Air and vapour are one phase - gas. You then model the gas phase as a species mixture of air and vapour.
Second phase is then the liquid water.
Droplet size is more difficult if you're using the single size options. With 2021Rx and onwards I'd look at the wall film and DPM model rather than a full multiphase approach. For Mixture, I'd pick a single droplet size but then look at upwards velocity and see what should fall (look up turbulent Stokes Law).
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