An aerosol generator includes a housing, a heater and a mouthpiece wherein the heater volatilizes liquid material within a flow passage and forms an aerosol in the mouthpiece. Mixing ambient air with the vaporized liquid material controls a droplet size of the aerosol. The ambient air can be directed into the mouthpiece by at least one air passageway in an airflow entrainment control member. The at least one air passageway provides a desired volume and/or velocity of ambient air entering into the mouthpiece thereby achieving a desired droplet size distribution of an aerosol. In an alternative arrangement, a funnel shaped airflow entrainment control member includes a narrow end proximate the outlet end of the flow passage. A cone angle of the funnel-shaped member can be selected to provide a desired volume of ambient air which mixes with the vaporized liquid material and achieves a desired aerosol droplet size distribution.
