the size of the water droplets (liquid or ice) downstream a: (i) Heat exchanger, (ii) Pack outlet turbine and (iii) Mixmanifold3) Validation of this toolThe proper implementation of this research requires two-phase flow expertise in two different fields: (i) numerical modelling and (ii) measurement techniques."