Natural (stack) ventilation augmented with air flow induction jets.

The inherent unreliability of the forces which drive natural ventilation can make such systems unattractive for the designer. Developing interest in mixed-mode ventilation is prompting difficulties in sourcing components suitable for ultra-low velocity flow generation in large ducts. This work examines the possibility of using air induction. A theoretical analysis generates equations which assist the designer in sizing a suitable inducer for ventilation purposes. Preliminary tests which verify the theory are described. Possible benefits include easier installation, use of widely available fans and low obstruction. Further work is needed to evaluate such benefits against the problems of low overall efficiency and potential noise nutsance.