Our team designed, built, and tested a fan/duct assembly (Figures 1 and 2), to investigate general airflow properties, only to inadvertently discover that HVAC ducts designed in the last 60 years in the U.S. have a significant design error. Now we need answers and more investigation.
Our fan/duct assembly is schematically illustrated in Figure 3. By adjusting dampers, it can operate in three ways: as a continuously, closed, recirculating air system; as an open, positive pressure supply system discharging to atmosphere; or as an open, negative pressure exhaust system also discharging to atmosphere.